Brandy is made by distilling ethyl alcohol,
which is done by boiling the alcohol until it
turns into a gas. How much heat is required
to completely distil 0.750 kg of ethyl alcohol?
Multiply the heat of vaporization of ethyl alcohol by the mass.
The heat of vaporization of ethyl alcohol is about 200 cal/g.
To calculate the heat required to completely distill a substance, we need to use the concept of specific heat capacity and the heat of vaporization.
Specific heat capacity is the amount of heat required to raise the temperature of a substance by one degree Celsius per unit mass. Its unit is J/(kg·°C). The specific heat capacity of ethyl alcohol is approximately 2.44 J/(g·°C) or 2.44 × 10^3 J/(kg·°C).
Heat of vaporization is the amount of heat required to change a substance from its liquid phase to its gaseous phase at a constant temperature and pressure. For ethyl alcohol, the heat of vaporization is approximately 853 kJ/kg or 853 × 10^3 J/kg.
To calculate the heat required, we need to consider two steps:
Step 1: Heating the ethyl alcohol from its initial temperature to its boiling point.
Step 2: Vaporizing the ethyl alcohol at its boiling point.
Step 1: Let's assume the initial temperature of the ethyl alcohol is 20 °C and its boiling point is 78.37 °C.
The heat required to raise the temperature of the ethyl alcohol from 20 °C to 78.37 °C can be calculated using the formula:
Heat = mass × specific heat capacity × temperature change
Heat = 0.750 kg × 2.44 × 10^3 J/(kg·°C) × (78.37 °C - 20 °C)
Step 2: Once the ethyl alcohol reaches its boiling point, we need to calculate the heat required to vaporize it.
Heat = mass × heat of vaporization
Heat = 0.750 kg × 853 × 10^3 J/kg
Now, we can calculate the total heat required by adding the heats obtained from step 1 and step 2:
Total Heat = Heat from Step 1 + Heat from Step 2
Finally, plug in the values and calculate the total heat required.