# General Chemistry/Useful Equations

 General Chemistry Book Cover · Introduction ·  v • d • e

### General

 Density: ${\displaystyle {\frac {mass}{volume}}}$ Moles: ${\displaystyle {\frac {given~mass~(g)}{gram~formula~mass}}}$ Percent Error: ${\displaystyle {\frac {measured-accepted}{accepted}}\times 100\%}$ Percent Composition (by mass): ${\displaystyle {\frac {mass~of~part}{mass~of~whole}}\times 100\%}$ Molarity: ${\displaystyle {\frac {moles~of~solute}{volume~of~solution}}}$ Molality: ${\displaystyle {\frac {moles~of~solute}{mass~of~solvent~in~kg}}}$ Rate of Reaction: ${\displaystyle {\frac {Difference~in~quantity}{Difference~in~time}}}$ de Broglie's law: ${\displaystyle \lambda }$ = ${\displaystyle {\frac {h}{mv}}}$

### Atomic Structure

Symbol Meaning Symbol Meaning
${\displaystyle E}$ energy ${\displaystyle c}$ speed of light
${\displaystyle v}$ frequency ${\displaystyle \lambda }$ wavelength
${\displaystyle Q}$ charge ${\displaystyle r}$ distance
${\displaystyle k_{e}}$ Coulomb's constant ${\displaystyle h}$ Plank's constant H/nkne
 Energy of Wave: ${\displaystyle E=hv}$ Wave Relation: ${\displaystyle c=\lambda v}$ Coulomb's Law: ${\displaystyle F_{e}=k_{e}{\frac {Q_{1}Q_{2}}{r^{2}}}}$

### Solutions, Liquids, Gases

Symbol Meaning
${\displaystyle P}$ pressure
${\displaystyle V}$ volume
${\displaystyle n}$ number of moles
${\displaystyle T}$ temperature (in Kelvin)
${\displaystyle K_{f}}$ molal freezing point constant
${\displaystyle K_{b}}$ molal boiling point constant
${\displaystyle \chi }$ mole fraction
${\displaystyle m}$ molality
${\displaystyle M}$ molarity
${\displaystyle c}$ specific heat capacity
${\displaystyle M_{w}}$ mass of water (Kg)
${\displaystyle E_{h}}$ heat energy released

 Rauolt's Law: ${\displaystyle P_{solution}=P_{1}\chi _{1}+P_{2}\chi _{2}+\dots }$ Boiling Point Elevation: ${\displaystyle \Delta T_{solution}=K_{b}\cdot m_{solute}}$ Freezing Point Depression: ${\displaystyle \Delta T_{solution}=K_{f}\cdot m_{solute}}$ Ideal Gas Law: ${\displaystyle PV=nRT}$ Combined Gas Law: ${\displaystyle {\frac {P_{1}V_{1}}{n_{1}T_{1}}}={\frac {P_{2}V_{2}}{n_{2}T_{2}}}}$ Titration: ${\displaystyle M_{A}V_{A}=M_{B}V_{B}}$ Dilution: ${\displaystyle M_{1}V_{1}=M_{2}V_{2}}$ Heat released by burning: ${\displaystyle E_{h}=cM_{w}\Delta T}$

### Equilibrium

Symbol Meaning
${\displaystyle K_{eq}}$ equilibrium constant (general)
${\displaystyle K_{p}}$ pressure equilibrium constant
${\displaystyle K_{c}}$ concentration equilibrium constant
${\displaystyle R}$ gas law constant
${\displaystyle T}$ temperature (in Kelvin)
${\displaystyle \Delta n}$ moles of product – moles of reactant
 pH: ${\displaystyle \mathrm {pH} =-\log {[\mathrm {H^{+}} ]}}$ pOH: ${\displaystyle \mathrm {pOH} =-\log {[\mathrm {OH^{-}} ]}}$ (for water): ${\displaystyle \mathrm {pH} +\mathrm {pOH} =14}$ Pressure/Concentration: ${\displaystyle K_{p}=K_{c}(RT)^{\Delta n}}$ Equilibrium, for a reaction ${\displaystyle a\mathrm {A} +b\mathrm {B} \rightarrow c\mathrm {C} +d\mathrm {D} }$: ${\displaystyle K_{eq}={\frac {[\mathrm {C} ]^{c}[\mathrm {D} ]^{d}}{[\mathrm {A} ]^{a}[\mathrm {B} ]^{b}}}}$

### Thermochemistry

Symbol Meaning
${\displaystyle q}$ heat energy
${\displaystyle m}$ mass
${\displaystyle c}$ specific heat
${\displaystyle T}$ temperature (in Kelvin)
${\displaystyle S}$ entropy
${\displaystyle H}$ enthalpy
${\displaystyle G}$ Gibbs free energy
 Heat Transfer: ${\displaystyle q=mc\Delta T}$ Enthalpy: ${\displaystyle \Delta H=H_{products}-H_{reactants}}$ Entropy: ${\displaystyle \Delta S=S_{products}-S_{reactants}}$ Free Energy: ${\displaystyle \Delta G=\Delta H-T\Delta S}$