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Chemistry C-2 > Exam Questions > Flashcards

Exam Questions Flashcards

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1
Q

Name the type of bond between the hydrongen and the chlorine atoms in a molecule of hydrogen choride

A

Covalent bond

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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
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3
Q

Why is it important to repeat the experiment?

A

To find a mean

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4
Q

What is the meaning of the term of a precipitation reaction?

A

Insoluble substances beiong formed

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5
Q

How can magnesium hydroxide be seperated from the calcium chloride solution?

A

Filtration

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6
Q

Name a method that can be used to change calcium chloride solution into solid calcium chloride

A

Crystallisation

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7
Q

half equation:

Ca —> Ca ^2+ + ….

A

2e^-

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8
Q

Why can the formation of calcium ions from calcium atoms be described as oxidisation?

A

Because electrons are lost

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9
Q

Explain why diamonds are hard

A

Because they have a giant structure, covalent bonds which are very strong

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10
Q

How is ammonia separated from unreacted nitrogen andhydrogenn in the separator

A

Mixing is cooled so that ammonia turns into a liquide

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11
Q

Why does the yield of ammonia at equilibrium increase as the temperature is decreased?

A

Becuase it is an exothemic reaction

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12
Q

Explain, in terms of particles, why increasing the temperature makes a reaction fo faster

A

particles move faster

collide more frequently

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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

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14
Q

Why would a higher pressure not be used?

A

Coast

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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

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16
Q

Describe the structure and bonding of gold

A

Giant structure
Delocalised electrons
Possitive ions and negative electrons attract to each other

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17
Q

Why is gold a good conductor of electrisity?

A

free electrons

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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

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19
Q

How did Wohler prove that a life force is NOT needed to make organic compounds?

A

He made another organic comound

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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

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21
Q

How solid lead nitraste can be obtained fro lead nitrate solution?

A

evapouration

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22
Q

The water and CO2 produced escape from the test tube, why?

A

because they are gases

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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

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24
Q

How could a graph give a conclusion?

A

by having a straight line

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25
Q

Why does the rate of reaction increase whent he conetration increases?

A

increase in the frequency of collision

particlies are closer together

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26
Q

Why do metals have a high melting point?

A

gaint structure
made of positive ions surrounded by free elecrons
stonge bonds
so alot pf energy is needed to break them

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27
Q

What does the term “nano” tell you about the carbon nanotubes?

A

they are very small

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28
Q

Why do carbon nanotubes conduct electricity?

A

free electrons

one non-bonded electron from each atom

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29
Q

Mg^2+ I^-

What happens when magnesium reacts with iodine?

A

magnesium loses 2 electrons

iodine gains 1 electron

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30
Q

Explain why a high temperature is needed to melt potassium iodide

A

bonds are strong
because oppositly charged ions attract
giant structure

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31
Q

HOw does a decrease in temperature affect the yeild of ammonia at equilibrium?

A

increase yeild

becuase the reaction is exothermic

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32
Q

HOw does an increase in pressure affect the yield of ammonia at equilibrium?

A

increase yield

becuase greater volume on the left than on the right

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33
Q

Do the reactants need to be heated?

A

yes to strat the reaction

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34
Q

A student investigates the reaction between magnesium and hydrochloric acid. Give two observatios the student could make during the reaction.

A

effervescence

magnesium dissolves

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35
Q

Name the type of reaction between aqueous ammonia solution and an acid

A

neutralisation

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36
Q

Davy first tried to elecrolise a solid potassium salt to produce potassium. Explain why this electrolysis did NOT work

A

current cannot flow because ions couldn’t move

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37
Q

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

A

gas = hydorgen
the ions as positve
potassium is more reactive than hydrogen

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38
Q

potassium metal was produced at the negative electrode. Describe how potassium atoms are formed from potassium ions

A

loses one electron

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39
Q

Why are alloys harder than pure metals?

A

because particles in alloys are different sizes, so the layers are distroted and they can no longer slide over one another

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40
Q

describe the stucture of a dimonde

A

giant structure
stong bonds between atoms
convalent bonds
each carbon atom froms 4 bonds

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41
Q

describe the structure and bonding in a thermosftening polymer and explain why thermosoftening polymers melt when heated

A

large molecules with weak intermolecular forces and are easily btocken when heated

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42
Q

Explain why, in terms of structure, CO2 is a gas, even at a low tempwerature

A

has simple molecules. The intermolecular forces are qweak and only a small amount of energy is needed to overcome the forces

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43
Q

What is the purpose of chromatography?

A

To split the properties of the gases

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44
Q

What information do the molecular ion peak from the mass spectrometer give about the substances?

A

relative molecular mass

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45
Q

suggests why scientists in 1800 could not extract aluminium from alumina

A

no method

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46
Q

How was Wohler able to prove that he had made a new metal?

