Exam Questions Flashcards
(130 cards)
1
Q
Name the type of bond between the hydrongen and the chlorine atoms in a molecule of hydrogen choride
A
Covalent bond
2
Q
Suggest two causes of experimental error in an experiment
A
change in temerature loss of gas reacted unexpectadly using balance incorrectly faulty balance
3
Q
Why is it important to repeat the experiment?
A
To find a mean
4
Q
What is the meaning of the term of a precipitation reaction?
A
Insoluble substances beiong formed
5
Q
How can magnesium hydroxide be seperated from the calcium chloride solution?
A
Filtration
6
Q
Name a method that can be used to change calcium chloride solution into solid calcium chloride
A
Crystallisation
7
Q
half equation:
Ca —> Ca ^2+ + ….
A
2e^-
8
Q
Why can the formation of calcium ions from calcium atoms be described as oxidisation?
A
Because electrons are lost
9
Q
Explain why diamonds are hard
A
Because they have a giant structure, covalent bonds which are very strong
10
Q
How is ammonia separated from unreacted nitrogen andhydrogenn in the separator
A
Mixing is cooled so that ammonia turns into a liquide
11
Q
Why does the yield of ammonia at equilibrium increase as the temperature is decreased?
A
Becuase it is an exothemic reaction
12
Q
Explain, in terms of particles, why increasing the temperature makes a reaction fo faster
A
particles move faster
collide more frequently
13
Q
Why does the yield of ammonia at equilibrium increase as the pressure is increased?
A
Greater volume on left hand side than on the right
14
Q
Why would a higher pressure not be used?
A
Coast
15
Q
Give two reasons why it does not matter that the percentage of yield ammonia is low.
A
Unreacted gases are recycled
Rate if production is fast
16
Q
Describe the structure and bonding of gold
A
Giant structure
Delocalised electrons
Possitive ions and negative electrons attract to each other
17
Q
Why is gold a good conductor of electrisity?
A
free electrons
18
Q
The surface of some metals, such as iron, corrode when exposed to the air. Suggest why this reduces the electrical conductivity of the metal
A
ionic compound formed
ions not free to move
19
Q
How did Wohler prove that a life force is NOT needed to make organic compounds?
A
He made another organic comound
20
Q
In 1828 most scientists continued to beleieve that a life force was needed to produce an organic compound. Suggest by they did not believe Wohler’s idea until 1845.
A
lack of evidence before
later there was more evidence
21
Q
How solid lead nitraste can be obtained fro lead nitrate solution?
A
evapouration
22
Q
The water and CO2 produced escape from the test tube, why?
A
because they are gases
23
Q
Suggest two reasons why al of the points do not lie on the line of best fit
A
results not recoreded correctly
apparatus error
24
Q
How could a graph give a conclusion?
A
by having a straight line
25
Why does the rate of reaction increase whent he conetration increases?
increase in the frequency of collision
| particlies are closer together
26
Why do metals have a high melting point?
gaint structure
made of positive ions surrounded by free elecrons
stonge bonds
so alot pf energy is needed to break them
27
What does the term "nano" tell you about the carbon nanotubes?
they are very small
28
Why do carbon nanotubes conduct electricity?
free electrons
| one non-bonded electron from each atom
29
Mg^2+ I^-
| What happens when magnesium reacts with iodine?
magnesium loses 2 electrons
| iodine gains 1 electron
30
Explain why a high temperature is needed to melt potassium iodide
bonds are strong
because oppositly charged ions attract
giant structure
31
HOw does a decrease in temperature affect the yeild of ammonia at equilibrium?
increase yeild
| becuase the reaction is exothermic
32
HOw does an increase in pressure affect the yield of ammonia at equilibrium?
increase yield
| becuase greater volume on the left than on the right
33
Do the reactants need to be heated?
yes to strat the reaction
34
A student investigates the reaction between magnesium and hydrochloric acid. Give two observatios the student could make during the reaction.
effervescence
| magnesium dissolves
35
Name the type of reaction between aqueous ammonia solution and an acid
neutralisation
36
Davy first tried to elecrolise a solid potassium salt to produce potassium. Explain why this electrolysis did NOT work
current cannot flow because ions couldn't move
37
The sudent exoected to see potassuim metal at the negative elcrode, but instead saw bubbles of a gas.
name the gass produced at the negative elecrode
explain why this fas was produced and why pottassium was not produced
gas = hydorgen
the ions as positve
potassium is more reactive than hydrogen
38
potassium metal was produced at the negative electrode. Describe how potassium atoms are formed from potassium ions
loses one electron
39
Why are alloys harder than pure metals?
because particles in alloys are different sizes, so the layers are distroted and they can no longer slide over one another
40
describe the stucture of a dimonde
giant structure
stong bonds between atoms
convalent bonds
each carbon atom froms 4 bonds
41
describe the structure and bonding in a thermosftening polymer and explain why thermosoftening polymers melt when heated
large molecules with weak intermolecular forces and are easily btocken when heated
42
Explain why, in terms of structure, CO2 is a gas, even at a low tempwerature
has simple molecules. The intermolecular forces are qweak and only a small amount of energy is needed to overcome the forces
43
What is the purpose of chromatography?
