Question

How many moles of h2o are there in 180g of water (molar mass is 18.001g/mole)

Answer 1

First, remember that:

1 mol of any compound is the same thing as the molecular mass of the compound.

So, we could say that 1 mol of H2O is equal to the molecular mass of H2O, which is 18.001g/mole.

Given that we have 180g of water, we could write:

$180gH_2O\cdot\frac{1molH_2O}{18.001gH_2O}=10molesH_2O$

Therefore, there are 10 moles of water in 180g of water.

To convert grams to moles, we just divide the amount in grams we have by the molecular mass.

$\text{moles}=\frac{\text{mass given}}{molecular\text{ mass}}$