If you need to completely react 5.00 g of NaOH with H2SO4 according to the equation 2 NaOH + H2SO4 → Na2SO4 + 2 H2O, what is the minimum mass of H2SO4 required?

• A. 1.28 g
• B. 2.55 g
• C. 4.90 g
• D. 9.80 g

Answer: (B)

Verified step by step guidance

1. Write down the balanced chemical equation: \[2\ \text{NaOH} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + 2\ \text{H}_2\text{O}\]
2. Calculate the number of moles of NaOH you have using its molar mass. The molar mass of NaOH is approximately 40.00 g/mol, so use the formula: \[\text{moles of NaOH} = \frac{5.00\ \text{g}}{40.00\ \text{g/mol}}\]
3. Use the mole ratio from the balanced equation to find the moles of H2SO4 needed. According to the equation, 2 moles of NaOH react with 1 mole of H2SO4, so: \[\text{moles of H}_2\text{SO}_4 = \frac{1}{2} \times \text{moles of NaOH}\]
4. Calculate the mass of H2SO4 required by multiplying the moles of H2SO4 by its molar mass. The molar mass of H2SO4 is approximately 98.08 g/mol, so: \[\text{mass of H}_2\text{SO}_4 = \text{moles of H}_2\text{SO}_4 \times 98.08\ \text{g/mol}\]
5. This final mass is the minimum mass of H2SO4 required to completely react with 5.00 g of NaOH.