CHAPTER 1 – EXPERIMENTAL CHEMISTRY
1.1 Experimental Design
Volumes of Liquids
SI unit: cubic metre (m3)
Large volume measurement: decimetres (dm3)
1 dm3 = 1 000 cm3
Daily life measurement: millilitres (ml) or litres(l)
1 litre = 1 000 ml
Apparatus for measuring liquids depends on:
- The volume being measured
- How accurate the measurement needs to be
- Beaker hold approximate volume of 100 cm3 and 250 cm3.
- Conical flask hold approximate volume of 100 cm3 and 250 cm3.
- Measuring cylinder has accuracy to 1 cm3.
- Reading to be taken nearer to the meniscus (bottom line).
- If reading is 23 cm3, should not write 23.0 cm3 as the ‘0’ means accurate to
0.1 cm3.
- Burette has long scale of 0 – 50 cm3, accurate to 0.1 cm3.
- Liquid level to be measured before and after tap opening. The difference of
volume gives the liquid volume poured off.
- Bulb pipette measures exact volumes such as 20.0, 25.0 or 50.0 cm3, not odd
volumes such as 31.0 cm3.
Volumes of Gases
Measured with gas syringe, up to 100 cm3
Temperature
Measured with thermometer. 2 types are:
a) Mercury-in-glass
b) Alcohol-in-glass
SI Unit: Kelvin (K)
Daily life measurement: degree Celcius (oC)
K = oC + 273
Time
SI Unit: seconds (s)
Other Units: minutes (min)/hour (h)
Measured with:
(a) Clock
(b) Digital stopwatch
Mass
Mass – the measure of amount of matter in a substance
SI Unit: kilogram (kg)
Other Units: grams (g)/milligrams (mg)
Large volume measurements: tonnes (t)
1 tonne = 1 000 kg
Measured with:
(a) Electric “top-pan” balance
(b) Triple beam balance
