posted by Johnny on .
Ethanol (C2H5OH) has been produced since antiquity by the fermentation of fruits and vegetables. Given the following data, if 5.87 kJ of energy are transferred to 13.3 g of frozen ethanol at -130.0 °C, what is the final temperature of the sample?
Heat capacity (solid) = 0.97 J/°C • g
Heat capacity (liquid) = 2.72 J/°C • g
Heat capacity (gas) = 2.42 J/°C • g
Normal melting point = −114.0 °C
Normal boiling point = 78.4 °C
Heat of fusion = 7.61 kJ/mol
Heat of vaporization = 39.3 kJ/mol
How much heat is required to raise T of solid ethanol from -130 to -114? That will be mass ethanol x specific heat solid ethanol x (Tf-Ti) = ?
How much heat has is left?
5870 J - ? = x
How much heat is required to melt the ethanol. That is mass ethanol x heat fusion = y
x-y = z = heat remaining from the original 5870 J.
z = mass liquid ethanol x specific heat liquid ethanol x (Tf - Ti). Substitute and solve for Tf.