Chemistry

Question 1

Give the name of the gas that is produced in the test for nitrate ions from:
- ammonia
- carbon dioxide
- carbon monoxide
- ethene
- fluorine
- oxygen
- sulfur dioxide
- xenon

Answer 1

Ammonia

Question 2

The electrolyte contains aluminium oxide and one other substance. Name the other substance and explain why it is used. [2]

Answer 2

Cryolite
Lower the operating temperature

Question 3

Explain the apparent unreactivity of aluminium [2]

Answer 3

Aluminium has an oxide layer
Oxide layer is unreactive

Question 4

Suggest why the metal nitrates and not the metal sulfates of these four metals are used as the aqueous solutions.

Answer 4

All nitrates are soluble.

Question 5

State the test for oxygen gas.
Test:
Observations:

Answer 5

Test: relights
Observations: glowing splint

Question 6

State two conditions needed in the fermentation of aqueous glucose other than room temp. and pressure

Answer 6

Yeast
Anaerobic condition

Question 7

State why the catalytic addition of steam to an alkene is referred to as an addition reaction

Answer 7

Only one product

Question 8

Ethanoic acid reacts with calcium to form a salt and one other product.

Answer 8

2CH3COOH + Ca —> (CH3COO)2Ca + H2
Hydrogen

Question 9

Determine the oxidation number of phosphorous in the PO4 3- ion

Answer 9

P O4
Oxygen has charge of -2
-2 * 4 = -8
(Phosphorous charge) + (-8) = -3
Therefore phosphorous charge = +5

Question 10

Suggest a practical problem that using 50cm^3of solution C in this investigation would cause. Suggest a possible solution to the problem.

Answer 10

Problem: volume of potassium manganate(or whatever solution A is) needed to titrate exceeds 50cm^3
Solution: use two burettes