CHM 1046 Fall, 2007
Quiz 1
Name (print)_________________________
Show your work for complete (and partial) credit. Report your answers to the correct
number of significant figures, and use units where appropriate. All chemical
equations should balance; indicate phases. q = smT
1. An electric heater coil provided heat to a 15.5g sample of solid iodine, I2(s), at the rate
of 3.48J/s. It took 4.54min from the time the iodine began to melt until the iodine was
completely melted. What is the molar heat of fusion, ΔHºHºfus, for iodine?
2. Explain why a liquid’s vapor pressure depends on temperature. Why does a liquid’s
vapor pressure increase as temperature increases?
3. Explain why a liquid’s boiling point increases if the external pressure increases.
4.
Compound m.w. Hfus Hvap at 100Specific heat
H2O(l) 18.015g/mol 6.009kJ/mol 40.7kJ/mol 4.184Jg-1C-1
How much heat would it take to heat 35.5g of water, originally at 25.0°C, to 100°C, then
vaporize the water.
5. Compound A has greater intermolecular forces than Compound B. Which compound,
A or B, would:
___ have a greater vapor pressure at a given temperature?
___ have a higher boiling point?
___ have a greater Hvap?