2 - Measurement and experimental techniques

Question 1

S.I unit of mass

Answer 1

kg

Question 2

How many kg in 1 tonne (t)

Answer 2

1000kg

Question 3

what is used to measure mass quickly and accurately, temp.

Answer 3

Beam/ electronic balance (2 d.p)

Question 4

S.I unit for time

Answer 4

Seconds, minute, hour

Question 5

Tool to measure time?

Answer 5

Stopwatch

Question 6

S.I unit for temp.

Answer 6

K (Kelvin), Degree celsius

Question 7

Tool to measure temp.

Answer 7

Mercury/ alcohol thermometer, data logger

Question 8

S.I unit for volume and its value

Answer 8

Cubic cm, Cubic decimeter

1m3 = 1000dm3
1dm3 = 1000cm3

Question 9

Tools to measure volume?

Answer 9

Measuring cylinder, burette, pipette

Question 10

Measuring cylinder accuracy

Answer 10

Measures to the nearest 0.5 cm cube

Question 11

Burette accuracy and purpose

Answer 11

• ACCURATELY measures liquid to nearest 0.05 cm cube
• Scale marked (graduated) in 0.1 cm cube devisions
• Used to deliver different volumes of liquid

Question 12

Pipette accuracy

Answer 12

ACCURATELY measures out fixed volumes of liquids (25cm3)

Question 13

How to read volume of liquid?

Answer 13

Curved surface called meniscus (read at either top or bottom of it, depending on where it curves)

Question 14

How measure volume of gas?

Answer 14

Gas syringe

Question 15

Methods for collecting gas

Answer 15

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

Question 16

Describe displacement of water (in terms of when collecting gas)

Answer 16

• Suitable for collecting gases that are insoluble or SLIGHTLY soluble in water
  e. g (for this method) Oxygen, CO2, hydrogen

[Note: acid and alkalis are soluble in water, also CO2 is a weak acid]

Question 17

Describe downward delivery (in terms of when collecting gas)

Answer 17

• Collect gas that is soluble in water AND denser than air
  e. g (for this method) chlorine, hydrogen chloride

[Note: Poisonous gas should be carried out in a fume cupboard]

Question 18

Describe upward delivery (in terms of when collecting gas)

Answer 18

• Collect gases that are soluble in water AND lighter than air
  e. g (for this method) ammonia

Question 19

3 methods to dry a gas

Answer 19

1. Concentrated sulfuric acid [H2SO4]
2. Quicklime (calcium oxide) [CaO]
3. Fused calcium chloride [CaCl]

Question 20

Describe concentrated sulfuric gas (drying a gas)

Answer 20

• Can dry MOST gases

- Can’t dry alkalis/ bases like ammonia as it would react with the acid

Question 21

Describe Quicklime [calcium oxide] (drying a gas)

Answer 21

Used to dry ammonia (look at this royal gas, has a whole method of drying to itself)

Question 22

Describe fused calcium chloride (drying a gas)

Answer 22

• Calcium chloride is heated to remove all traces of water in a gas
  (can dry most gases, except ammonia)