Chemistry: Solubility
Inquiry Question
Ever wonder why Gatorade or other drink crystals don’t
always dissolve fully? How do different conditions affect
the rate of compounds going into solution? How is the
concentration of a substance related to its solubility?
Name: ___________________________
Date: ____________
Image in public domain.
Have you ever become frustrated when trying to dissolve drink crystals such as Gatorade Powder, ice
tea crystals, chocolate milk or hot chocolate powders, or similar? What can you do to make it dissolve
better? Do some thing dissolve better than others? Does the liquid you are dissolving in make a
difference? These all revolve around the topic of solubility and solutions. The characteristics of different
solvents and solutes strongly impacts the ability for things to dissolve.
In this project you will further explore the concept of ‘concentration’ and how different substances can
dissolve better than others. Though a simulation and some calculations we will see how ion
concentrations are related to solution concentrations etc.
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Chemistry: Solubility
Instructions
The goal for this project is to use a PHET simulation to learn more about solutions. Specifically how
changing various factors will affect the concentration (Molarity) of the solution. You will also explore
the concepts of saturation, ion concentration and dilution further.
Begin by defining a series of solubility related terms and learning about two important concentration
formulas. Explore the PHET simulation where you can try out different substances and learn about
different factors affecting solubility. Finally, engage in a series of exploration questions and calculate
saturated solution concentrations, ion concentrations, and how dilutions work.
This Project will be graded according to the marking rubric.
Definitions:
Start by looking up definitions for the following words:
1. Solution:
2. Solute:
3. Solvent:
4. Molarity:
5. Dilution:
Formulas:
There are two important formulas for solutions. The first is how you calculate molarity. The second
is the dilution formula. Complete them below. Note: M = molarity. V = Volume.
Molarity =
Dilution:
M1V1 =
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Chemistry: Solubility
Exploration:
Ctrl-Click on the link to the right to open the PHET simulation. Solutions
Try each of the following to get a feel for how the sim works then answer the questions below
2. Add different amounts of the solute “drink mix” to the beaker. There are two ways to add a solute.
You can shake in solid from the shaker, which comes out in small grains, or you can add a
concentrated solution using the dropper. You may switch between the “solid” shaker or “solution”
dropper.
3. Measure the concentration by sliding the purple meter tool into the solution.
4. Observe what happens to the concentration when water is added or taken out of the tank. This is
done by sliding the blue knob on the top or bottom faucet.
5. Explore the above options but change the type of solute.
Exploration Questions:
1. What are the visual changes to the solution in the beaker when a solute is first added?
2. What happens visually and to the concentration as more and more solute is added?
3. What happens visually and to the concentration when water is added to the beaker?
4. What happens visually and to the concentration when liquid is drained from the beaker?
5. What happens visually and to the concentration when water is evaporated?
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Chemistry: Solubility
Saturated Concentrations:
As you continue to add drink mix, eventually you reach a point where no more will dissolve. This is
called saturation. Determine the concentration at which saturation is reached for dink mix and then
repeat that process for each solute and fill in the table below.
Solute
Concentration Solute
Concentration
Drink Mix
Molarity Calculations:
Using the simulation and the formula for Molarity, complete the table below.
Moles of
Compound
(mol)
Liters of
Solution
(L)
0.53
0.79
0.86
0.34
0.88
1.0
0.20
3.5
0.67
0.67
Molarity of
Solution (M)
Moles of
Compound
(mol)
Liters of
Solution (L)
Molarity of
Solution (M)
0.78
0.59
1.8
8.4
6.4
8.5
Ion Concentrations:
Just as an entire solution has a concentration, so does each individual ion. For instance, since there are
three ions when a Calcium Chloride (CaCl2) molecule dissolves into solution, a 3.0 M solution of CaCl2
is 3.0 M with respect to Ca2+ ions and 6.0 M with respect to Cl- ions. An analogy for this would be
taking 3 bikes apart. You would end up with 3 frames and 6 wheels. Copy the saturated concentrations
from above and then determine the concentration of each ion in solution.
Compound
Saturated Concentration
(from Part 3)
Cation Molarity
Co(NO3)2
CoCl2
K2Cr2O7
K2CrO4
NiCl2
CuSO4
KMnO4
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Anion Molarity
Chemistry: Solubility
Dilution:
Adding water to a solution will dilute it which lowers the concentration. We're going to use the
simulation to do some dilution activities and calculate new concentrations.
1. Complete the table below, using
in an empty beaker. Begin by changing the
button at the top right to read solution. You should see a dropper like the one shown the right except
it will read CoCl2 instead of drink mix. Click on the red button until you have 0.20L of solution.
Copy the concentration reading into the first box of the table below. Next click the spout on the left
to add 0.20L of water. This will give you a total of 0.40 L of solution. Copy the new concentration
and then continue adding water 0.20L at a time and copying the concentration.
.20L of dropper
.20L dropper+.20L
.20L dropper+.40L
.20L dropper+
solution
water
water
.60Lwater
Repeat the exercise, using
.20L of dropper
.20L dropper+.20L
solution
water
in an empty beaker.
.20L dropper+.40L
water
.20L dropper+
.60Lwater
2. What do you notice about the concentration change as each addition of .25L of water is added to the
concentrated spigot solution?
3. The formula M1V1 = M 2V2 is a great way to calculate the concentration of a solution that undergoes
dilution. M1V1 refers to the concentration and volume of the original solution, and M 2V2 refers to that
solution after it has been diluted.
0.20 L of
has a concentration of 5.0 M. (M1 = 5.0 M and V1 = 0.20 L) If the
solution’s volume, V2 is increased with water to .50 L, calculate the new concentration, M 2. Show
your work below and then check your work in the sim AFTER your calculation.
Your Calculated M2:
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Chemistry: Solubility
New concentration shown in the simulation:
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