pH of Salt Solution Calculator

Calculate pH of salt solutions formed from acid-base reactions. Determine if a salt gives acidic, basic, or neutral pH using Ka and Kb of parent acid and base.

🔬 Acid-Base📐 pH from Kh = Kw/Ka or Kw/Kb🧪 Chemistry

Salt concentration C (mol/L)

Ka of parent weak acid (or Ka of conjugate acid for basic salts)

Salt type

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
pH of Salt Solution Calculator	—	pH from Kh = Kw/Ka or Kw/Kb	pH

Step-by-Step Examples

Example 1

Sodium Acetate (Basic Salt)

0.100 M NaCH3COO. Ka(acetic acid)=1.8x10^-5.

Kh = Kw/Ka = 10^-14/1.8x10^-5 = 5.56x10^-10
[OH-] = sqrt(Kh*C) = sqrt(5.56x10^-10 x 0.100)
= sqrt(5.56x10^-11) = 7.46x10^-6
pOH = 5.13, pH = 14-5.13 = 8.87

✓ pH = 8.87 (basic salt solution)

Example 2

Ammonium Chloride (Acidic Salt)

0.100 M NH4Cl. Kb(NH3)=1.8x10^-5, Ka(NH4+)=Kw/Kb=5.6x10^-10.

Kh = Ka(NH4+) = 5.6x10^-10
[H+] = sqrt(5.6x10^-10 x 0.100) = 7.48x10^-6
pH = -log(7.48x10^-6) = 5.13

✓ pH = 5.13 (acidic salt solution)

Example 3

Neutral Salt

NaCl: Na+ from strong base, Cl- from strong acid. Neither hydrolyzes.

pH = 7.00 at 25 C
Strong acid + strong base salts are always neutral

✓ pH = 7.00

Real-World Applications

🧪

Buffer Chemistry

Salt of weak acid/strong base or weak base/strong acid has non-neutral pH, important for buffer design.

🌊

Ocean Chemistry

Seawater pH ~8.1 partly due to carbonate/bicarbonate equilibrium (basic salt effect of Na2CO3 equivalent).

💊

Drug Formulation

Salt forms of drugs chosen partly for desired pH of resulting solution.

🏭

Industrial Chemistry

Salt solutions in process streams may be acidic or basic; predicting pH is critical for corrosion and reaction control.

Common Mistakes to Avoid

⚠️

Identify parent acid and base first

NaCH3COO comes from NaOH (strong) + CH3COOH (weak). Weak acid parent: anion hydrolyzes to give basic solution.

⚠️

Ka given is for parent acid, not salt ion

For sodium acetate: Ka = 1.8x10^-5 is Ka of acetic acid. Kh of acetate anion = Kw/Ka.

⚠️

Strong acid + strong base salts: always pH 7

NaCl, KNO3, LiClO4: both ions from strong acid/base; no hydrolysis; pH = 7.

Frequently Asked Questions

What is salt hydrolysis? ▾

Reaction of salt ion with water: CH3COO- + H2O to CH3COOH + OH- (basic hydrolysis) or NH4+ + H2O to NH3 + H3O+ (acidic hydrolysis).

How do I determine if a salt is acidic or basic? ▾

Strong acid + strong base: pH = 7. Weak acid + strong base: basic (anion hydrolyzes). Strong acid + weak base: acidic (cation hydrolyzes). Weak acid + weak base: depends on Ka vs Kb.

What is Kh (hydrolysis constant)? ▾

For basic salt: Kh = Kb(anion) = Kw/Ka(parent acid). For acidic salt: Kh = Ka(cation) = Kw/Kb(parent base).

What are examples of acidic salts? ▾

NH4Cl (Ka=5.6x10^-10), AlCl3 (Al^3+ hydrolyzes), Fe(NO3)3 (Fe^3+ hydrolyzes strongly, pH~3).

What is the buffer action of Na2CO3? ▾

Na2CO3 is basic salt of carbonic acid (Ka2=4.7x10^-11). CO3^2- hydrolyzes to HCO3-, giving pH ~11.6 for 0.1 M Na2CO3.

Related Chemistry Calculators

Formula Explorer connections

Interpretation: This relationship connects hydrogen-ion activity, dissociation, conjugate ratios or titration stoichiometry to acid–base behavior. Assumption: Concentration approximates activity mainly in dilute solutions. Temperature, ionic strength, acid strength and equilibrium approximations affect accuracy.

Strong Acid/Base pH Calculator →pKa Calculator →pOH Calculator →Chemistry Formula Explorer →