Topic 2: Chemical Changes

Question 1

In a school laboratory what piece of equipment is used to heat a substance?

Answer 1

Bunsen Burner

Question 2

Name the FIVE different sections of a Bunsen burner.

Answer 2

Barrel, regulating collar, air hole, gas tubing and the base.

Question 3

What SIX safety precautions should you take when using a Bunsen?

Answer 3

Tie long hair back, roll up sleeves/take off blazer, tuck in your tie, put on safety goggles, remove any flammable liquids and don’t leave gas on for too long before lighting.

Question 4

Number the following statements 1-4 according to the order you must follow when lighting a Bunsen burner:

• Move the collar until the air hole is 1/3 open
• Turn on the gas by moving the gas tap
• Attach the rubber tubing to the gas tap
• Light a wooden splint and hold it above the chimney

Answer 4

1. Attach the rubber tubing to the gas tap
2. Move the collar until the air hole is 1/3 open
3. Turn on the gas by moving the gas tap
4. Light a wooden splint and hold it above the chimney

Question 5

What is the colour of the flame when the air hole is 1/3 open?

Answer 5

Yellow/tinged blue

Question 6

What is the colour of the flame once the air hole is fully opened?

Answer 6

2 toned blue

Question 7

What is the colour of the flame when the air hole is completely closed?

Answer 7

Yellow (safety flame)

Question 8

What are the THREE observations for each type of flame when the air hole is open and when the air hole is closed?

Answer 8

Air hole open: 1. roaring 2. slight blue colour 3. hard to notice

Air hole closed: 1. quiet 2. yellow/orange 3. easy to see

Question 9

What is the colour of the flame and metal present of sodium chloride when heated?

Answer 9

Flame colour: yellow

Metal present: sodium

Question 10

What is the colour of the flame and metal present of potassium chloride when heated?

Answer 10

Colour of flame: lilac

Metal present: potassium

Question 11

What is the colour of the flame and metal present of strontium chloride when heated?

Answer 11

Colour of flame: red

Metal present: strontium

Question 12

What is the flame colour and metal present when calcium chloride is heated?

Answer 12

Flame colour: brick red ( orange red )

Metal present: calcium

Question 13

What is the flame colour and metal present of copper chloride when heated?

Answer 13

Flame colour: blue-green

Metal present: copper

Question 14

What is the flame colour and metal present when barium chloride is heated?

Answer 14

Flame colour: apple green

Metal present: barium

Question 15

What colour of flame does sodium produce?

Answer 15

Yellow

Question 16

What is the correct change of state when a solid turns to liquid and then to gas?

Answer 16

The solid melts into a liquid and then the liquid evaporates into a gas

Question 17

What is the correct change of state when a gas changes into a liquid and then to a solid?

Answer 17

The gas condenses into a liquid and then the liquid freezes into a solid

Question 18

What are changes called when something is heated that can be changed back on cooling?

Answer 18

Reversible changes

Question 19

What are changes called on heating that cannot be changed back on cooling?

Answer 19

Irreversible changes

Question 20

Is ice melting reversible or irreversible?

Answer 20

Reversible

Question 21

Is the wax on a candle burning reversible or irreversible?

Answer 21

Reversible

Question 22

Is the wick on a candle burning reversible or irreversible?

Answer 22

Irreversible

Question 23

Is boiling an egg reversible or irreversible?

Answer 23

Irreversible

Question 24

Is baking a cake reversible or irreversible?

Answer 24

Irreversible

Question 25

Is making a clay pot and firing it in a kiln reversible or irreversible?

Answer 25

Irreversible

Question 26

What are the observations of magnesium ribbon being heated and is it reversible or irreversible?

Answer 26

Observations: bright white light Irreversible

Question 27

What are the observations of ice being heated and is it reversible or irreversible?

Answer 27

Observations: melts ( turns into a liquid) Reversible

Question 28

What are the observations of candle wax being heated and is it reversible or irreversible?

Answer 28

Observations: Melts Reversible

Question 29

What are the observations of copper carbonate being heated and is it reversible or irreversible?

Answer 29

Observations: green powder turns black Irreversible

Question 30

What are the observations of a wooden splint being heated and is it reversible or irreversible?

