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Multiple Choice
Calculate the amount of heat (in kilojoules) required to vaporize 2.58 kg of water at its boiling point, given that the enthalpy of vaporization for water is 40.7 kJ/mol.
A
5850 kJ
B
3200 kJ
C
1047 kJ
D
2100 kJ
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Verified step by step guidance
1
First, determine the number of moles of water you have. Use the formula: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \). The molar mass of water (H₂O) is approximately 18.02 g/mol.
Convert the mass of water from kilograms to grams. Since 1 kg = 1000 g, multiply 2.58 kg by 1000 to get the mass in grams.
Calculate the number of moles of water using the mass in grams and the molar mass of water. Substitute the values into the formula from step 1.
Use the enthalpy of vaporization to find the total heat required. The formula is: \( q = n \times \Delta H_{\text{vap}} \), where \( q \) is the heat in kilojoules, \( n \) is the number of moles, and \( \Delta H_{\text{vap}} \) is the enthalpy of vaporization (40.7 kJ/mol).
Multiply the number of moles by the enthalpy of vaporization to find the total heat required in kilojoules.