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JEE Main 202331 JanuaryEvening Shift
Exam
JEE Main
Year
2023
Date
31 January
Shift
Evening Shift
Subject
Chemistry
Chapter
Thermodynamics (C)

JEE Main 2023 · 31 January · Evening Shift · Chemistry · Thermodynamics (C)

Enthalpies of formation of CCl _ 4 ( g ) , H _ 2 O ( g ) , CO _ 2 (...

Enthalpies of formation of CCl4(g),H2O(g),CO2(g){CCl}_{4} ( g ) , {H}_{2}O ( g ) , {CO}_{2} ( g ) and HClHCl are −105,−242,−394- 105, - 242, - 394 and −92kJmol−1- 92kJ{mol}^{- 1} respectively. The magnitude of enthalpy of the reaction given below is kJmol−1{kJmol}^{- 1}. (nearest integer) CCl4(g)+2H2O(g)→CO2(g)+4HCl(g){CCl}_{4} ( g ) + 2{H}_{2}O ( g ) \to {CO}_{2} ( g ) + 4HCl ( g )

Correct answer

0

Step-by-step solution

Using Hess's law of constant heat summation:
Enthalpy of reaction = Enthalpy of formation of products - Enthalpy of formation of reactants
∴ΔHf°=ΔHf°(CO2,g)+4ΔHf°(HCl)−ΔHf°(CCl4)−2ΔHf°(H2O,r)∴ {\Delta H}_{f} ° = {\Delta H}_{f} ° \left({CO}_{2}, g\right) + 4{\Delta H}_{f} ° ( HCl ) - {\Delta H}_{f} ° \left({CCl}_{4}\right) - 2{\Delta H}_{f} ° \left({H}_{2}O, r\right)

=[−394]+4[−92]+105−2×[242]= [ - 394 ] + 4 [ - 92 ] + 105 - 2 \times [ 242 ]

=−394−368+105+484= - 394 - 368 + 105 + 484

=−173kJ/mole= - 173kJ / mole

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