Question

The weight of 1 litre of ozonized oxygen at STP was found to be 1.5 gm. When 100 ml of this mixture at STP was treated with turpentine oil, the volume was reduced to 90 ml. The molecular weight of ozone is:

• A. 49
• B. 47
• C. 46
• D. 47.94

Answer 1

Answer: (D)

47.94

Volume of $O_3$ in 100 ml of ozonised $O_2=100-90=10ml$ (dissolved in turpentine)

Volume of $O_3$ in 1 litre of ozonised $O_2=\frac{10\times 100}{100}=100ml$

Volume of $O_2$ in 1 litre $=1000-100=900ml$

weight of 900 ml of $O_2$ at STP $=\frac{900\times 32}{22400}=1.286gm$

weight of 900 ml of $O_2$ at STP $=1.5-1.286=0.214gm$

Now, 100 ml of $O_3$ at STP weight $=0.214gm$

22400 ml of $O_3$ at STP weight $=\frac{0.214\times 22400}{100}=47.94gm$

Therefore, molecular weight of $O_3=47.94$

Hence, the correct option is $D$