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Chemistry Flashcards - OCR 21st Century > C1 - Air and Water > Flashcards

C1 - Air and Water Flashcards

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1
Q

How are particles arranged in solids,

liquids and gases?

A

How are particles arranged in solids, liquids and
gases?
● Solid - regular arrangement, very close
together.
● Liquid - random arrangement, close together.
● Gas - random arrangement, far apart.

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2
Q

Describe the energy and movement of

particles in solids

A

Solid - vibrate in a fixed position, low energy.

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3
Q

Describe the energy and movement of

particles in liquids

A

Liquid - move around each other, higher

energy.

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4
Q

Describe the energy and movement of

particles in gases

A

Gas - move randomly in all directions,

highest energy.

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5
Q

What are the names for the state
changes from solid to liquid and vice
versa?

A

What are the names for the state changes from solid
to liquid and vice versa?

Solid → liquid: Melting
Liquid → solid: Freezing

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6
Q

Describe what happens, in terms of

particles, when a solid melts

A

Describe what happens, in terms of particles, when a
solid melts

When heated the particles absorb thermal energy
which is converted into kinetic energy. The
particles in the solid vibrate more. This causes
the solid to expand until the structure breaks and
becomes a liquid.

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7
Q

What is the term describing when a solid

changes straight into a gas?

A

What is the term describing when a solid changes
straight into a gas?

Sublimation

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8
Q

What are the names for the state
changes from liquid to gas and vice
versa?

A

What are the names for the state changes from
liquid to gas and vice versa?

Liquid → gas: Evaporation
Gas → liquid: Condensation

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9
Q

Describe what happens, in terms of

particles, when a liquid evaporates

A

Describe what happens, in terms of particles, when a
liquid evaporates

When heated, the particles in a liquid expand and
some particles on the surface gain sufficient
energy to overcome the intermolecular forces
and evaporate. At the boiling point, all of the
liquid particles gain enough energy to evaporate.

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10
Q

Describe, in terms of energy what

happens when a liquid freezes

A

Describe, in terms of energy what happens when a
liquid freezes

Energy is transferred from the liquid to
the surroundings. The particles have less
kinetic energy so the liquid becomes a
solid.

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11
Q

Do particles have the same properties as

the bulk substance?

A

Do particles have the same properties as the bulk
substance?

No
The arrangement and movement of all the
particles affects the physical properties of a
bulk substance.

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12
Q

Explain the physical properties of solids

A

Explain the physical properties of solids
- Fixed shape because the particles can’t
move.
- They cannot be compressed because the
particles are very close together so there
is no space for particle to move into.

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13
Q

Explain the physical properties of liquids

A

Explain the physical properties of liquids
- Flow because the particles can move
around each other.
- Cannot be compressed because the
particles are quite close together so there
is no space for particles to move into.

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14
Q

Explain the physical properties of gases

A

Explain the physical properties of gases
- Fill a container because the particles move rapidly
in all directions.
- Can be compressed because the particles are far
apart together with space for particle to move into.
- Flow because the particles can move around each
other.

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15
Q

How does a physical change differ from

a chemical change?

A

How does a physical change differ from a chemical
change?
A physical change involves changes in the forces
between particles. The particles and chemical
properties remain the same.
A chemical change affects the chemical properties of
the substance.

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16
Q

What are the limitations of the particle

model?

A

What are the limitations of the particle model?

  • It assumes particles are spherical.
  • All particles are shown as the same size.
  • Gaps between gaseous atoms should be much
    larger.
  • It doesn’t show the difference in the forces of
    attraction between particles.
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17
Q

Substance A melts at 42°C and boils at
107°C. What state is substance A at 50°
C?

A

Substance A melts at 42°C and boils at 107°C. What
state is substance A at 50°C?

Liquid

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18
Q

Substance B melts at -17°C and boils at

2°C. What state is substance B at 20°C?

A

Substance B melts at -17°C and boils at 2°C. What
state is substance B at 20°C?

Gas

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19
Q

Substance C melts at -30°C and boils at
-5°C. What state is substance C at -45°
C?

A

Substance C melts at -30°C and boils at -5°C. What
state is substance C at -45°C?

