8. Reaction Kinetics A2 Flashcards
(6 cards)
Rate equation
An equation that relates the rate of reaction to the concentration of reactants raised to the appropriate power
Rate constant
Constant of proportionality for a given reaction at a given temperature
Order of reaction
The power to which the concentration of a reactant is raised in the rate equation
Half-life of a reaction
The time taken for the concentration of a reactant to halve
Describe 2 ways of using these results to show the reaction is first order with respect to H2 (g) concentration. [3m]
Method 1
- plot a graph of concentration of H2 against time
- constant half-life shows it is 1st order
Method 2
- draw tangent AND determine gradient on conc-time graph
- plot a graph of rate against concentration of H2
- gives a straight line through the origin of graph
Magnesium carbonate was heated in an open test-tube. It was difficult to see whether a thermal decomposition reaction took place. Explain why. [2m]
- CO2 gas produced is colourless, cannot be seen
- colour of solid (MgCO3 –> MgO) doesn’t change, remains white after heating