Lab Report 5 - John Xu Lab Report Experiment 5 Physical...

John Xu
3/29/07
Lab Report
Experiment 5: Physical Properties of Pure Substances and Solutions
Part A: Phase Behavior of Water, Carbon Dioxide, and t -Butanol
1. Running cold water over the flask with boiling water will cause the steam inside
to condense, and therefore reduces the pressure of the gas above the liquid. The
liquid cools slower than the gas, and will have a greater vapor pressure than the
gas. Therefore, as seen on the phase diagram, water will start to boil as long as the
pressure is low enough.
2. Increasing the temperature of the dry ice causes the solid to begin to sublimate,
which explains the observation of the expansion of the pipet. Along with this, the
pressure of the container also increases, which allows carbon dioxide to reach its
critical point, and form water in addition to the solid and gas states.
3. Phase Diagram of t -Butanol
Part B: Colligative Properties- Freezing Point Depression
4. Freezing point of t -butanol: 24.6 ° C
∆T
f
= 24.6 ° C – 13.0 ° C = 11.6 ° C (Trial 1)
∆T
f
= 24.6 ° C – 12.9 ° C = 11.7 ° C (Trial 2)
Molality of particles = 11.6 ° C / 8.3 kg * ° C/mol = 1.4 mol/kg