What is the change in enthalpy when 250 g of steam condenses at 100oC? (Hv = 40.67 kJ/mol)
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To determine the change in enthalpy when 250 g of steam condenses at 100°C, we need to use the equation:
ΔH = m × Hv
where:
ΔH = change in enthalpy
m = mass of the substance
Hv = enthalpy of vaporization
In this case, the given mass is 250 g, and the enthalpy of vaporization, Hv, is 40.67 kJ/mol.
To use this equation, we need to convert the mass of steam into moles. To do this, we'll use the molar mass of water.
The molar mass of water (H2O) is approximately 18.02 g/mol. We can calculate the number of moles, n, using the equation:
n = m / M
where:
n = number of moles
m = mass of the substance
M = molar mass
Plugging in the values, we find:
n = 250 g / 18.02 g/mol
n ≈ 13.87 mol
Now we can calculate the change in enthalpy:
ΔH = m × Hv
ΔH = 13.87 mol × 40.67 kJ/mol
ΔH ≈ 564.47 kJ
Therefore, the change in enthalpy when 250 g of steam condenses at 100°C is approximately 564.47 kJ.