# My I just started lab and my teacher gave this as a practice problem but I don’t understand it at all.

My I just started lab and my teacher gave this as a practice problem but I don’t understand it at all. I don’t know where to begin or how to work out these sort of problems, but they will be on our midterm. Can you help me understand how to do problems like this step by step?

Based on the standard analytical practice during a titration of taking pH-volume measurements every 0.3 pH units, how many measurements should you take between the addition of 5 mL and 7.5 mL of titrant,

(a) in the titration of a 10-mL aliquot of standard 0.1500 M TRIS base (Kb = 1.2 X 10-6) (in beaker) with 0.1000 M HCl (in buret).

(b) in the titration of a 10-mL aliquot of 0.1500 M NaOH (in buert) with standard 0.1000 M HCl (in buret).

Hints: To solve these questions, it may be helpful to draw a diagram of the titration set up. Before starting, reason out whether the pH will increase or decrease with the addition of titrant.

You need to calculate the pH at the 5 and 7.5 mL points in each of the two titrations.  Because HCl and NaOH are a strong acid and base respectively, they dissociate completely and the pH of the solution is dependent only on the excess acid or base in the beaker at that point in the titration.

Remember to take into account the dilution that occurs in the beakers due to the added titrant.