Natonton Karlo Chemistry 153-45 TA: Jessica Experiment 10 November 20, 2009 Part A: Measuring the pH of Common Acids and Bases 1. Place 25mL of the solutions into separate beakers. 2. Using a pH meter, measure the pH of the solutions. 3. Before moving the electrode to another solution, rinse the electrode. 4. Record the pH of each solution. a. 0.1 M HCl b. 0.1 M H3BO3 c. 0.1 M NH3(aq) d. 0.1 M NaOH 5. Using pH paper, measure the pH of the same solutions and record the values. 6. Determine the approximate hydronium ion molarity of each solution using the measured pH values and the pH scale on page 173. 7. pH of 4.0 indicates a hydronium ion concentration of 1 X 10-4 M. pH of 5.0 indicates concentration of 1 X 10-5 M. pH of 4.6 indicates between 1 X 10-4 and 1 X 10-5 M. Part B: Measuring the pH of Salt Solutions 1. Place 25mL of the solutions into separate beakers. 2. Using a pH meter, measure the pH of the solutions and record the pH. a. 0.1 M Na2CO3 b. 0.1 M (NH4)2SO4 c. 0.1 M NaCl Part C: Measuring the pH of Some Common Household Chemicals 1. Determine the pH of household chemicals using pH paper. 2. Prepare solutions if needed. 3. If chemical is a solid, dissolve about in 0.1g 2mL of deionized water. 4. If chemical is a liquid, place 10 drops in a beaker. 5. Using a clean stirring rod, obtain a droplet of each solution and touch it to a piece of pH paper. 6. Record the identity of the material and its pH. Part D: Buffer Action 1. Using a pipet, place 25mL of 0.1 M sodium acetate, NaC2H3O2, into a 100mL beaker. 2. Using a pipet, place 25mL of 0.1 M acetic acid, HC2H3O2, into the same beaker. 3. Mix the solution. 4. Measure the pH of the buffer solution and record the value. 5. Add 5 drops of 1.0 M HCl to the solution one drop at a time. 6. Swirl the solution after each drop.
7. Measure pH after each drop and record. 8. Add 5 drops of 1.0 M NaOH to the buffer. 9. Stir solution and measure pH. 10. Add 5 drops of 1.0 M NaOH to the solution one drop at a time. 11. Swirl after each drop and record the pH each time. 12. Dispose of solution. 13. Place 25mL of boiled deionized water into a 100mL beaker. 14. Measure pH of water and record. 15. Add 5 drops of 1.0 M HCl one drop at a time. 16. Swirl the solution after each drop and record the pH. 17. Dispose of solution. 18. Repeat steps 13 to 17 using 1.0 M NaOH rather than 1.0 M HCl.