Answer 30

Observations: black ash Irreversible

Question 31

What are the observations of bread being heated and is it reversible or irreversible ?

Answer 31

Observations: burns/chars Irreversible

Question 32

Does sugar dissolve or melt into tea?

Answer 32

Dissolve

Question 33

Does ice dissolve or melt into lemonade?

Answer 33

Melts

Question 34

Does salt dissolve or melt into soup?

Answer 34

Dissolve

Question 35

Does ice cream dissolve or melt on a sunny day?

Answer 35

Melt

Question 36

What is the term of a liquid that can dissolve a solid?

Answer 36

Solvent

Question 37

What is the term of a solid dissolves in a liquid?

Answer 37

Solute

Question 38

What is the term of something does not dissolve?

Answer 38

Insoluble

Question 39

What is the term of the liquid formed when a solute is dissolved in a solvent?

Answer 39

Solution

Question 40

What is the term of a substance which can dissolve?

Answer 40

Soluble

Question 41

What is the definition of soluble?

Answer 41

A substance which can dissolve

Question 42

What is the definition of insoluble?

Answer 42

Something which does not dissolve

Question 43

What is the definition of solute?

Answer 43

A solid that dissolves in a liquid

Question 44

What is the definition of solvent?

Answer 44

A liquid that can dissolve A solid

Question 45

What is the definition of solution?

Answer 45

The liquid formed when a solute is dissolved in a solvent

Question 46

What is the appearance of sugar before mixing with water and the appearance after mixing with water?

Answer 46

Before: white crystals After: clear, colourless liquid

Question 47

What is the appearance off flour before mixing with water and the appearance of flour after mixing with water?

Answer 47

Before: white powder After: white cloudy fog/suspension

Question 48

What is the appearance of copper sulfate before mixing with water after mixing with water?

Answer 48

Before: blue crystal powder After: a light blue clear substance

Question 49

What is the appearance of calbalt chloride before mixing with water and after mixing with water?

Answer 49

Before: a purple wet powder After: a red/purple clear substance

Question 50

What is the appearance of sand before mixing with water and after mixing with water?

Answer 50

Before: dry mud/rocky/sandy After: foggy and clear with mixture at the bottom, cloudy suspension

Question 51

Does the substance sugar form a solution and is it soluble or insoluble?

Answer 51

Yes Soluble

Question 52

Does the substance flour form a solution and is it soluble or insoluble?

Answer 52

No Insoluble

Question 53

Does the substance copper sulfate form a solution and is it soluble or insoluble?

Answer 53

Yes Soluble

Question 54

Does the substance cobalt chloride form a solution and is it soluble or insoluble?

Answer 54

Yes Soluble

Question 55

Does the substance sand form a solution and is it soluble or insoluble?

Answer 55

No Insoluble

Question 56

Why is it important to use the same volume of water when testing each substance?

Answer 56

To keep it a fair test

Question 57

A suspension is a solid that does not dissolve but just mixes with a liquid. Which substances in the experiment formed a suspension?

Answer 57

Flour and sand

Question 58

Describe what happens to a suspension that has been allowed to sit for some time.

Answer 58

It sinks to the bottom of the test tube

Question 59

How could you separate the insoluble solid from the water?

Answer 59

Filtration

Question 60

What happens when you use filtration to separate the insoluble solid from the water?

Answer 60

The sand residue gets caught on filter paper and the clear water passes through

Question 61

What are the SEVEN pieces of apparatus to carry out a filtration experiment?

Answer 61

Filtered liquid ( filtrate ), filter funnel, filter paper, liquid and insoluble solid, beaker, filtered solid residue, conical flask

Question 62

How could you retrieve the sugar from the sugar solution?

Answer 62

Heat some on an evaporation basin with a Bunsen burner

Question 63

Name the apparatus used to retrieve sugar from a sugar solution.

Answer 63

Tripod, wire gauze, Bunsen burner, evaporating basin

Question 64

Name apparatus used for finding out the maximum amount of copper sulfate that will dissolve in 25 cm³ of water at room temperature.

Answer 64

Wire gauze, measuring cylinder, beakers, spatula, filter paper funnel, evaporating basin, tripod, mass balance, Bunsen burner

Question 65

What safety precautions do you have to remember whilst using a Bunsen burner?

