Question

How many atoms are in 75 grams of calcium?

Answer 1

`1.13`x`10^24`atoms Ca

Explanation:

First, we need to take the `75g` of calcium and convert it into moles

To get moles we need to find the molar mass of calcium, we do this by referring to the periodic table, finding calcium then find its mass

In this case, the molar mass is `(40.08g)/(1 mol)`

So now we convert our grams to moles

`75cancelg` x `(1 mol)/(40.08cancelg)` = `1.87mol`

*Note that when converting, you put the unit you want to convert to over the unit you already have

Now in order to get to atoms, we use Avogadro's number
`6.022`x`10^23` particles / mol

`1.87cancel(mol)` x `6.022`x`10^23` atoms/`1cancel(mol)` = `1.13`x`10^24`atoms Ca