Solid

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20
Q

What three types of evidence are there
for the composition of the early
atmosphere?

A

Volcanoes - modern volcanoes release CO2
and water suggesting the early atmosphere was mostly made up of these compounds.

Ancient rocks - iron sulfide is only found in rocks formed before oxygen was in the atmosphere. Rocks with iron oxide need oxygen to form.
Dating rocks suggests when oxygen was first in the atmosphere.

Fossils - life processes affect the atmosphere. Early plants suggest how oxygen was added to the atmosphere.

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21
Q

How did oceans initially form?

A

How did oceans initially form?

Condensation of water vapour from
volcanoes.

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22
Q

How did the amount of carbon dioxide in

the atmosphere decrease after oceans formed?

A

How did the amount of carbon dioxide in the
atmosphere decrease after oceans formed?

Carbon dioxide dissolved into the oceans
so the amount of carbon dioxide in the
atmosphere decreased.

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23
Q

How did the oxygen-rich atmosphere

develop?

A

How did the oxygen-rich atmosphere develop?

The growth of early plants used carbon dioxide
for photosynthesis and released oxygen. This
increased the amount of oxygen and decreased
the amount of carbon dioxide in the
atmosphere.

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24
Q

What is the main source of carbon

monoxide and carbon particulates?

A

What is the main source of carbon monoxide and
carbon particulates?

Incomplete combustion

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25
Q

What are the problems with carbon

monoxide?

A

What are the problems with carbon monoxide?
Carbon monoxide is a toxic gas.

It is colourless and odourless and if breathed
in can cause death by preventing the red
blood cells from carrying oxygen around the
body.

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26
Q

What is the problem with carbon

particulates?

A

What is the problem with carbon particulates?

  • Causes breathing problems
  • Blackens buildings
  • Can block appliances and cause fires
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27
Q

What is the main source of sulphur

dioxide?

A

What is the main source of sulphur dioxide?

Combustion of sulphur impurities in fuel.

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28
Q

What is the problem with sulphur dioxide?

A

What is the problem with sulphur dioxide?
Sulphur dioxide reacts with water in clouds to form acid rain.
Acid rain:
- Corrodes metal structures.
- Damages stone buildings and statues.
- Damages the waxy layer on leaves.
- Increases the acidity of aquatic environments such as lakes.

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29
Q

What is the main source of oxides of

nitrogen?

A

What is the main source of oxides of nitrogen?

Oxidation of nitrogen at high temperatures
(i.e. when fuels are combusted in
engines) followed by further oxidation in
the air.

30
Q

What is the problem with oxides of

nitrogen?

A

What is the problem with oxides of nitrogen?

  • React with sunlight to form smog
  • Toxic
  • Causes bronchitis / lung diseases
  • React with water to form acid rain
31
Q

List three ways the emission of

atmospheric pollutants can be reduced

A

List three ways the emission of atmospheric
pollutants can be reduced

  • Use catalytic converters
  • Use lower sulfur fuel
  • Use gas scrubbers
32
Q

Describe how a catalytic converter
reduces emissions of atmospheric
pollutants

A

Describe how a catalytic converter reduces
emissions of atmospheric pollutants

Nitrogen monoxide and carbon
monoxide are converted to nitrogen and
carbon dioxide which are less harmful.

33
Q

Describe how gas scrubbers reduce

emissions of atmospheric pollutants

A

Describe how gas scrubbers reduce emissions of
atmospheric pollutants

Reduces emissions of sulphur dioxide in flue
gases from power stations.

An alkaline slurry (calcium oxide and water)
or sea water are used in wet scrubbing.

34
Q

Use chemical symbols to write the
formula of carbon dioxide, nitrogen and
methane

A

Use chemical symbols to write the formula of carbon
dioxide, nitrogen and methane

Carbon dioxide - CO2
Nitrogen - N2
Methane - CH4

35
Q

Write the word and balanced symbol

equations for the combustion of methane

A

Write the word and balanced symbol equations for
the combustion of methane
Methane + oxygen → carbon dioxide + water
CH4 + 2O2 → CO2 + 2H2O

36
Q

Describe the test for oxygen

A

Describe the test for oxygen

A test tube of oxygen will relight a
glowing splint.

