UG Solubility Lab Report

Fill out the ksp report sheet using the data and provided under ksp notebook entry and the ksp spring 2020 document to find the formulas needed.

Report Sheet
Experiment 9
Solubility: Determination of the
Ksp of Barium Nitrate
Name: ____________________________
Instructor: _________________________
Group Members: _________________________________________
Data
Initial Mass of Ba(NO3)2
Trial 1
____________
Trial 2
____________
Trial 3
____________
Mass of Ba(NO3)2 remaining after dissolution
____________
____________
____________
Mass of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Moles of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Molarity of Ba(NO3)2
____________
____________
____________
Molarity of Ba2+
____________
____________
____________
Molarity of NO3-
____________
____________
____________
Ksp of Ba(NO3)2
____________
____________
____________
Show your work for the calculation of Ksp in Trial 1.
Page 1
Common Ion Effect
Initial Mass of Ba(NO3)2
Trial 4
____________
Trial 5
____________
Trial 6
____________
Mass of Ba(NO3)2 remaining after dissolution
____________
____________
____________
Mass of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Moles of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Molarity of Ba(NO3)2
____________
____________
____________
Molarity of Ba2+
____________
____________
____________
Molarity of NO3- (common ion)
____________
____________
____________
Ksp of Ba(NO3)2
____________
____________
____________
Show your work for the calculation of the molarity of NO3- in Trial 4 and use that
answer to determine the Ksp.
Compare the molar solubility values of Ba(NO3)2 in trials 1-3 and trials 4-6. How
do they differ? Explain.
2
Experiment 9
Solubility: Determination of
the Ksp of Barium Nitrate
An ionic compound is often described as being soluble or insoluble in water. We
can more carefully examine the degree of solubility by writing an equilibrium
expression for the dissolution of the ionic compound. We learned from the
solubility rules that AgCl, silver chloride, is not soluble in water. We can write an
equilibrium expression and a solubility product constant, Ksp. The Ksp for this
equation is related to the ion concentrations in the saturated solution as follows:
AgCl(s)
Ag+(aq) + Cl-(aq)
Ksp = [Ag+][Cl-]
Solubility product constants are used to describe saturated solutions of ionic
compounds with relatively low solubility. A saturated solution is in a state of
dynamic equilibrium between the dissolved, dissociated, ionic compound and the
undissolved solid. When the Ksp value is known, we can calculate the molar
solubility of a compound. For example, the Ksp value for AgCl is 1.77 X 10-10 which
gives a molar solubility value of 1.33 X 10-5.
Ksp = [x][x] = x2
In this experiment, we will calculate Ksp for an ionic compound with low solubility
in water.1 We will also observe the common ion effect. In general, the solubility
of an ionic compound is lower in a solution containing a common ion than in pure
water. This is in agreement with Le Chatelier’s principle. For example, if AgCl(s) is
dissolved in sea water, the solution already contains Cl- ions before AgCl(s) is
added. The common ion, Cl-(aq), will cause the equilibrium to shift to the left and
thus lower the solubility.
Page 1
Procedure
Record the mass of a clean, dry 250 mL Erlenmeyer flask. Add ~5 g of Ba(NO3)2 to
the beaker and reweigh, recording the exact mass. Next, use a graduated cylinder
to add 50.0 mL of distilled water to the flask. Stir the contents for 10 minutes.
Measure the temperature of the solution. Carefully, decant the solution into a
beaker and save the solid that remains in the flask. Place the flask on the hotplate
and evaporate to dryness. Use tongs to remove the flask from the hot plate.
Allow the flask to cool to room temperature and record the mass of the flask and
its contents. Discard the barium nitrate solid and liquid waste into the designated
waste containers. Barium nitrate is toxic if ingested. To reduce the hazardous
waste generated from this experiment, you will collect data from two other
groups instead of completing three trials.
The Common Ion Effect
Use a clean, dry flask to repeat the procedure dissolving the Ba(NO3)2 in 50.0 mL
of 0.5 M HNO3 instead of distilled water. Again, discard the waste into designated
containers. Collect data from two other groups for comparison.
References
(1) Wruck, B.; Reinstein, J. J. Chem Educ. 1989, 66,515-6.
2
Report Sheet
Experiment 9
Solubility: Determination of the
Ksp of Barium Nitrate
Name: ____________________________
Instructor: _________________________
Group Members: _________________________________________
Data
Initial Mass of Ba(NO3)2
Trial 1
____________
Trial 2
____________
Trial 3
____________
Mass of Ba(NO3)2 remaining after dissolution
____________
____________
____________
Mass of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Moles of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Molarity of Ba(NO3)2
____________
____________
____________
Molarity of Ba2+
____________
____________
____________
Molarity of NO3-
____________
____________
____________
Ksp of Ba(NO3)2
____________
____________
____________
Show your work for the calculation of Ksp in Trial 1.
3
Common Ion Effect
Initial Mass of Ba(NO3)2
Trial 4
____________
Trial 5
____________
Trial 6
____________
Mass of Ba(NO3)2 remaining after dissolution
____________
____________
____________
Mass of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Moles of Ba(NO3)2 in 50.0 mL saturated solution ____________
____________
____________
Molarity of Ba(NO3)2
____________
____________
____________
Molarity of Ba2+
____________
____________
____________
Molarity of NO3- (common ion)
____________
____________
____________
Ksp of Ba(NO3)2
____________
____________
____________
Show your work for the calculation of the molarity of NO3- in Trial 4 and use that
answer to determine the Ksp.
Compare the molar solubility values of Ba(NO3)2 in trials 1-3 and trials 4-6. How
do they differ? Explain.
4