2 Inorganic Chemistry Flashcards
(118 cards)
1
Q
what happens when lithium reacts with water
A
relatively slow reaction
lithium doesn’t melt
effervescence can be observed
2
Q
what happens when sodium reacts with water
A
sodium melts into a ball as large amounts of heat energy is released
hydrogen released catches fire and causes the Na to dash around the surface of water
3
Q
what happens when potassium reacts with water
A
creates a lilac flame
melts into a shiny ball which dashes across the surface of the water
4
Q
what are the group 1 metals called
A
alkali metals
5
Q
what happens to the reactivity as you go down group one
A
increases because as we go down the group each element has one more outer shell meaning the distance between the outer most shell and the nucleus increases. this decreases the electrostatic force of attraction meaning its easier to lose the one electron as less energy is required
group one elements only need to lose one electron to form a complete outer shell
6
Q
trends in the group one / alkali metals
A
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
7
Q
how do the alkali metals react with oxygen
A
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
8
Q
how do the alkali metals react with water
A
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
9
Q
predicting properties in group 1
A
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
10
Q
colour and physical state (at room temp) of fluorine
A
yellow gas
11
Q
colour and physical state (at room temp) of chlorine
A
pale yellow/green gas
12
Q
colour and physical state (at room temp) of bromine
A
red/brown liquid
13
Q
colour and physical state (at room temp) of iodine
A
grey solid
14
Q
colour and physical state (at room temp) of astatine
A
black solid
15
Q
trend in properties of the halogens
A
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
16
Q
what is a metal halide
A
when a halogen reacts with a metal they form ionic compounds which are metal halide salts
17
Q
what is a halide
A
a halogen ion
18
Q
what is a displacement reaction
A
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
19
Q
why does the reactivity decrease when you go down the halogen group
A
as you go down the group the amount mass of the halogens increase and so does the number of electron shells
halogens form negative ions (they gain an electron)
the distance from the nuclei (positive) to the outer shell increases which means there is a smaller force of attraction so it is harder to gain an electron
20
Q
what % of nitrogen is there in the air
A
78%
21
Q
what % of oxygen is there in the air
A
21%
22
Q
what % of argon is there in the air
A
0.9%
23
Q
what % of CO2 is there in the air
A
0.04%
24
Q
how to determine the percentage by volume of oxygen in air using experiments involving the reactions of metals (e.g. iron) with air
A
- place an excess of wet iron filings into a conical flask (100cm3) full of air
- 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
25
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
26
combustion of magnesium in oxygen
intense white flame
white powder produced
27
combustion of hydrogen in oxygen
exothermic
water is produced
28
combustion of sulpher in oxygen
blue flame
colourless, poisonous gas produced
29
what is thermal decomposition
a reaction where a substance breaks down due to the action of heat
30
what is the formation of carbon dioxide from the thermal decomposition of metal carbonates
metal carbonate → metal oxide + carbon dioxide
31
what is the happens when copper(II) carbonate is thermally decomposed
copper(II) carbonate → copper(II) oxide + carbon dioxide
green -> black
32
what happens if we increase the amount of CO2 in the atmosphere
contribute to the enhanced greenhouse effect and climate change
33
what type of gas is CO2
a greenhouse gas
34
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
35
what is the order of the reactivity series
potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, lead, hydrogen, copper, silver, gold
36
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
metal + water ⟶ metal hydroxide + hydrogen
37
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
metal + acid ⟶ salt + hydrogen
38
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
39
how does displacement work with the reactivity series
a more reactive metal will displace a less reactive metal from a compound
40
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
41
what conditions does iron need to rust
water and oxygen
42
what is rust
hydrated iron oxide
43
how to stop iron rusting
barrier methods
galvanising
44
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
45
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
46
what is OILRIG
oxidation is loss of electrons
reduction is gain of electrons
47
what is oxidation
Oxidation is any reaction in which a substance gains oxygen
oxidation is loss of electrons
48
what is reduction
Reduction is a reaction in which a substance loses oxygen
reduction is gain of electrons
49
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
50
what is a oxidising agent
makes oxidation happen
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
51
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
52
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
53
where are metals extracted from
from ores found in the Earth’s crust
54
what are unreactive metals found as
often found as the uncombined element as they do not react easily so they don't combine with other things
55
what is an ore
a naturally occurring rock which contains metals or metal compounds (eg iron oxide) in sufficient amounts to make them worthwhile extracting them
56
how is the method of extraction of a metal from a ore related to its reactivity
a more reactive metal can displace a less reactive metal
the metals (aluminium) more reactive than carbon cannot be displaced by carbon so they need to be displaced by electrolysis
metals (iron) less reactive then carbon can be displaced by carbon so they can be extracted by carbon extraction
silver and gold are unreactive so they don't react with oxygen or anything else to form compounds which means they exist by themselves and therefore don't need to be extracted
57
what are the uses of aluminium
aeroplane bodies - very strong and low density (so it doesn't weigh a lot)
power cables - good electrical conductor
food cans - non-toxic, resistant to corrosion and acidic food
window frames - resistant to corrosion
58
what are the uses of copper
wires - great electrical conductor
cooking pans - great heat conductor
water pipes - unreactive and malleable
59
what are the uses of iron
making steel - steel is more useful
60
what are the uses of low-carbon steel
ships, cars, bridges - strong and malleable
