Question

The mass of MgO is 1.04 g in a reaction. How many moles of MgO were used?

Answer 1

`2.58*10^-2` moles

Explanation:

Magnesium oxide's molar mass is `40.3044 \ "g/mol"`. So here,

`(1.04color(red)cancelcolor(black)"g")/(40.3044color(red)cancelcolor(black)"g""/mol")~~2.58*10^-2 \ "mol"`

of magnesium oxide were used.

Answer 2

0.03 moles

Explanation:

`n=m/(mm)`

where:
n= number of moles
m= mass
mm= molar mass

SO

number of moles
=`1.04/ (16+24.31)`

=`1.04/40.31`

=`0.03` moles