paper 1 Flashcards
1
Q
what are the 3 states of matter
A
solid, liquid, gas
2
Q
arrangement of a solid
A
has least energy – particles are not moving/are just vibrating and they are arranged regularly and very closely together and all touching
3
Q
arrangement of a liquid
A
particles have more energy than those in a solid, but less than those in a gas and the particles are closer together but have a random arrangement
4
Q
arrangement of a gas
A
particles have the most energy – as the particles are the most spread apart with a random arrangement
5
Q
what is melting
A
solid -> liquid
increase in particle energy
6
Q
what is boiling
A
liquid -> gas
increase in particle energy
7
Q
what is freezing
A
liquid -> solid
decrease in particle energy
8
Q
what is evaporation
A
liquid -> gas (at surface)
increase in energy
9
Q
what is condensation
A
gas -> liquid
decrease in energy
10
Q
what is sublimation
A
solid -> gas
increase in energy
11
Q
what is deposition
A
gas -> solid
decrease in energy
12
Q
how does melting occur
A
The process requires heat energy which transforms into kinetic energy, allowing the particles to move.
It occurs at a specific temperature known as the melting point which is unique to each pure solid
13
Q
how does boiling occur
A
This requires heat which causes bubbles of gas to form below the surface of a liquid, allowing for liquid particles to escape from the surface and from within the liquid
It occurs at a specific temperature known as the boiling point which is unique to each pure liquid
14
Q
how does freezing occur
A
This is the reverse of melting and occurs at exactly the same temperature as melting, hence the melting point and freezing point of a pure substance are the same
It requires a significant decrease in temperature (or loss of thermal energy) and occurs at a specific temperature which is unique for each pure substance
15
Q
how does evaporation occur
A
Evaporation occurs only at the surface of liquids where high energy particles can escape from the liquid’s surface at low temperatures, below the boiling point of the liquid
The larger the surface area and the warmer the liquid/surface, the more quickly a liquid can evaporate
Evaporation occurs over a range of temperatures, but heating will speed up the process as particles need energy to escape from the surface
16
Q
how does condensation occur
A
When a gas is cooled its particles lose energy and when they bump into each other, they lack energy to bounce away again, instead grouping together to form a liquid
17
Q
what is diffusion
A
The random movement of particles from a high to low concentration
18
Q
why does diffusion occur slower in a liquid than a gas
A
Diffusion in liquids is slower than in gases because the particles in a liquid are closely packed together and move more slowly
19
Q
why does the colour get paler when a solution is diluted
A
when you add water the evenly spaced particles become much more spread out making the colour paler
20
Q
solvent
A
the liquid in which something is dissolved in
eg the water in sea water
21
Q
solute
A
the substance which is dissolved in something to form a solution
eg salt in sea water
22
Q
solution
A
the mixture of solvent and dissolved solute
eg sea water
23
Q
saturated solution
A
a solution with the maximum concentration of solute dissolved in the solvent
24
Q
soluble
A
something that will dissolve in a specific liquid
eg salt is soluble in water
25
insoluble
something that will not dissolve in a specific liquid
eg sand in water
26
whats an element
a substance made up of the same atoms
eg a beaker containing all carbon
27
whats a compound
a substance made up of 2 or more elements chemically joined
eg a beaker containing water (H2O)
28
what a mixture
a substance made up of 2 or more elements not chemically bonded
eg a beaker containing O2 and N2 but they aren't joined to each other
29
why does a pure substance have a fixed melting point
there is only 1 type of thing in it so it will all have the same melting point
eg water boils at 100c
30
how to distinguish between a pure substance and a mixture
slowly heat the substance up as a pure substance will boil at one temperature whereas the mixture will boil of a range of temperatures
31
what does simple distillation separate
a liquid and soluble solid from a solution (e.g., water from a solution of salt water) or a pure liquid from a mixture of liquids
32
simple distillation method
1. heat the solution
2. the thing with the lower boiling point will evaporate first leaving the other substance
eg in a water and ethonal mixture, the ethanol would evaporate first leaving the water
3. if you want to keep both substances use a simple distillation set up (a delivery tube surrounded with cold water, to recondense the evaporated substance, leading into a beaker)
33
what does fractional distillation separate
This is used to separate two or more liquids that have different boiling points which are mixed together
34
fractional distillation method
1. heat the solution
2. the thing with the lower boiling point will evaporate first leaving the other substances
eg in a water, ethanol and methanol mixture, the methanol would evaporate first leaving the ethanol and water
3. if you want to keep all substances use a simple distillation set up (a delivery tube surrounded with cold water, to recondense the evaporated substance, leading into a beaker)
35
what does filterisation seperate
an undissolved solid from a mixture of the solid and a liquid / solution (eg sand from a mixture of sand and water)
36
filtration method
1. place a piece of filter paper in a funnel
2. place the funnel above a beaker
3. pour the substance through the funnel
the liquid will be in the beaker and the solid will be left in the filter paper
37
what does crystallisation separate
a dissolved solid from a solution, when the solid is much more soluble in hot solvent than in cold solvent
38
crystallisation method
1. heat the solution until its fully saturated (test by dipping clean, dry cold glass rod in and crystals will form on it)
2. once saturated remove from heat to allow cooling
3. filter
39
what is a atom
a single particle of an element
eg one carbon
40
what is a molecule
2 or more atoms chemically joined together to form
41
where is a proton found
in the nucleus
42
where is a neutron found
in the nucleus
43
where is an electron found
orbiting the nucleus in shells
44
relative mass of a proton
1
45
relative mass of a neutron
1
46
relative mass of a electron
1/1840
0.00054
47
charge of a proton
1+
48
charge of a neutron
0
49
charge of an electron
-1
50
what is the atomic number
number of protons an atom has
eg the atomic number of carbon is 6
51
what is the mass number
the sum of the number of protons and neutrons in an atom
eg carbons mass is 12
52
what is an isotope
an atom with the same number of protons and electrons but a different number of neutrons
53
what is the RAM (relative atomic mass or Ar)
the weighted average mass of an atom of an element, compared to 1/12th the mass of a carbon 12 atom
