Question

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

Answer 1

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 `"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 = "39.0983 g/mol"`
`M_N= "14.0067 g/mol"`
`M_O = "15.999 g/mol"`

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

`M_ ("KNO"_3)= M_K + M_N + 3M_O`

`M_ ("KNO"_3)= ("39.0983 g/mol") + ("14.0067 g/mol") + 3("15.999 g/mol")`

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

Use

`n=m/M`

where:

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

So

`n="5.3g"/"101.102 g/mol"`

`n = "0.052 moles"`