Question

Calculate the no. of molecules present in 34g of H3PO4?

Answer 1

`~~2.11*10^23` molecules of phosphoric acid.

Explanation:

We first find the number of moles of `H_3PO_4` present in the sample by dividing by the molar mass.

So, we get:

`n_(H_3PO_4)=(34color(red)cancelcolor(black)"g")/(97.994color(red)cancelcolor(black)"g""/mol")`

`~~0.35 \ "mol"`

In one mole of molecules, there exist approximately `6.02*10^23` molecules. So here we have:

`0.35color(red)cancelcolor(black)("mol" \ H_3PO_4)*(6.02*10^23 \ H_3PO_4 \ "molecules")/(color(red)cancelcolor(black)("mol" \ H_3PO_4)`

`~~2.11*10^23 \ H_3PO_4 \ "molecules"`