54
how to find the number of electrons in an element
same as the atomic number
55
how to find the number of neutrons in an element
mass number - the atomic number
56
how to calculate RAM (Ar) from isotope abundance
( % of isotope A x mass of isotope A ) + ( % of isotope B x mass of isotope B ) / 100
57
how are the elements arranged in the periodic table
in the order of atomic number
in groups and periods
58
what does a group tell you
the number of electrons in the outer shell of the elements
59
what does a period tell you
how many electron shells an element has
60
what is the number of outer shell electrons in a metal
1 or 2 or 3
61
what is the number of outer shell electrons in a non-metal
5 or 6 or 7 or 8
62
how to tell a metal or non-metal based on electrical conductivity
metals are good electrical conductors
non-metals are poor electrical conductors
63
what forms when metals react with water
metal oxide + hydrogen
metal oxide is a base
64
what forms when nonmetals react with water
an acid
65
how to split the periodic table into metals and nonmetals
zigzag line going down right between boron and aluminium
66
why do elements in the same group react in the same way
they all have the same number of electrons in the outer shell ad it is the outer shell of electrons that react
67
why don't the noble gasses react
atoms with a full outer shell are stable
they have a full outer shell of electrons so they don't need to react to achieve a full outer shell
68
what is a mole
a unit for a substance
69
what is the difference between the relative formula mass (Mr) and relative atomic mass (Ar)
the Mr is the mass of the a whole molecule whereas the Ar is the mass of an atom
70
how to calculate the Mr of a molecule from the Ar's of the atoms in the molecule
add up the masses of each of the atoms
the big numbers do not apply
small numbers apply only to the element that they are behind
everything in a bracket is multiplied by the small number outside the bracket
for water (h2O)
H= 1 x 2 = 2 (1 is the mass of hydrogen and times by 2 because there is 2 hydrogen's in water)
0= 16 x 1 = 16
2+16 = 18
71
1 mol =
6.022 x 10 ^23 atoms / molecules
72
mass, moles and Ar/Mr formula
moles = mass / Ar or Mr
73
how to calculate reacting masses
1. balance the symbol equation if not alr
2. calculate the moles from mass given
3. work out the ratio of substances (using the
large numbers)
4. convert moles to mass
74
how to calculate percentage yield
actual yield / theoretical yield x 100
75
how to experimentally find the formula for metal oxides
1. measure mass of crucible and lid
2. measure a mass of the metal and add
into the crucible
3. heat strongly and lift the occasionally
4. every 5 minutes remove from heat and
reweigh
5. once mass stops increasing stop heating
6. calculate metal oxide weight by:
final mass - mass of crucible and lid
to find the formula:
1. work out the mass of the metal and the
oxygen individually
2. work out the moles of the metal and the
oxygen individually
3. divide both moles by the smallest mole
76
how to experimentally find the formula for water / hydrated salts
(water of crystallisation)
1. measure mass of evaporating basin
2. measure a mass of hydrated salt and add
into the evaporating basin
3. heat strongly until the salt turns completely
white
4. reweigh the crucible and white salt
5. calculate anhydrous salt weight by:
the basins mass and white salt - just the
basin
6. calculate the mass of water lost by:
hydrated salt mass - unhydrated salt mass
to find the formula:
1. find mass of the water and the mass of the
unhydrated salt
2. work out the Mr of the salt and water
individually
3. work out the moles of the salt and the
water individually
4. divide both moles by the smallest mole
77
what is the molecular formula
shows the number and type of each atom in a molecule
78
what is the empirical formula
simplest whole number ratio of the atoms of each element of a compound
79
how to calculate the empirical formula
1. work out the moles of each atom in the
molecule
2. divide both sets of moles by the smallest
mole
3. if the answer contains a 0.5 then times all
by 2
80
how to determine the formula of a metal oxide by combustion
1. measure mass of crucible and lid
2. measure a mass of the metal and add
into the crucible
3. heat strongly and lift the lid occasionally
4. every 5 minutes remove from heat and
reweigh
5. once mass stops increasing stop heating
6. calculate metal oxide weight by:
final mass - mass of crucible and lid
then calculate the empirical formula
81
how to determine the formula of a metal
oxide by reduction
1. Measure mass of the empty boiling tube
2. Place metal oxide into a horizontal boiling tube and measure the mass again
3. Support the tube in a horizontal position held by a clamp
4. A steady stream of natural gas(methane) is passed over the copper(II)oxide and the excess gas is burned off (methane takes up all space in test tube preventing oxygen entering and reactive with copper again and its burnt to show that the stream is still present)
5. The copper(II)oxide is heated strongly using a Bunsen burner
6. Heat until metal oxide completely changes colour, meaning that all the oxygen has been removed
7. Measure mass of the tube with remaining metal powder and subtract the mass of the tube to work out mass of metal
for copper oxide turns green -> black
to work out empirical formula:
1. work out mass of oxygen by
mass of metal oxide - metal
2. then work out empirical formula
82
how are ions formed
by the loss or gain of electrons
83
what is the charge of a metal ion in group 1
1+
84
what is the charge of a metal ion in group 2
2+
85
what is the charge of a metal ion in group 3
3+
86
what is the charge of a nonmetal ion in group 5
3-
87
what is the charge of a nonmetal ion in group 6
2-
88
what is the charge of a nonmetal ion in group 7
1-
89
what is the charge of a Ag ion
1+
90
what is the charge of a Cu(II) ion
2+
91
what is the charge of a Fe(II) ion
2+
92
what is the charge of a Fe(III) ion
3+
93
what is the charge of a Pb ion
2+
94
what is the charge of a Zn ion
2+
95
what is the charge of a hydrogen ion
1+
96
what is the charge of a hydroxide (OH) ion
-1
97
what is the charge of a ammonium (NH4) ion
1+
98
what is the charge of a carbonate (CO3) ion
2-
99
what is the charge of a nitrate (NO3) ion
1-
100
what is the charge of a sulfate (SO4) ion
2-
101
what is an ion
atoms which do not have an equal number of protons and electrons
102
how to write formulas for ions which bond to form compounds
charges must cancel out to equal 0 as compounds are uncharged
so Li (1+) and O (2-) create Li2O
103
ionic bonding definition
the electrostatic force of attraction between 2 oppositely charged ions
104
why do compounds with giant ionic lattices have high melting and boiling points
lots of strong ionic bonds which require tons of energy to break
105
when do ionic compounds conduct electricity
in an aqueous solution or when molten as the ions have more energy and are able to move
