Question

What is stoichiometry?

Answer 1

See this old answer and links. All chemical reactions observe `"stoichiometry"`.

Explanation:

The balancing of chemical equations follows conservation of mass. If there are `10*g` of products from all sources, AT MOST there can be `10*g` of products. Chemical equations balance mass and charge absolutely, and due to (inevitable) losses on handling, yields are therefore less than quantitative.

In the case of multi-step syntheses (and some chemists specialize in the reactions), even a four step sequence with 90% yield at each step (and a synthetic chemist would gladly accept a 90% yield), the overall yield is reduced to 66% automatically. And this reflects mass equivalence: `"garbage in equals garbage out"`.