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Concentration part 2: Activities
Web link:
• PhET Concentration
Activity 1: Molar Mass Calculations
For this activity, you will need the periodic table in Appendix A of the prelab.
Using the periodic table, determine the molar mass of the following compounds:
1. Cobalt(II) nitrate, Co(NO3)2
2. Cobalt(II) chloride, CoCl2
3. Potassium dichromate, K2Cr2O7
4. Potassium chromate, K2CrO4
5. Nickel(II) chloride, NiCl2
6. Copper(II) sulfate, CuSO4
7. Potassium permanganate, KMnO4
8. Sodium chloride, NaCl
Concentration
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Activity 2: Saturated Solutions
For this activity, you will be using the Concentration simulation on the PhET website. The web address
for this simulation is given at the beginning of the lab handout under Web Links. You can also click here
to take you to the simulation. You are going to investigate the effect of varying the amount of solute,
solvent, and solution on the saturation of the solution.
1. Open the PhET Concentration Simulation.
2. Move the crosshairs end of the concentration meter into the solution. It will read 0.000 mol/L. Leave
the solute selection dropdown menu set to “Drink Mix”.Shake the solute shaker a few times. This will
add drink mix to the water. Notice the change in the concentration. In table 1, in the “Drink mix is
added” describe what happens to the concentration, e.g. remains the same, increases, decreases, goes
to zero.
3. Then add additional water to the solution. In table 1 column 3, describe what happens to the
concentration, e.g. remains the same, increases, decreases, goes to zero.
4. Adjust the evaporation slider, so that it is no longer set to “none”. Describe the effect on the
concentration of the solution in table 1 column 4.
5. Drain some (not all) of the solution and describe the effect on the concentration of the solution in table
1 column 5.
6. Click on the “Remove Solute” button and describe the effect on the concentration of the solution in
table 1 column 6.
Figure 1: PhET Concentration Simulation. The arrows point to the pieces that move and affect the concentration and or
amount of solution. The solute can be changed using the drop-down menu at the top right.
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Table 1: Effect of Various Actions on the Concentration of a Solution
Action
Drink mix is
added
Water is added
Evaporation
occurs
Solution is drained
Solute is removed
What happens to
concentration?
7. Reset the simulation and insert the concentration meter into the solution.
8. Keep the solute to “Drink mix” and add as much as you can.
9. How do you know when a solution is saturated?
10. While the solution is saturated, add additional solid solute. What happens?
11. Why do you think this is?
12. How does adding this additional solute change the concentration of the saturated solution?
13. Increase the evaporation of the saturated solution. How does evaporation change the concentration of
the saturated solution?
Concentration
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Activity 3: Solute Mass of Saturated Solutions
For this activity, you will continue using the Concentration simulation on the PhET website. You are
going to use the simulation to determine the saturation concentration of different solutes dissolved in
water. Then you will calculate the mass of the solute in the saturated solutions.
1. Reset the Concentration Simulation.
2. Fill the beaker to 1 L.
3. Keep the evaporation set to “none”, and place the concentration sensor in the solution.
4. For each solute in table 2, find and record the concentration when saturation occurs. (You can do this
by shaking the solute shaker until the word “saturated” appears. Then read the concentration on the
sensor.) Complete the second column of table 2 with your results.
Table 2: Concentration and Solute Mass for Various Solutes
Solute Concentration for
Saturation
(mol/L)
Solute Mass
(grams)
Drink mix
Cobalt (II) nitrate
Cobalt (II) chloride
Potassium dichromate
Potassium chromate
Nickel (II) chloride
Copper (II) sulfate
Potassium permanganate
Sodium chloride
5. Does each solute have the same concentration at saturation?
6. For each solute, determine the mass in grams required to saturate 1 L of solution. Record these
values in column 3 of the table 2. See example 6 in the prelab for a reminder of how to determine the
mass of a one liter saturated solution.
References
1. This lab was adapted from an activity provided by: University of Colorado. (). PhET Interactive
Simulations – Physics, PhET: Interactive simulations. Retrieved at May 7, 2020, from the website
