A student creates a solution by dissolving some Na2SO4 (molar mass = 142.05 g/mol) in enough water to create 0.500 L of solution. If [Na+ ] = 0.125 M then what mass of Na2SO4 was used?

Answer : The mass of is, 4.43 grams.

Explanation :

As we know that, when dissolve in water then it dissociates to give 2 mole of sodium ion and 1 mole of sulfate ion

The chemical reaction will be:

Thus, the concentration of =

First we have to calculate the moles of

Now we have to calculate the mass of

Molar mass of = 142 g/mol

Thus, the mass of is, 4.43 grams.