Question

A chemist prepares a solution by dissolving 0.3 mole of CaCl2 in enough water to make 1000 mL of solution. What is the molar concentration of chloride ions?

Answer 1

`CaCl_(2)` dissolves in water to give
`Ca^(2+)` and
`Cl^(-)` ions according to the following reaction:


`CaCl_(2)` -------->
`Ca^(2+)` + 2
`Cl^(-)`

So, according to the above reaction, 1 mole of
`CaCl_(2)` produce 2 moles of
`Cl^(-)` ion,

So, 0.3 mole will give = 0.3 x 2 = 0.6 moles of
`Cl^(-)` ion

So, Molar concentration =
`(0.6moles)/(1L) = 0.6`

Note: 1L = 1000mL