# What is stoichiometry? Can you explain the concept?

Aug 31, 2015

Easy: getting the right change from a $20-00 note for an$8-95 purchase.

#### Explanation:

Stoichiometry is a word that simply means in the right measure . Stoichiometry is practised every time you make a purchase with cash or make an electronic transaction.

The value of the purchase + the value of your change must add up to the total amount of money that you gave to the shopkeeper. If you make the purchase electronically, the debit placed on your account must match up to the credit that is made to the shop's account. If they don't add up, then someone has made a mistake, and either you or your creditor has cause for complaint. (Of course, sometimes they don't add up, that's when you end up on a call queue to complain about the $99-00 debit made to your account for your$9-99 purchase; this is a simple and common accounting error, so I am told.)

There is a saying in the banking/stock marketing industry, $\text{for every credit, there must be a corresponding debit}$, i.e. $\text{Rob Peter, pay Paul; debit one account; credit another}$. This is a clear and prime example of stoichiometry.

You can see how stoichiometry applies to chemical reactions, and why teachers insist that chemical reactions are properly balanced. And this is stoichiometry writ large. For every reactant particle, there must be a corresponding product particle. And for every electric charge possessed by the reactants, there must be an equal and corresponding electric charge possessed by the products. If there is not, someone (usually you) has made a mistake.