pH Meter and Measurment of Various Solutions

 

Hazards: 

Hazards: HCl and NaOH are corrosive and toxic.

Chemicals and Solutions: 

Sodium carbonate, 0.1 M (basic solution)

Sodium acetate, 0.1 M (basic solution)

Ferric nitrate, 0.1 M (acid solution)

Hydrochloric acid, 0.01 M (acidic solution)

Sodium hydroxide, 0.01 M (basic solution)

Materials: 

pH meter

Combination pH electrode

Digital readout voltmeter and pH interface

Leads to connect pH meter, interface, and voltmeter

Kimwipes

Polyethylene wash bottle of distilled water

6- 150 ml beakers

400 ml beaker for waste

Procedure: 

Electrode must remain in distilled water when not in use.

After each measurement, rinse electrode with distilled water.

Hint: 

Discussion: 

In the dissociation of sodium carbonate, carbonate anion reacts with water to give OH- thereby forming a basic solution:

CO32- + H2O ---> HCO3- + OH-

Similarily, in the dissociation of sodium acetate, acetate ion reacts with water to form OH-, thereby also giving a basic solution:

CH3COO- + H2O ---> CH3COOH + OH-

The hydrated ions of metals of small radius and high charge, like Fe3+ are stronger acids than water and donate protons to water molecules.  The ferric nitrate solution is acidic:

Fe(H2O)63+ + H2O ---> Fe(H2O)5(OH)2+ + H3O+

To schedule a demonstration, please send an email to the demonstration lab.

 

Contact:

Eric Camp

Lecture Demonstration Technician

Bagley Hall 171

(206) 543-1606

ericcamp@uw.edu

 

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