posted by Alex on .
Given the data below, calculate the total heat (in J) needed to convert 20.0 g of liquid ethanol (C2H5OH) at 40.0 oC to gaseous ethanol at 125 oC.
A. 3.23 x 103 B. 3.67 x 103 C. 4.17 x 103 D. 2.08x104 E. 2.12 x 104
It would have helped to give the data below. Here is how you do the problem.
I assume there is a density. Use the density to calculate the mass. mass -= volume x density.
Then for heat used there are two formula to use.
Within a phase you use
mass x specific heat x (Tfinal-Tinitial)
For example, for liquid ethanol between the freezing point and boiling point you will use
mass ethanol x specific heat ethanol x (b.p. temp - freezing point temp).
Then for the change of phase use
mass ethanol x heat fusion at the melting/freezing point or
mass ethanol x heat vaporization at the boiling point.
Then add all of the heats together for the total.
Post your work if you get stuck.