61
what are the uses of high-carbon steel
tools (knives + screwdrivers) - strong and less malleable so won't change shape
62
what are the uses of stainless steel
cutlery, kitchen sinks - Cr forms oxide layers that is resistant to corrosion and stays shiny and clean
63
what does malleable mean
can be hammered into different shapes without cracking
64
what does ductile mean
can be drawn into wires
65
what is low-carbon steel made of
Fe + 0.1% C
66
what is high-carbon steel made of
Fe + 1% C
67
what is stainless steel made of
Fe + 1% C + 10% Cr
68
what is an alloy
a mixture of a metal and one or more elements, usually other metals or carbon
69
why are alloys harder than pure metals
the different-sized atoms/ions which distorts the regular arrangement therefore preventing the layers of metal ions from sliding over each other making it harder
70
things to comment on for electrolysis
large amounts of electricity are required making it very expensive
71
things to comment on for carbon extraction
much cheaper than electrolysis and is a source of heat as well
72
test for hydrogen
place a lit splint into hydrogen and you will hear a squeaky pop
73
test for oxygen
place a glowing splint into oxygen and it will relight
74
test for carbon dioxide
bubble through limewater and it will turn cloudy
75
test for chlorine
place a damp blue litmus paper into chlorine and it will bleach (turn white)
76
whats an anion
a negative ion
77
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
78
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
79
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
80
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
81
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
82
litmus indicator
red in acid
blue in alkali
83
phenolphthalein indicator
colourless in acid
pink in alkali
84
methyl orange
red in acid
yellow in alkali
85
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
86
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
87
solubility of common sodium, potassium, ammonium compounds
they are soluble with everything
88
solubility of nitrates
they are soluble with everything
89
solubility of common chlorides
soluble with everything except silver and lead(II)
90
solubility of common sulfates
soluble with everything except barium, calcium, lead(II)
91
solubility of common carbonates
insoluble except with sodium, potassium, and ammonium
92
solubility of common hydroxides
insoluble except with sodium, potassium, and calcium (calcium hydroxide is slightly soluble)
93
what is a acid
a proton (H+ ion) donor
94
what is a base
a proton (H+ ion) acceptor
95
why do metals less reactive the hydrogen not react with acids
they can't displace the H so can't react
96
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
97
reaction between bases and acids
Acid + Base → Salt + Water
observations:
the base disappears as it is used up in the reaction
98
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
99
whats an alkali
a OH- donor
bases that are soluble in water
100
examples of bases
a metal oxide, metal hydroxide and ammonia
101
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
102
describe an experiment to prepare a pure, dry sample of a soluble salt, starting from an acid and alkali
acid + alkali (soluble base) --> salt + water
titration
1. the alkali and a few drops of indicator to a conical flask
2. add acid to a burette and note the starting volume
3. slowly add the acid to the alkali until the indicator changes colour
4. record the final volume of acid and calculate the total volume of acid added
5. get the same amount of alkali without the indicator and add the total volume of acid added to the other one (this creates pure crystals without the indicator in them)
5. heat the salt solution until crystals just start to appear
6. as soon as they appear, remove from heat
7. leave evaporating basin in a warm place in the sun for a few days to allow water to evaporate
103
describe an experiment to prepare a pure, dry sample of an insoluble salt, starting from two soluble reactants
soluble salt 1(aq) + soluble salt 2(aq) --> insoluble salt(s) + soluble salt 3(aq)
1. mix the 2 soluble salts together in water using a stirring rod
2. filter the solution using a funnel and filter paper
3. pour distilled water through the filter paper to wash the insoluble salt
4. place the insoluble salt in a warm dry sunny place to dry the salt
104
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
105
practical: prepare a sample of pure, dry lead(II) sulfate
insoluble salt from 2 soluble reactants
1. Measure out 25 cm3 of 0.5 mol dm3 lead(II)nitrate solution and add it to a small beaker
2. Measure out 25 cm3 of 0.5 mol dm3 of potassium sulfate add it to the beaker and mix together using a stirring
rod
3. Filter to remove precipitate from mixture
4. Wash filtrate with distilled water to remove traces of other solutions
5. leave in sunny warm place to dry
106
what is a precipitate
a solid formed when 2 solutions are mixed
107
test for ammonia (NH3) (gas)
hold damp red litmus paper in the NH3
will turn blue
108
colour of Li+ flame
(bright) red
109
colour of Na+ flame
yellow
110
colour of K+ flame
lilac
111
colour of Ca2+ flame
orange/red (brick red)
112
colour of Cu2+ flame
blue/green
113
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
114
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
115
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
116
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
117
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
118
how to carry out an acid-alkali titration
Titrations are a method of analysing the concentration of solutions
They can determine exactly how much alkali is needed to neutralise a quantity of acid – and vice versa
Use the pipette and pipette filler and place exactly 25 cm3 known acid solution into the conical flask
fill the burette with an alkali
Place the conical flask on a white tile so the tip of the burette is inside the flask
Add a few drops of phenolphthalein indicator to the solution in the conical flask
Perform a rough titration by taking the burette reading and running in the solution in 1 – 3 cm3 portions, while swirling the flask vigorously
Quickly close the tap when the end-point is reached (sharp colour change) and record the volume, placing your eye level with the meniscus
Now repeat the titration with a fresh batch of acid
As the rough end-point volume is approached, add the solution from the burette one drop at a time until the indicator just changes colour
Record the volume to the nearest 0.05 cm3
Repeat until you achieve two concordant results (two results that are within 0.1 cm3 of each other) to increase accuracy
