e.g : Calculate the percentage by mass of Nitrogen in NH4Cl
- To calculate the percentage by mass first calculate the mass of the compound
Formula mass of NH4Cl= (14+1*4+35.5)= 53.5
- Next calculate the mass of the element in the copound
Mass of N in NH4Cl= 14
- Use the equation to find the percentage
relative mass of the element in the compound/ relative formula mass of the compound *100
14/53.5 *100= 26.168 %
Note if more than one atom of that element is present in the compound the total mass of the element has to be taken for the calculation.
e.g : Calculate the percentage by mass of N in NH4NO3
Total mass of the compound= (14+1*4+14+16*3)= 80
mass of N in the compound since there are two N atoms= 14*2=28
Percentage mass= 28/80 *100= 35%
Questions:
1. Calculate the percentage by mass of Oxygen in carbon dioxide
2. Calculate the percentage by mass of Hydrogen in NH3
