Question

We have two solutions: 500mL 5M CaCl2, and 400mL 6M CaCl2. We mixed them. Productivity is 40%. Calculate final percentage concentration of total solution.

Answer 1

No. of Moles of CaCl₂ in Solution 1 : (500/1000)L * 5 moles/L = 2.5 moles

No. of Moles of CaCl₂ in Solution 2 : (400/1000)L * 6 moles/L = 2.4 moles

No. of Moles of CaCl₂ after mixing Solution 1 and 2 : = 2.5 + 2.4 = 4.9 moles

Total Volume = (500/1000)L + (400/1000)L = 0.9 L

Molarity (moles/Lt) after mixing = No. of moles of CaCl₂ / Total Volume = 4.9/0.9 = 5.444 M

Since productivity is 40%, So the Molarity after mixing should be 40% of 5.444 M = 2.177 M

Or No. of moles of CaCl2 (Solute) in 1000 ml (Solution) = 2.177

Mol wt of CaCl₂ = 110.98 gm/mol

Wt in gms of CaCl₂ in 2.177 moles = 110.98 gm/mol* 2.177 mol = 241.68 gm

Weight/Volume Percentage : Unit in g/100mL.

w/V % = [Wt of Solute(i.e CaCl₂)/ Volume of Solution ]* 100

= [241.68 gm/1000 ml ]* 100

w/V % = 24.168%