MEASUREMENT & EXPERIMENTAL TECHNIQUES
International System of Units (SI units)
MASS (Kg)
-
Beam balance or electronic balance
-
1 kg = 1000 g
-
1 tonne = 1000 kg
TIME (s)
-
Stopwatch or stop-clock
-
1 hour = 60 minutes
-
1 minute = 60 seconds
TEMPERATURE (K)
-
Mercury thermometer or alcohol thermometer
-
K = Temp in Celsius + 273
VOLUME (m^3)
-
1 m^3 = 1000 dm^3
-
1 dm^3 = 1000 cm^3
-
deci = 10^2 ​
-
centi = 10^1
-
Figure 1. Triple Beam Balance
Figure 2. Mercury Thermometer
Figure 3. Stopwatch
Measuring Gases & Liquids
GAS SYRINGE - Used to measure the volume of a gas
MEASURING CYLINDER - Measures to the nearest 0.5 cm^3
​
BURETTE - To deliver different volumes of liquid, 0.05 cm^3
​
PIPETTE - Accurately measures fixed volumes of liquid, 0.5 cm^3
Methods for collecting gas
1) Displacement of Water: Collecting insoluble or slightly soluble gases in water (e.g. CO2, O2, H2).
​
2) Downward Delivery: Collecting gases soluble in water that are denser than air (e.g. Cl2 and HCl).
​
3) Upward Delivery: Collecting gases soluble in water that are less dense than air (e.g. ammonia).
Figure 4. Methods for collecting gases
3 Ways to Dry a Gas
1) Concentrated sulfuric acid - Used for most gases, EXCEPT ammonia ​
2) Quicklime (calcium oxide) - For ammonia
3) Fused calcium chloride - Most gases
​
Figure 5. Concentrated Sulfuric Acid
Figure 6. Fused Calcium Chloride
.jpg)
Figure 7. Quicklime