HEATING CURVES AND PHASE CHANGE DIAGRAMS
PART A – HEATING CURVES. Use the heating curve below to answer the
following questions.
1. What is the melting point of the substance?
2. What is the boiling point of the substance?
3. Which letter represents heating of the solid?
4. Which letter represents heating of the vapor?
5. Which letter represents melting of the solid?
6. Which letter represents boiling of the liquid?
PART B – PHASE DIAGRAMS. Use the phase diagram for water below to answer the following questions.
7. What is the state of water at 2 atm and 50
8. What phase change will occur if the temperature is
lowered from 80C to -5C at 1 atm?
9. You have ice at -10C and 1 atm. What could you do in
order cause the ice to sublime?
For each of the questions on this worksheet, refer to the phase diagram for mysterious compound X.
1) At what temperature and pressure will all three phases coexist?
3) If I have a bottle of compound X at a pressure of 45 atm and
temperature of 1000 C, what will happen if I raise the temperature to
4000 C?
4) Why can’t compound X be boiled at a temperature of 2000 C?
5) If I wanted to, could I drink compound X?
Changes in State – Ch. 12
CHEM
Molar Enthalpies Problems
1. If ΔHfus of sodium is 2.60 kJ/mol, how much energy is required to melt 145.50 g of sodium?
2. The ΔHfus for water is 6.01 kJ/mol. How much energy is needed to melt 5.28 x 1024 ice molecules?
3. The ΔHsolid for mercury is -2.30 kJ/mol. How much energy is lost when 9.26 g of mercury freezes.
4. The ΔHvap of NH3 is 23.3 kJ/mol. How much energy is needed to vaporize 100.0 g of NH 3.
5. a. Jessica has 250.0 g of water that she needs to boil. If the ΔHvap is 40.66 kJ/mol, how much heat energy will she
need to boil her water?
b. What is this amount in Joules?
6.
Yash needs to burn 875.0 g of glucose (C6H12O6). If the molar heat of combustion is -2800.0 kJ/mol, how much
heat will be released when the glucose burns?
7. Given that the ΔHcombustion for hydrogen is -286 kJ/mol, how much heat is released when Ben blows up a balloon
containing 4.50 L of hydrogen gas at STP?
8. The ΔHfus of ethanol (C2H5OH) is 4.94 kJ/mol. How much heat is needed to freeze 250.0 mL of ethanol if the
density of ethanol is 0.789 g/mL?
Changes in State – Ch. 12
CHEM