How to measure the speed of a reaction as the change in concentration with time. Average and instantaneous rate, the rate law, order and molecularity, and the units of the rate constant.
3 lessons, about 1 h 45 min3 simulations11 problems7 practice questionsPython in every lesson
Created by StemPy LabA match flares in a second, and an iron nail takes months to rust. The rate of a reaction tells us how fast the amount of a reactant falls, or the amount of a product rises, in one unit of time. We find an average rate over an interval, and the rate at one moment from the slope of a tangent.
Pour twice as much acid into a flask and the reaction usually goes faster. The rate law says exactly how much faster: . The powers and are the orders, and only experiment can give them. We find them from the initial rates of several runs.
A balanced equation shows where a reaction starts and where it ends. It does not show how it gets there. Most reactions go in steps, and each step is an elementary reaction with a molecularity of 1, 2 or 3. The slowest step sets the rate, so the rate law of that step is the rate law of the whole reaction.
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