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Calculate change in internal energy if D...

Calculate change in internal energy if `Delta H= - 92.2 kJ, P = 40` atm and `Delta V = - 11`.

A

a. `- 42 kJ`

B

b. `-88 kJ`

C

c. `+88 kJ`

D

d. `+42 kJ`

Text Solution

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The correct Answer is:
To calculate the change in internal energy (ΔU) given the change in enthalpy (ΔH), pressure (P), and change in volume (ΔV), we can use the following relationship: \[ \Delta H = \Delta U + P \Delta V \] From this equation, we can rearrange it to solve for ΔU: \[ \Delta U = \Delta H - P \Delta V \] ### Step-by-Step Solution: 1. **Identify the given values:** - ΔH = -92.2 kJ - P = 40 atm - ΔV = -1 L (Note: The problem states ΔV as -11, but the transcript indicates it is -1 L.) 2. **Convert ΔH to the same units as PΔV:** - Since P is in atm and ΔV is in liters, we need to convert ΔH from kJ to joules for consistency. - 1 kJ = 1000 J, thus: \[ \Delta H = -92.2 \text{ kJ} = -92200 \text{ J} \] 3. **Calculate PΔV:** - PΔV = (40 atm) × (-1 L) - We need to convert atm·L to joules. The conversion factor is: \[ 1 \text{ atm·L} = 101.325 \text{ J} \] - Therefore: \[ P \Delta V = 40 \text{ atm} \times (-1 \text{ L}) = -40 \text{ atm·L} = -40 \times 101.325 \text{ J} = -4053 \text{ J} \] 4. **Substitute the values into the ΔU equation:** \[ \Delta U = \Delta H - P \Delta V \] \[ \Delta U = -92200 \text{ J} - (-4053 \text{ J}) = -92200 \text{ J} + 4053 \text{ J} \] \[ \Delta U = -88147 \text{ J} \] 5. **Convert ΔU back to kJ:** \[ \Delta U = -88.147 \text{ kJ} \approx -88.15 \text{ kJ} \] 6. **Final Answer:** \[ \Delta U \approx -88 \text{ kJ} \] ### Summary: The change in internal energy (ΔU) is approximately -88 kJ.

To calculate the change in internal energy (ΔU) given the change in enthalpy (ΔH), pressure (P), and change in volume (ΔV), we can use the following relationship: \[ \Delta H = \Delta U + P \Delta V \] From this equation, we can rearrange it to solve for ΔU: ...
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