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

C1 - Air and Water Flashcards

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
What are the problems with carbon | monoxide?
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.
26
What is the problem with carbon | particulates?
What is the problem with carbon particulates? - Causes breathing problems - Blackens buildings - Can block appliances and cause fires
27
What is the main source of sulphur | dioxide?
What is the main source of sulphur dioxide? | Combustion of sulphur impurities in fuel.
28
What is the problem with sulphur dioxide?
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.
29
What is the main source of oxides of | nitrogen?
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
What is the problem with oxides of | nitrogen?
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
List three ways the emission of | atmospheric pollutants can be reduced
List three ways the emission of atmospheric pollutants can be reduced - Use catalytic converters - Use lower sulfur fuel - Use gas scrubbers
32
Describe how a catalytic converter reduces emissions of atmospheric pollutants
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
Describe how gas scrubbers reduce | emissions of atmospheric pollutants
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
Use chemical symbols to write the formula of carbon dioxide, nitrogen and methane
Use chemical symbols to write the formula of carbon dioxide, nitrogen and methane Carbon dioxide - CO2 Nitrogen - N2 Methane - CH4
35
Write the word and balanced symbol | equations for the combustion of methane
Write the word and balanced symbol equations for the combustion of methane Methane + oxygen → carbon dioxide + water CH4 + 2O2 → CO2 + 2H2O
36
Describe the test for oxygen
Describe the test for oxygen A test tube of oxygen will relight a glowing splint.
37
Describe the test for hydrogen
Describe the test for hydrogen A lighted splint placed in a test tube of hydrogen will make a squeaky pop.
38
Describe the test for carbon dioxide
Describe the test for carbon dioxide Turns limewater (calcium hydroxide) from colourless to cloudy as calcium carbonate precipitate is produced.
39
In terms of oxygen, what is meant by | oxidation?
In terms of oxygen, what is meant by oxidation? Gain of oxygen
40
What is an example of a common | oxidation reaction?
What is an example of a common oxidation reaction? Combustion
41
What does exothermic mean?
Exothermic - a reaction that gives out | energy to the surroundings.
42
What does endothermic mean?
Endothermic - a reaction that takes in | energy from the surroundings.
43
During a chemical reaction, the | temperature of the surroundings increases. Is this reaction exothermic or endothermic?
During a chemical reaction, the temperature of the surroundings increases. Is this reaction exothermic or endothermic? Exothermic - energy is released during the reaction.
44
Check CGP for reaction profiles
Ok
45
What does the term activation energy | mean?
What does the term activation energy mean? The minimum energy required for a reaction to occur.
46
In terms of bond energies, what happens during a chemical reaction? Describe exothermic and endothermic reactions in terms of bonds breaking / forming.
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
How can the energy change of a reaction | be calculated from bond energies?
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
Describe an experiment to investigate whether a reaction is exothermic or endothermic
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
How can a chemical cell be set up to | produce a potential difference?
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
When does a chemical cell stop | producing a potential difference?
When does a chemical cell stop producing a potential difference? When the reactants have been used up.
51
What are the advantages of using | hydrogen fuel cells in vehicles?
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
What are the disadvantages of using | hydrogen fuel cells in vehicles?
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
Describe the greenhouse effect
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
How does human activity cause climate | change?
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
What is the trend between carbon dioxide concentration and use of fossil fuels?
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
Why are there uncertainties in the evidence used to look at the causes of climate change?
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
What are the effects of increasing levels of carbon dioxide and methane in the atmosphere?
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
How can the effects of increasing levels | of carbon dioxide be reduced?
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
How can the effects of increasing levels | of methane be reduced?
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
What is meant by potable water?
What is meant by potable water? Water that is safe to drink.
61
Describe the main steps involved in | treating groundwater
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
The 3 main steps involved in treating wastewater
The 3 main steps involved in treating wastewater 1) Sedimentation 2) Filtration 3) Chlorination
63
Steps involved in treating wastewater - 1) Sedimentation
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
Steps involved in treating wastewater - 2) Filtration
Steps involved in treating wastewater - 2) Filtration 2. Filtration: Removes small insoluble particles by passing the water through layers of sand and filters.
65
Steps involved in treating wastewater - 3) Chlorination
Steps involved in treating wastewater - 3) Chlorination 3. Chlorination: Kills bacteria and microorganisms which are too small to be removed by filtration.
66
Describe the main steps involved in treating | wastewater
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
What is the name of the process used to | remove salt from water?
What is the name of the process used to remove salt from water? Desalination
68
Describe two methods that could be | used to treat salt water
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
Why is chlorine added to water? What is | the problem with chlorine?
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
Describe the test for chlorine
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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