not as a solid as there are no free ions to move
106
how is a covalent bond formed
nonmetal atoms sharing pairs of electrons
107
covalent bond definition
the electrostatic force of attraction between the nuclei and a shared pair of electrons
108
why are substances with simple molecular formulas liquids or gases or solids with low boiling points
the covalent forces between atoms are strong but the inter-molecular forces connecting each molecule are weak
the weak inter-molecular forces are easy to overcome (require a low temperature to break) meaning at room temperature the bonds are broken and therefore are liquids or gases or solids with a low boiling points
109
why do giant covalent structures have a higher melting point then simple molecular ones
to melt giant covalent bonds you must break the strong covalent bonds whereas melting a simple molecular structure only requires overcoming the weak intermolecular forces
110
why does the melting points of simple molecular structures increase as the relative molecular mass increases
the increase in mass means there will also be more electrons and therefore there are more intermolecular forces of attraction that need to be overcome which increases the melting point
111
why do giant covalent structures have a high melting point
As lots of covalent bonds are present in the compound and not many weak intermolecular bonds (which are easy to overcome and require low heat)
the covalent bonds are very hard to break so requires lots of energy to break them
112
do covalent compounds conduct electricity
no as there are no free electrons to move
113
how does the structure of diamond influence its physical properties including electrical conductivity and hardness
giant covalent structure
very hard as in order to break you have to break the strong covalent bonds
does not conduct electricity because there are no free electrons or ions
high melting and boiling point
each carbon is bonded to 4 others
114
what is the strength of the attraction in a metallic bond determined by
the charge of the metal ions and by how many electrons there are
115
how does the structure of graphite influence its physical properties including electrical conductivity and hardness
giant covalent structure
arranged in layers where there are weak intermolecular forces in between the layers however there are layers themselves are bonded covalently which means the layers can slide over each other
high melting and boiling point
soft and slippery
can conduct as it has declocalized electrons
used as a lubricant
116
how does the structure of bucminster fullerene influence its physical properties including electrical conductivity and hardness
simple molecular structure
low melting and boiling points as it has weak intermolecular forces so easy to overcome
it is also soft for the same reason
it can conduct as there are delocalised electrons -> each carbon is only bonded to 3 others
used as a lubricant or a drug delivery system -> non reactive/toxic
117
chromatography method
Use a ruler to draw a horizontal pencil line (as a pens ink would run into the other samples) 2 cm from the end of the chromatography paper
Use a different capillary tube to put a tiny spot of each colouring A, B, C and D on the line
Use the fifth tube to put a small spot of the unknown mixture U on the line
Make sure each spot is no more than 2-3 mm in diameter and label each spot in pencil
Pour water into the beaker to a depth of no more than 1 cm (to avoid the samples washing into the solvent container) and clip the top of the chromatography paper to the wooden spill. The top end is the furthest from the spots
Carefully rest the wooden spill on the top edge of the beaker. The bottom edge of the paper should dip into the solvent
Allow the solvent to travel undisturbed at least three quarters of the way up the paper
Remove the paper and draw another pencil line on the dry part of the paper as close to the wet edge as possible. This is called the solvent front line
Measure the distance in mm between the two pencil lines. This is the distance travelled by the water solvent
For each of food colour A, B, C and D measure the distance in mm from the start line to the middle of the spot
calculate the Rf values for each one. Compare the Rf values from the known samples to the unknown dye to see what it is composed of
118
how to calculate Rf value
Rf = distance travelled by substance / distance traveled by solvent
These values are used to identify the components of mixtures
The Rf value of a particular compound is always the same but it is dependent, however, on the solvent used
If the solvent is changed then the value changes
Calculating the Rf value allows chemists to identify unknown substances because it can be compared with Rf values of known substances under the same conditions
These values are known as reference values
The Rf value will always lie between 0 and 1; the closer it is to 1, the more soluble is that component in the solvent
119
what does a chromatogram do
This technique is used to separate substances that have different solubilities in a given solvent (e.g., different coloured inks that have been mixed to make black ink)
An impure substance will show up with more than one spot, a pure substance should only show up with one spot
120
what happens when lithium reacts with water
relatively slow reaction
lithium doesn't melt
effervescence can be observed
floats on the top of the water and slowly moves around
121
what happens when sodium reacts with water
sodium melts into a ball as large amounts of heat energy is released
hydrogen released causes the Na to dash around the surface of water
effervescence
122
what happens when potassium reacts with water
creates a lilac flame
melts into a shiny ball which dashes across the surface of the water
123
trends in the group one / alkali metals
increase in reactivity as we go down the group because the number of electron shells increase
all soft and easy to cut and get softer as we move down the group
low melting points which decrease as we go down the group
124
how do the alkali metals react with oxygen
when the alkali metals react with oxygen they form metal oxides
this causes a dull coating on the metals
this happens quicker as we go down the group
alkali metal + oxygen -> metal oxide
125
how do the alkali metals react with water
reactivity increases as you go down the group
general reaction formula:
alkali metal + water -> metal hydroxide + hydrogen
The hydroxides formed all have the same general formula and are colourless, aqueous solutions
126
predicting properties in group 1
reactivity increases as we go down the group
melting point decreases as we go down the group
get softer as we go down the group
the density increases as we go down the group
127
colour and physical state (at room temp) of fluorine
yellow gas
128
colour and physical state (at room temp) of chlorine
pale yellow/green gas
129
colour and physical state (at room temp) of bromine
red/brown liquid
130
