General Practicals

Question 1

Safety precaution for irritants

Answer 1

Wear goggles

Question 2

Safety precaution for corrosive

Answer 2

Wear goggles

Question 3

Safety precaution for flammable

Answer 3

Keep away from naked flames

Question 4

Safety precaution for toxic

Answer 4

Wear gloves, avoid skin contact, wash hands after use

Question 5

Safety precaution for oxidising

Answer 5

Keep away from flammable/ easily oxidised materials

Question 6

When heating in a crucible why is a lid used

Answer 6

Improves accuracy as it prevents the loss of solid from crucible.
Should be loose fitting to allow gas to escape

Question 7

Why should large amount of solid not be used when heating in a crucible

Answer 7

Decomposition is likely to be incomplete

Question 8

Why should very small amounts of solid not be used when heating in a crucible

Answer 8

Percentage uncertainties in weighing will be too high

Question 9

Errors in using a gas syringe

Answer 9

Gas escapes before the bung is inserted
The syringe sticks
Some gases like CO2 and SO2 are soluble in water so the true amount of gas is not measured

Question 10

When heating hydrated compounds in a crucible why should large amounts not be used

Answer 10

The decomposition is likely to be incomplete

Question 11

When heating in a crucible why should the crucible be dry

Answer 11

A wet crucible would give an inaccurate result. It would cause mass loss to be too large as the water would be lost when heating