C8 Rates and Equilibrium
C8.1 Rate of reaction
Rate: how fast it takes for reactants to turn to products
How to work out rate:
1. Measuring decreasing mass of reaction mixture
- When it gives off gas, mass is lost
- As the reaction takes place the mass decreases as gas is lost to the surroundings
2. Measuring increase of volume of gas given off
- Using a gas syringe to collect the gas in a certain time
- More amount of gas after certain time - faster the rate
3. Measure the decreasing light pass through
- Is subjective: people judge opacity in different waysThe amount of time it takes for
the object to disappear (opacity)
1
2
3
C8.2 Surface area and collision theory
Collision theory:
Particles need to collide with each other in order to cause a reaction to take place
Activation energy:
The minimum amount of energy needed before they can react
More likely to happen if:
Increase the frequency of collision, increase the energy with which the collide
- More particles of the solid are exposed so reactions take place much more quickly
- The ratio of surface area to volume is bigger so faster reaction time
Mean rate of reaction = mass of reactant used up (g) / time (s)
or
Mass of products formed (g) / time (s)
C8.1 Rate of reaction
Rate: how fast it takes for reactants to turn to products
How to work out rate:
1. Measuring decreasing mass of reaction mixture
- When it gives off gas, mass is lost
- As the reaction takes place the mass decreases as gas is lost to the surroundings
2. Measuring increase of volume of gas given off
- Using a gas syringe to collect the gas in a certain time
- More amount of gas after certain time - faster the rate
3. Measure the decreasing light pass through
- Is subjective: people judge opacity in different waysThe amount of time it takes for
the object to disappear (opacity)
1
2
3
C8.2 Surface area and collision theory
Collision theory:
Particles need to collide with each other in order to cause a reaction to take place
Activation energy:
The minimum amount of energy needed before they can react
More likely to happen if:
Increase the frequency of collision, increase the energy with which the collide
- More particles of the solid are exposed so reactions take place much more quickly
- The ratio of surface area to volume is bigger so faster reaction time
Mean rate of reaction = mass of reactant used up (g) / time (s)
or
Mass of products formed (g) / time (s)
