pH meter CCC Kei Heep Secondary School F.6 Chemistry by Wong CS Chemistry CE Homepage Chemistry AL Homepage

pH value pH =  log [H + ] For 1 M HCl (aq), pH = 0 For 0.1 M HNO 3 (aq), pH = 1 For 10 M NaOH (aq), pH = 15

Apparatus pH with a glass electrode Thermometer Buffer solution of pH 4 and 7

Calibration Step 1 Insert the electrode and thermometer in distill water. Adjust the temperature knob to the reading of room temperature.

Calibration Step 2 Insert the electrode in the buffer solution with pH = 7. Adjust the AP knob to 7.00.

Calibration Step 3 Wash the electrode with distill water. Insert the electrode in the buffer solution with pH = 4. Adjust the pH knob to pH = 4.00.

Measure pH value Wash the electrode with distill water. Insert the electrode in the solution which you want to test. Record the reading when steady.

Weak Acid HA (aq) + H 2 O (l)  H 3 O + (aq) + A  (aq) Initial: x At eq.: x-y y y Assume x >> y

Buffer solution HA (aq) + H 2 O (l)  H 3 O + (aq) + A  (aq) Initial: x x At eq.: x-y y x+y Assume x >> y [H + ] = y = K pH = pK

Test the pH of most common solution - pH panel