# General Chemistry/Useful Equations

 General Chemistry Book Cover · Introduction ·  v • d • e Appendices: Periodic Table · Units · Constants · Equations · Reduction Potentials · Elements and their Properties

## Contents

### General

 Density $\frac{mass}{volume}$ Moles $\frac{given~mass~(g)}{gram~formula~mass}$ Percent Error $\frac{measured - accepted}{accepted} \times 100%$ Percent Composition (by mass) $\frac{mass~of~part}{mass~of~whole} \times 100%$ Molarity $\frac{moles~of~solute}{volume~of~solution}$ Molality $\frac{moles~of~solute}{mass~of~solvent~in~kg}$

De,broglies law ¥ = h/mv

### Atomic Structure

Symbol Meaning Symbol Meaning
$E$ energy $c$ speed of light
$v$ frequency $\lambda$ wavelength
$Q$ charge $r$ distance
$k_e$ Coulomb's constant $h$ Plank's constant
 Energy of Wave $E = h v$ Wave Relation $c = \lambda v$ Coulomb's Law $F_e = k_e\frac{Q_1Q_2}{r^2}$

### Solutions, Liquids, and Gases

Symbol Meaning
$P$ pressure
$V$ volume
$n$ number of moles
$T$ temperature (in Kelvin)
$K_f$ molal freezing point constant
$K_b$ molal boiling point constant
$\chi$ mole fraction
$m$ molality
$M$ molarity

 Rauolt's Law $P_{solution} = P_{1} \chi_{1} + P_{2} \chi_{2} + \dots$ Boiling Point Elevation $\Delta T_{solution} = K_b \cdot m_{solute}$ Freezing Point Depression $\Delta T_{solution} = K_f \cdot m_{solute}$ Ideal Gas Law $PV = nRT$ Combined Gas Law $\frac{P_1 V_1}{n_1 T_1} = \frac{P_2 V_2}{n_2 T_2}$ Titration $M_A V_A = M_B V_B$ Dilution $M_1 V_1 = M_2 V_2$

### Equilibrium

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

### Thermochemistry

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