37
Q

Describe the test for hydrogen

A

Describe the test for hydrogen

A lighted splint placed in a test tube of
hydrogen will make a squeaky pop.

38
Q

Describe the test for carbon dioxide

A

Describe the test for carbon dioxide

Turns limewater (calcium hydroxide) from colourless to cloudy as calcium carbonate precipitate is produced.

39
Q

In terms of oxygen, what is meant by

oxidation?

A

In terms of oxygen, what is meant by oxidation?

Gain of oxygen

40
Q

What is an example of a common

oxidation reaction?

A

What is an example of a common oxidation
reaction?

Combustion

41
Q

What does exothermic mean?

A

Exothermic - a reaction that gives out

energy to the surroundings.

42
Q

What does endothermic mean?

A

Endothermic - a reaction that takes in

energy from the surroundings.

43
Q

During a chemical reaction, the

temperature of the surroundings increases. Is this reaction exothermic or endothermic?

A

During a chemical reaction, the temperature of the
surroundings increases. Is this reaction exothermic
or endothermic?

Exothermic - energy is released during
the reaction.

44
Q

Check CGP for reaction profiles

A

Ok

45
Q

What does the term activation energy

mean?

A

What does the term activation energy mean?

The minimum energy required for a
reaction to occur.

46
Q

In terms of bond energies, what happens
during a chemical reaction? Describe
exothermic and endothermic reactions in
terms of bonds breaking / forming.

A

Energy is needed to break bonds and is released when bonds are made.

Exothermic: Energy released from breaking bonds is greater than the energy used to make bonds.

Endothermic: Energy released in forming new bond is greater than the energy used to break old bonds.

47
Q

How can the energy change of a reaction

be calculated from bond energies?

A

How can the energy change of a reaction be
calculated from bond energies?
Energy change (kJ mol-1) =
Total energy of bonds broken - total energy of bonds made

48
Q

Describe an experiment to investigate
whether a reaction is exothermic or
endothermic

A

Describe an experiment to investigate whether a
reaction is exothermic or endothermic

Place a thermometer into the first reactant, and record
the initial temperature. Add a second reactant and mix,
observing the temperature change. A temperature rise
means the reaction is exothermic. A fall in temperature
means it’s endothermic.

49
Q

How can a chemical cell be set up to

produce a potential difference?

A

How can a chemical cell be set up to produce a
potential difference?

Two different metals are placed in salt solutions of
their own ions. The metals are connected by a wire.

Electrons flow through the wire from the more
reactive metal to the less reactive metal. This flow of
electrons produces a potential difference.

50
Q

When does a chemical cell stop

producing a potential difference?

A

When does a chemical cell stop producing a
potential difference?

When the reactants have been used up.

51
Q

What are the advantages of using

hydrogen fuel cells in vehicles?

A

What are the advantages of using hydrogen fuel
cells in vehicles?

  • No pollutants produced (only water) so
    less air pollution
  • Reduces carbon dioxide emissions
  • Reduces use of fossil fuels
52
Q

What are the disadvantages of using

hydrogen fuel cells in vehicles?

A

What are the disadvantages of using hydrogen fuel
cells in vehicles?
● Hydrogen is produced by electrolysis which uses
electricity (pollutants produced when burning fossil fuel).
● Difficult to store hydrogen.
● Fuel cells and electric motors aren’t as durable as
petrol/diesel engines.
● Very expensive.

53
Q

Describe the greenhouse effect

A

Describe the greenhouse effect

  • Electromagnetic radiation passes through the atmosphere and is absorbed by the Earth, causing the Earth to warm up.
  • The Earth releases energy as infrared radiation (IR).
  • Some IR goes into space but some is absorbed by
    greenhouse gases in the atmosphere. This warms the
    lower atmosphere.
54
Q

How does human activity cause climate

change?

A

How does human activity cause climate change?
- Burning of fuels releases carbon dioxide.
- Raising livestock releases methane which is
a greenhouse gas.
- Deforestation limits the amount of vegetation
absorbing carbon dioxide for photosynthesis.

55
Q

What is the trend between carbon
dioxide concentration and use of fossil
fuels?

