1. 50 mL of 20.8 % (w/V) BaCl2 (aq) and 100 ml of 9.8 % (w/V) H2So4 (aq) solutions are mixed. What is the Molarity of cl- ions in the resulting solution ( At. Wt of Ba is137)

Dear Student,

I) 20.8 w/V % of BaCl₂ means 20.8 g in 100 ml of aqueous solution.
Therefore, in 50 ml of aqueous solution, we will have 20.8 / 2 = 10.4 g of BaCl₂​.
Mass of Cl^- in 50 ml aqueous solution = $=\frac{\left(2\times 35.5\right) g mo{l}^{-1}}{208 g mo{l}^{-1}}\times 10.4 g=3.55 g$

​II) Similarly, in 100 ml of aqueous solution H₂SO₄ we will have 9.8 g of ​H₂SO₄ .

After mixing the total volume of the solution will be = 50 + 100 = 150 ml

Mass of Cl^- in total solution (150 ml) remains the same, which is 3.55 g. Or in terms of moles it is = 3.55 g / 35.5 g mol^-1 = 0.1 moles

As molarity = moles of solute / in a litre of solution

Molarity  = $\frac{0.1}{150}\times 1000=0.666 M$

Best Wishes !