Chemistry help for high school

Chemical equation balancer and chemistry calculatorsUnderstand every step.

OneChemLab helps high school students balance chemical equations, explore stoichiometry, and work through chemistry calculations—from moles and molar mass to gas laws and pH.

A Google sign-in is required to use the calculators.

Learn chemistry by working through it

Clear explanations and focused tools connect the formulas you learn in class to the problems you solve.

Step-by-step calculations

Follow the setup and see how values fit into a chemistry relationship, rather than treating the result as a black box.

Chemical equation balancer

Compare atom counts on both sides and use whole-number coefficients to conserve each element in a chemical reaction.

Core chemistry topics

Practice molar mass, mole conversions, dilution, gas laws, pH, equilibrium, and electrochemistry in one place.

Stoichiometry calculator: from balanced equations to mole ratios

A balanced reaction gives the mole ratios used in stoichiometry. Use those coefficients to relate a known amount of one substance to the amount of another, then convert between moles, mass, or other quantities as needed.

Example: forming water

2H2 + O2 → 2H2O

The coefficients show a 2:1:2 mole ratio: two moles of hydrogen react with one mole of oxygen to form two moles of water. The small subscripts are part of each substance's formula and stay unchanged when balancing; only coefficients in front of formulas are adjusted.

Chemistry calculators for key topics

Start with foundational quantities and build toward solutions, gases, acids and bases, and electrochemistry.

Foundations

  • Molar mass calculator
  • Mole conversion calculator
  • Percent composition calculator
  • Equation balancing and mole ratios

Solutions & gases

  • Dilution calculator (C₁V₁ = C₂V₂)
  • Ideal gas law calculator (PV = nRT)
  • Boyle's law and Charles's law calculators
  • Stoichiometry relationships

Further topics

  • pH and pOH calculator
  • Equilibrium constant calculator
  • Nernst equation calculator
  • Electrochemistry

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Chemistry calculator FAQ

Quick answers for students learning equations and calculations.

How do I calculate molar mass from a chemical formula?

Multiply each element's atomic mass by its atom count, then add the contributions. For water, H2O, this is 2 × 1.008 + 15.999 = 18.015 g/mol. The molar mass calculator helps you see how each element contributes to the total.

When should I use an ideal gas law calculator?

Use PV = nRT to relate a gas's pressure, volume, amount in moles, and absolute temperature when the ideal-gas approximation is appropriate. Convert temperature to kelvin and choose a gas constant with units that match your pressure and volume.

How do I balance a chemical equation?

Count each type of atom on both sides, then adjust coefficients in front of formulas until the counts match. For example, hydrogen and oxygen combine as H2 + O2 → H2O; balancing gives 2H2 + O2 → 2H2O. Do not change a chemical formula's subscripts: changing them changes the substance.

What is another example of a balanced equation?

HCl + NaOH → NaCl + H2O is balanced as written. There are two hydrogen atoms and one each of chlorine, sodium, and oxygen on each side.

How does equation balancing connect to stoichiometry?

Coefficients in a balanced equation give mole ratios between reactants and products. For water formation, the ratio 2H2 : O2 : 2H2O lets you relate the amount of one substance to another before converting to mass or another unit.

Are AI reactant suggestions always correct?

No. Suggestions based on reactants can depend on reaction conditions and the information provided, so they are not guaranteed. Check suggested products against your course materials and verify that the resulting equation is balanced.

Do I need an account to use the calculators?

Yes. A Google sign-in is required to access the calculators.