GCSE Chemistry C3 - Periodic Table, Water and Analysis

Question 1

Cu2+ ions with OH- (hydroxide) ions?

Answer 1

blue precipitate forms Cu(OH)2

Question 2

How does adding sodium carbonate soften water?

Answer 2

The Mg and Ca ions form a precipitate (carbonate) which can be fitered off. The ions are thus removed

Question 2

Flame test colour - potassium

Answer 2

potassium - lilac

Question 2

What 2 products are made when an alkali metal reacts with water?

Answer 2

A hydroxide (alkaline) and hydrogen gas.

Question 3

Fe3+ ionswith OH- (hydroxide) ions?

Answer 3

rusty brown precipitate forms Fe(OH)3

Question 4

What are the products when a carbonate reacts with acid?

Answer 4

carbon dioxide, water and a salt.

Question 5

The alkali metals’ is the name for which group in the periodic table?

Answer 5

Group 1

Question 6

How is limescale formed?

Answer 6

hydrogen carbonate ions decompose on heating to form solid (precipitate) carbonates

Question 7

In the periodic table, are elements arranged in order of mass number or atomic number?

Answer 7

Atomic number

Question 8

What is the key difference between permanent and temporary hard water?

Answer 8

Temporary hardness ca be removed by boiling.

Question 8

What is the chemical test for sulphate ions?

Answer 8

Add barium chloride solution - a white precipitate forms if a sulhate is present.

Question 9

Why is chlorine added to our drinking water?

Answer 9

To kill microbes

Question 10

Flame test colour - barium

Answer 10

barium - green

Question 10

Which is more reactive - lithium or potassium?

Answer 10

potassium

Question 10

Which is more likely to form a coloured compound - chromium or calcium?

Answer 10

Chromium - because it is a transition metal.

Question 12

Which two physical processes are involved in distillation?

Answer 12

boiling and condensing

Question 13

Fe2+ ions with OH- (hydroxide) ions?

Answer 13

green precipitate forms Fe(OH)2

Question 14

Al3+ ions with OH- (hydroxide) ions?

Answer 14

White precipitate of Al(OH)3 which dissolves in excess hydroxide

Question 15

What is the chemical test for chloride ions?

Answer 15

Add silver nitrate + nitric acid - white precipitate forms

Question 17

Flame test colour - sodium

Answer 17

sodium - yellow

Question 18

What is the chemical test for carbon dioxide?

Answer 18

Bubble it through lime water - it goes milky / cloudy white as a precipitate forms

Question 20

Why can’t water softened using ion exchange be given to babies?

Answer 20

The Mg and Ca are replaced by sodium ions. Too much sodium is bad for you.

Question 21

Describe the trend in reactivity in group 1

Answer 21

As you go down the group they get more reactive.

Question 23

Which group 7 element, other than chlorine, is sometimes added to water?

Answer 23

Fluorine, for healthy teeth.

Question 24

What is the chemical test for bromide ions?

Answer 24

Add silver nitrate + nitric acid - cream precipitate forms

Question 25

Which dissolved ions make water hard?

Answer 25

magnesium and calcium

Question 27

Is bond breaking an exo or endothermic process?

Answer 27

Endothermic - you put energy in to break bonds

Question 28

What is the charge on each halide ion?

Answer 28

1- (group 7 - they gain 1 electron to get a full shell of 8 or 18)

Question 29

Is bond making an exo or endothermic process?

Answer 29

Exothermic - energy is released when bonds are made

Question 30

What is the chemical test for siodide ions?

Answer 30

Add silver nitrate + nitric acid - yellow precipitate forms

Question 31

The halogens' is the name for which group in the periodic table?

Answer 31

Group 7

Question 32

Give an advantage of living in a hard water area

Answer 32

Calcium in water is good for growing strong teeth and bones. Also reduces heart disease

Question 33

Flame test colour - lithium

Answer 33

lithium - crimson

Question 34

Flame test colour - calcium

Answer 34

calcium - red

Question 35

Ca2+ and Mg 2+ ions with OH- (hydroxide) ions?

Answer 35

White precipitates of Mg(OH)2 and Ca(OH)2 form