Question

Calculate the actual mass of :
(a) an atom of oxygen,

(b) an atom of hydrogen,
(c) a molecule fo $N{H}_3$,

(d) the atom of silver
(e) th emolecule fo oxygen
(f) 0.25 gram atom of calcium.

Answer 1

(a) $6.023\times {10}^{23}$ atoms of oxygen has mass = 16 g

So, 1 atom has mass $=\frac{16}{6.023\times {10}^{23}}=2.656\times {10}^{-23}g$

(b) 1 atom of Hydrogen has mass $=\frac{1}{6.023\times {10}^{23}}=1.666\times {10}^{-24}$

(c) 1 molecule of $N{H}_3$ has mass $=\frac{17}{6.023\times {10}^{23}}=2.82\times {10}^{-23}g$

(d) 1 atom of silver has mass $=\frac{108}{6.023\times {10}^{23}}=1.701\times {10}^{-22}$

(e) 1 molecule of $O_2$ has mass $=\frac{32}{6.023\times {10}^{23}}=5.314\times {10}^{-23}g$

(f) 0.25 gram atom of calcium has mass $=0.25\times 40=10g$