To split the properties of the gases
44
What information do the molecular ion peak from the mass spectrometer give about the substances?
relative molecular mass
45
suggests why scientists in 1800 could not extract aluminium from alumina
no method
46
How was Wohler able to prove that he had made a new metal?
when tesated it had the properties of a a metal
| properties were dofferect from other known matals
47
Give two reasons why they should have repeated the experiment
improve reliablitly
| reduce the effect of errors
48
name the method that could be used to seperate magenisium hydroxide from the solution
filtration
49
Why is the reaction a reduction reaction?
because electrons are gained
50
Why are metals very good conductors?
because their electrons can move freely through the structure and carry a charge
51
Suggests one reason why nanosized particles of silver might help to transfer heat bettwe than normal sized particles
more can fit into the gaps
52
Why does an increase in preassure increase the yield of ethanol at equilibrium?
2 particles on the left and one the right
53
Ethanol has a low boiling point and evapourates easily, why?
becaus ethe bonds betweent the molecules are weak
54
Why is graphene strong?
giant structuer
convalent bonds
which are strong
55
Why can graphene conducet electricity?
free electrons
| 3 electrons per atom used in bonding
56
suggests why a sheet of graphite which has a large number of carbon layers would not be suitable for the touchscreen
because it is opaque
57
In peper chromatography the start line line should be drawn with a ruler and a .......
Why?
pencil
| the pencil will not run whereas the ink would
58
Why do differenct compounds seperate a gas chromatograpohy colum?
pass through the colum at different speeds adna different retnetion times
59
Why is chlorine a gas at room temperature?
```
simple molecule
convalent bonds between the atoms
weaf forces betweenthe molecules
weak intermolecular forces
therefore low boiling point and is a gas ar room temperature
```
60
Why is sodium chloride a solid at room temperature?
```
ionic bonds
electrostatic attractions
giant lattice
strong bonds
large amounts of engery needed to break the bonds so it is a solid
```
61
State the effects of increasing the pressure on the rate of reaction
increases the rate of reaction
more particles in a smaller space
increase frequency of collision
62
What is actovation energy?
The minimum amount of energy particles need for a reaction to take place
63
A student concluded that potassium would NOT be a suitable metal to react with sulfuric acid, why?
too reactive
| would be dangerous
64
What happens at the negative electrode (with zinc chloride)?
zinc ions are attracted to the negative electrode
gains 2 electrons
froms zinc
65
Whta is an indication that a reaction is done at a high temperature?
gas is produced
66
endothermic:
A reaction wich takes in energy from its surroundins
67
Suggests one reason why carbon nanotubes are used in lubricants
nanotubes can slide over each other
| There are weak intermolecular forces / no convalent bonds between them
68
Mg^2+ O^2-
| What happens when magnesium atoms react with oxygen atoms to produce magnesium oxide?
Mg loses 2 electrons
O gains 2 electrons
They get a full outer shell
69
suggests why gas melts at a lower tmeperature than silicon dioxide
weaker bonds
70
Explain, in terms of ions, why sodium chloride solution conducts wlwctricity
ions can move
71
2 5 7 13
| which of these pH values could be the one of sodium hydroxide?
13
72
suggests how the student could check the reliablitlity of the results
repeat the experiment
73
Explai in terms od electrons how an ion atom (Fe) can change into an iron(III) ion (Fe^3+)
it loses
| 3 electrons
74
Explain why metals can be shaped
made pf layers
| which can slide over one another
75
What would you observe when magnesum reacts with an acid?
hydrogen gas is produced
| it get hot
76
HOw could you obtain solid magnesium sulfate from this solution?
crystalisation
77
Why are catalysits used in chemical reactions?
they speed up a reactio
78
Suggests why different catalysists are used for different experiment
different temperatures
79
Suggests and explain why the use of nanosized particles reduce the cost of the catalyst converter
smaller than normal sized atoms
bigger surface area
less catalys needed
80
Describe the structure and bonding in silicon dioxide and explain why it is a suitable material for making welding blakets
giant structure
strong bonds
high melting point
81
Why is using methanol an advantage to the artists?
less drying time
82
describe the bonds in methanol
stong convalent bonds
83
Explain why methanol has a low boiling point
bonds between the molecules are weak
84
Explain why the best equilibrium yields is obtained when the pressure is high
fewer product molecules
85
suggest one reason why the yields obtained is less than the maxiumum yield
reversable reaction
86
suggests why silver stops unpleasent smell when wearing socks with silver nanoparticles in them
kils bateria
87
The silver nanoparticles are more effective at preventing unpleasent smells than normal sized silver particles, why?
react faster
88
Name the particles which carry the electric current through:
the metal wire
the solution
The metal wire = electrons
| The solution = ions
89
Hydrogen has a low melting point, why?
weak intermolecular forces
90
Name the raw materials that are used to supply nitogen and hydrogen
```
Nitrogen = air
Hydrogen = natural gas
```
91
Explain why a temperature of 405 0C is used than a much higher temperature por a much lower temperature
higher temperature gives a low yield because reaction is exothermic
but at low temperature the rate is too slow
92
Ammonia is made by passing nitogen and hydrogen over hot iron.
