# How many moles of compound are there in 4.5 kg Ca(OH)_2?

Feb 8, 2016

#### Answer:

$\text{4.5 kg Ca(OH)"_2}$ contains $\text{61 moles}$.

#### Explanation:

Determine Moles of Calcium Hydoroxide

You will need to divide the given mass by the molar mass of $\text{Ca(OH)"_2}$.

The molar mass of calcium hydroxide, $\text{Ca(OH)"_2}$ is $\text{74.09268 g/mol}$. https://pubchem.ncbi.nlm.nih.gov/compound/6093208

Since molar mass is given in g/mol, 4.5 kg needs to be converted to grams.

Convert kg to grams.

$4.5 \cancel{\text{kg"xx(1000"g")/(1cancel"kg")="4500 g}}$

Determine the moles of calcium hydroxide contained in $\text{4500 g Ca(OH)"_2}$ by dividing the given mass by its molar mass.

$4500 \cancel{\text{g Ca(OH)"_2xx(1"mol Ca(OH)"_2)/(74.09268 cancel"g Ca(OH)"_2)="61 mol Ca(OH)"_2}}$ (rounded to two significant figures)