Graphical representation of the reaction rate
The concentration of products increases as time passes, and this is shown as a curve with a positive slope. A curve representing the reactants will have a negative slope since its concentration decreases.
When the reaction ends, no more products are formed and no more reactants are consumed. The concentration curves each level off to form a plateau.
The gradient of the graph reflects the rate of reaction.
The product curve is steep (has a higher gradient) at the start of the reaction. This indicates that the reaction is faster.
As the reaction proceeds, the gradient of the product curve gets gentler as the reaction rate declines.
The reaction rate for a given reaction is rarely constant throughout the reaction.
When the reaction is almost complete, the product curve starts to plateau as the concentrations change more slowly.