Theory:

Calculate the gram molecular mass of the following compounds.
 
i. \(H_2O\)
ii. \(CO_2\) 
iii. \((Ca)_3(PO_4)_2\)
 
i.  \(H_2O\)
  
Data:
  
Atomic mass of \(H=1\)
 
Atomic mass of \(O=16\)
 
Solution:
  
GrammolecularmassofH2O=2×1+1×16=2+16=18
 
Hence, the gram molecular mass of \(H_2O=18\) \(g\).
 
ii.   \(CO_2\)
 
Data:
 
Atomic mass of \(C=12\)
 
Atomic mass of \(O=16\)
 
Solution:
  
GrammolecularmassofCO2=1×12+2×16=12+32=44
 
Hence, the gram molecular mass of \(CO_2=44\) \(g\).
 
iii.\((Ca)_3(PO_4)_2\)
 
Data:
  
Atomic mass of \(Ca=40\)
 
Atomic mass of \(P=30\)
 
Atomic mass of \(O=16\)
 
Solution:
 
GrammolecularmassofCa3PO42=3×40+30+4×16×2=120+30+64×2=120+94×2=308
 
Hence, the gram molecular mass of \((Ca)_3(PO_4)_2=308\) \(g\).