High School

What is the molarity of the HCl solution if 35.5 mL of 0.10 M NaOH are needed to neutralize 25.0 mL of the sample?

Answer :

Final answer:

To calculate the molarity of the HCl solution, we firstly calculate the moles of NaOH using its molarity and volume, and because this is a 1:1 reaction, the moles of HCl will equal the moles of NaOH. We then use the volume of the HCl solution to calculate its molarity which comes out to be approximately 0.14 M.

Explanation:

The subject this question pertains to is a neutralization reaction in Chemistry, specifically titration, which is used in determining the molarity of an unknown solution, in this case, an HCl solution. According to the balanced chemical equation for a neutralization reaction, one mole of acid reacts with one mole of base (NaOH in this case). This allows us to create the equivalence: Moles of HCl = Moles of NaOH.

First, we calculate the moles of NaOH using its molarity and volume: Molarity = Moles/Volume => Moles = Molarity * Volume = 0.10 M * 35.5 mL = 0.00355 mol.

Therefore, the moles of HCl = 0.00355 mol. Now, we calculate the molarity of HCl using the volume of HCl and the moles we calculated: Molarity = Moles/Volume => Molarity = 0.00355 mol / 25.0 mL = 0.142 M or 0.14 M when rounded to two decimal places.

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