Answer 65

Wear safety goggles and tie long hair back

Question 66

Describe the method of finding out the maximum amount of copper sulfate that will dissolve in 25 cm³ of water at room temperature.

Answer 66

1. Measure out 25 cm³ of water into a 100 cm³ beaker 2. Add one spatula of copper sulfate to the water and stirred, repeat until no more will dissolve 3. Weigh an evaporating basin and record mass in a suitable table 4. Filter copper sulfate solution and collect filtrate in evaporating basin 5. Evaporate of water from solution 6. Allow basin to cool and reweigh,record in table 7. Use your results to work out how much copper sulfate was dissolved in the 25 cm³ of water.

Question 67

If your result was 5g and over all you had 25 cm³ work out how many grams of copper sulfate would dissolve in 100 cm³ off water at room temperature.

Answer 67

Answer: 20 cm³

Question 68

How many grams are the same as 1 cm³?

Answer 68

1g

Question 69

What is the appearance before and after magnesium burns?

Answer 69

Before: silver metal After: white ash

Question 70

What is the appearance before and after paper burns?

Answer 70

Before: white paper After: dark grey ash

Question 71

What colour are the ashes when you burn magnesium and paper?

Answer 71

Magnesium: white ash Paper: dark grey ash

Question 72

What colour are the flames whenever magnesium and paper burns?

Answer 72

Paper: orange and smokey Magnesium: bright white light

Question 73

What other substance is needed for burning to occur other than fuel and heat?

Answer 73

Oxygen

Question 74

What is the new substance formed called when magnesium burns?

Answer 74

Magnesium oxide

Question 75

What is the bright light when magnesium burns used for?

Answer 75

Stress flares or fireworks

Question 76

What are the three essential things in a fire triangle to keep a fire burning?

Answer 76

Fuel,heat and oxygen

Question 77

If a chip pan catches fire should you A. Place a damp tea towel over the fire or B. Lift the pan and put it on the worktop away from the heat?

Answer 77

A. Place a damp tea towel over the fire

Question 78

What colour of flame would sodium chloride burn with?

Answer 78

Yellow

Question 79

What colour of flame would calcium chloride burn with?

Answer 79

Brick red

Question 80

What colour of flame would strontium chloride burn with?

Answer 80

Red

Question 81

What colour of flame would potassium chloride burn with?

Answer 81

Lilac

Question 82

What change is solid - liquid?

Answer 82

Melting

Question 83

What change is gas - liquid?

Answer 83

Condensing

Question 84

What change is liquid - gas?

Answer 84

Boiling

Question 85

What change is liquid - solid?

Answer 85

Freezing

Question 86

Is ice a liquid,solid or gas?

Answer 86

Solid

Question 87

Is oxygen a liquid, solid or gas?

Answer 87

Gas

Question 88

Is petrol a liquid, solid or gas?

Answer 88

Liquid

Question 89

Give two examples of a reversible change

Answer 89

Candle wax,ice

Question 90

Give two examples of an irreversible change

Answer 90

Magnesium ribbon, copper carbonate, wooden splint, bread

Question 91

Name the process that causes the clothes on a line to dry

Answer 91

Evaporation

Question 92

Name TWO substances that dissolve readily in water.

Answer 92

Sugar, copper sulfate and cobalt chloride

Question 93

Name TWO substances that do not dissolve in water.

Answer 93

Sand and flour

Question 94

Give a definition for soluble.

Answer 94

A substance which can dissolve

Question 95

Give a definition for solute.

Answer 95

A solid that dissolves in a liquid

Question 96

Give a definition for solvent.

Answer 96

A liquid that can dissolve a solid

Question 97

Give a definition for solution.

Answer 97

The liquid formed when a solute is dissolved in a solvent

Question 98

How would you separate an insoluble solid from water?

Answer 98

Filtering/filtration

Question 99

A mixture of chalk and water is filtered using a filter paper and funnel. The chalk stays in the filter paper because it is what?

Answer 99

Insoluble

Question 100

What are the units for solubility?

Answer 100

g/100g

Question 101

Describe what happens when magnesium burns.

Answer 101

Bright white shining flame and it turns into white ash

Question 102

Three essential things are needed for burning, what are they?

Answer 102

Heat fuel and oxygen