Num8ers chemistry reference
Complete K-12 Chemistry Formula Guide
Search 370 chemistry formulas across measurement, matter, atomic structure, bonding, mole concept, stoichiometry, reactions, solutions, pH, gases, thermochemistry, equilibrium, kinetics, electrochemistry, organic chemistry, nuclear chemistry, and AP or IB extensions.
How to use this chemistry guide
Search by formula, variable, or topic.
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Read the expression, definition, and variables.
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Chemistry Formula FAQs
Does this K-12 chemistry formula page include all 370 formulas?
Yes. It includes all 370 formulas from the uploaded K-12 chemistry checklist, grouped by category with formulas, definitions, and variable explanations.
How should students use this chemistry formula guide?
Start by choosing a category or searching a keyword, then read the formula, definition, and variables before substituting values.
What is the mole formula?
The main mole formula is n = m / M, where n is moles, m is mass, and M is molar mass.
How do you calculate molarity?
Molarity is M = n / V, where n is moles of solute and V is solution volume in liters.
What is the difference between molarity and molality?
Molarity uses liters of solution, while molality uses kilograms of solvent.
What is the dilution formula?
The dilution formula is M1V1 = M2V2, meaning moles of solute stay constant when a solution is diluted.
What is the pH formula?
The pH formula is pH = -log[H+], where [H+] is hydrogen ion concentration.
How are pH and pOH related?
At 25 degrees Celsius, pH + pOH = 14.
What is percent yield?
Percent yield is actual yield divided by theoretical yield, multiplied by 100 percent.
What is percent composition?
Percent composition is the mass of an element in a compound divided by total compound mass, multiplied by 100 percent.
What is the difference between empirical and molecular formula?
An empirical formula gives the simplest whole-number ratio, while a molecular formula gives the actual number of atoms in a molecule.
What is the ideal gas law?
The ideal gas law is PV = nRT, connecting pressure, volume, moles, gas constant, and temperature.
How do you find the limiting reactant?
Compare n divided by the balanced coefficient for each reactant; the smallest value identifies the limiting reactant.
What is an equilibrium constant?
An equilibrium constant compares product and reactant concentrations at equilibrium using balanced-equation powers.
What does Le Chatelier's principle mean?
It means a system at equilibrium shifts to oppose a stress such as concentration, pressure, or temperature change.
What is a rate law?
A rate law shows how reaction rate depends on reactant concentrations, usually written rate = k[A]^m[B]^n.
What does the Nernst equation calculate?
The Nernst equation calculates cell potential under non-standard electrochemical conditions.
What is the Henderson-Hasselbalch equation used for?
It is used to estimate buffer pH from pKa and the ratio of conjugate base to acid.
What formula is used for heat in chemistry?
For temperature change, use q = mc Delta T, where q is heat, m is mass, c is specific heat, and Delta T is temperature change.
What is half-life in nuclear chemistry?
Half-life is the time required for half of a radioactive sample to decay, often calculated with t1/2 = ln2 / lambda.