Chapter 2: Measurement and experimental techniques

Question 1

What is the S.I unit for mass and what are the commonly used units

Answer 1

S.I unit: Kg (kilograms)
Commonly used units:
gramme (g)
tonne (t)

Question 2

How is mass measured?

Answer 2

1. Beam balance
2. Electronic balance (used for fast and precise weighing of small amounts of substances with an accuracy up to +-0.01g

Question 3

What is the S.I unit for time and the commonly used units

Answer 3

S.I: Seconds (s)
Commonly used units:
Hours (h)
Minutes (min)

Question 4

How do is time measured and its accuracy?

Answer 4

1. Analogue stopwatch (accuracy: +-0.15)
2. Digital stopwatch (accuracy +-0.015)

Question 5

What is the S.I unit for temperature and its commonly used unit

Answer 5

S.I unit: Kelvin (k)
Commonly used unit: Degree Celsius

Temp in K = Temp in Celsius + 273

Question 6

How is temperature measured and its accruacy

Answer 6

1. Mercury thermometer (accuracy: +-0.5 degree Celsius)
2. Data logger (More accurate than mercury or alcohol thermometer, saves data which can be used to produce graphs and charts, disadvantage is that it is expensive)

Question 7

What is the S.I unit for volume and its commonly used units

Answer 7

S.I: cubic metre (m3)
Commonly used units:
Cubic centimetre (cm3)
Cubic decimetre (dm3)

1dm3 = 1000 cm3

Question 8

How is liquid measured?

Answer 8

1. Measuring cylinder (measures up to the nearest cm3)
2. Beaker (used to hold liquids, not for measurement)
3. Burette (measures to nearest 0.05cm3)
4. Pipette (measures accurately fixed volumes of liquids ex. 20.0cm3 or 25.0cm3)

Question 9

How is gas measured

Answer 9

Using a gas syringe. It has a maximum volume of 100cm3

Question 10

Name the 3 experiments/methods of collecting gas

Answer 10

1. Upward delivery
2. Downward delivery
3. Displacement of water

Question 11

Explain upward delivery

Answer 11

• For collecting gases that are soluble in water and less dense than air
• Ex. Ammonia (NH3)

Question 12

Explain downward delivery

Answer 12

• For collecting gases that are soluble in water and denser than air
• Ex. Chlorine (Cl2), Hydrogen chloride (HCL)

Question 13

Explain displacement of water

Answer 13

• For collecting gases that are insoluble or slight soluble in water
• Ex. Carbon dioxide (Co2), Hyfrogen (H2), Oxygen (O2)