Analysis

Question 1

Describe the gas test for oxygen and the results if oxygen is present. Explain why this works.

Answer 1

Insert a glowing splint into the gas. If the glowing splint relights oxygen is present. Oxygen is an oxidising agent.

Question 2

Describe the gas test for hydrogen and the results if hydrogen is present. Explain why this works.

Answer 2

Insert a lit splint into the gas. If you hear a squeaky pop hydrogen is present. Hydrogen is explosive.

Question 3

Describe the gas test for carbon dioxide and the results if carbon dioxide is present. Explain why this works.

Answer 3

Bubble the gas through limewater. If carbon dioxide is present, the lime water will turn milky. This is because a precipitate of calcium carbonate is formed.

Question 4

Describe the gas test for chlorine and the results if chlorine is present. Explain why this works.

Answer 4

Insert a damp piece of blue litmus paper into the gas. If chlorine is present the paper will go red then bleach this is because chlorine is a bleaching agent.

Question 5

Describe the gas test for ammonia and the results if ammonia is present. Explain why this works..

Answer 5

Insert a damp piece of red litmus paper into the gas. The paper will turn blue if ammonia is present this is because ammonia is a base.

Question 6

Explain how to carry out a flame test.

Answer 6

Clean a platinum wire loop by dipping it in some hydrochloric acid. Hold the loop in the Bunsen burner until it shows no colour. Dip the loop into the sample and hold it in the flame. Record the colour of the flame.

Question 7

In a flame test, what colour flame would you expect if the sample is lithium?

Answer 7

Red

Question 8

In a flame test, what colour flame would you expect if the sample is sodium?

Answer 8

Yellow

Question 9

In a flame test what colour flame would you expect if the sample is potassium?

Answer 9

Lilac

Question 10

In a flame test, what colour flame would you expect if the sample is calcium?

Answer 10

Orange-red

Question 11

In a flame test, what colour flame would you expect if the sample is copper?

Answer 11

Blue-Green

Question 12

Describe how to carry out a sodium hydroxide test

Answer 12

Add 1ml of the sample solution, to be tested, to a test tube. Add sodium hydroxide. Observe a precipitate form. Record the colour.

Question 13

What is formed in a sodium hydroxide test?

Answer 13

A precipitate

Question 14

In a sodium hydroxide test, what colour will the precipitate be if the sample is copper(II)?

Answer 14

Blue

Question 15

In a sodium hydroxide test what colour will the precipitate be if the sample is iron (II)?

Answer 15

Green

Question 16

In a sodium hydroxide test what colour will the precipitate be if the sample is iron (III)?

Answer 16

Reddish-Brown

Question 17

Describe the sodium hydroxide test for ammonium

Answer 17

Add 1ml of the sample solution, to be tested, to a test tube. Add sodium hydroxide. Heat gently in a water bath. Insert damp red litmus paper into the mouth of the tube

Question 18

In a sodium hydroxide test, what colour will the litmus paper turn if ammonium is present?

Answer 18

Red litmus paper will turn blue if ammonium is present

Question 19

Describe which chemicals to use in an anion test when testing for chloride, bromide or iodide

Answer 19

Add nitric acid followed by silver nitrate

Question 20

In an anion test what colour precipitate will be formed if chloride is present?

Answer 20

White precipitate

Question 21

In an anion test what colour precipitate will be formed if bromide is present?

Answer 21

Cream precipitate

Question 22

In an anion test what colour precipitate will be formed if iodide is present?

Answer 22

Yellow precipitate

Question 23

In an anion test describe which chemicals to use when testing for sulphate

Answer 23

Add hydrochloric acid followed by barium chloride

Question 24

In an anion test, what colour will the precipitate be if sulphate is present?

Answer 24

White precipitate

Question 25

In an anion test, which chemical should be used to test for carbonate

Answer 25

Add an acid. Bubble any gas produced through limewater

Question 26

In an anion test if a carbonate is present what colour would you expect the lime water to turn?

Answer 26

Milky

Question 27

When testing for water, which chemical is used? What colour is it before the test? What colour does it turn if water is present?

Answer 27

Add anhydrous copper sulphate. Copper sulphate will go from white to blue.

Question 28

When testing for water using anhydros copper sulphate, what is formed if water is present?

Answer 28

If water is present, hydrated copper sulphate is formed which is blue

Question 29

How do you test the purity of water? What results would you expect if the water is pure?

Answer 29

Measure the melting and boiling points. The melting point would be exactly 0° C. The boiling point will be exactly 100° C.

Question 30

When testing the purity of water, what would you expect the results to be if the water is impure?

Answer 30

If the water is impure, it would lower the melting and boiling points. It would also cause the water to melt and boil over a range of temperatures rather than at precise temperatures.

Question 31

What is the word equation when testing for water using anhydrous copper sulphate?

Answer 31

Copper sulphate + water —> hydrated copper sulphate

Question 32

What is the symbol equation when testing for water using anhydrous copper sulphate?

Answer 32

CuSO4 + 5H2O —> CuSO4 5H2O