RP9- pH change for Strong Base + Weak Acid

Question 1

To create calibration, a pH meter is used to measure the pH of separate solutions, each with a known, accurate pH.
Suggest why the pH probe is washed with distilled water between each of the calibration measurements. (1)

Answer 1

• diff solutions x contaminate each other//
• wash off any residual solution that could interfere w/ the reading

Question 2

The calibrated pH meter is used to monitor the pH during a titration of hydrochloric acid with sodium hydroxide.
Explain why the volume of sodium hydroxide added between each each pH measurement is smaller as the end point of the titration is approached. (1)

Answer 2

To avoid missing the end point
// large change in pH near end point