Shells Chemistry

Question 1

What two chemicals are used to test for the presence of water and what colour change is seen if water is there?

Answer 1

Anhydrous copper sulphate goes from white to blue Cobalt chloride goes from blue to pink

Question 2

What is the percentage of oxygen in the air?

Answer 2

21%

Question 3

What is the percentage of nitrogen in the air?

Answer 3

78%

Question 4

What is the percentage of carbon dioxide in the air?

Answer 4

0.03%

Question 5

Approximately 1% of the air is made up of “other gases” what are these gases?

Answer 5

Mainly argon and water vapour

Question 6

What is the reactivity series for metals? From most to least reactive (include hydrogen and carbon).

Answer 6

Potassium, sodium, (lithium), calcium, magnesium, aluminium, carbon, zinc, iron, tin, lead, hydrogen, copper, silver, gold, platinum.

Question 7

What is the name given to the type of reaction where a more reactive element pushes a less reactive on from a compound?

Answer 7

Displacement reaction.

Question 8

What is used to test whether a liquid is acidic or alkali?

Answer 8

Universal indicator paper or litmus paper

Question 9

What colour does litmus paper go in acid?

Answer 9

red

Question 10

What colour does litmus paper go in alkali?

Answer 10

Blue

Question 11

What colour does universal indicator go in weak acid (pH 5-6)?

Answer 11

Yellow

Question 12

What colour does universal indicator go in medium alkali (pH 10-11)?

Answer 12

Blue

Question 13

What is the pH of a strong acid?

Answer 13

1 or 2

Question 14

What is the pH of a strong alkali?

Answer 14

13 -14

Question 15

Vinegar is a medium acid, what colour would it go in universal indicator?

Answer 15

Orange

Question 16

Magnesium oxide dissolves to make a weak alkali solution, what colour will it go in universal indicator?

Answer 16

blue

Question 17

The liquid from wasp stings turn universal indicator blue. What does this tell us about the pH of the liquid. What could be used to neutralise it?

Answer 17

It is alkali and could be neutralised by a weak acid e.g. vinegar.

Question 18

What colour would you expect universal indicator to go in juice from a human stomach?

Answer 18

Red

Question 19

Is boiling easily reversed?

Answer 19

yes

Question 20

Is melting easily reversed?

Answer 20

yes

Question 21

Is neutralisation easily reversed?

Answer 21

no, it is a chemical reaction

Question 22

What gas is formed when metals react with acids or when more reactive metals react with water?

Answer 22

hydrogen

Question 23

How do you test to prove that a gas is hydrogen

Answer 23

A lit splint gives a squeaky pop.

Question 24

How do you test to prove that a gas is carbon dioxide?

Answer 24

Limewater turns from clear to cloudy when carbon dioxide is passed through it.

Question 25

How do you test to prove a gas is oxygen?

Answer 25

It will relight a glowing splint.

Question 26

What is a fuel?

Answer 26

A substance (normally a hydrocarbon) which is burned to release energy.

Question 27

Give the word equation for complete combustion of a hydrocarbon fuel.

Answer 27

hydrocarbon+oxygen --\> carbon dioxide + water + energy

Question 28

What is formed when there is not enough oxygen for complete combustion of a fuel?

Answer 28

carbon monoxide + carbon (soot) + water

Question 29

Sodium reacts with water, what two other metals did we see behave in a similar way?

Answer 29

Potassium and lithium (alkali metals, group 1)

Question 30

What is meant by the pH of a liquid?

Answer 30

How acidic or alkaline it is.

Question 31

What is an element?

Answer 31

A substance containing only one type of atom.

Question 32

What is a compound?

Answer 32

A substance containing two or more types of atom chemically bonded together.

Question 33

Carbonates break down when heated strongly. What name is given to this type of reaction?

Answer 33

thermal decomposition

Question 34

What gas is released when carbonates are thermally decomposed?

Answer 34

Carbon dioxide

Question 35

What would you expect to happen to the mass of a carbonate as it is heated?

Answer 35

It will decrease as carbon dioxide is released.

Question 36

What do iron, magnesium and sodium have in common?

Answer 36

They are all metals so they all conduct electiricy and are shiny.

Question 37

What pH woul dyou expect water to be? What does this mean?

Answer 37

pH 7 - neutral