Question

The flask contains 10.0mL of HCl and a few drops of phenolphthalein indicator. The buret contains 0.320 M NaOH. What is the initial concentration of HCl

Answer 1

This question is incomplete, the complete question is;

The flask contains 10.0mL of HCl and a few drops of phenolphthalein indicator.

The buret contains 0.320 M NaOH,

It requires 11.2 mL of the NaOH solution to reach the end point of the titration

What is the initial concentration of HCI?

Answer:  

initial concentration of HCl is 0.3584 M

Explanation:

Given that;

the reaction between HCl and NaOH is 1:1 molar

HCl(aq) + NaOH(aq) -------> NaCl(aq) + H2O(l)

we know that molarity is the number of moles of solute per liter of solution

so moles of NaOH consumed

= ( 0.320 mol / 1000ml) × 11.2ml

= 0.003584 mol

now

0.003584 moles of NaOH reacts with 0.003584 moles of HCl

moles of HCl present in the 10.0ml solution = 0.003584 mol

therefore the initial concentration of HCl

= ( 0.003584 mol / 10.0ml )× 1000ml

= 0.3584 M

the initial concentration of HCl is 0.3584 M