Question

Calculate the concentration of all ions present when 0.160 g of MgCl₂ is dissolved in 100.0 mL of solution.

Short answer

Thus, there are 0.016 M of magnesium ions and 0.032 M of chloride ion present in solution.

Step-by-step solution

Definition of molarity of a solution.

Molarity which is basically the concentration can be calculated by fractionating the number of moles with the volume of solution in litre.

It can be formulated as
$Molarity\left(Mormol{L}^{-1}\right)=\frac{Numberofmoles\left(n\right)}{Volumeofsolution\left(inL\right)}·····\left(1\right)$

Ions present in MgCl2.

The sample (MgCl₂) contains two different ions which are $M{g}^{2+}andC{l}^{-}$.Two ions will have same number of ions but different molarities.

1. The number of moles of the solution will remain same as in the process temperature is increased and since temperature is an intrinsic property it will not depend upon the amount of substance (number of moles of solution).

1. The molarity changes as it depends upon volume of the solution which is an extrinsic property (whose value changes with change in amount).

Solubility reaction of magnesium chloride. 

The balanced chemical reaction of MgCl₂ dissociating into magnesium ion and chloride ion can be written as

$MgC{l}_{2\left(s\right)}\to M{g}^{2+}+2C{l}^{-}$

From the reaction, it can be concluded that one magnesium chloride molecule dissociates into one magnesium ion and two chloride ions.