## Zero-Order Reactions

Zero-order reactions aren't common, but they're included with lots of chemistry courses because the math behind them is straightforward. Most examples of zero-order reactions are

**thermal decompositions**- where a chemical just breaks apart because there's so much heat - because it isn't the reactant concentration controlling the reaction, it's the temperature!## The Rate Equation

Zero-order reactions mean the exponent on the reactant concentration is 0:

Notice how the whole rate expression simplifies to Rate = k. This type of reaction doesn't depend on reactant concentration!

## How Concentration Changes with TimeJust like with first- and second-order reactions, you can integrate the rate equation to determine how the concentration of the reactant changes with time. If you know a little calculus (antiderivatives) you'll be able to follow the integration that I've put on the right. If you can't, just skip to the second-last line.
If the reaction is zero-order, a graph of Remember (from grade 9) how y=mx+b is the equation of a line? Well here, y is [A], the reactant concentration. x is t, the time elapsed. m (the slope) is -k and b (the y-intercept, where t=0) is [A]o, the initial reactant concentration.[A] vs. t will give a line! |