Question

A 1.2 g sample was dissolved in a 100 mL volumetric flask. A 25 mL portion from the solution was titrated with 0.12 M HCl. It required 7.8 mL to reach the phenolphthalein end point and required 22.4 mL to reach the methyl orange end point. Determine the composition of the sample and calculate the percent of titrated component.

Answer 1

To find the concentration of the hydrochloric acid solution, use the equation for the titration reaction and the known volume and concentration of NaOH solution.

Step-by-step explanation:

To find the concentration of the hydrochloric acid solution, we can use the equation for the titration reaction:

HCl(aq) + NaOH(aq) → NaCl (aq) + H₂O (l)

We know the volume of NaOH solution used (31.416 mL) and its concentration (0.1234 M). From the balanced equation, we can see that the molar ratio between HCl and NaOH is 1:1. Therefore, the moles of HCl is equal to the moles of NaOH.

By using the equation: moles = concentration x volume, we can calculate the concentration of the HCl solution.