Question

Alice needs a minimum of 200 mL of 1.0 M nitric acid for a titration experiment. Only commercial concentrated acid (16 M nitric acid) is available to her. How could she prepare the acid she needs (she wants to be accurate but minimize wastage)?

(A) measure out 16 mL of 16 M acid and add it to enough water to make 200 mL of solution

(B) measure out 16 mL of 16 M acid and add it to enough water to make 250 mL of solution

(C) measure out 20 mL of 16 M acid and add it to enough water to make 300 mL of solution

(D) measure out 13 mL of 16 M acid and add it to enough water to make 200 mL of solution

(E) measure out 25 mL of 16 M acid and add it to enough water to make 400 mL of solution

Answer 1

Alias needs to prepare 200 ml 1.0 M of HNO₃ from 16 M HNO₃. To know how much ml of 16 M HNO₃ is required, we need to use following equation:

M1V1 = M2V2

Here M1= 1.0 M

V1= 200 ml

M2 = 16 M

V2 = ?

V2 = 1.0 × 200 ÷ 16

V2 = 12.5 ml

Thus when 12.5 ml of 16 M acid and add it to enough water to make 200 mL of solution will give 1.0 M HNO₃ solution.

Thus (E) Measure out 25 mL of 16 M acid and add it to enough water to make 400 mL of solution is the correct option.

From other options, Alias will not get accurate 1.0 M HNO3 concentration.