Answer :
Final answer:
To calculate ΔS when 0.5 mol of ethanol evaporates at constant pressure, use the equation ΔS = q/T. The heat absorbed during the evaporation of ethanol can be calculated using the equation q = n * ΔHvap. Plugging the values into the equation, we find ΔS = 0.056 J/K.
Explanation:
To calculate ΔS when 0.5 mol of ethanol evaporates at constant pressure, we need to use the equation
ΔS = q/T,
where q is the heat absorbed or released during the process, and T is the temperature in Kelvin.
The heat absorbed during the evaporation of ethanol can be calculated using the equation q = n * ΔHvap,
where n is the number of moles and ΔHvap is the enthalpy of vaporization.
Substituting the given values, we have q = 0.5 mol * 39.3 kJ/mol
= 19.65 kJ.
The temperature can be converted from Celsius to Kelvin by adding 273.15,
so T = 78.3°C + 273.15
= 351.45 K.
Plugging these values into the equation for ΔS, we find ΔS = 19.65 kJ / 351.45 K
= 0.056 J/K.
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