Question

Find the :
(a) Number of molecules in 73 g of HCl,
(b) Weight of 0.5 mole of $O_2$ ,
(c) Number of molecules in 1.8 g of $H_{2}O,$
(d) Number of moles in 10 g of $CaC{O}_3$
(e) Weight of 0.2 mole fo $H_2$ gas,
(f) Number of molecules in 3.2 g of $S{O}_2$

Answer 1

(a) mol. mass of HCl = 36.5

No. of molecules in 73 g $HCl=6.023\times {10}^{23}\times \frac{73}{36.5}=12.04\times {10}^{23}$

(b) mol. Mass of $O_2$ = 32

Weight of 0.5 mole of $O_2$ is $=32\times 0.5=16g$

(c) No. of molecules in 1.8 g $H_{2}O=6.023\times {10}^{23}\times \frac{1.8}{18}=6.023\times {10}^{22}$

(d) Mass $CaC{O}_3$ = 100

No. of moles in 10g of $CaC{O}_3=\frac{10}{100}=0.1mole$

(e) Mol. Mass of $H_2$ = 2

Weight of 0.2 mole $H_2$ gas $=2\times 0.2=0.4g$

(f) No. of molecules in 3.2 g of $S{O}_2=6.023\times {10}^{23}\times \frac{3.2}{64}=3.023\times {10}^{22}$