Question

20ml of 1.5* 10^-5 m bacl2 solution is mixed with 40ml of

Answer 1

BaCl2 →Ba2+  +  2Cl-

Amount of Ba2+ ions = 1.5 ×10-5 ×20/1000 = 3.0 ×10-7 moles

Na2SO4  →2Na+  + SO42-

Amount of SO42- ions = 0.9 ×10-5 ×40/1000 = 3.6×10-7 moles​

Now the total volume of solution is 20 mL + 40 mL = 60 mL

​Concentration of Ba2+ ions = 3.0 ×10-7 ×1000/60 = 50  ×10-7 M

Concentration of SO42-​ ions = 3.6×10-7 × 1000/60​ = 60 ×10-7 M

ionic product of BaSO4 = 50  ×10-7 M  × 60  ×10-7 M​ = 3.0×10-11

Ionic product 3.0×10-11 is less than the solubility product, 1.2  ×10-10 therefore BaSO4 will not precipitate

Answer 2

Pay attention for conversions.