Determination of oxalate by titration
This presentation is the property of its rightful owner.
Sponsored Links
1 / 10

Determination of Oxalate by Titration PowerPoint PPT Presentation


  • 66 Views
  • Uploaded on
  • Presentation posted in: General

Determination of Oxalate by Titration. Lab 9. Outline. Purpose Redox Reaction Procedure Calculation Sequence Glassware Setup Safety Concerns Waste Next Lab Reminder. Purpose. Analyze three unknown samples for oxalate via titration.

Download Presentation

Determination of Oxalate by Titration

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Determination of oxalate by titration

Determination of Oxalate by Titration

Lab 9


Outline

Outline

  • Purpose

  • Redox Reaction

  • Procedure

  • Calculation Sequence

  • Glassware Setup

  • Safety Concerns

  • Waste

  • Next Lab Reminder


Purpose

Purpose

  • Analyze three unknown samples for oxalate via titration.

  • Compare the analytical results of your redox reactions with the percent oxalate in three known compounds.

  • Identify the unknowns.

  • Gain experience in completing a titration without the use of a formal indicator.


Redox reactions

Redox Reactions

Half reaction for the oxidation of C2O42-:

C2O42-(aq) 2CO2(g) + 2e-

Half reaction for the reduction of Mn7+:

8H+(aq) + MnO4-(aq) + 5e- Mn2+(aq) + 4H2O(l)

Complete reaction:

16H+(aq) + 5C2O42-(aq) + 2MnO4-(aq) 10CO2(g) + 8H2O(l) + 2Mn2+(aq)


Procedure

Procedure

  • Start off with a known mass of unknown oxalate compound.

  • Determine the moles of oxalate in the unknown by performing a titration with permanganate.

  • At the point where all the oxalate has reacted with the permanganate we are adding by way of the buret, we see a color change from yellow to light pink.

  • This end point is indicative of passing the equivalence point slightly. An end point error is introduced and needs to be minimized as much as possible.

  • From the known concentration and measured volume of permanganate added, we calculate the moles of oxalate, keeping in mind our stoichiometric ratio given by the complete reaction (2:5).


Calculation sequence

Calculation Sequence

Sample calculations are on pp. 222 and 223

  • Percent oxalate in your “known” compounds

  • Moles of permanganate

  • Moles of oxalate

  • Mass of oxalate

  • Percent oxalate present by mass

  • Percent error (experimental values compared to “known” values)


Glassware setup

Glassware Setup


Safety concerns

Safety Concerns

  • Reagents:

    • Oxalate salts

    • Potassium permanganate

    • Sulfuric acid

    • Sodium meta-bisulfite

  • Inhalation:

    • Poisonous! Nervousness, cramps, CNS depression, burns / irritation to respiratory tract, irritation of nose and throat, difficulty breathing, lung edema, damage to mucosa, coughing, shortness of breath, allergic reaction.

  • Ingestion:

    • Poisonous! Burns of the throat, mouth and stomach, nausea, vomiting, abdominal pain, edema, hypotension, circulatory collapse, gastric irritation, asthma, diarrhea, death.

  • Skin Contact:

    • Redness, itching, pain, burning, blurred vision, circulatory collapse, irritation, death.

  • Eye Contact:

    • Irritation, redness, pain, irreversible eye damage.


Waste

Waste

  • Oxalate solid goes in the garbage.

  • Pink, yellow and orange solutions must be disposed in the acid waste container in the fume hood.

  • Purple solutions must go in the permanganate waste container in the fume hood.

  • Small quantities of excess H2SO4can be used in your experiment.


Next week lab 9 continued

Next Week – Lab 9 continued

  • Submit reports.


  • Login