Question

250 ml 0.1M HCl solution is mixed with 250ml 0.2M NaOH .The concentration of OH- in the mixture is
(1)0.025 M
(2)0.05 M
(3)0.01 M
(4)0.02 M

Answer 1

Answer:

(3) 0.01

Explanation:

0.01 is answer of this question

Answer 2

Answer:

The correct answer is Option 1

Explanation:

• 0.1 M NaOH means to dissolve 0.1 moles NaOH in 1 liter of solution.  Since you don't want to make 1 liter of solution, but want only 250 ml (0.25 liters), then you also don't need 0.1 moles NaOH.  You need only 1/4 of that.  So done by dimensional analysis, it looks like this...
• $0.1 moles/liter * 0.25\ liters = 0.025\ moles\ NaOH$ needed
• The molar mass of NaOH is 23 + 16 + 1 = 40 g/mole
• Thus, 0.025 moles NaOH x 40 g/mole = 1 gram NaOH
• To make 250 ml of 0.1 M NaOH, you dissolve 1 gram NaOH in enough water to make a final volume of 250 mls.