Lab8. Determine the concentration of an unknown NaCl solution

docx

School

Florida SouthWestern State College, Lee *

*We aren’t endorsed by this school

Course

2046L

Subject

Chemistry

Date

Feb 20, 2024

Type

docx

Pages

5

Uploaded by MinisterRainGoose27

Report
Determine the concentration of an unknown NaCl solution The Solubility Product* A solute with finite solubility can yield a  saturated  solution when it is added to a solvent in an amount exceeding its solubility, resulting in a heterogeneous mixture of the saturated solution and the excess, undissolved solute. For example, a saturated solution of silver chloride is one in which the equilibrium shown below has been established. AgCl(s) ⇌ Ag + (aq) + Cl − (aq) In this solution, an excess of solid AgCl dissolves and dissociates to produce aqueous Ag +  and Cl –  ions at the same rate that these aqueous ions combine and precipitate to form solid AgCl (as shown below). Because silver chloride is a sparingly soluble salt, the equilibrium concentration of its dissolved ions in the solution is relatively low. The equilibrium constant for solubility equilibria such as this one is called the  solubility product constant,  K sp , in this case AgCl(s) ⇌ Ag + (aq)+Cl − (aq) K sp =[Ag + ][Cl − ] Note that only gases and solutes are represented in equilibrium constant expressions, so the  K sp  does not include a term for the undissolved AgCl. The Ksp for Silver Chloride is: 1.83 x 10 -10 . Common Ion Effect* Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a  common ion  (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the  common ion effect , which is a consequence of the law of mass action that may be explained using Le ChÂtelier’s principle. Consider the dissolution of silver chloride: AgCl(s) ⇌ Ag + (aq)+Cl − (aq) * Atom first, 2e, OpenStax
This solubility equilibrium will be shifted left by the addition of chloride ions, resulting in the precipitation of AgCl and lowered concentrations of dissolved Ag + . In solutions that already contain Cl - , less AgCl will be dissolved, and the concentration of Ag + will be lower than that in pure water. This effect may also be explained in terms of mass action as represented in the solubility product expression: AgCl(s) ⇌ Ag + (aq)+Cl − (aq) K sp =[Ag + ][Cl − ] The mathematical product of silver(I) and chloride ion molarities is constant in an equilibrium mixture  regardless of the source of the ions , and so an increase in [Cl − ] must be balanced by a proportional decrease in [Ag + ]. This virtual lab activity asks you to perform an experiment to determine the mass of NaCl present in the solution labeled "Unknown NaCl". For this activity, the solution viewer in the virtual lab shows only the concentration of silver ion (Ag + ) in the selected solution. This mimics a common experimental situation. Techniques such as spectroscopy or electrochemistry often make it easy to measure the concentration of only a single species, such as Ag + . Chemists must then design experiments that meet their goals, while collecting data only on the concentration of that species. In this activity, you must determine the amount of NaCl in an unknown solution, using measurements of [Ag + ]. Procedure: Copy this to your web browser. Enable JavaScript to run the lab. Internet explorer might be the best selection of web browser as it supports Java. http://chemcollective.org/activities/autograded/122 1. Place the unknown NaCl solution, AgCl reagent bottle, a 250 mL beaker, a 10 mL pipette, a balance, and a weighing boat (in “Glassware” → ”Others”) on the work bench. 2. Click on the container of unknown NaCl solution, read the information window, and record the volume of the NaCl solution in Data Sheet. 3. Transfer 10 mL unknown NaCl solution to the empty beaker with the 10mL pipette. 4. Place the weighing boat on the balance and tare the balance. transfer 1.00 g of solid AgCl into the weighing boat and then add the weighted AgCl into the beaker containing 10 mL unknown NaCl solution. 4. Click on the beaker containing the mixture of unknown NaCl solution and AgCl. Read the information window. Record the concentration of Ag + on Data Sheet.
5. Calculate the concentration of Cl - in the unknown NaCl solution. Then calculate the mass of NaCl in the original unknown solution. Show your math work in Data Sheet. 6. When you complete your calculation, use the form at the bottom of the page to check your answer. Once your answers are confirmed, take a screen shot of the confirmation page and and save it. You will upload it when you take the online quiz. Data Sheet 1. Original volume of unknown NaCl solution = _____________ mL 2. The concentration of Ag + within the 10 mL unknown NaCl solution after AgCl is added [Ag + ] = ______________________ 3. Calculate the concentration of Cl - in the 10mL unknown NaCl solution. The Ksp for Silver Chloride is: 1.83 x 10 -10 . Show your work below. AgCl(s) ⇌ Ag + (aq)+Cl − (aq) K sp =[Ag + ][Cl − ] 4. Calculate the mass of NaCl in the 10 mL unknown solution. Show your work. Hint: mole = molarity x L; mass = mole x molar mass 5. Calculate the mass of NaCl in the original unknown solution. Show your work. mass of NaCl in the original unknown solution = mass of NaCl in the 10 mL unknown solution x mLof original volume of unknown NaCl solution 10 mL
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Post Lab Questions: 1. Calculate molar solubility of AgCl in pure water. The K sp for Silver Chloride is: 1.83 x 10 -10 . Then calculate the mass of AgCl that can be dissolved in 10 mL of water. Show your work below. Does adding 1.00 g of AgCl into 10 mL water make the resultant solution saturated with AgCl? Considering the common ion effect, does adding 1.00 g of AgCl into 10 mL unknown NaCl solution make the solution saturated with AgCl? 2. Calculate the molarity of AgCl in 0.102 M NaCl solution. The K sp for Silver Chloride is: 1.83 x 10 -10 . 3. What is the molarity of NaCl in which AgCl has a molar solubility of 2.38 x 10 -9 mol /L? The Ksp for Silver Chloride is: 1.83 x 10 -10 . 4. To a new word file, paste together these two items: the confirmation page of your experiment (you can take a screen shot of this page and posted to the word file) and completed sections of Data Sheet. Upload the file to Canvas when you take the online quiz. (5 points) 5. Take the online quiz (10 points). The quiz is based on Post Lab Assignments. Make sure you know how to answer the post lab questions before you take the quiz. The post lab questions themselves won’t be graded, instead, they are used for you to study for the quiz.

