Introduction to Solubility PhET Lab (created 3/2011)

We can express concentrations in terms of moles solute per liters of solution

When we cook pasta, we frequently dissolve table salt in water. Is there a limit to how

much salt we can get into the water?

When ionic-bonded compounds (like table salt, NaCl) are dissolved in polar solvents

(like water), the polar water molecules act to pull the ions in the compound apart.

When this happens (called dissociation), ions are released into the solution. Is there a

limit to the number of ions that can exist in solution?

Please use your textbook, your notes, or the internet to define the following terms:

Saturated ____________________________________________________________________________

Unsaturated ____________________________________________________________________________

Supersaturated ____________________________________________________________________________

Molarity ____________________________________________________________________________

Cation ____________________________________________________________________________

Anion ____________________________________________________________________________

Dissociation ____________________________________________________________________________

Solubility ____________________________________________________________________________

Procedure PhET Simulations ? Play With Sims ? Chemistry? Salts and Solubility ?

Take some time and familiarize yourself with the simulation before answering the below questions:

1. What happens to the bound Na+ and Cl- ions as they enter the water?

______________________________________________________________________________________

2. Is there a point at which no more sodium and chloride ions will dissolve? How do you know?

______________________________________________________________________________________

3. What do we call a solution that has as many ions as it can hold?

__________________________________________________________________________

4. What happens if you add additional, solid NaCl after the maximum has been reached?

__________________________________________________________________________

5. What happens when more water is added to a saturated solution?

__________________________________________________________________________

6. What happens to the ions bound together as a solid when the solution’s volume is reduced?

__________________________________________________________________________

7. How many total Na + ions can you add until no more will dissolve (the maximum amount)?

__________________________________________________________________________

8. How many moles does this many ions represent? (recall, 1 mole = 6.02 x 10 23 things)

______________________________________________________________________________________

9. What volume (in Liters) did you use to get the saturation point in #7 above?

______________________________________________________________________________________

10. What concentration is this? (In mole/L, use #8 and #9’s answers) This is molarity, M.

______________________________________________________________________________________

For each slightly soluble salt…

1. Determine the Chemical Formula

2. Write a Dissociation Equation (Example: NaCl (s) ? Na + (aq) + Cl – (aq) )

3. Determine Concentration (mole/L) of the molecule and EACH ION in the compound in a saturated solution.

Remember…to find concentration in Molarity: calculate moles present, divide moles into volume in Liters.

?Scratch area to show your work?

1. Chemical Formula: ___________________________________________

2. Dissociation Equation: _________________________________________

3. Concentration of entire molecule at saturation (M): ___________________

4. Concentration of cation (+) at saturation (M): ________________________

5. Concentration of anion (-) at saturation (M): ________________________

6. Chemical Formula: ___________________________________________

7. Dissociation Equation: _________________________________________

8. Concentration of entire molecule at saturation (M): ___________________

9. Concentration of cation (+) at saturation (M): ________________________

10. Concentration of anion (-) at saturation (M): ________________________

11. Chemical Formula: ___________________________________________

12. Dissociation Equation: _________________________________________

13. Concentration of entire molecule at saturation (M): ___________________

14. Concentration of cation (+) at saturation (M): ________________________

15. Concentration of anion (-) at saturation (M): ________________________

16. Chemical Formula: ___________________________________________

17. Dissociation Equation: _________________________________________

18. Concentration of entire molecule at saturation (M): ___________________

19. Concentration of cation (+) at saturation (M): ________________________

20. Concentration of anion (-) at saturation (M): ________________________

Name:_______________________

Post-Lab Conclusion Questions and Calculations

1. Adding water to a solution of ions increases / decreases / doesn’t change concentration.

2. Reducing volume of an entire solution increases / decreases / doesn’t change concentration.

3. Adding more solid compound to an unsaturated solution increases / decreases / doesn’t change concentration.

4. Adding more solid compound to a saturated solution increases / decreases / doesn’t change concentration.

5. The bound ions of a solid compound at the bottom of a saturated solution stay bound / dissolve and are

6. Determine the concentration of a solution of 2.4 moles of sugar (no dissociation) in 3.5 L of water

_______________________ M

7. How many moles of NaCl would be required to produce .95 L of a .58 M NaCl solution?

_______________________ mol

8. What volume of water would be required to dissolve 67 grams of Lithium Fluoride (LiF) to a concentration of

_______________________ L

9. What is the concentration of a solution of 3.5 x10 22 molecules of sugar in 25 mL of water?

_______________________ M

10. How many moles of FeCl 3 (compound) are present in 2.1 L of a .85 M solution?

11. How many moles of Fe 3+ ions are present in this solution?

12. How many moles of Cl- are present in this solution?

13. What is the concentration of a solution made from 130 grams of Cu 3 (PO 4 ) 2 in 3.9 L of water?

__________________ mol FeCl 3

___________________ mol Fe 3+

_____________________mol Cl –

14. What is the concentration of Copper (II) ions in the above solution?

15. What is the concentration of Phosphate ions in the above solution?

_______________________ M

_______________________ M

_______________________

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