1. Experimental Techniques
Syllabus objectives :
(a)Name appropriate apparatus for the measurement of time, temperature, mass and volume, including burettes, pipettes, measuring cylinders and gas syringes;
(b)Suggest suitable apparatus, given relevant information, for a variety of simple experiments, including collection of gases and measurement of rates of reaction.

2. Measurement of Time Apparatus : stopwatch or stopclock
Unit : seconds (s)
minutes (min) or
hours (h)

3. Measurement of Temperature
Apparatus : thermometer
Unit : degree Celsius (°C)
Kelvin (K)
thermometer

4. Measurement of Mass Apparatus : electronic balance Unit : gram (g)
kilogram (kg)
mass of the chemical can be read off the balance display
electronic ‘top pan’ balance

5. Measurement of Volume Volume of Liquids : Apparatus : burette
0 ml mark
Apparatus : burette
for measuring accurately the volume of a liquid (0 to 50.0cm3)
Accuracy : to nearest 0.1cm3
accurate volume from 0 to 50 cm3 can be measured by reading the differences of the levels before and after the liquid is released; commonly used in titrations
50 ml mark

6. Measurement of Volume
0 ml mark
50 ml mark
Burette reading :
3.4cm3

7. Measurement of Volume Final : 26.5cm3 Initial : 0.8cm3
Volume of liquid added =
( )cm3
= cm3
Initial reading
Final reading

8. Measurement of Volume Volume of Liquids : Apparatus :pipette
accurate set volume of exactly 20, 25 or 50 cm3 of liquid (to the nearest 0.1cm3) can be drawn to a mark, using a pipette filler
Volume of Liquids :
Apparatus :pipette
for measuring accurately a fixed volume of liquid (20.0cm3 or 25.0cm3 usually)
Accuracy : to nearest 0.1cm3

9. Measurement of Volume Pipette
accurate set volume of exactly 20, 25 or 50 cm3 of liquid (to the nearest 0.1cm3) can be drawn to a mark, using a pipette filler
pipette

10. accurate volume to the nearest cm3 of liquid can be measured
Measurement of Volume
Volume of Liquids :
measuring cylinder
accurate volume to the nearest cm3 of liquid can be measured
Apparatus :measuring cylinder
Accuracy : to nearest 1cm3

11. Measurement of Volume Measuring cylinder Correct reading: 46 cm3

12. Measurement of Volume Volume of Liquids : Apparatus :beaker
For approximate volume of liquids

13. hydrochloric acid + lumps of calcium carbonate
Measurement of Volume
Volume of Gases :
Apparatus : gas syringe
rubber bung
gas syringe
conical flask
hydrochloric acid + lumps of calcium carbonate
accurate volume of gas can be manually read on the graduated scale, or automatically recorded using data logging

14. Measurement of Volume cubic centimetres (cm3), decimetres (dm3),
Units :
cubic centimetres (cm3),
decimetres (dm3),
litres(l) and millilitres(ml)
Some conversions:
1 l = 1000 ml
1 l = 1 dm3 = 1000 cm3
1 ml = 1cm3

15. Experimental Set-up To dry a gas :
Use of concentrated sulfuric acid, quick lime (calcium oxide) or fused calcium chloride.

16. Experimental Set-up Collecting Gases in the laboratory :
Gases may be collected (1) using a gas syringe OR
(2) based on the physical properties of the gas:
The solubility of the gas in water
The density of the gas compared to the density of air
3 Methods of collecting gases:
Displacement of water
Displacement of air – downward displacement
Displacement of air – upward displacement

17. Collecting gases Gas Delivery tube Gas jar Displacement of water :
Used on gases that are insoluble or slight soluble in water, e.g. hydrogen, oxygen, carbon dioxide, etc.
Delivery tube
Gas
Gas jar

19. Collecting gases Gas jar Gas Delivery tube
Displacement of air - downward delivery
For fairly soluble or very soluble gases in water that are heavier or denser than air.
E.g. chlorine, hydrogen chloride
Delivery tube
Gas jar
Gas

21. Collecting gases Gas Gas jar Delivery tube
Displacement of air - upward delivery For fairly soluble or very soluble gases in water that are lighter or less dense than air. E.g. ammonia
Delivery tube
Gas jar
Gas