2. Calculate the formula unit masses of $ \mathrm{ZnO}, \mathrm{Na}_{2} \mathrm{O}, \mathrm{K}_{2} \mathrm{CO}_{x} $ given atomic masses of $ Z n=65 u $, $ N a=23 u, K=39 u, C=12 u . $ and $ O=16 u $.
Formula unit mass is defined as the sum of the atomic masses of all atoms that are present in a formula unit of the given compound.
Atomic mass of Zn = 65u
Atomic mass of Na = 23u
Atomic mass of K = 39u
Atomic mass of C = 12u
Atomic mass of O = 16u
Calculating the formula unit masses of the given compounds:
ZnO = Zn + O
ZnO = (65 + 16)u = 81u
Na2O = 2Na + O
Na2O = [(2 x 23)+16]u
Na2O = (46 + 16)u = 62u
K2CO3 = 2K + C + 3O
K2CO3 = [(2 x 39) + 12 + (3×16)]
K2CO3 = (78 + 12 + 48)u = 138u
Hence, the formula unit mass of ZnO is 81u, Na2O is 62u and K2CO3 is 138u.
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