Answer :
Sure! Let's find the change in energy needed to condense 0.707 mol of ethanol using the given information.
1. Understand the Process:
- When ethanol is vaporized, it absorbs energy, specifically called the enthalpy of vaporization. To condense ethanol (change it from gas back to liquid), this energy must be released.
- The enthalpy of vaporization for ethanol is provided as 38.6 kJ/mol. This means 38.6 kilojoules of energy are required to vaporize one mole of ethanol. Conversely, the same amount of energy is released when one mole of ethanol condenses.
2. Given Values:
- The enthalpy of vaporization: 38.6 kJ/mol
- Moles of ethanol to condense: 0.707 mol
3. Calculate the Energy Change:
- To calculate the amount of energy released when condensing the ethanol, we multiply the enthalpy of vaporization by the number of moles of ethanol.
- Energy change = enthalpy of vaporization × moles of ethanol
- Energy change = 38.6 kJ/mol × 0.707 mol
4. Including the Sign:
- Since energy is released during condensation, the change in energy should have a negative sign to indicate that energy is leaving the system.
5. Result:
- The change in energy needed to condense 0.707 mol of ethanol is approximately -27.3 kJ.
Therefore, the energy change is -27.3 kJ, rounded to three significant figures with the proper sign.
1. Understand the Process:
- When ethanol is vaporized, it absorbs energy, specifically called the enthalpy of vaporization. To condense ethanol (change it from gas back to liquid), this energy must be released.
- The enthalpy of vaporization for ethanol is provided as 38.6 kJ/mol. This means 38.6 kilojoules of energy are required to vaporize one mole of ethanol. Conversely, the same amount of energy is released when one mole of ethanol condenses.
2. Given Values:
- The enthalpy of vaporization: 38.6 kJ/mol
- Moles of ethanol to condense: 0.707 mol
3. Calculate the Energy Change:
- To calculate the amount of energy released when condensing the ethanol, we multiply the enthalpy of vaporization by the number of moles of ethanol.
- Energy change = enthalpy of vaporization × moles of ethanol
- Energy change = 38.6 kJ/mol × 0.707 mol
4. Including the Sign:
- Since energy is released during condensation, the change in energy should have a negative sign to indicate that energy is leaving the system.
5. Result:
- The change in energy needed to condense 0.707 mol of ethanol is approximately -27.3 kJ.
Therefore, the energy change is -27.3 kJ, rounded to three significant figures with the proper sign.
