1 ml of gaseous aliphatic compound CnH3nOm is completely burnt in an excess of O2 and cooled to room temperature. The contraction in volume is 

A.   A   (1+1/2n-3/4m)

B.   B   (1+1/4n-1/4m)

C.   C   (1+3/4n-1/4m)

 D.  D   (1+3/4n-1/2m)

     please mention the steps used in finding the answer


Asked by Ashok Maheshwari | 28th Jun, 2015, 02:20: PM

Expert Answer:

The gaseous aliphatic organic compound = CnH3nOm 
Volume= 1 mL
The balanced reaction for the combustion is,
CxHyOz + (x+y/4-z/2)O2 → xCO2 + y/2H2O
Here, x=n, y=3n, z=m
Hence, the balanced reaction for the combustion of given organic compound will be,
CnH3nOm + (n+3n/4-m/2)O2 → nCO2 + 3n/2 H2O
At RT, the volume of H2O is ognored as it becomes liquid,
Hence, contraction in volume = 1 + n + 3n/4 - m/2 - n = 1+ 3n/4 - m/2
Therefore, the correct answer option is D.

Answered by Prachi Sawant | 28th Jun, 2015, 06:45: PM

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