1. 11.8 Acid–Base Titration
The titration of an acid. A known volume of an acid is placed in a flask with an indicator and titrated with a measured volume of a base solution, such as NaOH, to the neutralization endpoint.
Learning Goal Calculate the molarity or volume of an acid or base from titration information.

2. Acid–Base Titration Titration
is a laboratory procedure used to determine the molarity of an acid.
uses a base such as NaOH to neutralize a measured volume of an acid.
requires a few drops of an indicator such as phenolphthalein to identify the endpoint.
Core Chemistry Skill Calculating Molarity or Volume of an Acid or Base in a Titration

3. Acid–Base Titration
In the following titration, a specific volume of acidic solution is titrated to the endpoint with a known concentration of NaOH.
Base 
NaOH
Acid 
Solution

4. Indicator The indicator phenolphthalein
is added to identify the endpoint.
turns pink when the solution is neutralized.

5. Endpoint of Titration At the endpoint of the titration,
the moles of base are equal to the moles of acid in the solution.
the concentration of the base is known.
the volume of the base used to reach the endpoint is measured.
the molarity of the acid is calculated using the neutralization equation for the reaction.

6. Guide to Calculating Boiling Point Elevation, Freezing Point Lowering
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.

7. Acid–Base Titration Calculations
What is the molarity of an HCl solution if 18.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 1 State given and needed quantities and concentrations.
ANALYZE Given Need Equation
THE mL of molarity of HCl(aq) + NaOH(aq) 
PROBLEM M NaOH HCl solution NaCl(aq) + H2O(l)
L HCl

8. Acid–Base Titration Calculations
What is the molarity of an HCl solution if 18.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 2 Write a plan to calculate molarity or volume.
mL NaOH
solution
Metric factor
L NaOH
solution
Molarity
moles of
NaOH
moles of
NaOH
Mole–Mole factor
moles of
HCl
Divide by liters
molarity of
HCl solution

9. Acid–Base Titration Calculations
What is the molarity of an HCl solution if 18.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 3 State equalities and conversion factors including concentration.

10. Acid–Base Titration Calculations
What is the molarity of an HCl solution if 18.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 4 Set up the problem to calculate the needed quantity.

11. Study Check
What is the molarity of an HCl solution if 25.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)

12. Solution
What is the molarity of an HCl solution if 25.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 1 State given and needed quantities and concentrations.
ANALYZE Given Need Equation
THE mL of molarity of HCl(aq) + NaOH(aq) 
PROBLEM M NaOH HCl solution NaCl(aq) + H2O(l)
L HCl

13. Solution
What is the molarity of an HCl solution if 25.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 2 Write a plan to calculate molarity or volume.
Metric factor
L NaOH
solution
Molarity
mL NaOH
solution
moles of
NaOH
Mole–Mole factor
moles of
HCl
Divide by liters
molarity of
HCl solution

14. Solution
What is the molarity of an HCl solution if 25.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 3 State equalities and conversion factors including concentration.

15. Solution
What is the molarity of an HCl solution if 25.5 mL of M NaOH is required to neutralize L of HCl?
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
STEP 4 Set up the problem to calculate the needed quantity.