Quick Dilution Helper

See how dilution affects pH. Enter a dilution factor (e.g., 10 for a 1:10 dilution).

Dilution Factor

1x 10x 1000x

Or enter factor

Diluted pH

3.00

Concentration: 0.00100 M

Note: This assumes dilution with pure water and no other acid/base present.

Understanding Strong Acid/Base pH

Why this matters: Strong acids and bases completely dissociate in water, making their pH calculation straightforward but foundational. Accurate pH estimation is critical for buffer preparation, titration planning, and ensuring reaction conditions in synthesis and analysis.

Step-by-Step Usage

Select whether your solution is a strong acid (e.g., hydrochloric, nitric) or strong base (e.g., sodium hydroxide, potassium hydroxide).
Enter the concentration. Use the unit dropdown to match your measurement (M, mM, µM).
Click Calculate. The tool computes pH, pOH, and ion concentrations.
Use the Quick Dilution Helper to predict pH changes upon dilution.

Realistic Examples

Type	Concentration	[H⁺] or [OH⁻]	pH	pOH
1 M HCl	1 M	1 M [H⁺]	0.00	14.00
0.1 M NaOH	0.1 M	0.1 M [OH⁻]	13.00	1.00
1 mM HNO₃	1 mM (0.001 M)	0.001 M [H⁺]	3.00	11.00

Common Mistakes Checklist

Confusing molarity with molality (this tool uses molarity, M).
Forgetting that strong bases give high pH, not low pH.
Using the wrong K_w value if temperature is not 25°C (this tool uses 1.0×10⁻¹⁴ at 25°C).
Neglecting dilution effects when preparing solutions from concentrated stocks.
Assuming pH + pOH = 14 holds at all temperatures (only at 25°C with K_w=1e-14).

Frequently Asked Questions

What are the limits of this calculator?

It assumes 100% dissociation (valid for strong acids/bases), temperature of 25°C (K_w=1e-14), and monoprotic species. For concentrations below ~10⁻⁶ M, water autoionization contributes significantly—use the “exact calculation” option if added in future versions.

Why does my measured pH differ from the calculated one?

Real solutions have ionic strength effects, temperature variations, and possible impurities. Always calibrate your pH meter with standard buffers and account for activity coefficients in precise work.

Can I use this for concentrated acids like 12 M HCl?

The calculation will give pH ≈ -1.08, but at such high concentrations, the concept of pH becomes less meaningful due to extreme activity effects. Handle concentrated acids with extreme care—always add acid to water, never water to acid.

What safety precautions are essential?

Always wear appropriate PPE (gloves, goggles, lab coat). Work in a fume hood for volatile acids/bases. Know the SDS for each chemical. Have spill kits and neutralizers readily available. Never pipette by mouth.

Formulas & Assumptions

Core Equations

Strong acid: [H⁺] = C_acid; pH = -log₁₀([H⁺])
Strong base: [OH⁻] = C_base; pOH = -log₁₀([OH⁻])
pH + pOH = pK_w = 14.00 (at 25°C)
K_w = [H⁺][OH⁻] = 1.0×10⁻¹⁴

Assumptions

Complete dissociation of strong electrolyte
Temperature = 25°C (constant K_w)
Ideal dilute solution (activity ≈ concentration)
Monoprotic acid/base (one H⁺ or OH⁻ per formula unit)

Constants Used

K_w (ionic product of water) = 1.0×10⁻¹⁴
pK_w = -log₁₀(K_w) = 14.000
Unit conversions: 1 M = 1000 mM = 1,000,000 µM

Rounding Policy

Results are rounded to the selected decimal places. Intermediate calculations use full precision. pH values are reported with 0.01 resolution by default. Concentration values use scientific notation when <0.001 or ≥1000.

For informational and educational purposes only. Estimates depend on your inputs and simplifying assumptions. This tool does not replace professional judgment, lab SOPs, or safety procedures. Always follow SDS guidance and institutional policies.

Sources & References

Common chemistry constants: R, N_A, F
Standard unit conversions and lab measurement best practices
General analytical chemistry and uncertainty concepts
Intro physical chemistry relationships (ideal gas, Arrhenius, equilibrium)
Laboratory safety basics and SDS principles

pH from Strong Acid & Base Calculator

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