`1.11g CaCl_(2)` is added to water forming `500ml` of solution `20ml` of this solution is taken and diluted `10` folds Find moles of `Cl` ions in `2ml` of diluted solution .

Explanation

`(1.11)/(111) = 0.01 mol CaCl_(2)`
Moles of `CaCl_(2)` in 20 ml solution `= (0.01)/(500) xx 20 = (0.01)/(25)`
In 200 ml solution moles of `CaCl_(2) = (0.01)/(25)` [Note: Dilution does not change moles of solute]
In 2 ml of dilute solution moles of `CaCl_(2) = ((0.01)/(25))/(200) xx 2 = (0.01)/(2500) = 8 xx 10^(-6)`
`:.` moles of `Cl^(-) = 2 xx 8 xx 10^(-6) = 1.6 xx 10^(-5)`