Final answer:
To prepare a 0.5N solution of Na2SO4 for 1.2 liters, 42.6 grams of Na2SO4 are needed.
Step-by-step explanation:
To calculate the number of grams of Na2SO4 needed to make 1.2 liters of a 0.5N solution, we must first understand what a normality (N) is. Normality is a measure of concentration that is equivalent to the gram equivalent weight per liter of solution. Since Na2SO4 can provide 2 equivalents of sulfate ions per molecule, the gram equivalent weight is half of its molecular weight (MW).
The molecular weight (MW) of Na2SO4 is given as 142 g/mol. Thus, the gram equivalent weight is 142 g/mol ÷ 2 = 71 g/equiv.
For a 0.5N solution, we need 0.5 equivalents per liter. For 1.2 liters, the calculation will be:
0.5 eq/L × 71 g/eq × 1.2 L = 42.6 grams
Therefore, 42.6 grams of Na2SO4 are required to make 1.2 liters of a 0.5N solution.