Obtain approximately 15 mL of 0.5M HCl (red solution) in a clean beaker and15 mL 0.5M NaOH (blue solution) in a clean beaker.

Using a graduated cylinder, measure out and combine exactly 10 mL of NaOH with 10mL of HCl in a clean 250mL beaker.

Place the beaker with the acid-base mixture on a hot plate and set to 100 ^oC. Allow the mixture to boil gently until all liquid has evaporated.

Place a watch glass over the mouth of the beaker if the salt starts to “spit” out.

While the solution is boiling off, continue on to part 2.

Calibrate the pH meter using the three way calibration procedure provided by your TA.

Collect 100 mL of D.I. water and measure the pH.  Record the pH in your lab notebook.

Collect a 25 mL volumetric flask from the front counter.

Using a graduated 1.0 mL pipette, the 25mL volumetric flask and either the acid or base,  perform four serial dilutions using 0.5 mL of stock solution at each step.

For example: Dilution one, pipette, using the three way bulb, 0.5 mL of 0.5M HCl OR 0.5 mL of 0.5M NaOH into the 25mL volumetric flask and dilute to the 25mL mark with DI water. Pour the solution into a clean beaker and then repeat until all dilutions are made.

Calculate the resulting, NaCl, H⁺ and OH^- concentrations as you did in your pre-lab.

Record the pH of all 4 HCl dilutions and then of all 4 NaOH dilutions

Combine the solutions of acid and base by adding the 0.5M solution of NaOH with the 0.5M solution of HCl. Record the resulting pH. Repeat the combination of solutions for the other four dilutions. Record the pH for each combination.

Carefully remove the breaker and watch glass from the hotplate using the oven gloves provided. Allow the beaker to cool to room temperature.

Separately weigh the beaker and watch glass containing the salt residue to the nearest 0.001g and record the value in your lab notebook.

After weighing, clean and dry the beaker and watch glass thoroughly. Reweigh the now empty beaker and watch glass to the nearest 0.001g and record the value in your lab notebook.