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Year 9 Chemistry > Gases > Flashcards

Gases Flashcards

1
Q

What percentage by volume is the air nitrogen?

A

78%

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2
Q

What percentage by volume is the air oxygen?

A

21%

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3
Q

What percentage by volume is the air Argon?

A

0.93%

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4
Q

What percentage by volume is the air carbon dioxide?

A

0.04%

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5
Q

What percentage by volume is the air inert gases, water vapour and pollutants?

A

0.03%

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6
Q

Describe the method which you could use to measure the percentage of oxygen in the air with copper

A
  • assemble the equipment so that two gas syringes, one containing 100ml of air, the other none, facing one another are both connected to a tube containing copper powder by capillary tubes.
  • make sure the area is sealed so that no air escapes and the test is accurate
  • heat the tube containing the copper powder with a blue/ roaring flame, from different angles to ensure all copper is heated (uniform heating)
  • push a syringe on one side so that the air is pushed through the tube, into the opposite syringe. Repeat this step to ensure all the oxygen can react
  • remove the Bunsen burner and leave the apparatus to cool. You will start to see the copper change in colour
  • you started with 100ml of air in one of the syringes, but the volume of air will have decreased during the reaction
  • you can calculate the volume of oxygen in the air by subtracting the remaining mass of air from 100ml
  • the answer should be around 20 or 20% of the air (by volume)

MY CALCULATION:
100-79=21

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7
Q

What is the equation for copper reacting with oxygen?

A

Copper + oxygen ➡️ copper oxide

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8
Q

Why should the Bunsen burner be moved along the tube containing the copper?

A

To ensure that all copper particles are heated so that the test is more fair and accurate

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9
Q

Why should the copper be in excess?

A

So that there is enough copper for all of the oxygen to react with and ensure that all the oxygen is able to react

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10
Q

Why does the plunger go outwards initially when heating started?

A
  • because as the gas is heated, its volume increases so the plunger is pushed outwards
  • any excess water, air etc is evaporated off the copper and will join the air
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11
Q

Why should the apparatus be allowed to cool fully before the final reading on the gas syringe is taken?

A

The gaps between particles expand when heated, so the results would be falsely high. When the apparatus is cooled, the volume decreases and is more accurate.

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12
Q

What happens in an oxidisation reaction?

A

Oxidation is the loss of electrons from a substance. It is also the gain of oxygen by a substance. For example, magnesium is oxidised when it reacts with oxygen to form magnesium oxide:

magnesium + oxygen → magnesium oxide
2Mg + O2 → 2MgO

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13
Q

What happens in a reduction reaction?

A

Reduction is the gain of electrons by a substance. It is also the loss of oxygen from a substance. For example, copper(II) oxide can be reduced to form copper when it reacts with hydrogen:

copper(II) oxide + hydrogen → copper + water
CuO + H2 → Cu + H2O

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14
Q

What is a redox reaction?

A

A reaction where oxidation and reduction take place at the same time.

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15
Q

What are the oxidising agent and the reducing agent?

A
  • the oxidising agent is the chemical that causes oxidation

- the reducing agent causes the other chemical to be reduced

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16
Q

What substance is formed when metals react with oxygen?

A

A metal oxide

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17
Q

What is the observation of sulphur burning in air?

A

Starts to turn red and melts

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18
Q

What is the observation of carbon burning in air?

A

Red/yellow flame is emitted

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19
Q

What is the observation of magnesium burning in air?

A

Bright white flame is emitted

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20
Q

What is the observation of sulphur burning in oxygen?

A

Blue flame is emitted

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21
Q

What is the observation of carbon burning in oxygen?

A

Bright red/yellow flame is emitted

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22
Q

What is the observation of magnesium burning in oxygen?

A

Extremely bright white flame is emitted

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23
Q

What is the appearance of the product of burning sulphur?

A

red liquid

Colourless gas

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24
Q

What is the appearance of the product of burning carbon (e.g metal carbonates)?

A

Colourless gas (carbon dioxide)

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25
Q

What is the appearance of the product of burning magnesium?

A

White, powdery ash

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26
Q

What does the colour of universal indicator go after adding water to the product of sulphur and shaking?

A

Red (acidic)

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27
Q

What does the colour of universal indicator go after adding water to the product of carbon and shaking?

A

Yellow/green (neutral)

28
Q

What does the colour of universal indicator go after adding water to the product of magnesium and shaking?

A

Greeny blue

29
Q

What is the equation for the combustion of sulphur in oxygen?

A

Sulphur + oxygen ➡️ sulphur dioxide

30
Q

What is the equation for the combustion of carbon in oxygen?

A

Carbon + oxygen ➡️ carbon dioxide

31
Q

What is the equation for the combustion of magnesium in oxygen?

