Question

Calculate the number of molecules present in each of the following samples.

4.75 millimoles of phosphine, PH3

Answer 1

`2.8*10^(21)moleculesPH_(3)`

Step-by-step explanation:

1. Convert from milimoles to moles:

`4.75millimolesPH_(3)*(0.001molPH_(3))/(1millimolPH_(3))= 4.75*10^(-3)moles`

2. Use the Avogadro´s number to find the number of molecules in one mol:

`4.75*10^(-3)molesPH_(3)*(6.022*10x^(23)moleculesPH_(3))/(1molPH_(3))=2.8*10^(21)moleculesPH_(3)`