Normality Formula
Express solution concentration as equivalents per liter
Definition
N = equivalents of solute / liters of solution
Variables
- N = normality (eq/L)
- equivalents = moles × n-factor
- V = volume of solution (L)
- n-factor = reactive capacity per mole (acid/base/redox)
Quick Uses
- Acid-base titrations with polyvalent species
- Redox reactions using equivalents of electrons
- Precipitation reactions with ionic charge balance
How to Calculate
- Identify the reaction and determine the n-factor (protons, electrons, or charge exchanged).
- Compute equivalents = moles of solute × n-factor.
- Measure or convert solution volume to liters.
- Divide equivalents by liters to get N (eq/L).
For acids/bases: n-factor = number of H+ donated/accepted per formula unit. For redox: n-factor = electrons transferred per formula unit.
Worked Example
Problem: Find the normality of 0.50 M H2SO4 for an acid-base titration (assume both protons react).
1) n-factor for H2SO4 = 2 (two acidic hydrogens).
2) Equivalents per liter = 0.50 mol/L × 2 = 1.00 eq/L.
3) Normality N = 1.00 eq/L.
Answer: 1.00 N
Common Pitfalls
Wrong n-factor
Match n-factor to the actual reaction stoichiometry, not just the formula.
Volume units
Use liters, not mL; divide by 1000 if needed.
Assuming full dissociation
Polyprotic acids may donate fewer protons depending on pH and reaction context.
Mixing M and N
Normality depends on reaction; 1 M is not always 1 N.
Related Calculators
FAQ
Is normality still commonly used?
It appears in titration contexts, but molarity is generally preferred. Use N when equivalents simplify calculations.
How do I find n-factor in redox?
Balance the half-reaction and count electrons transferred per formula unit.
Can I convert between M and N?
Yes: N = M × n-factor for the specific reaction.