Warm Up: Write the formulas for M, m, % by weight, and salinity (ppm).
Learning Objective: Using salinity to determine freezing point of salt water.
Agenda: Practice problems
Table quiz
Ice caps and Global warming video.
Salt water comes in a variety of concentrations and there is a name for each;
| Water salinity based on dissolved salts | |||
|---|---|---|---|
| Fresh water | Brackish water | Saline water | Brine |
| < 0.05% | 0.05–3% | 3–5% | > 5% |
For this exercise, use the following values;
| FRESH WATER | BRACKISH WATER | SALINE WATER | BRINE |
|---|---|---|---|
| 0.025% | 1% | 3.5% | 7% |
Q1: convert concentrations from % to ppt
a) Fresh Water
b) Brackish Water
c) Saline
d) Brine
Q2: Calculate the molal concentration for a – d
a) Fresh Water
b) Brackish Water
c) Saline
d) Brine
Q3: Write the formula for freezing point depression of water (hint: the coefficient Kf = 1.86 degree C/m)
Q4: How many ions does 1 molecule of salt create when it is dissolved in water?
Q5: The freezing point of water is 0 degrees C (32 deg F), calculate the freezing point depression for a – d
a) Fresh Water
b) Brackish Water
c) Saline
d) Brine
Q6: Calculate the freezing point for a-d
a) Fresh Water
b) Brackish Water
c) Saline
d) Brine
This completes the quiz.