Topic 5 - Non-Metals and Their Compounds

Question 1

Test for Hydrogen

Answer 1

Apply a lighted splint

Result: popping sound

Question 2

Test for Oxygen

Answer 2

Apply a glowing splint

Result: it relights

Question 3

Test for Carbon Dioxide

Answer 3

Use limewater

Result: it changes from colourless to milky

Question 4

Test for Ammonia

Answer 4

Apply a glass rod dipped in concentrated hydrochloric acid

Result: white smoke

Question 5

Describe the laboratory preparation and collection of hydrogen using a suitable metal.

Answer 5

Prepare a thistle funnel with hydrochloric acid above a conical flask containing Zinc.

Drip the hydrochloric acid from the tap into the conical flask.

The Zinc and hydrochloric acid will react to give Zinc chloride and hydrogen gas, which will be collected by the delivery tubing.

Apply a rubber bung to the conical flask to prevent hydrogen gas from escaping.

The delivery tubing will carry the hydrogen gas to a trough of water, beehive shelf and gas jar, where the hydrogen gas will be collected.

Question 6

Does hydrogen exist as a monatomic, diatomic or triatomic molecule?

Answer 6

Diatomic

Question 7

What is meant by the term diatomic?

Answer 7

A molecule composed of two atoms covalently bonded together.

Question 8

What are the physical properties of hydrogen?

Answer 8

Colourless
Odourless
Lighter than air
Insoluble in water

Question 9

Why is hydrogen described as a ‘clean fuel’?

Answer 9

Hydrogen is considered as a clean fuel due to its reaction with oxygen. The only ‘waste’ product produced is water, a harmless liquid. This reaction with oxygen burns to give out large amounts of energy, creating water in the form of steam.

Question 10

Give a balanced symbol and word equation for the reaction of Oxygen and Hydrogen.

Answer 10

Hydrogen gas + Oxygen gas = Water (Steam)

2H2 + O2 = 2H*2O

Question 11

Why are hydrogen fuel cells not used extensively in place of fossils fuels?

Answer 11

Few filling stations sell hydrogen.

Hydrogen must be compressed and liquefied, and then stored in tough, insulated fuel tanks.

Atmospheric pollution may be generated during the production of hydrogen.

Hydrogen fuel cells do not work at very low temperatures.

They may require a platinum catalyst (platinum is expensive and prone to contamination by impurities).

Question 12

What are some of the uses of hydrogen gas?

Answer 12

Meteorological balloons

Rocket engines

Question 13

Why is hydrogen used in meteorological balloons?

Answer 13

Lower cost than using helium.

Lower density (lighter) than air, allows balloons to rise to high altitudes.