# How many moles are there in "5.3 g" of "KNO"_3 ?

Feb 20, 2018

It is $0.052$ moles. You need to use the molar masses to convert from grams to moles.

#### Explanation:

You need to first find the molar mass of ${\text{KNO}}_{3}$. You do this by adding the individual molar mass of each element, these can be found on a periodic table or online.

${M}_{K} = \text{39.0983 g/mol}$
${M}_{N} = \text{14.0067 g/mol}$
${M}_{O} = \text{15.999 g/mol}$

The molar mass is the sum of all of the elements times the number of moles of each element.

${M}_{{\text{KNO}}_{3}} = {M}_{K} + {M}_{N} + 3 {M}_{O}$

${M}_{\text{KNO"_3)= ("39.0983 g/mol") + ("14.0067 g/mol") + 3("15.999 g/mol}}$

M_ ("KNO"_3) = "101.102 g/mol"

Use

$n = \frac{m}{M}$

where:

• $n =$number of moles
• $m =$mass
• $M =$molar mass

So

$n = \text{5.3g"/"101.102 g/mol}$

$n = \text{0.052 moles}$