Some Basic Concepts Of Chemistry Question 132

Question: 23.2 g of an organic compound having molecular formula CnH2n+2 is burnt in excess of O2(g) initially taken in a 44.82 L steel vessel. Before reaction the gaseous mixture w at 273 K with pressure of 2 aim. After complete combustion and loss of considerable amount of heat the mixture of product and excess of had a temperature of 546 K and 4.6 atm pressure. The formula of compound is

Options:

A) C5H12

B) C6H10

C) C3H8

D) C4H10

Show Answer

Answer:

Correct Answer: D

Solution:

[d] Idea This problem can be solved by using concept of ideal gas equation and chemical equation involved in combustion reaction. Students are advised to follow steps. • Write chemical equation involved in combustion of hydrocarbon. • Assume initial pressure = p • Calculate increased pressure • Then, calculate number of mole using ideal gas equation. Equation of combustion CnH2n+2+(3n+12)O2nCO2+(n+1)H2O Initial pressure of CnH2n+2 is p (assumed) Increase in pressure =p[(2n+1)1(3n+12)]=(n12)p

Mass of organic compound =14×n+2 546 K and 4.6 atm or 273 K 2.3 atm Increase
2.32=0.3 atm p=nRTV=23.2M×(0.0821×27344.82)

=23.2M×0.544.82

=116(14n+2)×(n1)2 also =(n1)2×11.614n+2=0.3 On solving, n=4 So, compound will be C4H4×2+2C4H10



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