Initial Rate

What is Initial Rate?

The rate of a reaction at the instant it begins, found from the gradient of the tangent drawn to the curve at time zero. It is the fastest rate of the whole reaction, because the reactants are at their highest concentration and the greatest area of solid is exposed at that moment.

This definition is part of the Chemical Reactions chapter in Cambridge O Level Chemistry.

Concepts related to Initial Rate

• tangent
• gradient
• plateau

Examiner tips on Initial Rate

• Comparing two curves in one sentence each. Say something about the steepness and something about the plateau, and say what each one tells you. “Curve A is steeper at the start, so its initial rate is higher; both curves level off at the same volume, so both experiments contained the same amount of limiting reactant.” That single sentence pattern answers most graph-comparison questions in this topic.