Rates of Reactions

Orders, Rate Equations and Rate Constants

Rate = change in concentration/ change in time. [A] is shorthand for ‘concentration of A’.  Rate of Reaction: The change in concentration of a reactant or product per unit time.  Units: Usually it is mol dm-3 s-1. -1 in superscript means ‘per’ or ‘divide’.  Orders...

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Concentration- Time Graphs

Colorimeter: Monitoring colour change/ concentration. Amount of light absorbed by solution.  Experiment Method: Prepare standard solutions of known concentrations of solution. Choose filter with complementary colour to coloured chemical. Zero colorimeter with water....

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Rate- Concentration Graphs

Rate- Concentration Graphs:  Zero Order: Straight horizontal line with zero gradient. Rate = k[A]0 so rate = k = Y intercept. Reaction rate does not change with concentration. Can confirm first order of reaction of graph by calculating two half-lives and constant....

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Rate- Determining Step

Reaction Mechanism: Reactions take place in series of steps called reaction mechanism. - Collision unlikely between more than 2 species in one step. - Also stoichiometry in rate equation may not match overall equation.  Rate- Determining Step: The steps in reactions...

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Rate Constants and Temperature

Temperature Increase: As temperature increases, rate increases and the value of rate constant k increases. This is due to two factors…  Kinetic Energy: As temperature increases, particles move faster and collide more frequently.  Activation Energy: Increasing...

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