Chemistry Reference
Equations & Reference Data
Essential chemical equations, formulas, and reference data for students and professionals
🔢Important Chemical Constants
Basic Chemical Formulas
Water
Two hydrogen atoms, one oxygen atom
Carbon Dioxide
One carbon atom, two oxygen atoms
Methane
One carbon atom, four hydrogen atoms
Ammonia
One nitrogen atom, three hydrogen atoms
Sodium Chloride
Table salt - sodium and chlorine
Glucose
Simple sugar molecule
Ethanol
Alcohol compound
Calcium Carbonate
Limestone, marble component
Gas Laws
Ideal Gas Law
Pressure × Volume = moles × Gas constant × Temperature
Boyle's Law
Pressure and volume are inversely related (constant T)
Charles' Law
Volume and temperature are directly related (constant P)
Gay-Lussac's Law
Pressure and temperature are directly related (constant V)
Combined Gas Law
Combines Boyle's, Charles', and Gay-Lussac's laws
Avogadro's Law
Volume and moles are directly related (constant P,T)
Thermochemistry
Heat Capacity
Heat = mass × specific heat × temperature change
Enthalpy Change
Change in enthalpy during reaction
Hess's Law
Total enthalpy change is sum of individual steps
Calorimetry
Heat lost by one substance equals heat gained by another
Standard Enthalpy
Standard enthalpy of formation calculation
Solutions & Concentrations
Molarity
Moles of solute per liter of solution
Molality
Moles of solute per kilogram of solvent
Mass Percent
Percentage by mass concentration
Parts Per Million
Concentration in parts per million
Dilution Formula
Initial molarity × volume = final molarity × volume
Mole Fraction
Fraction of total moles contributed by component
Acids & Bases
pH Formula
Negative logarithm of hydrogen ion concentration
pOH Formula
Negative logarithm of hydroxide ion concentration
pH + pOH
Relationship between pH and pOH at 25°C
Ka Expression
Acid dissociation constant
Kb Expression
Base dissociation constant
Ka × Kb
Relationship between Ka and Kb
Equilibrium & Kinetics
Equilibrium Constant
Concentration-based equilibrium constant
Reaction Quotient
Momentary ratio of concentrations
Rate Law
Reaction rate dependence on concentrations
Half-life (1st order)
Time for concentration to decrease by half
Arrhenius Equation
Temperature dependence of rate constant
Le Chatelier's Principle
System shifts to counteract applied stress
⚗️Common Chemical Reaction Types
Combustion
Hydrocarbon + oxygen → carbon dioxide + water
Acid-Base
Acid + base → salt + water
Synthesis
Simple substances combine to form complex compound
Decomposition
Complex compound breaks down into simpler substances
Single Replacement
More active metal replaces less active metal
Double Replacement
Two compounds exchange ions
Periodic Table Quick Reference
Group 1 - Alkali Metals
Group 17 - Halogens
Group 18 - Noble Gases
Common Elements
⚠️Laboratory Safety Guidelines
Personal Protection
- •Always wear safety goggles and lab coat
- •Use gloves when handling chemicals
- •Tie back long hair and secure loose clothing
- •Wear closed-toe shoes, no sandals
Chemical Handling
- •Read all labels before using chemicals
- •Never pipette by mouth, use pipette bulbs
- •Dispose of chemicals according to protocols
- •Work in well-ventilated areas or fume hoods
About Chemistry
Chemistry is the scientific study of matter, its properties, composition, structure, and the changes it undergoes during chemical reactions. It bridges physics and biology, providing fundamental understanding of how atoms and molecules interact to form the vast variety of materials and substances in our world.
This comprehensive chemistry reference provides essential formulas, equations, and constants used in general chemistry, organic chemistry, and analytical chemistry. From basic molecular formulas to complex equilibrium expressions, these tools are fundamental for understanding chemical principles and solving chemistry problems.
Whether you're a student learning basic chemistry concepts, a researcher conducting experiments, or a professional working in chemical industries, this reference guide provides quick access to the most important chemical relationships and calculations you'll encounter in your work.
How to Use Chemical Formulas
Identify the Chemical System
Determine what type of chemical problem you're solving: stoichiometry, equilibrium, acid-base, etc.
Check Units and Conditions
Ensure all quantities are in compatible units and note any special conditions (temperature, pressure, etc.).
Apply Appropriate Formula
Select the correct formula or equation that relates the known and unknown quantities in your problem.
Verify Results
Check that your answer makes chemical sense and has appropriate significant figures and units.
Chemistry Study Tips
Understand, Don't Memorize
Focus on understanding chemical principles rather than memorizing formulas.
Practice with Real Examples
Work through actual chemical problems to reinforce formula usage.
Draw Lewis Structures
Visualize molecular structures to better understand chemical behavior.
Balance Chemical Equations
Practice balancing equations to understand stoichiometric relationships.
Master Unit Conversions
Be comfortable converting between different units and concentration expressions.
Check Your Work
Always verify that answers are chemically reasonable and properly formatted.
Frequently Asked Questions
Get answers to common questions about chemistry reference