What volume (in mL) of 0.2600 M HBr is required to completely neutralize 40.00 mL of 0.8000 M NaOH?

• A. 123.1 mL
• B. 80.00 mL
• C. 40.00 mL
• D. 12.50 mL

Answer: (A)

Verified step by step guidance

1. Write the balanced chemical equation for the neutralization reaction: \(\mathrm{HBr} + \mathrm{NaOH} \rightarrow \mathrm{NaBr} + \mathrm{H_2O}\). This shows a 1:1 mole ratio between HBr and NaOH.
2. Calculate the moles of NaOH present using the formula: \(\text{moles NaOH} = M_{\mathrm{NaOH}} \times V_{\mathrm{NaOH}}\), where \(M_{\mathrm{NaOH}} = 0.8000\,M\) and \(V_{\mathrm{NaOH}} = 40.00\,mL\) (convert mL to L by dividing by 1000).
3. Since the mole ratio of HBr to NaOH is 1:1, the moles of HBr required to neutralize the NaOH will be equal to the moles of NaOH calculated.
4. Use the moles of HBr and its molarity to find the volume of HBr needed: \(V_{\mathrm{HBr}} = \frac{\text{moles HBr}}{M_{\mathrm{HBr}}}\), where \(M_{\mathrm{HBr}} = 0.2600\,M\).
5. Convert the volume of HBr from liters to milliliters by multiplying by 1000 to get the final answer in mL.