| State the collision theory | For a chemical reaction to occur, the reactant molecules must collide with enough energy |
| Activation energy definition | The minimum amount of energy needed for particles to react |
| Name the factors for increasing rate of reaction | Increasing temperature, increasing pressure, increasing surface area, adding a catalyst |
| What effect does temperature have on rate reaction? | Increasing temperature means:
Particles move faster
Particles collide more frequently
More collisions creates more energy, increasing rate of reaction |
| What effect does pressure have on rate reaction? | Increasing pressure means:
More particles in a set volume
Particles collide more frequently
More collisions creates more energy, increasing rate of reaction |
| What effect does surface area have on rate reaction? | Increasing surface area means:
Higher surface to volume ratio
Particles collide more frequently
More collisions creates more energy, increasing rate of reaction |
| What effect does a catalyst have on rate on reaction? | Using a catalyst means:
Provides an alternative reaction pathway with lower activation energy
Activation energy needed decreases
Reaction happens faster increasing rate |
| Equation to calculate rate of reaction | RofR = Amount of reactant or product formed/Time |
| Give 3 ways (excluding the equation) to measure rate of reaction | Disappearing mark through solution, change in mass (usually gas given off), volume of gas given off |
| Method for investigating effect of concentration on R of R by volume of gas produced [Method 1] | Set volume of dilute HCl acid in conical flask placed on mass balance
Add magnesium ribbon and plug flask with cotton wool
Start stopwatch and measure initial mass
Take mass reading at regular intervals
Plot on a graph [Loss in mass/Time]
Repeat with different acid concentrations |
| Independent, dependent and control variables for concentration experiment Method 1 | Independent- concentration of acid
Dependent- Loss in mass
Control- Volume of acid, mass of magnesium ribbon |
| Method for investigating effect of concentration on R of R by change in colour [Method 2] | Set volume of dilute sodium thiosulphate in conical flask on paper with black X
Add dilute HCl and start stopwatch
Measure amount of time it takes for X to disappear
Repeat reaction with different concentrations of either reactants [only one at a time] |
| Independent, dependent and control variables for concentration experiment Method 2 | Independent- concentrations of reactants
Dependent- Time for X to disappear
Control- Volume of reactants, black X |
| Conclusion for experiment | The higher the concentration, the faster the rate of reaction. |
| Mean rate of reaction = | Change in y / change in x |
| Reversible reaction definition | A reaction where the products can react to form the reactants |
| Name 2 reversible reactions | Ammonium chloride <=> Ammonia + hydrogen chloride
Nitrogen + Oxygen <=> Nitric acid |
| Dynamic equilibrium definition | When both forward and backward reactions are happening at the same time but there is no overall effect |
| Define Le Chatelier's principle | If the conditions of a reversible reaction are changed at equilibrium, the system [where the reaction takes place] will try to counteract the change |
| Effect of changing temperature in a reaction system | Decreasing:
Reaction shifts to exothermic direction to produce more heat
More products for the exothermic reaction than the endothermic
Increasing :
Reaction shifts to endothermic direction to reduce heat
More products for endothermic reaction than the exothermic reaction |
| Effect of changing the pressure in a reaction system | Increase:
Equilibrium tries to reduce pressure
Moves in direction where there are fewer molecules of gas
Decrease:
Equilibrium tries to increase pressure
Moves in direction where there are more molecules of gas |
| Effect of changing the concentration in a reaction system | Any change in concentration:
System tries to bring itself back to equilibrium
Increase in reactants causes an increase in products
Decrease in products causes a decrease in reactants |
