Calculate the heat required for the following two processes, and compare the results.a. A 100.0 g sample of solid ethanol melts at its melting point. Hfus = 4.94 kJ/mol
b. A 100.0 g sample of liquid ethanol vaporizes at its boiling point. Hvap = 38.6 kJ/mol
Answers
The heat required for the following two processes are:
a. 10.74 KJ
b. 83.92 KJ
Part a)
Given:
Mass (m) of ethanol = 100g
Heat of fusion, Hfus = 4.94 kJ/mol
To find:
Heat (Q) =?
Calculation for number of moles:
Mass of C₂H₅OH = 100g
Molar mass of C₂H₅OH = (2x12)+ (5x1) + 16 + 1 = 46g/mol
Number of Mole = Mass /Molar Mass
Number of mole (n) of C₂H₅OH = 100/46 = 2.174 moles.
Calculation for Heat of fusion:
Q = n x Hfus
Q = 2.174 mol x 4.94 kJ/mol
Q = 10.74KJ
Therefore, 10.74 KJ of heat is required to melt the ethanol.
Part b)
Given:
Mass of C₂H₅OH = 100g
Heat of vaporization, Hvap = 38.6 kJ/mol
To find:
Heat (Q) =?
Calculation for Heat of vaporization:
As calculated above, the number of mole in 100g of ethanol, C₂H₅OH is 2.174 moles.
The heat required to vaporize the ethanol can be obtained as follow:
Q = n x Hvap
Q = 2.174 mol x 38.6 kJ/mol
Q = 83.92 KJ
Therefore, 83.92 KJ of heat is required to vaporize the ethanol.
Find more information about Heat of fusion here:
Answer:
A. 10.74 KJ
B. 83.92 KJ
Explanation:
A. Data obtained from the question include the following:
Mass (m) of ethanol = 100g
Heat of fusion, Hfus = 4.94 kJ/mol
Heat (Q) =..?
Next, we shall determine the number of mole in 100g of ethanol, C2H5OH. This is illustrated below:
Mass of C2H5OH = 100g
Molar mass of C2H5OH = (2x12)+ (5x1) + 16 + 1 = 46g/mol
Number of mole (n) of C2H5OH =..?
Mole = Mass /Molar Mass
Number of mole (n) of C2H5OH = 100/46 = 2.174 moles.
Now, we can obtain the heat required to melt the ethanol as follow:
Q = n x Hfus
Q = 2.174 mol x 4.94 kJ/mol
Q = 10.74KJ
Therefore, 10.74 KJ of heat is required to melt the ethanol.
B. Data obtained from the question include the following:
Mass of C2H5OH = 100g
Heat of vaporisation, Hvap = 38.6 kJ/mol
Heat (Q) =..?
As calculated above, the number of mole in 100g of ethanol, C2H5OH is 2.174 moles.
The heat required to vaporise the ethanol can be obtained as follow:
Q = n x Hvap
Q = 2.174 mol x 38.6 kJ/mol
Q = 83.92 KJ
Therefore, 83.92 KJ of heat is required to vaporise the ethanol.
C. From the above calculations, a higher amount of heat energy i.e 83.92 KJ is required to vaporise the ethanol and a lesser amount of heat energy i.e 10.74 KJ is needed to melt the ethanol.
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Answer;
= 48,828.125 mi/hr²
Explanation and solution;
- Centripetal acceleration is the rate of change of angular velocity. Centripetal acceleration occurs towards the center of the circular path along the radius of the circular path.
- Centripetal acceleration is given by; V²/r ;
V = 125 mi/h and r = 0.320 miles
- Thus; centripetal acceleration = 125²/0.320
=15625/0.320
= 48,828.125 mi/hr²