# Problem: A 20.0-mL sample of 0.125 M HNO3 is titrated with 0.150 M NaOH. Calculate the pH for at least five different points throughout the titration curve and make a sketch of the curve.

🤓 Based on our data, we think this question is relevant for Professor Harwood's class at UNI.

###### FREE Expert Solution

Five points:

1. start of titration
2. VNaOH < VHNO3
3. equivalence point: pH = 7
4. VNaOH = VHNO3
5. VNaOH > VHNO3

1) At start of titration:

When getting the pH of a strong acid solution (HNO3):

1) pH = 0.903

Reaction:            HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq)

2) Recall:

• VNaOH < VHNO3

moles HNO3 = 0.0025 mol HNO3

moles NaOH = 0.00225 mol NaOH

moles NaOH < moles HNO3pH depends on molarity of acid (NaOH is consumed)

• moles HNO3 reacted = moles NaOH
• moles HNO3 = 0.0025 - 0.00225 = 2.5 x 10-4

7.14 x 10-3 M

:

2) pH = 2.15 ###### Problem Details

A 20.0-mL sample of 0.125 M HNO3 is titrated with 0.150 M NaOH. Calculate the pH for at least five different points throughout the titration curve and make a sketch of the curve.