colour and physical state (at room temp) of iodine
grey solid
131
colour and physical state (at room temp) of astatine
black solid
132
trend in properties of the halogens
melting and boiling points increase as you go down the group because the atoms become larger and therefore the intermolecular forces get stronger
the colours of the halogens get darker in colour as you go down the group
halogens decrease in reactivity as you go down the group
the rate of reaction is slower as you go down the group
133
what is a metal halide
when a halogen reacts with a metal they form ionic compounds which are metal halide salts
134
what is a halide
a halogen ion
135
what is a displacement reaction
where a more reactive halogon is added to a salt (another halogen thats reacted to a metal) and the more reactive halogen displaces the less reactive halogen from the salt
Cl2(aq) + 2KI(aq) → 2KCl(aq) + I2(aq)
here chlorine displaces iodine showing how chlorine is more reactive
136
what % of nitrogen is there in the air
78%
137
what % of oxygen is there in the air
21%
138
what % of argon is there in the air
0.9%
139
what % of CO2 is there in the air
0.04%
140
how to determine the percentage by volume of oxygen in air using experiments involving the reactions of metals (e.g. iron) with air
1. place an excess of wet iron filings into a conical flask (100cm3) full of air
2. place a bung on the top of the conical flask connected to a syringe
over time the iron will rust (react with oxygen) until all of the oxygen is used up. this will move the syringe reading from 100 to 79ish showing oxygen makes up 21% of the air
141
how to determine the percentage by volume of oxygen in air using experiments involving the reactions of non-metals (e.g. phosphorus) with air
1. place a small amount of phosphorus onto a evaporating dish in a bell jar which is sitting in a trough of water
2. set the phosphorus on fire
As the phosphorus burns it uses up the oxygen inside the bell jar and the water level rises
By making careful measurements of water levels before and after the experiment you can determine the percentage of oxygen in the air
142
combustion of magnesium in oxygen
intense white flame
white powder produced
143
combustion of hydrogen in oxygen
exothermic
water is produced
144
combustion of sulpher in oxygen
blue flame
colourless, poisonous gas produced
145
what is thermal decomposition
a reaction where a substance breaks down due to the action of heat
146
what is the formation of carbon dioxide from the thermal decomposition of metal carbonates
metal carbonate → metal oxide + carbon dioxide
147
what is the happens when copper(II) carbonate is thermally decomposed
copper(II) carbonate → copper(II) oxide + carbon dioxide
green -> black
148
what happens if we increase the amount of CO2 in the atmosphere
contribute to the enhanced greenhouse effect and climate change
149
what type of gas is CO2
a greenhouse gas
150
practical: determine the approximate percentage by volume of oxygen in air using a metal or a non-metal
1. place an excess of wet iron filings into a conical flask (100cm3) full of air
2. place a bung on the top of the conical flask connected to a syringe
over time the iron will rust (react with oxygen) until all of the oxygen is used up. this will move the syringe reading from 100 to 79ish showing oxygen makes up 21% of the air
151
what is the order of the reactivity series
potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, lead, hydrogen, copper, silver, gold
152
how can metals be arranged into a reactivity series based on their reaction with water
whichever reacts most violently with water is the most reactive
for example potassium is the most reactive with water because it is the top of the reactivity series
153
how can metals be arranged into a reactivity series based on their reaction with dilute acids
whichever reacts most violently with dilute acid is the most reactive
for example potassium is the most reactive with dilute acid because it is the top of the reactivity series
only elements more reactive than copper will react with acid as copper silver gold are less reactive than hydrogen so can't displace it
metal + acid ⟶ salt + hydrogen
154
how can metals be arranged in a reactivity series based on their displacement reactions between metal and metal oxides
a more reactive metal will displace a less reactive metal from a compound
to do this in metal oxides you can heat it
for example more reactive zinc will displace less reactive copper
zinc + copper(II) oxide → zinc oxide + copper
we can repeat this reaction with different metals to determine which is more / less reactive
so potassium will displace everything as it as the most reactive metal
155
how does displacement work with the reactivity series
a more reactive metal will displace a less reactive metal from a compound
156
how can metals be arranged in a reactivity series based on their displacement reactions between metal and aqueous solutions of metal salts
a more reactive metal will displace a less reactive metal from a compound so
This is easily seen as the more reactive metal slowly disappears from the solution, displacing the less reactive metal
For example, magnesium is a reactive metal and can displace copper from copper(II)sulfate solution:
Mg + CuSO4→ MgSO4 + Cu
The blue colour of the CuSO4 solution fades as colourless magnesium sulfate solution is formed
Copper coats the surface of the magnesium and also forms solid metal which falls to the bottom of the beaker
157
what conditions does iron need to rust
water and oxygen
158
what is rust
hydrated iron (III) oxide
159
how to stop iron rusting
barrier methods
galvanising
160
what is the barrier method to stop iron rusting
the barrier such as paint or oil stop the oxygen reaching the iron and therefore stopping rusting
161
what is galvanising to stop iron rusting
by coating the iron in a more reactive metal (such as zinc) means that more reactive metal will react with oxygen and water instead of iron stopping it from rusting
If the coating is damaged or scratched, the iron is still protected from rusting because more reactive preferentially corrodes as it is higher up the reactivity series than iron
The iron stays protected as it accepts the electrons released by more reactive metal, remaining in the reduced state and thus it does not undergo oxidation
162
what is OILRIG
oxidation is loss of electrons
reduction is gain of electrons
163
what is oxidation
Oxidation is any reaction in which a substance gains oxygen
oxidation is loss of electrons
164
what is reduction
Reduction is a reaction in which a substance loses oxygen
reduction is gain of electrons
165
what is a redox reaction
a reaction where reduction and oxidation happen (loss and gain of electrons)
Oxidation cannot occur without reduction happening simultaneously, hence these are called redox reactions
166
what is a oxidising agent
oxidises other reactants
so it is the thing that is being reduced as it will take the electrons from the thing being oxidised allowing oxidation to happen
