Acid Base Titration Calculator

Calculator Inputs

Sample Name

Analyte Role

Analyte Strength

Titrant Role

Titrant Strength

Indicator or Endpoint Label

Analyte Molarity (mol/L)

Analyte Volume (mL)

Titrant Molarity (mol/L)

Titrant Volume Added (mL)

Used for current pH and status.

Acid Equivalent Coefficient

Example: H₂SO₄ uses 2.

Base Equivalent Coefficient

Example: Ca(OH)₂ uses 2.

pKa of Weak Acid

pKb of Weak Base

Endpoint Factor

1.000 means equivalence; 0.980 gives 98% of equivalence.

Example Data Table

Case	Analyte	Titrant	Key Inputs	Expected Equivalence Volume	Note
Strong acid vs strong base	0.100 M HCl, 25.00 mL	0.120 M NaOH	1 acid eq, 1 base eq	20.83 mL	Classical neutralization curve with sharp jump near equivalence.
Weak acid vs strong base	0.100 M acetic acid, 25.00 mL, pKa 4.76	0.100 M NaOH	1 acid eq, 1 base eq	25.00 mL	At half-equivalence, pH is close to 4.76.
Strong base vs strong acid	0.150 M NaOH, 30.00 mL	0.100 M HCl	1 acid eq, 1 base eq	45.00 mL	Initial pH is high and falls quickly near equivalence.
Weak base vs strong acid	0.100 M NH₃, 20.00 mL, pKb 4.75	0.100 M HCl	1 acid eq, 1 base eq	20.00 mL	Equivalence pH drops below seven due to conjugate acid formation.

Formula Used

Moles = Molarity × Volume in liters

Acid equivalents = Acid moles × acid equivalent coefficient

Base equivalents = Base moles × base equivalent coefficient

At equivalence: M_acidV_acidz_acid = M_baseV_basez_base

Normality = Molarity × equivalent coefficient

Half-equivalence volume = Equivalence volume ÷ 2

Weak acid buffer: pH = pKa + log([A⁻] / [HA])

Weak base buffer: pOH = pKb + log([BH⁺] / [B])

Strong acid excess: pH = −log[H⁺]

Strong base excess: pOH = −log[OH⁻], then pH = 14 − pOH

For weak systems, this calculator uses standard approximation methods commonly taught in chemistry courses. Polyprotic and weak/weak systems are treated with practical approximations for planning and reporting.

How to Use This Calculator

Enter whether the analyte in the flask is an acid or base.
Select strong or weak behavior for both analyte and titrant.
Input analyte molarity, analyte volume, and titrant molarity.
Set acid and base equivalent coefficients for balanced neutralization.
Enter pKa or pKb when weak species are present.
Type the titrant volume already added to estimate current pH.
Set an endpoint factor if you want a target before or after equivalence.
Submit the form to view pH, equivalence volume, status, graph, and exports.

Frequently Asked Questions

1. What does the equivalence volume mean?

It is the titrant volume needed for stoichiometric neutralization. At this point, acid and base equivalents are equal according to the balanced reaction.

2. Why is endpoint factor useful?

It lets you target a fraction or multiple of equivalence. This helps when planning indicator endpoints, process control, or slight excess conditions.

3. When should I enter pKa?

Enter pKa whenever the acid in the system is weak. The value improves buffer-region and equivalence-region pH estimation.

4. When should I enter pKb?

Enter pKb whenever the base in the system is weak. It helps the calculator model buffer behavior and post-equivalence pH more realistically.

5. What are equivalent coefficients?

They represent reactive H⁺ or OH⁻ units per mole. Sulfuric acid often uses 2, while sodium hydroxide commonly uses 1.

6. Why can weak-system results be approximate?

Weak acid and weak base titrations involve equilibria and conjugate species. Fast calculators usually apply accepted approximations instead of full numerical solving.

7. What does the graph show?

It plots estimated pH against titrant volume. The curve helps you see buffering, half-equivalence behavior, and the jump around equivalence.

8. What do the CSV and PDF downloads include?

They export the visible results table. This is useful for lab notebooks, class submissions, calibration records, or quick reporting.