A

when tesated it had the properties of a a metal

properties were dofferect from other known matals

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47
Q

Give two reasons why they should have repeated the experiment

A

improve reliablitly

reduce the effect of errors

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48
Q

name the method that could be used to seperate magenisium hydroxide from the solution

A

filtration

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49
Q

Why is the reaction a reduction reaction?

A

because electrons are gained

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50
Q

Why are metals very good conductors?

A

because their electrons can move freely through the structure and carry a charge

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51
Q

Suggests one reason why nanosized particles of silver might help to transfer heat bettwe than normal sized particles

A

more can fit into the gaps

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52
Q

Why does an increase in preassure increase the yield of ethanol at equilibrium?

A

2 particles on the left and one the right

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53
Q

Ethanol has a low boiling point and evapourates easily, why?

A

becaus ethe bonds betweent the molecules are weak

54
Q

Why is graphene strong?

A

giant structuer
convalent bonds
which are strong

55
Q

Why can graphene conducet electricity?

A

free electrons

3 electrons per atom used in bonding

56
Q

suggests why a sheet of graphite which has a large number of carbon layers would not be suitable for the touchscreen

A

because it is opaque

57
Q

In peper chromatography the start line line should be drawn with a ruler and a …….
Why?

A

pencil

the pencil will not run whereas the ink would

58
Q

Why do differenct compounds seperate a gas chromatograpohy colum?

A

pass through the colum at different speeds adna different retnetion times

59
Q

Why is chlorine a gas at room temperature?

A 
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
Q

Why is sodium chloride a solid at room temperature?

A 
ionic bonds
electrostatic attractions
giant lattice
strong bonds
large amounts of engery needed to break the bonds so it is a solid
61
Q

State the effects of increasing the pressure on the rate of reaction

A

increases the rate of reaction
more particles in a smaller space
increase frequency of collision

62
Q

What is actovation energy?

A

The minimum amount of energy particles need for a reaction to take place

63
Q

A student concluded that potassium would NOT be a suitable metal to react with sulfuric acid, why?

A

too reactive

would be dangerous

64
Q

What happens at the negative electrode (with zinc chloride)?

A

zinc ions are attracted to the negative electrode
gains 2 electrons
froms zinc

65
Q

Whta is an indication that a reaction is done at a high temperature?

A

gas is produced

66
Q

endothermic:

A

A reaction wich takes in energy from its surroundins

67
Q

Suggests one reason why carbon nanotubes are used in lubricants

A

nanotubes can slide over each other

There are weak intermolecular forces / no convalent bonds between them

68
Q

Mg^2+ O^2-

What happens when magnesium atoms react with oxygen atoms to produce magnesium oxide?

A

Mg loses 2 electrons
O gains 2 electrons
They get a full outer shell

69
Q

suggests why gas melts at a lower tmeperature than silicon dioxide

A

weaker bonds

70
Q

Explain, in terms of ions, why sodium chloride solution conducts wlwctricity

A

ions can move

71
Q

2 5 7 13

which of these pH values could be the one of sodium hydroxide?

A

13

72
Q

suggests how the student could check the reliablitlity of the results

A

repeat the experiment

73
Q

Explai in terms od electrons how an ion atom (Fe) can change into an iron(III) ion (Fe^3+)

A

it loses

3 electrons

74
Q

Explain why metals can be shaped

A

made pf layers

which can slide over one another

75
Q

What would you observe when magnesum reacts with an acid?

A

hydrogen gas is produced

it get hot

76
Q

HOw could you obtain solid magnesium sulfate from this solution?

A

crystalisation

77
Q

Why are catalysits used in chemical reactions?

A

they speed up a reactio

78
Q

Suggests why different catalysists are used for different experiment

A

different temperatures

79
Q

Suggests and explain why the use of nanosized particles reduce the cost of the catalyst converter

A

smaller than normal sized atoms
bigger surface area
less catalys needed

80
Q

Describe the structure and bonding in silicon dioxide and explain why it is a suitable material for making welding blakets

A

giant structure
strong bonds
high melting point

81
Q

Why is using methanol an advantage to the artists?

A

less drying time

82
Q

describe the bonds in methanol

A

stong convalent bonds

83
Q

Explain why methanol has a low boiling point

A

bonds between the molecules are weak

84
Q

Explain why the best equilibrium yields is obtained when the pressure is high

A

fewer product molecules

85
Q

suggest one reason why the yields obtained is less than the maxiumum yield

A

reversable reaction

86
Q

suggests why silver stops unpleasent smell when wearing socks with silver nanoparticles in them

A

kils bateria

87
Q

The silver nanoparticles are more effective at preventing unpleasent smells than normal sized silver particles, why?

A

react faster

88
Q

Name the particles which carry the electric current through:
the metal wire
the solution

A

The metal wire = electrons

The solution = ions

89
Q

Hydrogen has a low melting point, why?