the thing that is reduced is the oxidising agent
167
what is a reducing agent
makes reduction happen
so it is the thing that is being oxidised as it will gain the electrons from the thing being reduced allowing reduction to happen
the thing that is oxidated is the reducing agent
168
practical: investigate reactions between dilute hydrochloric and sulfuric acids and metals
1. place 3 test tubes in a rack
2. Using a small measuring cylinder, add 5 cm3 of dilute hydrochloric acid to each of three test tubes
3. Add about 1 cm length of magnesium ribbon to the first tube, observe and note down what you see
4. Use a lit splint to test for any gases given off
5. To the second test tube add a few pieces of iron filings and to the third some zinc turnings
6. Observe what happens, test for any gases and note down your observations
7.Repeat the experiment with dilute sulfuric acid
The metals can be ranked in reactivity order Mg > Zn > Fe
169
test for hydrogen
place a lit splint into hydrogen and you will hear a squeaky pop
170
test for oxygen
place a glowing splint into oxygen and it will relight
171
test for carbon dioxide
bubble through limewater and it will turn cloudy
172
test for chlorine
place a damp blue litmus paper into chlorine and it will bleach (turn white)
173
test for Cl-, Br-, I-
silver nitrate solution
dissolve the sample (which you are testing for the anion) in water
add nitric acid (prevents false positives)
add silver nitrate solution
if Cl, Br, I are present then a precipitate will form
Cl - white precipitate
Br - cream precipitate
I - yellow precipitate
174
test for carbonates
hydrochloric acid
add the solution into a test tube with a delivery tube connected to another test tube
add hydrochloric acid to the solution
if the solution effervesces then the gas produced will be captured
test the captured gas for CO2 in limewater
if carbonate was present then the limewater will turn cloudy
175
test for sulphates
barium chloride
add hydrochloric acid to the solution and look for effervescence
if there's not effervescence then add barium chloride (stops false positives)
if theres sulphates present then a white precipitate will form
176
test for water
anhydrous copper(II) sulfate
add the solution to anhydrous copper(II) sulfate
if water is present then the solution will turn from white to blue
177
physical test to show water is pure
check boiling point
gently heat the solution to 100'c
if the water is pure then it will all boil at 100'c
178
litmus indicator
red in acid
blue in alkali
179
phenolphthalein indicator
colourless in acid
pink in alkali
180
methyl orange
red in acid
yellow in neutral
yellow in alkali
181
universal indicator colours
0-3 strongly acidic - dark red/red/orange
4-6 weakly acidic - orange/yellow/light green
7 neutral - green
8-10 weakly alkaline - dark green/light blue
11-14 strongly alkaline - dark blue/purple
add a few drops to a solution and match the colour it turns to the universal indicator chart to find out the pH
182
what happens if an acid is added to a alkali
a neutralisation reaction
the H+ in the acid reacts with the OH- in a base forming water
183
solubility of common sodium, potassium, ammonium compounds
they are soluble with everything
184
solubility of nitrates
they are soluble with everything
185
solubility of common chlorides
soluble with everything except silver and lead(II)
186
solubility of common sulfates
soluble with everything except barium, calcium, lead(II)
187
solubility of common carbonates
insoluble except with sodium, potassium, and ammonium
188
solubility of common hydroxides
insoluble except with sodium, potassium, and calcium (calcium hydroxide is slightly soluble)
189
what is a acid
a proton (H+ ion) donor
190
what is a base
a proton (H+ ion) acceptor
191
why do metals less reactive the hydrogen not react with acids
they can't displace the H so can't react
192
reaction between metals and acids
Acid + Metal → Salt + Hydrogen
a salt is formed because the H is displaced from the acid
observations:
the metal will disappear as it is used up in the reaction
there is fizzing because a gas (H) is produced
193
reaction between bases and acids
Acid + Base → Salt + Water
observations:
the base disappears as it is used up in the reaction
194
reaction between metal carbonates and acids
Acid + Carbonate → Salt + Water + Carbon dioxide
observations:
the carbonate disappears because it is used up in the reaction
there is fizzing because a gas (CO2) is being produced
195
whats an alkali
a OH- donor
bases that are soluble in water
196
examples of bases
a metal oxide, metal hydroxide, metal carbonate and ammonia
197
describe an experiment to prepare a pure, dry sample of a soluble salt, starting from an insoluble reactant
solid metal, insoluble base or insoluble carbonate
metal/metal oxide/metal carbonate + acid --> salt + water
1. gently heat acid in a beaker until warm
2. add excess insoluble metal/oxide/carbonate
3. to ensure all acid is reacted stir
4. stop heating and filter out any excess undissolved metal
5. filter it into an evaporating basin
6. gently heat again until crystals first appear
7. as soon as they appear stop heating
8. leave evaporating basin in a warm place in the sun for a few days to allow water to evaporate
198
practical: prepare a sample of pure, dry hydrated copper(II) sulfate crystals starting from copper(II) oxide
soluble salt from insoluble reactant method
1. Add 50 cm3 dilute acid into a beaker and warm gently using a Bunsen burner
2. add the copper(II) oxide slowly to the hot dilute acid and stir until the base is in excess (i.e. until the base stops
dissolving and a suspension of the base forms in the acid)
3. Filter the mixture into an evaporating basin to remove the excess base
4. Gently heat the solution in a water bath or with an electric heater to evaporate the water and to make the
solution saturated
5. Check the solution is saturated by dipping a cold glass rod into the solution and seeing if crystals form on the
end
6. Leave the filtrate in a warm sunny place to dry and crystallise
199
what is a precipitate
a solid formed when 2 solutions are mixed
200
test for ammonia (NH3) (gas)
hold damp red litmus paper in the NH3
will turn blue
201
colour of Li+ flame
(bright) red
202
colour of Na+ flame
yellow
203
colour of K+ flame
lilac
204
colour of Ca2+ flame
orange/red (brick red)
205
colour of Cu2+ flame
blue/green
206
method to carry out the flame test
1. turn the bunsen burner onto non-luminous
2. get a nichrome wire loop and dip it into HCl
3. Dip the nichrome wire into the substance
4. hold the wire into the blue cone in the bunsen
5. observe the colour change and repeat
207
test for ammonium cation
1. place 1cm of ammonia solution into a test tube
2. add 2cm of sodium hydroxide solution into the test tube
3. place the test tube into a beaker containing warm water
4. hold damp red litmus over the test tube
turns from red to blue
208
test for Cu2+ cation
