10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume up to the mark with distilled water. The solution in this flask is :
- 0.2 M NaCl solution
- 20 M HCl solution
- Neutral solution
- 10 M HCl solution
Answer
(2) 20 M HCl solution
Solution
Moles of NaOH = 2 101000 = 0.02 mol
Moles of HCl = 1 201000 = 0.02 mol
NaOH + HCl NaCl + H2O
Complete neutralisation; the 30 mL mixture contains only 0.02 mol NaCl (neutral).
10 mL of this mixture adds only 0.023 = 6.7 10-3 mol NaCl and no acid or base.
In the flask: moles of HCl = 2 mol, volume = 100 mL = 0.1 L
Molarity of HCl = 20.1 = 20 M
The flask contains 20 M HCl solution.
Answer: (2)