Question

Which mass of urea CO(NH2)2 contain the same mass of nitrogen as 101.1g of potassium nitrate?

Answer 1

M(KNO₃)=101.1 g/mol
M(CO(NH₂)₂)=60.1 g/mol

m(N)=M(N)m(KNO₃)/M(KNO₃)

m(N)=2M(N)m(CO(NH₂)₂)/M(CO(NH₂)₂)

2m(CO(NH₂)₂)/M(CO(NH₂)₂)=m(KNO₃)/M(KNO₃)

m(CO(NH₂)₂)=M(CO(NH₂)₂)m(KNO₃)/(2M(KNO₃))

m(CO(NH₂)₂)=60.1*101.1/(2*101.1)=30.05 g