Related Documents

Stull_Lab#5.docx
Stull_Lab#4.docx
Lab9. Determine the Formation Constant of a Coordination Complex.docx
Lab6. Titration Curves.docx
Lab7. Designing a buffer solution.docx
Critical Care Dosage Examples (1).docx
Ion Short Report Template.docx
CH 06 READING AND LISTENING QUIZ - MUS112-N804_ Introduction to Jazz.pdf
CH 10 READING AND LISTENING QUIZ - MUS112-N804_ Introduction to Jazz.pdf
CH 05 READING AND LISTENING QUIZ - MUS112-N804_ Introduction to Jazz.pdf
CH 08 READING AND LISTENING QUIZ - MUS112-N804_ Introduction to Jazz.pdf
CH 07 READING AND LISTENING QUIZ - MUS112-N804_ Introduction to Jazz.pdf
Recommended textbooks for you
Text book image
General Chemistry - Standalone book (MindTap Cour...
Chemistry
ISBN:9781305580343
Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell
Publisher:Cengage Learning
Text book image
Chemistry for Engineering Students
Chemistry
ISBN:9781337398909
Author:Lawrence S. Brown, Tom Holme
Publisher:Cengage Learning
Text book image
Chemistry by OpenStax (2015-05-04)
Chemistry
ISBN:9781938168390
Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser
Publisher:OpenStax
Text book image
Chemistry: Principles and Reactions
Chemistry
ISBN:9781305079373
Author:William L. Masterton, Cecile N. Hurley
Publisher:Cengage Learning
Text book image
Chemistry: Principles and Practice
Chemistry
ISBN:9780534420123
Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Publisher:Cengage Learning
Text book image
Principles of Modern Chemistry
Chemistry
ISBN:9781305079113
Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler
Publisher:Cengage Learning
SEE MORE TEXTBOOKS
Recommended textbooks for you
Text book image
General Chemistry - Standalone book (MindTap Cour...
Chemistry
ISBN:9781305580343
Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell
Publisher:Cengage Learning
Text book image
Chemistry for Engineering Students
Chemistry
ISBN:9781337398909
Author:Lawrence S. Brown, Tom Holme
Publisher:Cengage Learning
Text book image
Chemistry by OpenStax (2015-05-04)
Chemistry
ISBN:9781938168390
Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser
Publisher:OpenStax
Text book image
Chemistry: Principles and Reactions
Chemistry
ISBN:9781305079373
Author:William L. Masterton, Cecile N. Hurley
Publisher:Cengage Learning
Text book image
Chemistry: Principles and Practice
Chemistry
ISBN:9780534420123
Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Publisher:Cengage Learning
Text book image
Principles of Modern Chemistry
Chemistry
ISBN:9781305079113
Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler
Publisher:Cengage Learning
SEE MORE TEXTBOOKS