Why is iron used in the reactor
How is ammonia separated from the unreacted nitogen over hot iron?
1) catalyst
| 2) cooled
93
What property of diamond makes it suitable for use on the cutting end of a drill bit?
hard
94
Why is diamond hard?
giant stucture
convalent bonds
bonds are stong
ecach carbon forms 4 bonds
95
Explain why graphite is a good conductor of electricity and why diamond is not
graphit:
free eletcrons
one electron from each atoms is delocalised and is free to move around the structure
diamond:
all electrons are used in bonding
96
suggest why sodium oxide and potassium oxide are dangerous in contact with the skin
corrosive
97
explain why changing the pressure does not affect the yield of hydrogen at equilibrium
same number of moecules on both sides of the euation
98
Suggest why the best yields of hydrogen at equilibrium is obtained at low temperature
forward reaction is exothermic
99
Scientists have developed catalysis which allow the reaction to take place quickly at lower temperature. How could this be good for the manufacture and for the environment?
more product
| less fuel needed
100
How is the nucleus of an oxygen-18 atom different from the one of an oxygen-16 atom?
O-18 has 2 more neutrons
101
If a reaction is exothermic, how will the temperature of the mixture change as the glue is mixed and a chemical reaction takes place?
increases
102
Why so substances with giant covalent structures have a high melting point?
nods are strong
| a lot of energy is needed to break the bonds
103
Suggest why using "nanocoated" tennis balls would be good for the environment
less tennis balls need to be made
| less pollution caused
104
Explain why the gel containing ions in solution can cunduct electricity
because the ions are free to move and carry a charge
105
Suggest how the use of a catalyst might reduce costs in the industrial production of aspirin
use a lower temperature
106
Explain why the highest equilibrium yield of methanol is obtained at high pressure
fewer product molecules than reactant molecules
107
Why are some local people worried about the use of chlorine compounds?
poisons released into the environment
108
Simple molecules like water have low boiling point, why?
weak intermolecular forces
109
Explain why at equilibrium the yield of ammonia for the reaction is greater at low temperatures
gives out heat/ exothermic reaction
110
What type of substance would be added to the water to provided the OH^- inons?
an alkali
111
what is a precipitate?
it is an insoluble substance
112
what method could be used to seperate the precipitate from the solution?
filtration
113
structure and bonding of graphite
```
only weak forces between the layers
layers can slide over each other
delocalised electrons
electrons can carry a charge
giant structure
```
114
What are the features of a reation which allows hydrogen to be released?
it is reversible
115
Why is hydrogen stored in a fuel tank filled with lithium nitride would be safer in an accident than a cylinder full of hydrogen?
hydrogen has bonded with lithium nitrate and therefore it does not leak
116
Explain how a flurine atom can hange into a fluoride ion, F^-
an electron is gained
117
Explain why the electrode would dry faster when washed with propanone instead of water
propane evapourates faster
118
Describe how electrolises is used to make pure copper from a lump of impure copper
copper loses electrons
copper forms at the positive ions
copper sulfate solution
impurities collected at the bottum
119
Why is silica used to make bricks for high-temperature furnaces
high melting point
covalent bonds
all atoms joined together no free electrons
120
What is ment by electrolyse?
electric current is passed through an ionic compound
121
Discus the economic, safety and environmental factors to be considered when there is an ammonia factory
Economic-factory provides employment
Safety-escape of dangerous chemicals
Environment-CO2 is produces by the burning fuels
122
What could cause a solution to go cloudy?
Sulphur which is insoluble
123
How can gas chromatography separate substance in a mixture of compounds?
Substances carried by gas
| Through a tube at different speeds
124
Suggests how an experiment could be improved
Use a more accurate digital thermometer
Put a lid on
Insulate the beaker
125
Give one reason why coins are not made of pure copper
| Not including cost
Malleable
| Softer
126
Aluminium is manufactures by the electrolysis of molten mixture of cryolite and ...
Aluminium oxide
127
The relative atomic mass of an element compares the mass of an atom of an element with the mass of an atoms of ...
Carbon-12
128
If it is a solid you...
Filter
129
If it is a solution you ...
Evaporate
130
Give some ethnic reasons why a compound if iodine should NOT be added to sodium chloride as food
Right to chose
| Different amounts neededNo evidence for the result
