Concentration-Time Graphs
- The reaction order can be inferred from a graph of concentration of reactant vs time
- Zero-order, first-order and second-order reactions have characteristic concentration vs time graphs for each of them
- In a zero-order reaction, the concentration of a reactant is inversely proportional to time
- The graph is a straight line that goes down as shown below
- The slope of a zero order reaction is the rate constant
Concentration-time graph of a zero-order reaction
A concentration-time graph of a zero-order reaction shows that concentration is inversely proportional to time
- In a first-order reaction, the concentration of the reactant decreases with time
- The graph is a curve that goes downwards and eventually levels out, as shown below:
Concentration-time graph of a first-order reaction
A concentration-time graph of a first-order reaction curves downwards
- In a second-order reaction, the concentration of the reactant decreases more steeply with time
- The graph is a curve that goes downwards, however the decrease in concentration is steeper and it eventually plateaus, as shown below:
Concentration-time graph of a second-order reaction
A concentration-time graph of a second-order reaction shows a downward curve with a steeper slope than the curve for a first-order reaction