From this chapter, you should know:
2. Observable changes
3. Determine different types of rate of reaction
4. Factors affecting the rate of reaction:
a. Size of Reactant
b. Concentration of solution
c. Temperature of mixture
d. The presence of catalyst
e. Gas Pressure
*a-d involves experiment
5. Explanation using the collision theory (continuation of The Kinetic Theory of Gases)
a. Daily Life
b. Industry (Haber Process, Contract Process, Ostwald Process)
A.Rate of Reaction
1. In general, Rate of reaction is the speed at which reactant(s) are converted into product(s) in a chemical reaction.
2. Different reactions occur in different rate.
When writing the relationship between the rate of reaction:
Use the terms ‘high’ or ‘low’
Students will lose marks because of writing ‘fast’ and ‘slow’
If want to be SAFE: use the term ‘increase’ or ‘decrease’
Example:When the mass increases, the rate of reaction increases.
a. Involve the release of gas bubbles
Slow Reaction: Photosynthesis
Fast Reaction: Carbonate + Acid
Slow Reaction: Burning copper metal
Fast Reaction: Burning magnesium metal
c. Formation of Precipitate
Slow Reaction: sodium thiosulphate solution (Na2S2O3) + acid
Fast Reaction: silver nitrate solution + sodium chloride solution
4. For fast reactions, the time taken for reaction is short. Therefore, the rate of reaction is high.
For slow reactions, the time taken for reaction is long. Therefore, the rate of reaction is low.
5. In short, the rate of reaction is inversely proportional to time taken. (DO NOT WRITE IN THE EXAM, THIS TERM IS JUST FOR UNDERSTANDING PURPOSES ONLY)
6. For Any Chemical Reactions,
Reactant(s) ——> Product(s)
Rate of reaction = Decrease in observable change of reactant / time taken
Rate of Reaction = Increase in observable change of product / time taken
7. The observable change refers to
a. Volume of gas released
b. Precipitation formed
c. Change in mass