Water has a molar heat capacity of 75.38 J/(mol . $\degree$C) and its enthalpy of vaporization is 40.7 kJ/mol at 100$\degree$C.How much energy is needed to convert 186 g liquid H₂O at 20.0$\degree$C to steam at 100$\degree$C?

Question

Quizplus · Accepted Answer

To convert 186 g of water at 20°C to steam at 100°C, calculate the energy needed to heat the water to 100°C and then vaporize it. First, convert grams to moles (186 g / 18.015 g/mol = 10.32 mol). Then, calculate the energy to heat the water: q = moles × heat capacity × temperature change = 10.32 mol × 75.38 J/(mol°C) × (100°C - 20°C) = 62.2 kJ. Next, calculate the energy for vaporization: q = moles × enthalpy of vaporization = 10.32 mol × 40.7 kJ/mol = 419.5 kJ. Total energy = 62.2 kJ + 419.5 kJ = 481.7 kJ, approximately 482 kJ.

Water Has a Molar Heat Capacity of 75 °\degree° C) and Its Enthalpy of Vaporization Is 40

Water Has a Molar Heat Capacity of 75 $\degree$ C) and Its Enthalpy of Vaporization Is 40