A 50.0 mL sample of a mixture of HCl and H2SO4 gives 0.699 g of BaSO4 (molar mass 233 g mol^-1) with excess BaCl2. A separate 25.0 mL portion needs 42.0 mL of 0.100 N NaOH for neutralisation. The molarity of HCl in the mixture is:

JEE Advanced levelSingle correct optionDifficulty 3 of 3eq054

A $50.0 mL$ sample of a mixture of $HCl$ and $H X_{2} SO X_{4}$ gives $0.699 g$ of $BaSO X_{4}$ (molar mass $233 g mo l^{- 1}$ ) with excess $BaCl X_{2}$ . A separate $25.0 mL$ portion needs $42.0 mL$ of $0.100 N$ $NaOH$ for neutralisation. The molarity of $HCl$ in the mixture is:

BaSO X_{4}

from

50.0 mL = 3.00

mmol, so

H X_{2} SO X_{4}

25.0 mL = 1.50

mmol

= 3.00

meq. Total acid in

25.0 mL = 0.100 \times 42.0 = 4.20

meq.

HCl = 4.20 - 3.00 = 1.20

meq

= 1.20

mmol, so

[HCl] = 1.20/25.0 = 0.048 M