0.25 grams of magnesium chloride are dissolved to make 50 milliliters of solution. What is the molarity of the solution?

When the molarity = moles / volume

so, we need to get the moles of MgCl2:

when moles = mass / molar mass

so, by substitution:

∴ moles = 0.25g / 95.211g/mol

= 0.0026 moles

∴'the molarity = 0.0026 / 0.05L

= 0.052 M