C3.4 Further Analysis and Quantitative Chemistry

Question 1

What colour flame does lithium give?

Answer 1

Crimson

Question 2

What colour flame does sodium give?

Answer 2

Yellow

Question 3

What colour flame does potassium give?

Answer 3

Lilac

Question 4

What colour flame does calcium give?

Answer 4

Red

Question 5

What colour flame does barium give?

Answer 5

Green

Question 6

What is the precipitate made when sodium hydroxide solution reacts with copper ion (Cu2+) ?

Answer 6

A blue one

Question 7

What is the precipitate made when sodium hydroxide solution reacts with iron II ion (Fe2+) ?

Answer 7

A green one

Question 8

What is the precipitate made when sodium hydroxide solution reacts with with iron III ion (Fe3+) ?

Answer 8

A brown one

Question 9

What is the precipitate made when sodium hydroxide solution reacts with with aluminium ion (Al3+) ?

Answer 9

A white one at first but then dissolves in excess sodium hydroxide solution.

Question 10

What is the precipitate made when sodium hydroxide solution reacts with with magnesium ion (Mg2+) ?

Answer 10

A white one

Question 11

What is the precipitate made when sodium hydroxide solution reacts with with calcium ion (Ca2+) ?

Answer 11

A white one

Question 12

How do you test for a carbonate?

Answer 12

• Add an acid, it should fizz as a reaction happens:
  acid + carbonate —–> CO2 + water + salt
• Test for the CO2 by doing the limewater test, bubble the gas through limewater, if it turns cloudy then it is CO2.

Question 13

How do you test for a halide ion?

Answer 13

• Add dilute nitric acid then silver nitrate solution

Question 14

What colour precipitate is looked for when testing for chloride ?

Answer 14

A white one

Question 15

What colour precipitate is looked for when testing for bromide?

Answer 15

A cream one

Question 16

How do you test for a sulfate?

Answer 16

Add dilute HCL followed by barium chloride solution

Question 17

What colour precipitate is looked for when testing for a sulfate?

Answer 17

A white one

Question 18

What is titration used for with acids and alkalis?

Answer 18

To see how much acid is needed to neutralise an alkali.

Question 19

Describe the titration process.

Answer 19

• Put some alkali in a flask with an indicator
• Add acid to the alkali using a burette, gradually while swirling the flask each time.
• The indicator will change colour as soon as the acid is neutralised.
• Measure how much acid was used and record.
• Repeat

Question 20

What indicator is used in titration?

Answer 20

Phenolphthalein or methyl orange

Question 21

Why isn’t universal indicator used in titration?

Answer 21

The change in colour would be too gradual, we need an indicator which changes colour right away as soon as the alkali is neutralised.