Question

The formula for Epsom salts is MgSO4*7H2O. If 1.250g of the compound is dissolved in water, calculatenthe number of milliliters of 0.200M Ba(NO3)2 that would be required to just precipitate all of the sulfate as barium sulfate.

Answer 1

Answer:

25 mL

Explanation:

From the balanced equation of reaction:

$MgSO_ {4(aq)} + Ba(NO_3)_{2 (aq)} --> BaSO_{4 (s)} + Mg(NO_3)_{2 (aq)}$

1 mole of the epsom salt requires 1 mole of $Ba(NO_3)_{2 (aq)}$ to precipitate barium sulfate.

mole of epsom salt = mass/molar mass

                              =  1.250/246.4746 = 0.0051 mole

Hence, 0.0051 mole of epsom salt will also require 0.0051 mole of $Ba(NO_3)_{2 (aq)}$ for sulafe's precipitation.

Molarity of $Ba(NO_3)_{2 (aq)}$ = mole/volume = 0.200 M

Volume = mole/molarity

                 = 0.0051/0.200

                      = 0.025 Liter

0.025 Liter = 25 milliliters.

25 milliliters of 0.200 M $Ba(NO_3)_{2 (aq)}$ would be required to precipitate all the sulfate as barium sulfate.