Calculate the mass percent of sulfuric acid in a solid sample given that a 0.8390 g sample of that solid required 32.22 mL of 0.2012 M NaOH for neutralization.
A)62.11
B)2.64
C)37.89
D)75.78
E)1.27

Question

Quizplus · Accepted Answer

1. Write the balanced chemical equation for the neutralization reaction between sulfuric acid (H2SO4) and sodium hydroxide (NaOH):

H2SO4 + 2NaOH → Na2SO4 + 2H2O

2. Calculate the number of moles of NaOH used in the titration:

moles NaOH = M × V = 0.2012 mol/L × 0.03222 L = 0.006485 moles

3. From the balanced chemical equation, we see that 1 mole of H2SO4 reacts with 2 moles of NaOH. Therefore, the number of moles of H2SO4 in the sample is:

moles H2SO4 = 0.006485 moles NaOH × (1 mol H2SO4 / 2 mol NaOH) = 0.0032425 moles H2SO4

4. Calculate the mass of H2SO4 in the sample, using its molar mass (98.08 g/mol):

mass H2SO4 = 0.0032425 moles × 98.08 g/mol = 0.3183 g

5. Finally, calculate the mass percent of H2SO4 in the sample:

% mass H2SO4 = (mass H2SO4 / sample mass) × 100% = (0.3183 g / 0.8390 g) × 100% = 37.89%

Therefore, the answer is choice C.

Calculate the Mass Percent of Sulfuric Acid in a Solid