Question 10.16: What is the normality of a solution made by diluting 6.5 g o...
What is the normality of a solution made by diluting 6.5 g of H_2SO_4 to a volume of 200 mL? What is the concentration of this solution in milliequivalents per liter? The molar mass of H_2SO_4 is 98.0 g.
ANALYSIS Calculate how many equivalents of H_2SO_4 are in 6.5 g by using the molar mass of the acid as a conversion factor and then determine the normality of the acid.
STEP 1: Identify known information. We know the molar mass of H_2SO_4, the mass of H_2SO_4 to be dissolved, and the final volume of solution.
MW of H_2SO_4 = 98.0 g/mol
Mass of H_2SO_4 = 6.5 g
Volume of solution = 200 mL
STEP 2: Identify answer including units. We need to calculate the normality of the final solution.
Normality = ?? (equiv./L)
STEP 3: Identify conversion factors. We will need to convert the mass of H_2SO_4 to moles, and then to equivalents of H_2SO_4. We will then need to convert volume from mL to L.
(6.5 \cancel{g H_2SO_4}) \left(\frac{1 \cancel{mol H_2SO_4}}{98.0 \cancel{g H_2SO_4}} \right) \left(\frac{2 Eq H_2SO_4}{ 1 \cancel{mol H_2SO_4}} \right) \\ = 0.132 Eq H_2SO_4 (don't round yet!) \\ (200 \cancel{mL}) \left(\frac{1 L}{1000 \cancel{mL}} \right) = 0.200 LSTEP 4: Solve. Dividing the number of equivalents by the volume yields the Normality.
\frac{0.132 Eq H_2SO_4}{0.200 L } = 0.66 NThe concentration of the sulfuric acid solution is 0.66 N, or 660 mEq/L.