Chapter 2

Question 1

State the apparatus, accuracy and SI unit for measuring time, temperature, mass and volume.

Answer 1

Time - stopwatch, SI unit=second (s), corrected to nearest s

Temperature - thermometer (mercury/alcohol) or data logger, SI unit=Kelvin (K), +/- 0.5 degrees C for thermometer, very accurate for data logger.

Mass - Electronic balance, SI unit=kg, +/-0.01g

Volume
gas-gas syringe (cm3 used), SI unit=m3, +/-1.5cm3

liquid: SI unit=ml/dm3
- beaker, +/-10cm3
- measuring cylinder, +/-0.5cm3
- pipette, +/-0.0cm3
- burette, +/-0.05cm3

Question 2

How to read the apparatus measuring volumes of liquids?

Answer 2

Align the eyes with the bottom or top of the meniscus.

Question 3

What two key factors do we consider when collecting gases?

Answer 3

1. solubility

2. density (compared to surrounding air)

Question 4

What are the methods for collecting gas?

Answer 4

1. Downward displacement of water
2. Downward displacement of air
3. Upward displacement of air / Downward delivery of gas
4. Gas syringe

Question 5

State the suitable method of collection for the following gases: hydrogen, oxygen, carbon dioxide, nitrogen, chlorine, hydrogen chloride, sulfur dioxide, ammonia

Answer 5

Downward displacement of water - hydrogen, oxygen, nitrogen, carbon dioxide

Downward displacement of air - hydrogen, ammonia

Upward displacement of air - carbon dioxide, chlorine, hydrogen chloride, sulfur dioxide

Question 6

What is gas syringe usually used for?

Answer 6

Experiments involving rate of reaction

Question 7

How do we obtain dry gas?

Answer 7

By using drying reagents such as concentrated sulfuric acid, quicklime or fused calcium chloride.

Question 8

State the suitable drying reagent for most gases. And ammonia?

Answer 8

Sulfuric acid - most gases (such as chlorine and hydrogen chloride) except ammonia.
Quicklime - ammonia
Fused calcium chloride - most gases