The flask contains 10.0 mL of HCl and a few drops of phenolphthalein indicator. The buret contains 0.160 M NaOH. It requires 18.2 mL of the NaOH solution to reach the end point of the titration. A buret filled with a titrant is held above a graduated cylinder containing an analyte solution. What is the initial concentration of HCl

Approximately (rounded to two significant figures.)

Explanation:

The unit of concentration is the same as (moles per liter.) On the other hand, the volume of both the solution and the original solution here are in milliliters. Convert these two volumes to liters:

Calculate the number of moles of in that of solution:

.

reacts with at a one-to-one ratio:

.

Coefficient ratio:

.

In other words, one mole of would neutralize exactly one mole of . In this titration, of was required. Therefore, the same amount of should be present in the original solution:

.

Calculate the concentration of the original solution:

.