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8Ne Year 8 Science > 8F Reactions > Flashcards

8F Reactions Flashcards

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1
Q

State two observations that a chemical reaction is occurring.

A

Temperature change, colour change, fizzing, smell, irreversible change

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2
Q

Describe what an exothermic reaction is.

A

A reaction which released thermal energy

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3
Q

Give one example of an exothermic reaction.

A

Combustion/burning, metal and acid, neutralisation/acid and alkali

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4
Q

What is a neutralisation reaction?

A

An acid reacts with an alkali

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5
Q

What happens in terms of energy when bonds are broken?

A

Energy is taken in

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6
Q

What happens in terms of energy when bonds are made?

A

Energy is given out

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7
Q

True or false: During an exothermic reaction, products have more energy than reactants.

A
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8
Q

How can we measure whether there is a temperature change during a reaction?

A

Thermometer

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9
Q

What happens when bonds in reactants are broken?

A

Energy is absorbed

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10
Q

What happens when bonds in products are made?

A

Energy is released

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11
Q

What are the reactants in an instant cold pack?

A

Water and ammonium nitrate

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12
Q

How does the instant cold pack work?

A

water and ammonium nitrate react in an endothermic reaction

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13
Q

Identify the independent variable during this investigation.

A

Mass of ammonium nitrate

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14
Q

Identify the dependent variable during this investigation.

A

Temperature change

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15
Q

Identify the control variables during this investigation.

A

Volume of water, the balance reading zero before use

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16
Q

How do you calculate the temperature change?

A

By finding the difference between the before and after temperature

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17
Q

What is a catalyst?

A

A substance that can be added to a chemical reaction to speed it up

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18
Q

Why are catalysts described as “specific”?

A

A catalyst which works for one reaction, will not work for another reaction

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19
Q

How do catalysts speed up reactions?

A

By lowering the activation energy

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20
Q

What is an enzyme?

A

A biological catalyst

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21
Q

Give an example of a reaction which is sped up by an enzyme

A

Digestion, respiration, photosynthesis

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22
Q

What is the name of the part of the enzyme which has a specific shape?

A

Active site

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23
Q

Which catalyst is used to manufacture ammonia?

A

Iron or platinum

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24
Q

Give one reason why industrial processes use catalysts

A

More product made in a shorter time, enzymes can be re-used, lower energy costs during production

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25
Q

What are the two reactants of combustion?

A

Fuel and oxygen

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26
Q

In addition to the reactants, what else is needed for combustion?

A

Heat

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27
Q

What are the products of combustion?

A

Carbon dioxide and water

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28
Q

What is a fuel?

A

A material that burns to release energy

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29
Q

Define hydrocarbon.

A

A compound containing only hydrogen and carbon

30
Q

What is complete combustion?

A

When a fuel burns in excess oxygen

31
Q

What is incomplete combustion?

A

When a fuel burns in a limited supply of oxygen

32
Q

What are the products of incomplete combustion?

A

Carbon monoxide, soot, water

33
Q

What are the three sides of the fire triangle?

A

Heat, fuel, oxygen

34
Q

How can we extinguish any fire?

A

By removing one side of the fire triangle

35
Q

Which side of the fire triangle is removed by water?

A

Heat

36
Q

Why can’t water be used to extinguish an electrical fire?

A

It will cause electrocution

37
Q

How does a carbon dioxide fire extinguisher put out a fire?

A

CO2 is more dense than air so sinks and prevents oxygen getting to the fire

38
Q

If not extinguished, why do most fires eventually go out?

A

The fuel runs out

39
Q

What is a fire blanket?

A

A heavy blanket which prevents oxygen getting to the fire

40
Q

What are two uses of fire blankets?

A

When a person’s clothing is on fire, chip pan fires

41
Q

What is a fuel?

A

A material which burns to release energy

42
Q

What is a fossil fuel?

A

A fuel made of dead plants and animals that died and were buried millions of years ago

43
Q

Name the three fossil fuels.

A

Coal, oil, natural gas

44
Q

State two uses of fuels.

A

To keep us warm, for transport, to generate electricity

45
Q

In the fuel investigation, what is the independent variable?

A

Different fuels

46
Q

In the fuel investigation, what is the dependent variable?

A

Mass of fuel burned

47
Q

In the fuel investigation, identify two control variables.

A

Volume of water, increase in temperature

48
Q

How do we calculate how much energy is needed for a 1°C temperature rise?

A

Divide the mass of fuels burned by the temperature change

49
Q

What is thermal decomposition?

A

Substances are broken down by heat

50
Q

Why are thermal decomposition and combustion not the same?

A

Combustion involves oxygen, thermal decomposition does not

51
Q

What are the products of thermal decomposition of a metal carbonate?

A

Metal oxide and carbon dioxide

52
Q

What are the products of thermal decomposition of magnesium carbonate?

A

Magnesium oxide and carbon dioxide

53
Q

What makes a carbonate?

A

One carbon atom and three oxygen atoms

54
Q

What solution is used to test for carbon dioxide?

A

Limewater

55
Q

What is a positive test for the presence of carbon dioxide?

A

Limewater goes cloudy

56
Q

Give one use of thermal decomposition.

A

To produce lime for glass, cement, and limewater, as the first step in extracting copper from its ore

57
Q

What do we mean if we say that a metal carbonate is “thermally stable”?

A

Metal carbonates which will not break down when heated

58
Q

Without doing an experiment, how can we decide whether a metal carbonate will be thermally stable?

A

Thermally stable metal carbonates usually contain more reactive metals

59
Q

Why can’t all metal carbonates be thermally decomposed using a Bunsen burner?

A

Bunsen burner does not reach high enough temperatures

60
Q

Which metal carbonate changes colour when it thermally decomposes?

A

Copper carbonate

61
Q

Which metal oxide glows yellow when heated?

A

Zinc carbonate

62
Q

How do we test for carbon dioxide?

A

Limewater

63
Q

Write a word equation for the thermal decomposition of zinc carbonate.

A

Zinc carbonate 🡪 Zinc oxide + Carbon dioxide

64
Q

How do we know that thermal decomposition is an endothermic reaction?

A

Heat energy is taken in during the reaction

65
Q

Give an example of a physical change.

A

Ice melting, any change of state

66
Q

Give an example of a chemical change.

A

Combustion

67
Q

What is the law of conservation of mass?

A

Mass of the reactants equals the mass of the products, it cannot be lost or gained

68
Q

Who described the law of conservation of mass?

A

Lavoisier

69
Q

What seems to happen to the mass of a reaction if one of the reactants is a gas?

A

Increases

70
Q

What seems to happen to the mass of a reaction if one of the products is a gas?

A

Decreases

71
Q

Why should you not look directly at the magnesium ribbon during heating?

A

It burns with a bright white light

72
Q

What is the purpose of the balloon over the neck of the conical flask?

A

To capture the gas produced

8Ne Year 8 Science (10 decks)

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