A

What is the trend between carbon dioxide
concentration and use of fossil fuels?
As fuel consumption increases so does the concentration of carbon dioxide in the atmosphere.

56
Q

Why are there uncertainties in the
evidence used to look at the causes of
climate change?

A

Why are there uncertainties in the evidence used to
look at the causes of climate change?

  • It is hard to model the complex idea of
    global climate change.
  • Evidence is largely based on simplified
    models.
57
Q

What are the effects of increasing levels
of carbon dioxide and methane in the
atmosphere?

A

What are the effects of increasing levels of carbon
dioxide and methane in the atmosphere?

  • Extinction of species.
  • Melting of polar ice caps leading to rising sea levels.
  • Flash flooding - impacting crop yield.
  • Extreme weather.
  • Fewer places suitable for growing crops.
58
Q

How can the effects of increasing levels

of carbon dioxide be reduced?

A

How can the effects of increasing levels of carbon
dioxide be reduced?

  • More carbon dioxide sinks to absorb CO2
    (reforestation of rainforests).
  • Lower vehicle emissions: Discourage car use with taxes, have more efficient and affordable public transport or improve engine efficiency.
  • Decrease power station emissions by reducing electricity consumption. Use carbon capture or different methods to generate electricity.
59
Q

How can the effects of increasing levels

of methane be reduced?

A

How can the effects of increasing levels of methane
be reduced?
- Reduce emissions from landfill by encouraging composting and incineration or by capturing methane for use as fuel.
- Reduce farming emissions by decreasing livestock numbers and by spreading manure on fields (where it doesn’t release methane).
- Use anaerobic digester to store and capture methane
produced by waste.

60
Q

What is meant by potable water?

A

What is meant by potable water?

Water that is safe to drink.

61
Q

Describe the main steps involved in

treating groundwater

A

Describe the main steps involved in treating
groundwater

Groundwater has passed through layers of rock and sand so has already been filtered. The water must be chlorinated to kill microorganisms and make it potable.

62
Q

The 3 main steps involved in treating wastewater

A

The 3 main steps involved in treating wastewater

1) Sedimentation
2) Filtration
3) Chlorination

63
Q

Steps involved in treating wastewater - 1) Sedimentation

A

Steps involved in treating wastewater - Sedimentation

  1. Sedimentation: Large insoluble particles sink to the
    bottom after the water is left still for a while
64
Q

Steps involved in treating wastewater - 2) Filtration

A

Steps involved in treating wastewater - 2) Filtration

  1. Filtration: Removes small insoluble particles by
    passing the water through layers of sand and filters.
65
Q

Steps involved in treating wastewater - 3) Chlorination

A

Steps involved in treating wastewater - 3) Chlorination

  1. Chlorination: Kills bacteria and microorganisms
    which are too small to be removed by filtration.
66
Q

Describe the main steps involved in treating

wastewater

A

Describe the main steps involved in treating
wastewater

  1. Sedimentation: Large insoluble particles sink to the
    bottom after the water is left still for a while.
  2. Filtration: Removes small insoluble particles by
    passing the water through layers of sand and filters.
  3. Chlorination: Kills bacteria and microorganisms
    which are too small to be removed by filtration.
67
Q

What is the name of the process used to

remove salt from water?

A

What is the name of the process used to remove salt
from water?

Desalination

68
Q

Describe two methods that could be

used to treat salt water

A

Describe two methods that could be used to treat
salt water
Distillation - filter the sea water, boil it, water
evaporates and collects in condenser.

Membrane filtration - extremely fine
membranes allow water molecule to pass
through but not dissolved salts.

69
Q

Why is chlorine added to water? What is

the problem with chlorine?

A

Why is chlorine added to water? What is the problem
with chlorine?
Adding chlorine to water to kill microorganisms.

Chlorine is toxic but reduces the risk of waterborne diseases. Only a small amount is added to water so most countries believe the benefits outweigh the risks.

70
Q

Describe the test for chlorine

A

Describe the test for chlorine gas

Insert damp blue litmus paper into a test
tube of gas. If chlorine is present, the
litmus paper turns red then fades to
white.

Chemistry Flashcards - OCR 21st Century (9 decks)

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