156k views
2 votes
what is the concentration of HCl if you have 8.57mL HCl and you add 14.69 mL of 0.76 M NaOH to reach the equivalence point?

User Justberare
by
7.6k points

1 Answer

3 votes

Final answer:

To calculate the concentration of HCl, we use the titration method. At the equivalence point, the moles of NaOH used are equal to the moles of HCl. The concentration of HCl is found to be approximately 1.302 M by dividing the moles of NaOH by the volume of HCl in liters.

Step-by-step explanation:

To determine the concentration of HCl, we can use the concept of titration. Titration is a technique where a solution of known concentration (titrant) is used to determine the concentration of an unknown solution (analyte). When the titrant is added to the analyte until the reaction reaches the equivalence point, where stoichiometrically equivalent amounts of the two solutions have reacted, we can use the number of moles of titrant to find the concentration of the analyte.

In the given question, the reaction that occurs is:

HCl + NaOH → NaCl + H₂O

This equation shows that the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) is a one-to-one mole reaction. To calculate the concentration of HCl, we first need to find the number of moles of NaOH used at the equivalence point:

Number of moles of NaOH = Volume of NaOH x Molarity of NaOH

Number of moles of NaOH = (0.01469 L) x (0.76 M) = 0.0111634 moles

Since the reaction ratio between NaOH and HCl is 1:1, the number of moles of HCl is the same as the number of moles of NaOH at the equivalence point:

Number of moles of HCl = 0.0111634 moles

Now we can calculate the molarity (concentration) of HCl by dividing the number of moles by the volume of HCl. It is important to convert the volume of HCl to liters:

Concentration of HCl (M) = Number of moles of HCl / Volume of HCl in liters

Concentration of HCl (M) = 0.0111634 moles / 0.00857 L = approximately 1.302 M

Therefore, the concentration of HCl in the solution before titration was approximately 1.302 M.

User Hsmit
by
6.9k points