Reading Chemical Reactions

Reading a chemical reaction is not quite as simple as you might think. We can’t just read the numbers and formulas, we need to read it (and think about it) in a way that makes sense of what is really happening. Let’s use a specific example to see what this means.

2 C4H10 + 13 O2 → 8 CO2 + 10 H2O

This is the reaction that occurs in a butane lighter or a butane camping stove.

It is tempting to read this reaction as

“2 butane react with 13 oxygen to make 8 carbon dioxide and 10 water.”

Although this matches what is written, it doesn’t really explain what it means. In other words, when you say 2 butane, the question remains 2 what of butane? Two pounds? Two liters? Two metric tons?

In the end there are only 2 valid answers to the question, and therefore only 2 valid ways to read the reaction. THose answers are molecules and moles. That means that the ONLY valid ways to read this reaction are:

2 molecules of butane react with 13 molecules of oxygen to make

8 molecules of carbon dioxide and 10 molecules of water.

Or

2 moles of butane react with 13 moles of oxygen to make

8 moles of carbon dioxide and 10 moles of water.

While both of these are correct, the second (bold) one is the useful one, for the simple reason that molecules are too small to actually measure or work with.