Rates

What do we mean when we talk about rates of reactions? Essentially, a rate is how fast something is going. For instance, how many words you type per minute is your typing rate. In chemistry, the rate of reaction is how fast the reaction proceeds. Typically, we measure this by finding out the change in a substances concentration in a certain amount of time. If we know that we bought two gallons of orange juiceat the store, and we had one gallon of OJ one hour later, we can say that someone drank one gallon in that one hour. This is our rate for orange juice drinking: one gallon per hour. A typical rate for a reaction looks something like this:

With this curve, it is apparent that the rate is slower than what we said earlier. Before, we drank one gallon in one hour. Here, it took almost three hours to finish off that gallon. We could say that the graph shows that the rate is slower here than what we had before.

What does this all mean? How are rates affected by outside factors? Both surface area and temperature affect the rate of a reaction. That is to say, if we added the same amount of Alka-Seltzer to two different glasses of water, but crushed up one of the tablets, the rates would not be the same. Similarly, if we added one tablet to cold water and one tablet to hot water, the rates of reaction again would be different.

In chemistry, we use models and mathematics to numerically represent these ideas. Find out more about the math behind rates by exploring what governs the rates: the rate laws. Or, if you want to know how rates affect equilibrium, do so.

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