### Video Transcript

The rate of a reaction can be calculated using the following equation: rate of reaction equals mass of product formed divided by time taken. If the mass is in grams and the time is in seconds, what is the unit of the rate of reaction?

We can determine the unit of the rate of reaction by substituting the units of mass and time into the equation. Mass is in the numerator of the equation, so we place the mass unit, grams, in the numerator. Time is in the denominator of the equation. So we place the unit of time, seconds, in the denominator. When multiplying and dividing, like units cancel when they appear in both the numerator and the denominator. Grams and seconds are not like units and cannot cancel one another. This means that the unit of rate of reaction will be grams per second.