A

weak intermolecular forces

90
Q

Name the raw materials that are used to supply nitogen and hydrogen

A 
Nitrogen = air
Hydrogen = natural gas
91
Q

Explain why a temperature of 405 0C is used than a much higher temperature por a much lower temperature

A

higher temperature gives a low yield because reaction is exothermic
but at low temperature the rate is too slow

92
Q

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?

A

1) catalyst

2) cooled

93
Q

What property of diamond makes it suitable for use on the cutting end of a drill bit?

A

hard

94
Q

Why is diamond hard?

A

giant stucture
convalent bonds
bonds are stong
ecach carbon forms 4 bonds

95
Q

Explain why graphite is a good conductor of electricity and why diamond is not

A

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
Q

suggest why sodium oxide and potassium oxide are dangerous in contact with the skin

A

corrosive

97
Q

explain why changing the pressure does not affect the yield of hydrogen at equilibrium

A

same number of moecules on both sides of the euation

98
Q

Suggest why the best yields of hydrogen at equilibrium is obtained at low temperature

A

forward reaction is exothermic

99
Q

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?

A

more product

less fuel needed

100
Q

How is the nucleus of an oxygen-18 atom different from the one of an oxygen-16 atom?

A

O-18 has 2 more neutrons

101
Q

If a reaction is exothermic, how will the temperature of the mixture change as the glue is mixed and a chemical reaction takes place?

A

increases

102
Q

Why so substances with giant covalent structures have a high melting point?

A

nods are strong

a lot of energy is needed to break the bonds

103
Q

Suggest why using “nanocoated” tennis balls would be good for the environment

A

less tennis balls need to be made

less pollution caused

104
Q

Explain why the gel containing ions in solution can cunduct electricity

A

because the ions are free to move and carry a charge

105
Q

Suggest how the use of a catalyst might reduce costs in the industrial production of aspirin

A

use a lower temperature

106
Q

Explain why the highest equilibrium yield of methanol is obtained at high pressure

A

fewer product molecules than reactant molecules

107
Q

Why are some local people worried about the use of chlorine compounds?

A

poisons released into the environment

108
Q

Simple molecules like water have low boiling point, why?

A

weak intermolecular forces

109
Q

Explain why at equilibrium the yield of ammonia for the reaction is greater at low temperatures

A

gives out heat/ exothermic reaction

110
Q

What type of substance would be added to the water to provided the OH^- inons?

A

an alkali

111
Q

what is a precipitate?

A

it is an insoluble substance

112
Q

what method could be used to seperate the precipitate from the solution?

A

filtration

113
Q

structure and bonding of graphite

A 
only weak forces between the layers
layers can slide over each other
delocalised electrons
electrons can carry a charge
giant structure
114
Q

What are the features of a reation which allows hydrogen to be released?

A

it is reversible

115
Q

Why is hydrogen stored in a fuel tank filled with lithium nitride would be safer in an accident than a cylinder full of hydrogen?

A

hydrogen has bonded with lithium nitrate and therefore it does not leak

116
Q

Explain how a flurine atom can hange into a fluoride ion, F^-

A

an electron is gained

117
Q

Explain why the electrode would dry faster when washed with propanone instead of water

A

propane evapourates faster

118
Q

Describe how electrolises is used to make pure copper from a lump of impure copper

A

copper loses electrons
copper forms at the positive ions
copper sulfate solution
impurities collected at the bottum

119
Q

Why is silica used to make bricks for high-temperature furnaces

A

high melting point
covalent bonds
all atoms joined together no free electrons

120
Q

What is ment by electrolyse?

A

electric current is passed through an ionic compound

121
Q

Discus the economic, safety and environmental factors to be considered when there is an ammonia factory

A

Economic-factory provides employment
Safety-escape of dangerous chemicals
Environment-CO2 is produces by the burning fuels

122
Q

What could cause a solution to go cloudy?

A

Sulphur which is insoluble

123
Q

How can gas chromatography separate substance in a mixture of compounds?

A

Substances carried by gas

Through a tube at different speeds

124
Q

Suggests how an experiment could be improved

A

Use a more accurate digital thermometer
Put a lid on
Insulate the beaker

125
Q

Give one reason why coins are not made of pure copper

Not including cost

A

Malleable

Softer

126
Q

Aluminium is manufactures by the electrolysis of molten mixture of cryolite and …

A

Aluminium oxide

127
Q

The relative atomic mass of an element compares the mass of an atom of an element with the mass of an atoms of …

A

Carbon-12

128
Q

If it is a solid you…

A

Filter

129
Q

If it is a solution you …

A

Evaporate

130
Q

Give some ethnic reasons why a compound if iodine should NOT be added to sodium chloride as food

A

Right to chose

Different amounts neededNo evidence for the result

Chemistry C-2 (8 decks)

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