CHEM 122 Chapter : 15.2 Rate Laws An Introduction.docx

• School: Simon Fraser University
• Department: Chemistry
• Course: CHEM 122
• Professor: John Canal

Document Summary

Chemical reactions are reversible: after a period of time, enough products accumulate so that the reverse reaction becomes significant. 2no2 -> 2no + o2 => o2 + 2no -> 2no2. Rate law: an expression that shows how the rate depends on the concentration of (significant) reactants. N: order of the reactant, must be determined by experiment. The [products] don"t appear in the rate law (because the reaction rate is being studied under conditions where the reverse reaction doesn"t contribute significantly to the overall rate. The value of the exponent n must be determined by experiment not from the balanced equation. 2no2 molecules are consumed for every o2 molecule produced. Rate = 2 x rate" ; k[no2]n = 2k"[no2]n ; k = k". Value of the rate constant depends on how the rate is defined. Differential rate law: expresses how the rate depends on concentration. Integrated rate law: expresses how the concentration depends on time.