Keeping Track of Units in Chemistry Calculations

By Heather Hattori, Richard H. Langley

Part of 1,001 Chemistry Practice Problems For Dummies Cheat Sheet

When completing a chemistry calculation, always write the number with the unit. Number, unit — it’s like having a first and last name.

Consistently writing down the units allows you to see what cancels and helps you spot an error when units don’t cancel. For example, look at the following conversion from miles to kilometers. The correct setup gives you an answer in kilometers. The incorrect setup gives you an answer in square miles per kilometer, which doesn’t make sense.