Question

What volume of 0.50 M $CaC{l}_2$ solution is needed to prepare 250 mL of solution that has a chloride concentration of 0.100 M?

• A. 12.5 mL
• B. 25.0 mL
• C. 50.0 mL
• D. 100 mL

Answer 1

The correct option is B

25.0 mL

2 moles of $C{l}^{-}$ are created when every mole of $CaC{l}_2$ is dissolved.
Total moles of chloride ion required: $250\times 0.1=25mmol$

V$\times$ 0.5$\times$ 2 = 25 m mol

V = 25 ml