Quantrex Academy · Free BITSAT PYQ solutions
BITSAT Chemistry Thermodynamics (C) 2023 BITSAT 2023 (Memory Based Paper 1)

BITSAT Chemistry Question (2023) — Solution

Question

If enthalpies of formation of C _2 H _4( ~g ), CO _2( ~g ) and H _2 O ( l ) at 25^ C and 1 ~atm pressure are 52,394 and -286 ~kJ / mol respectively, the change in enthalpy for combustion of C _2 H _4 is equal to

Options

  1. A. -141.2 ~kJ / mol
  2. B. -1412 ~kJ / mol
  3. C. +14.2 ~kJ / mol
  4. D. +1412 ~kJ / mol

Answer

B. -1412 ~kJ / mol

Step-by-step solution

Enthalpy of formation of C _2 H _4, CO _2 and H _2 O are 52,-394 and -286 ~kJ / mol respectively. (Given) The reaction is C _2 H _4+3 O _2 2 CO _2+2 H _2 O change in enthalpy, ( H)= H_ products - H_ reactants =2 (-394)+2 (-286)-(52+0) =-1412 ~kJ / mol .

Practice more on Quantrex App →

Related: Chemistry — Thermodynamics (C) · All PYQ Banks