A student is investigating the percentage purity of ibuprofen in a sample of tablets. 6.00 g of a sample of impure ibuprofen tablets was crushed and dissolved in 200 cm³ of 0.200 mol dm-³ aqueous sodium hydroxide.

25.0 cm³ of this solution was withdrawn and titrated against hydrochloric acid. The unreacted NaOH in this solution required 24.40 cm³ of 0.120 mol dm of hydrochloric acid for complete neutralisation.

i) Calculate the amount of sodium hydroxide that has reacted with hydrochloric acid. (ans: 0.002928mol)

ii) Calculate the amount of sodium hydroxide unreacted in 200 cm³ solution.
(ans: 0.002928 x (200/25.0) = 0.0234mol)

I KNOW HOW TO DO PART i. PLEASE EXPLAIN HOW TO GET THE ANSWER FOR PART ii WITH THE GIVEN SOLUTION thank you