LECTURE 9.1 – RATES OF REACTION

Today’s Learning Targets LT 8.1 – I can describe the rate of a reaction using the ideas of concentration of reactants, concentration of products, and time. I can explain why rate is dependent on concentration. LT 8.2 – I can calculate the average rate of reaction with respect to the reactants and/or products. LT 8.3 – I can hypothesize about the impact that concentration, temperature, and pressure have on the rate of a chemical reaction.

How are rates measured?

I. Rate of Reaction A rate describes how fast something changes with time. Rate is measured either by the rate of formation of product or the rate of disappearance of the reactants.

II. Calculating Rates of Reactions When we describe the rate, we can think of the reaction: aA  bB The average rate of this reaction is:

Class Example You run the reaction: 2H2 + O2  2H2O If initially you begin with a 0.5 M solution of H2 and 50 seconds later the concentration of H2 is 0.23 M

Table Talk You run the reaction: H2SO4 + 2NaOH  2H2O + Na2SO4 If initially you begin with a 0.12 M solution of NaOH and 150 seconds later the concentration of NaOH is 0.06 M