1. place 1cm dissolved Cu2+ in a test tube
2. slowly add drops of 0.5mol sodium hydroxide into test tube until precipitate is visible
light blue gelantinous precipitate is formed
floats on surface
209
test for Fe2+ cation
1. place 1cm of the salt (Fe) solution in a test tube
2. slowly add drops of 0.5mol sodium hydroxide into test tube until precipitate is visible
green gelantinous precipitate is formed
floats on the surface
210
test for Fe3+ cation
1. place 1cm of the salt (Fe) solution in a test tube
2. slowly add drops of 0.5mol sodium hydroxide into test tube until precipitate is visible
red/brown gelantinous precipitate is formed
floats on the surface
211
what is an exothermic reaction
where heat and light energy is given out
212
what is an endothermic reaction
where heat energy is taken in (from the surroundings)
213
method to work out the effect in change of surface area of a solid on the rate of reaction
1. Add dilute hydrochloric acid to a conical flask
2. Use a delivery tube to connect this flask to an inverted measuring cylinder upside down in a water trough
3. Add calcium carbonate chips into the conical flask and close the bung
4. Measure the volume of gas produced in a fixed time using the measuring cylinder
5. Repeat with different sizes of calcium carbonate chips (use 3g of small, medium, large chips)
results:
more gas will be produced from the smaller chips as they have a larger surface area
214
method to work out the effect in change of concentration of a solution on the rate of reaction
1. Measure 50 cm3 of sodium thiosulfate solution into a conical flask
2. Measure 5 cm3 of dilute hydrochloric acid into a measuring cylinder
3. Draw a cross on a piece of paper and put it underneath the flask
4. Add the acid into the flask and immediately start the stopwatch
5. Look down at the cross from above and stop the stopwatch when the cross can no longer be seen
6. Repeat using different concentrations of sodium thiosulfate solution (mix different volumes of sodium thiosulfate
solution with water to dilute it)
results:
with an increased of the concentration the rate of reaction will increase meaning the cross will disappear quicker
215
method to work out the effect in change of temperature of a solution on the rate of reaction
1. Dilute hydrochloric acid in a conical flask is heated to a set temperature using a water bath
2 .Add a strip of magnesium to the HCl and start the stopwatch
3. Stop the time when the magnesium fully dissolves
4. Repeat at different temperatures and compare results
results:
With an increase in the temperature the magnesium will dissolve quicker
216
method to work out the effect of using a catalyst has on the rate of reaction
1. Add hydrogen peroxide into a conical flask
2. Use a delivery tube to connect this flask to a measuring cylinder upside down in water trough
3. Add the catalyst (manganese(IV) oxide) into the conical flask and close the bung
4. Measure the volume of gas produced in a fixed time using the measuring cylinder
5. Repeat experiment without the catalyst of manganese(IV) oxide and compare results
results:
the catalyst will speed up the rate of reaction therefore the volume of gas produced will be greater when the catalyst is used
217
how does a catalyst affect the rate of reaction
the catalyst lowers the activation energy providing an alternate pathway for the reaction to take place
meaning the percentage of collisions with enough energy is higher
so there are more successful collisions per unit of time
increasing the rate of reaction
218
how does surface area affect the rate of reaction
with a larger SA rate of reaction increases because more surface area of the particles will be exposed to the other reactant
therefore more particles collide more frequently per unit of time
meaning there are more successful collisions per unit of time
and an increased rate of reaction
219
how does the temperature affect the rate of reaction
with higher temperature rate of reaction increases because the particles will have more kinetic energy
So the percentage of collisions with enough energy is higher
meaning more successful collisions per unit of time
increasing the rate of reaction
220
how does the concentration/pressure affect the rate of reaction
with a higher concentration/pressure the rate of reaction increases because there are more particles per given volume of mass
there for particles collide more frequently per unit of time
meaning there are more successful collisions per unit of time
increasing the rate of reaction
221
does the catalyst change the reaction
no the catalyst does not
the reaction is chemically unchanged at the end of the reaction
222
practical: investigate the effect of changing the surface area of marble chips and of changing the concentration of hydrochloric acid on the rate of reaction between marble chips and dilute hydrochloric acid
1. Add dilute hydrochloric acid to a conical flask
2. Use a delivery tube to connect this flask to an inverted measuring cylinder upside down in a water trough
3. Add calcium carbonate chips into the conical flask and close the bung
4. Measure the volume of gas produced in a fixed time using the measuring cylinder
5. Repeat with different sizes of calcium carbonate chips (use 3g of small, medium, large chips)
results:
more gas will be produced from the smaller chips as they have a larger surface area
223
practical: investigate the effect of different solids on the catalytic decomposition of hydrogen peroxide solution
1. Add hydrogen peroxide into a conical flask
2. Use a delivery tube to connect this flask to a measuring cylinder upside down in water trough
3. Add the catalyst (manganese(IV) oxide) into the conical flask and close the bung
4. Measure the volume of gas produced in a fixed time using the measuring cylinder
5. Repeat experiment with different catalysts and compare results
224
how to calculate heat energy change
Q=mcΔT
energy = mass x change in temp x specific heat capacity
225
how to calculate molar enthalpy change (ΔH)
ΔH = (Q / n) /1000 (to convert to kJ/mol)
enthalpy change = -energy change / moles
Reactions where energy has been released / the temperature has increased are exothermic- this means your answers for enthalpy changes should be negative
226
describe simple calorimetry experiments for reactions in solution
can be used for:
neutralisation reactions
dissolving solids in water
displacement reactions
To calculate the amount of energy produced by a chemical reaction in solution we measure the temperature change when the solutions are mixed together
The solutions need to be mixed together in an insulated contain to prevent heat loss
A fixed volume of one reagent is added to the calorimeter and the initial temperature taken with a thermometer
An excess amount of the second reagent is added and the solution is stirred continuously
The maximum temperature is recorded and the temperature rise calculated using Q=mcΔT
227
describe simple calorimetry experiments for combustion
