Question

A student completes a titration by adding 25.0mL of NaOH of unknown concentration to 35.0mL of 0.25M HCl. What is the molar concentration of NaOH? If it takes 15 mL of 0.5M sodium hydroxide solution to neutralize 200 mL of Hydrochloric acid, what is the concentration of HCl? THIS IS TIMED PLEASE HELP! (include work shown)

Answer 1

0.35M NaOH and 0.0375M HCl.

Step-by-step explanation:

NaOH reacts with HCl as follows:

NaOH + HCl → NaCl + H2O

Where 1 mole of NaOH reacts per mole of HCl

To solve the first question we must find the moles of HCl that reacted = Moles NaOH in the unknown. With the moles and the volume we can find its molar concentration:

Moles HCl = Moles NaOH:

0.0350L * (0.25mol / L) = 0.00875 moles NaOH

In 25.0mL = 0.0250L:

0.00875 moles NaOH / 0.0250L =

0.35M NaOH

For the second question, the moles of NaOH = moles HCl. With the 200mL = 0.200L the molarity is:

Moles NaOH = Moles HCl:

0.015L * (0.5mol / L) = 0.0075 moles HCl / 0.200L =

0.0375M HCl