A

Magnesium + oxygen ➡️ magnesium oxide

32
Q

Are non metal oxides acidic or alkali?

33
Q

Are metal oxides acidic or alkali?

34
Q

Describe how to test the volume of oxygen in the air using iron wool.

A
  • First soak some iron wool in acetic acid (The acid will catalyse the reaction). Then push the wall into a measuring cylinder and insert the measuring cylinder into a beaker of water.
  • Record of the starting position of the water using the scale on the measuring cylinder - this is the starting volume of air.
  • Over time the level of the water in the measuring cylinder will rise.
  • This is because the iron reacts with oxygen in the air to make iron oxide. The water rises to fill the space the oxygen took up.
  • Leave the measuring cylinder for around a week or until the water level stops changing.
  • Record the finishing position of the water - this is the final volume of air.

You can then calculate the percentage (by volume) of oxygen in the air using this formula.

Start volume - final volume
———————————— X 100
Start volume

The answer should be around 20%

35
Q

How does Carbon Dioxide get into the environment?

A

By burning fossil fuels

36
Q

What is the problem of Carbon Dioxide to the environment?

A

Acts as an insulating layer, causing global warming

37
Q

What is a possible solution to the problems of Carbon Dioxide into the environment?

A

Reduce burning fossil fuels and plant more trees

38
Q

How do nitrogen oxides get into the environment?

A

Are created when the temperature is high enough for nitrogen and oxygen in the air to react.
This often happens in car engines and power plants

39
Q

What is the problem of oxides of nitrogen to the environment

A

When they mix with sulphur dioxide and water vapour in clouds, acid rain happens.
Acid rain causes lakes to become acidic, causing plants and animals to die

40
Q

What is a possible solution to reduce the problems of the oxides of nitrogen affecting the environment?

A

Use less crude oil for fuel and reduce car usage

41
Q

How does sulphur oxide get into the environment?

A

It is formed mainly when crude oil is burnt for fuel

42
Q

What is the problem of sulphur dioxide for the environment?

A

Causes acid rain

43
Q

What is a possible solution to reduce the impacts of the problems for the environment by sulphur dioxide?

A

Use less crude oil for fuel

44
Q

What is thermal decomposition?

A

It is a type of reaction in which a compound breaks down to form two or more substances when it is heated.

45
Q

Describe the method to test for carbon dioxide in metal carbonates

A
  • place a small amount of one of the solid carbonates in a dry test tube
  • place about 2cm3 of lime water in another test tube. Heat the solid, gently at first, then more strongly
  • test any gas with the limewater, the limewater will go cloudy when in contact with carbon dioxide
46
Q

What is the appearance of calcium carbonate?

47
Q

What is the appearance of copper carbonate?

48
Q

What is the appearance of magnesium carbonate?

49
Q

What is the appearance of zinc carbonate?

50
Q

What is the appearance of the residue of calcium carbonate?

A

White solid

51
Q

What is the appearance of the residue of copper carbonate?

A

Black solid

52
Q

What is the appearance of the residue of magnesium carbonate?

A

White solid

53
Q

What is the appearance of the residue of zinc carbonate?

A

Yellow solid

54
Q

What is the equation for the thermal decomposition of metal carbonates?

A

Metal carbonate ➡️ metal oxide + carbon dioxide

55
Q

What is combustion?

A

Burning an element in oxygen

56
Q

Are elements created in thermal decomposition?

A

In decomposition reactions, elements are not created or taken away, just rearranged

57
Q

What is the equation for when a metal and acid react?

A

Metal ➕acid ➡️metal salt ➕hydrogen

58
Q

What is the equation for the reaction of magnesium and hydrochloride acid?

A

Magnesium ➕hydrochloride acid ➡️magnesium chloride ➕hydrogen

59
Q

What is the equation for the combustion of hydrogen?

A

Hydrogen ➕oxygen ➡️ water

60
Q

What is the physical test for water?

A

Measure the freezing and boiling point of the liquid, if it is pure water, it’s boiling point will be 100degreesC and the freezing point will be 0degreeesC

61
Q

What are the two chemical tests for pure water?

A
  • Add a few drops of the liquid to cobalt chloride paper, which will turn blue to pink if water is present
  • add the liquid to anhydrous copper sulphate which will turn from white to blue when in contact with water
62
Q

What is the equation for ahydrous copper sulphate with water?

A

Ahydrous copper sulphate ➕ water ➡️ hydrated copper sulphate

63
Q

What is an easy test for oxygen?

A

If oxygen is present, it will relight a glowing splint

64
Q

How many neutrons does a hydrogen atom have?

65
Q

What percentage by volume is the air other gases

66
Q

What is the observation of hydrogen burning in oxygen?

A

Explosive reaction

Year 9 Chemistry (5 decks)

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