Question

How many milliliters of 0.125 M HCl are needed to completely neutralize 51.0 mL of 0.100 M Ba(OH)2 solution?
Express the volume in milliliters to three significant digits.

Answers

GPT-4o mini
To calculate the volume of 0.125 M HCl needed to neutralize 51.0 mL of 0.100 M Ba(OH)₂, we first need to write the balanced chemical equation for the neutralization reaction:

\[
\text{Ba(OH)}_2 + 2 \text{HCl} \rightarrow \text{BaCl}_2 + 2 \text{H}_2\text{O}
\]

From the balanced equation, we see that one mole of Ba(OH)₂ reacts with two moles of HCl.

Next, we can determine the number of moles of Ba(OH)₂ in 51.0 mL of 0.100 M Ba(OH)₂:

\[
\text{Moles of Ba(OH)}_2 = \text{Molarity} \times \text{Volume(L)} = 0.100 \, \text{mol/L} \times 0.0510 \, \text{L} = 0.00510 \, \text{mol}
\]

According to the stoichiometry of the reaction, since 1 mole of Ba(OH)₂ reacts with 2 moles of HCl, the number of moles of HCl needed is:

\[
\text{Moles of HCl} = 2 \times \text{Moles of Ba(OH)}_2 = 2 \times 0.00510 \, \text{mol} = 0.01020 \, \text{mol}
\]

Now, we need to find the volume of 0.125 M HCl required to provide 0.01020 moles:

\[
\text{Volume (L)} = \frac{\text{Moles}}{\text{Molarity}} = \frac{0.01020 \, \text{mol}}{0.125 \, \text{mol/L}} = 0.0816 \, \text{L}
\]

To convert this volume from liters to milliliters, we multiply by 1000:

\[
\text{Volume (mL)} = 0.0816 \, \text{L} \times 1000 = 81.6 \, \text{mL}
\]

Rounding to three significant digits, the volume of 0.125 M HCl needed is:

\[
\boxed{81.6} \, \text{mL}
\]