Question #21205

Q. A gas mixture of 3 litres of propane and butane on complete combustion at 25'C produces 10 litres of CO2. Initial composition of propane and butane in the gas mixture is-

(i) 66.66%,33.33% (ii) 33.33%,66.66% (iii) 50%,50% (iv) 60%,40%

(i) 66.66%,33.33% (ii) 33.33%,66.66% (iii) 50%,50% (iv) 60%,40%

Expert's answer

The reactions propane and butane with oxygen:

C_{3}H_{8} + 5O_{2} --> 3CO_{2} + 4H_{2}O

C_{4}H_{10} + 6.5O2 --> 5H_{2}O + 4CO_{2}

If volume of propane is x , the volume of butane is 3-x. Than

volume of CO_{2} is

x 3x

C_{3}H_{8} + 5O_{2} --> 3CO_{2} + 4H_{2}O

(3-x) 5*(3-x)

C_{4}H_{10} + 6.5O_{2} --> 5H_{2}O + 4CO_{2}

Total volume of CO_{2} is:

3x + 4*(3-x) = 10

3x + 12 - 4x = 10

-2x = -2

x = 2

Initial composition of propane is 2.0/3*100 = 66.66%

Initial composition of butane is 33.34%

C

C

If volume of propane is x , the volume of butane is 3-x. Than

volume of CO

x 3x

C

(3-x) 5*(3-x)

C

Total volume of CO

3x + 4*(3-x) = 10

3x + 12 - 4x = 10

-2x = -2

x = 2

Initial composition of propane is 2.0/3*100 = 66.66%

Initial composition of butane is 33.34%

## Comments

Assignment Expert22.08.18, 13:01Thank you Crischal

Crischal22.08.18, 05:06For total volume of co2

3x+4(3-x)=10 should be written not 3x+5(3-x)=10.So please correct the solution.

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