How-to guides
Walkthroughs for the procedures that come up most often, with worked numerical examples and the parts students typically trip on.
How to Balance a Chemical Equation
Balance chemical equations with the inspection method — worked through methane combustion, rusting,
How to Balance Redox Equations
Balance redox equations with the half-reaction method — worked through permanganate-iron and dichrom
How to Calculate Activation Energy
Calculate activation energy from rate constants at two temperatures or from an Arrhenius plot, with
How to Calculate Bond Energy
Estimate reaction enthalpy from bond dissociation energies — worked through methane combustion, hydr
How to Calculate Buffer pH
Calculate buffer pH with the Henderson-Hasselbalch equation — worked through acetate and phosphate s
How to Calculate Calorimetry Problems
Solve calorimetry problems with q = mcΔT — coffee-cup and bomb setups, with the sign conventions tha
How to Calculate Cell Potential
Compute standard and Nernst-corrected cell potentials without flipping signs by hand — the safe way
How to Calculate Colligative Properties
Compute boiling point elevation, freezing point depression, and vapor pressure lowering — including
How to Calculate the Decay Constant
Convert between half-life and decay constant, then use λ for activity, dating, and exponential decay
How to Calculate Effusion Rate
Apply Graham's law to compare gas effusion rates, identify unknown gases, and predict effusion times
How to Calculate Enthalpy Change
Calculate ΔH for any reaction using formation enthalpies, Hess's Law, or bond energies — with worked
How to Calculate the Equilibrium Constant
Calculate Kc and Kp from equilibrium concentrations or ICE tables, convert between them, and use Q t
How to Calculate Gibbs Free Energy
Calculate ΔG with ΔG = ΔH − TΔS, predict spontaneity, find crossover temperatures, and link ΔG° to t
How to Calculate Heat Transfer
Use q = mcΔT for calorimetry, find unknown specific heats, and solve mixing problems with worked met
How to Calculate Ionic Strength
Compute ionic strength I = ½ Σ(cᵢzᵢ²) for any electrolyte mix, with worked NaCl, MgCl₂, and Na₂SO₄ e
How to Calculate Molality
Calculate molality (mol solute per kg solvent) with worked freezing-point and boiling-point examples
How to Calculate Molar Mass
Sum atomic masses for any chemical formula — including parentheses and hydrates — with worked exampl
How to Calculate Molarity
Compute molarity (mol/L) for any solution prep — solids, liquids, dilutions — with worked lab exampl
How to Calculate Mole Fraction
Compute mole fraction (X) for solutions and gas mixtures, with Raoult's Law and Dalton's Law worked
How to Calculate Osmotic Pressure
Use Π = iMRT to compute osmotic pressure for non-electrolytes, salts, and protein molar-mass determi
How to Calculate Partial Pressures
Dalton's Law worked end-to-end: mole fractions, water-vapor corrections, and the gas-collection trap
How to Calculate Percent Composition
Mass percent of every element in a compound — the math that drives empirical formulas, ore grading,
How to Calculate pH from Concentration
Move fluently between pH, pOH, [H+], and [OH-] — and stop treating weak acids like strong ones.
How to Calculate Rate Law
Pull reaction orders and the rate constant out of initial-rate data — including the fractional and z
How to Calculate Specific Heat
Determine specific heat from calorimetry data — sign conventions, water as your reference, and the D
How to Calculate Standard Entropy Change
Calculate DeltaS for any reaction from tabulated S values, with worked examples and the sign-predict
How to Calculate Theoretical Yield
Find theoretical and percent yield from a balanced equation, with a worked limiting-reagent example
How to Convert Between Temperature Scales
Convert Celsius, Fahrenheit, Kelvin, and Rankine with the right formulas — and the Kelvin rule that
How to Convert Between Concentration Units
Convert molarity, molality, mole fraction, mass percent, and ppm using the basis-of-1-liter trick th
How to Convert Moles to Grams
Convert between moles and grams using molar mass — the bridge from balanced equations to what you ac
How to Convert ppm to Molarity
Turn ppm readings from a water analysis report into molarity you can plug into stoichiometry, equili
How to Convert Pressure Units
Move between atm, kPa, mmHg, torr, psi, bar, and Pa without botching the gas constant pairing in PV
How to Determine Bond Order
Calculate bond order from MO diagrams or resonance structures and predict bond strength, length, and
How to Determine the Empirical Formula
Convert combustion-analysis or elemental-analysis percentages into the simplest whole-number formula
How to Determine Hybridization
Count electron domains around the central atom and read off sp, sp2, sp3, sp3d, or sp3d2 — the model
How to Determine a Molecular Formula
Combine an empirical formula with a measured molar mass to pin down whether you have CH2O, glucose,
How to Determine Oxidation States
Assign oxidation numbers using a priority list of rules — the bookkeeping that makes redox balancing
How to Find the Limiting Reagent
Identify the reagent that runs out first, then calculate theoretical yield without falling for the h
How to Identify Functional Groups
Spot alcohols, carbonyls, amines, and the rest at a glance — the heteroatom and bonding pattern tell
How to Perform Dimensional Analysis
If your units don't cancel, your answer is wrong. Use the factor-label method as your built-in error
How to Predict Precipitation Reactions
Use solubility rules to predict precipitates qualitatively, then check Q vs. Ksp when concentrations
How to Solve Half-Life Problems
Half-life is invariant: same isotope, same number, no matter the conditions. Solve for any of the fo
How to Solve Ideal Gas Law Problems
PV = nRT, but only in Kelvin and only with the R that matches your units. Solve for any variable wit
How to Use the Combined Gas Law
Same gas, different conditions — P1V1/T1 = P2V2/T2 handles two states at once without juggling Boyle
How to Use the Dilution Equation
C1V1 = C2V2 with worked examples, serial dilutions, and the safety rule that keeps you out of the ER
How to Use Faraday's Law of Electrolysis
Convert amperes and seconds into grams of metal plated. Faraday's law connects current to chemistry.
How to Use the Henderson-Hasselbalch Equation
Buffer pH from pKa and a ratio. Includes prep recipes, strong-acid challenges, and when the equation
How to Use ICE Tables
ICE tables turn equilibrium problems into algebra. Worked weak acid, weak base, gas, and common-ion
How to Use the Nernst Equation
Cell potential at non-standard concentrations. Includes concentration cells and the link to K and ΔG
How to Write Electron Configurations
Aufbau, Pauli, Hund, and the d-block exceptions. Configurations for atoms and ions worked end-to-end