JEE Advanced levelNumerical answerDifficulty 3 of 3eq147
Oleum is labelled by the mass of HX2SOX4 obtainable when water is added: '118%' oleum gives 118 g of HX2SOX4 per 100 g of oleum. How many mL of 1.00 M NaOH are needed to neutralise completely the acid obtained from 1.00 g of 118% oleum after adding sufficient water (HX2SOX4 = 98 g/mol; give answer to one decimal place)?
Numerical answer type, answer in mL, tolerance 0.06.
Answer: 24.1 mL
1.00 g of 118% oleum yields 1.18 g HX2SOX4 = 1.18/98 = 12.04 mmol. HX2SOX4 is dibasic (n = 2), so equivalents = 24.08 meq. NaOH volume = 24.08/1.00 = 24.1 mL.