Question

Find the mass percentages (mass %) of Na, H, C, and O in sodium hydrogen carbonate.

• A. 30, 20, 45, 5
• B. 28, 1, 14, 57
• C. 24, 23, 12, 1
• D. None of above

Answer 1

The correct option is B 28, 1, 14, 57

22.99 g (1 mol) of Na
12.01 (1 mol) of H
48.0 (1 mol) of C
48.0 (3 mole $\times$ 16.00 gram per mole) of O
The mass of one mole of $NaHC{O}_3$ is $22.99g+1.01g+12.01g+48.00g=84.01g$
And the mass percentages of the elements are
mass % $Na=\frac{22.99g}{84.01g}\times 100=27.36$%
mass % $H=\frac{1.01g}{84.01g}\times 100=1.20$%
mass % $C=\frac{12.01g}{84.01g}\times 100=14.30$%
mass % $O=\frac{48.00g}{84.01g}\times 100=57.14$%