Question

What is the mass of `0.1*mol` of sodium metal?

Answer 1

Well, the mass of one mole of sodium is `22.99*g`........

Explanation:

How do I know this? Well, I have got a Periodic Table beside me, and you should have one beside you too.

And so we take the product............

`0.1*cancel(mol)xx22.99*g*cancel(mol^-1)=2.30*g..........`

This is an example or what is called dimensional analysis. We wanted an answer in `"grams"`, and the product gave us an answer with dimensions of `"grams"`. This persuades us that we got the order of operations right. It is all too easy to divide when you should multiply, or vice versa.