Determining Rate Equations: The Initial Rates Method

Overview

Finding orders by comparing initial rates across experiments where one concentration is changed at a time.

What you need to know

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Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is the initial rates method used to determine?

   Model answer

   The rate equation for a reaction, including the orders with respect to each reactant

2. 2

   In the initial rates method, what is measured at the very start of a reaction?

   Model answer

   The rate of reaction

3. 3

   Why is the initial rate measured rather than the rate at a later time in the initial rates method?

   Model answer

   At the start, concentrations are known precisely and have not changed significantly from initial values

4. 4

   How is the initial rate typically obtained from a concentration-time graph?

   Model answer

   By measuring the gradient of the tangent to the curve at time zero

5. 5

   In the initial rates method, what must be done to the initial concentration of one reactant while keeping others constant?

   Model answer

   Varied systematically while measuring the corresponding initial rate

6. 6

   How can the order of reaction with respect to a particular reactant be determined using initial rates data?

   Model answer

   By comparing how the initial rate changes when the concentration of that reactant is changed by a known factor

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