Chemistry General Calculator
A collection of calculators for basic chemistry: moles, molarity, pH, ideal gas law, and dilution.
Mole (mol) Calculator
Enter mass and molar mass to calculate moles (mol) — the basis of quantitative chemistry.
Read MoreMolarity Calculator
Enter moles of solute and solution volume to calculate molarity (M, mol/L).
Read MorepH Calculator
Enter the hydrogen ion concentration to calculate pH and pOH and determine acidity or basi...
Read MoreIdeal Gas Law Calculator
Enter moles, volume, and temperature to calculate pressure using the ideal gas law (PV = n...
Read MoreDilution Calculator
Enter initial concentration/volume and target concentration to find the final volume and w...
Read MoreAbout This Category
Five core conversions from general chemistry: moles from mass, molarity from moles and volume, pH from hydrogen-ion concentration, the ideal-gas law, and dilution between two solutions.
Each assumes an idealised system. Activity coefficients are ignored, so concentrated solutions and strong ionic media give results that differ from the textbook value — the pages state this rather than hiding it.
Frequently Asked Questions
Why is pH only defined for dilute solutions?
Because it is the negative logarithm of hydrogen-ion activity, and activity approaches concentration only in dilute solutions (below about 0.1 mol/L).
Which gas constant should I use?
0.08206 L·atm/(mol·K) with litres and atmospheres, or 8.314 J/(mol·K) with pascals and cubic metres. Mixing the two is the most common error.
Does dilution change the number of moles?
No. Only the volume and therefore the concentration change: moles before equal moles after.
Calculators in This Category
Sources & last update
2026-10-19