Calculate the heat released (in joules) from the condensation of 25.0 g of ethanol (C2H5OH).
∆Hvap = 204 cal/g; MP = -114.3¢ªC , BP = 78.5¢ªC
(Draw a heating curve first!)
To calculate the heat released from the condensation of ethanol (C2H5OH), we need to consider the steps involved and use the relevant heat values.
First, let's draw the heating curve:
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Now let's break down the steps involved:
Step 1: Heating the ethanol from its melting point to its boiling point.
Step 2: Heating the ethanol from its boiling point to its condensing point.
Step 3: The actual condensation process.
To calculate the heat released in each step, we can use the equation:
q = m * ∆H
where q is the heat released, m is the mass of the substance, and ∆H is the heat of the process.
Step 1: Heating from melting point to boiling point
For this step, we need to calculate the heat required to raise the temperature of ethanol from its melting point (-114.3°C) to its boiling point (78.5°C).
q1 = m * Cp * ∆T
where Cp is the specific heat of ethanol (2.44 J/g°C) and ∆T is the change in temperature.
∆T1 = 78.5°C - (-114.3°C) = 192.8°C
q1 = 25.0 g * 2.44 J/g°C * 192.8°C = 11,878 J
Step 2: Heating from boiling point to condensing point
For this step, we also need to calculate the heat required to raise the temperature of ethanol from its boiling point (78.5°C) to its condensing point.
∆T2 = 78.5°C - 78.5°C = 0°C
q2 = 25.0 g * 2.44 J/g°C * 0°C = 0 J
Step 3: The actual condensation process
For this step, we need to consider the heat of vaporization (∆Hvap) of ethanol.
q3 = m * ∆Hvap
q3 = 25.0 g * 204 cal/g * (4.184 J/cal) = 21,060 J
Now, let's calculate the total heat released:
Total heat released = q1 + q2 + q3
= 11,878 J + 0 J + 21,060 J
= 32,938 J
Therefore, the heat released from the condensation of 25.0 g of ethanol is 32,938 Joules.
To calculate the heat released from the condensation of ethanol, we first need to determine the amount of heat required to vaporize the ethanol. Then we can use the given information about the calorimetric value of ethanol to find the heat released during the condensation process.
Step 1: Calculate the amount of heat required to vaporize the ethanol.
This can be done using the formula:
Q = m x ∆Hvap
where:
Q is the amount of heat required (in joules),
m is the mass of the substance (in grams),
∆Hvap is the heat of vaporization (in calories/g).
Given:
m = 25.0 g
∆Hvap = 204 cal/g
Let's convert the mass and heat of vaporization to the same units before calculating:
1 calorie = 4.184 joules (approx.)
So, ∆Hvap = 204 cal/g x 4.184 J/cal ≈ 852.336 J/g
Now we can calculate the amount of heat required to vaporize the ethanol:
Q = 25.0 g x 852.336 J/g
Step 2: Calculate the heat released during condensation.
Since the heat released during condensation is equal to the heat required to vaporize the substance, we can use the result obtained in step 1.
The heat released during condensation of 25.0 g of ethanol is:
Q = mass x ∆Hvap
Q = 25.0 g x 852.336 J/g
We can now substitute the values and calculate the result:
Q ≈ 21,308.4 J
Therefore, the heat released from the condensation of 25.0 g of ethanol is approximately 21,308.4 joules.