X (g) + 4Y (g) →2Z (g), ΔH∘=-75.0 kJ Before the reaction, the volume of the gaseous mixture was 5.00 L. After the reaction, the volume was 2.00 L. Calculate the value of the total energy change, ΔE, in kilojoules.

Question

Ruth Archer

Chemistry

12 December, 02:17

X (g) + 4Y (g) →2Z (g), ΔH∘=-75.0 kJ Before the reaction, the volume of the gaseous mixture was 5.00 L. After the reaction, the volume was 2.00 L. Calculate the value of the total energy change, ΔE, in kilojoules.

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Claire Moss · Answer 1

Isobaric transition, first law: H=ΔU+w for a gas expansion: w = P ext ∗ΔV to convert to joules, you need the gas constants. R = 0.08206 L atm/mol*K, R=8.314 J/mol*K w = P ext ∗ΔV∗ 8.314 J/mol∗K 0.08206 L atm/mol∗K ΔU=ΔH-[ P ext ∗ΔV∗ 8.314 J/mol∗K 0.08206 L atm/mol∗K ] ΔU=-75000 J-[ (43.0atm) ∗ (2-5) L∗ 8.314 J 0.08206 L atm ] Then you need to convert to kJ. by the way U=E, internal energy.