The principle here is to use the heat released by a combustion reaction to increase the heat content of water
Method:
Measure a fixed volume of water into a copper can
Weigh the spirit burner containing a fuel using a balance
Measure the initial temperature of the water
Burn the fuel and stir the water
Wait for 30s and extinguish the flame
Record the final temperature of the water and re-weigh the spirit burner
228
practical: investigate temperature changes accompanying salts dissolving in water:
Using a measuring cylinder, place 25 cm3 of water into the calorimeter
Measure and record the temperature of the solution
Add 5g of salt and stir
Measure and record the highest temperature reached by the mixture
(endothermic)
229
practical: investigate temperature changes accompanying neutralization reactions:
Using a measuring cylinder, place 25 cm3 of the NaOH solution into the calorimeter
Measure and record the temperature of the solution
Add 5 cm3 of the dilute HCl and stir
Measure and record the highest temperature reached by the mixture
(exothermic)
230
practical: investigate temperature changes accompanying displacement reactions:
Using a measuring cylinder, place 25 cm3 of the copper sulfate into the calorimeter
Measure and record the temperature of the solution
Add magnesium and stir
Measure and record the highest temperature reached by the mixture
(exothermic)
231
practical: investigate temperature changes accompanying combustion reactions:
Method:
Measure a fixed volume of water into a copper can
Weigh the spirit burner containing a fuel using a balance
Measure the initial temperature of the water
Burn the fuel and stir the water
Wait for 30s and extinguish the flame
Record the final temperature of the water and re-weigh the spirit burner
(exothermic)
232
what does this ⇌ mean
the reaction is reversible (can occur in both directions)
reactants are used up to form products and then the products react with themselves or decompose to form the reactants
233
describe reversible reaction of dehydration of hydrated copper(II) sulfate
hydrated the crystals are blue
can be heated/dehydrated to form anhydrous copper (II) sulfate which is endothermic as energy is taken in to remove water
anhydrous copper(II) sulfate is white and adding water rehydrates which is highly exothermic
hydrated -> heat -> anhydrous (endothermic)
blue -> white
anhydrous -> water -> hydrated (exothermic)
white -> blue
234
describe reversible reaction of heating ammonium chloride
heating ammonium chloride produces ammonia and hydrogen chloride gas
as the gases cool they recombine to for solid ammonium chloride forming a white ring of solid further up the boiling tube
235
what is a hydrocarbon
a compound made up of only hydrogens and carbons
236
what is crude oil
a mixture of different hydrocarbons
237
what is fuel
a substance that when it is burned it releases heat energy
238
how does fractional distillation work
Fractional distillation is carried out in a fractionating column which is very hot at the bottom and cool at the top
Crude oil enters the fractionating column and is heated so vapours rise
Vapours of hydrocarbons with very high boiling points will immediately condense into liquid at the higher temperatures lower down and are tapped off at the bottom of the column
Vapours of hydrocarbons with low boiling points will rise up the column and condense at the top to be tapped off
The different fractions condense at different heights according to their boiling points and are tapped off as liquids
The fractions containing smaller hydrocarbons are collected at the top of the fractionating column as gases
The fractions containing bigger hydrocarbons are collected at the lower sections of the fractionating column
239
what is a fraction
a group of similar length hydrocarbons
240
trend in colour, boiling point and viscosity of the fractions
boiling point and viscosity increase as the boiling point increases
colour gets darker as the boiling points increase
241
refinery gases
1-4 carbons
boiling point less then 25'c
fuel for home cooking
242
gasoline
4-12 carbons
boiling point between 40-100'c
fuel for cars
243
kerosene
12-16 carbons
boiling point between 150-240'c
fuel for aircrafts
244
diesel
14-18 carbons
boiling point between 220-300'c
fuel for trains
245
fuel oil
19-25 carbons
boiling point between 250-320'c
fuel for ships
246
bitumen
more than 70 carbons
boiling point more than 350'c
making roads
247
what is the empirical formula
the simplest possible ratio of the atoms in a molecule
For example: Hydrogen peroxide is H2O2 but the empirical formula is HO
248
what is the molecular formula
the actual number of atoms in a molecule
249
what is the general formula
A ratio of atoms in a homolgous series
250
what is the structural formula
In a structural formulae enough information is shown to make the structure clear, but most of the actual covalent bonds are omitted
Only important bonds are always shown, such as double and triple bonds
Identical groups can be bracketed together
Side groups are also shown using brackets
Straight chain alkanes are shown as follows:
CH3CH2CH2CH2CH3 or CH3(CH2)3CH3
Displayed formula:
H H H H
I I I I
H-C-C-C-C-H
I I I I
H H I H
I
H-C-H
I
H
251
what is the displayed formula
how the molecule is drawn
H H H H
I I I I
H-C-C-C-C-H
I I I I
H H I H
I
H-C-H
I
H
252
what is a homologous series
a series or family of organic compounds that have similar features and chemical properties due to them having the same functional group
All members of a homologous series have:
The same general formula
Same functional group
Similar chemical properties
trends in their physical properties
253
what is a functional group
A group of atoms of a molecule which determine its chemical reactions
254
what is isomerism
compounds that have the same molecular formula but different displayed formulae
255
how to name compounds
first part of the name second part of the name
NAME Number of C atoms name functional group Family
meth.. 1 ..ane none alkane
eth.. 2 ..ene C = C double bond alkene
prop.. 3 ..anol -OH alcohol
but.. 4 ..anoic acid -C=O-O-H carboxylic acid
pent.. 5 ..amine -NH2 amine
hex.. 6 ..yl ..anoate -C=O-O- ester
When there is more than one carbon atom where a functional group can be located it is important to distinguish exactly which carbon the functional group is on
Each carbon is numbered and these numbers are used to describe where the functional group is
When 2 functional groups are present di- is used as a prefix to the second part of the name
256
how to classify reactions of organic compounds as substitution, addition and combustion
A substitution reaction takes place when one ion is replaced by another
CH4 + Br2 → CH3Br + HBr
An addition reaction takes place when two or more molecules combine to form a larger molecule with no other products
C2H4 + Br2 → C2H4Br2
This is the scientific term for burning. In a combustion reaction, an organic substance reacts with oxygen to form carbon dioxide (or carbon monoxide if incomplete combustion) and water.
