What is the molarity of an HCl solution if 50.0 mL is neutralized in a titration by 40.0 mL of 0.400 M NaOH?

To determine the molarity of the HCl solution, it is important to understand the concept of titration and the reaction that occurs between HCl and NaOH. In this case, HCl (a strong acid) reacts with NaOH (a strong base) in a 1:1 molar ratio, meaning one mole of HCl neutralizes one mole of NaOH.

First, calculate the number of moles of NaOH used in the reaction. This can be done using the formula:

[

\text{Moles of NaOH} = \text{Molarity of NaOH} \times \text{Volume of NaOH (in L)}

]

Substituting the values:

[

\text{Moles of NaOH} = 0.400 , \text{M} \times 0.0400 , \text{L} = 0.0160 , \text{moles}

]

Since the reaction between HCl and NaOH is 1:1, the number of moles of HCl must also be 0.0160 moles.

Next, we need to find the molarity of the HCl solution. Molarity is