257
possible products of complete combustion of hydrocarbons with oxygen in air
Complete Combustion happens when there is enough oxygen available, producing carbon dioxide (CO2) and water (H2O)
eg CH4 + 2O2 -> CO2 + 2H2O
258
possible products of incomplete combustion of hydrocarbons with oxygen in air
Incomplete Combustion happens when there is not enough oxygen available, with possible products being carbon monoxide (CO), carbon (C, soot), carbon dioxide (CO2) and water (H2O)
eg ethane + oxygen -> carbon monoxide + water
259
effects of carbon monoxide on the capacity of blood to carry oxygen
Carbon monoxide is a toxic and odourless gas which can cause dizziness, loss of consciousness and eventually death
The CO binds well to haemoglobin which therefore cannot bind oxygen meaning less oxygen and CO2 can be transported to and from organs and working muscles
260
what do the high temperatures in car engines allow
the temperature goes high enough to allow and oxygen from the air and nitrogen to react, forming oxides of nitrogen (NO and NO2)
261
how does the combustion of some impurities in hydrocarbon fuels results in the formation of sulfur dioxide
Fossil fuels are often contaminated with small amounts of sulfur impurities
When these contaminated fossil fuels are combusted, the sulfur in the fuels get oxidised to sulfur dioxide
262
how does sulfer dioxide and and oxides of nitrogen contribute to acid rain
The sulfur dioxide produced from the combustion of fossil fuels dissolves in rainwater droplets to form sulfuric acid
2SO2 (g) + O2 (g) + 2H2O (l) → 2H2SO4 (aq)
Sulfuric acid is one of the components of acid rain which has several damaging impacts on the environment
Nitrogen dioxide produced from car engines reacts with rain water to form a mixture of nitrous and nitric acids, which contribute to acid rain:
2NO2 (g) + H2O (l) → HNO2 (aq) + HNO3 (aq)
263
process of catalytic cracking
Catalytic cracking involves heating the hydrocarbon molecules to around 600 – 700°C to vaporise them
The vapours then pass over a hot powdered catalyst of aluminium oxide or silica
This process breaks covalent bonds in the molecules as they come into contact with the surface of the catalyst, causing thermal decomposition reactions
The molecules are broken up in a random way which produces a mixture of smaller alkanes and alkenes
Hydrogen and a higher proportion of alkenes are formed at higher temperatures and higher pressure
264
why is cracking necessary
Crude oils vary considerably in their composition and some need more refining than others
Supply is how much of a particular fraction can be produced from refining the crude oil
Demand is how much customers want to buy
Generally, the demand for certain fractions outstrips the supply so this is why cracking is necessary to convert surplus unwanted fractions into more useful ones
This is mostly larger, heavier fractions that are cracked into smaller lighter fractions
265
what is the general formula for alkanes
CnH2n+2
266
why are alkanes classified as saturated hydrocarbons
they only have single carbon-carbon bonds, there are no double bonds
267
reactions of alkanes with halogens in the presence of ultraviolet radiation
Alkanes undergo a substitution reaction with halogens in the presence of ultraviolet radiation
eg CH4 + Br2 → CH3Br + HBr
methane + bromine → bromomethane + hydrogen bromide
268
what is the functional of alkenes
> C=C <
269
what is the general formula for alkenes
CnH2n
270
why are alkenes classified as unsaturated hydrocarbons
Compounds that have a C=C double bond are also called unsaturated compounds
That means they can make more bonds with other atoms by opening up the C=C bond and allowing incoming atoms to form another single bond with each carbon atom of the functional group
Each of these carbon atoms now forms 4 single bonds instead of 1 double and 2 single bonds
This makes them much more reactive than alkanes
271
reactions of alkenes with bromine
Alkenes undergo addition reactions in which atoms of a simple molecule add across the C=C double bond
The reaction between bromine and ethene is an example of an addition reaction
The same process works for any halogen and any alkene in which the halogen atoms always add to the carbon atoms across the C=C double bond
eg
H H H H
I I I I
C = C + Br2 -----> H - C - C - H
I I I I
H H Br Br
272
how can bromine water be used to distinguish between an alkane and an alkene
Alkanes and alkenes have different molecular structures
All alkanes are saturated and alkenes are unsaturated
The presence of the C=C double bond allows alkenes to react
Bromine water is an orange coloured solution
When bromine water is added to an alkane, it will remain as an orange solution as alkanes do not have double carbon bonds (C=C) so the bromine remains in solution as the alkane does not react with the bromine
But when bromine water is added to an alkene, the bromine atoms add across the C=C bond, hence the solution no longer contains free bromine so it loses its coloure
273
how is an addition polymer formed
by joining up many small molecules called monomers (repeating units) together to form longer chain polymers
addition monomers can only be formed from alkenes as the C=C bond breaks apart
for example: 1000s of molecules of ethene together
274
problems in disposel of addition polymers
Addition polymers are formed by the joining up of many small molecules with strong C-C bonds
This makes addition polymers unreactive and chemically inert so don’t easily biodegrade
Polymers release a lot of heat energy when they burn and produces carbon dioxide which is a greenhouse gas that contributes to climate change
Polymers that contain chlorine such as PVC release toxic hydrogen chloride gas when burned
If incinerated by incomplete combustion, carbon monoxide will be produced which is a toxic gas that reduces the capacity of the blood to carry oxygen
275
catalyst required to crack alkanes
silica or aluminum oxide
276
how to draw the repeating unit of an addition polymer
One of the bonds in each C=C bond breaks and forms a bond with the adjacent monomer with the polymer being formed containing single bonds only
so the monomer would be (ethene):
H H
I I
C=C
I I
H H
but when it forms a polymer (poly(ethene)):
H H
I I
-(-C-C-)- n
I I
H H
277
how to draw polychloroethene
monomer:
H Cl
I I
C=C
I I
H H
repeating unit:
H Cl
I I
-C-C-
I I
H H
Polymer:
H Cl
I I
-(-C-C-)- n
I I
H H
278
how to draw polypropene
monomer:
H CH3
I I
C=C
I I
H H
repeating unit:
H CH3
I I
-C - C-
I I
H H
polymer:
H CH3
I I
-(-C - C-)- n
I I
H H
279
how to draw polytetrafluoroethene
monomer:
F F
I I
C=C
I I
F F
repeating unit:
F F
I I
-C - C-
I I
F F
polymer:
F F
I I
-(-C - C-)- n
I I
F F
