12 formulas

Chemistry Formula Sheet

These are the formulas a high school chemistry course uses: density and the mole, solutions, composition, gases, acids and bases, half-life, and energy.

Each formula shows what its letters stand for and their units. Open any one for a worked example and a calculator, or print the sheet to keep beside your lab notes.

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Density and the mole

Density Formula
$\rho = \frac{m}{V}$
Density is mass per unit volume: how much matter is packed into a space.
$\rho$
Mass per unit volume (g/mL or kg/m³)
$m$
Amount of matter (g or kg)
$V$
Space occupied (mL or m³)
Worked example and calculator
Mole Conversion
$n = \frac{m}{M}$
Converts between grams and moles using molar mass.
$n$
Number of moles (mol)
$m$
Mass of the substance (g)
$M$
Mass of one mole of the substance (g/mol)
Worked example and calculator

Solutions

Molar Concentration
$C = \frac{n}{V}$
Moles of solute per liter of solution.
$C$
Molarity (mol/L (M))
$n$
Amount of solute (mol)
$V$
Volume of solution (L)
Worked example and calculator
Dilution Formula
$M_1V_1 = M_2V_2$
Relationship between concentration and volume before and after dilution.
$M_1$
Starting molarity (M)
$V_1$
Starting volume (L)
$M_2$
Final molarity (M)
$V_2$
Final volume (L)
Worked example and calculator

Composition

Percent Composition
$\% = \frac{m_{element}}{m_{compound}} \times 100$
Mass percentage of an element in a compound.
$%$
Percentage by mass (%)
$m_element$
Mass of the element (g)
$m_compound$
Total mass of compound (g)
Worked example and calculator
Empirical Formula
$\text{ratio}_i = \frac{n_i}{n_{min}}$
Simplest whole number ratio of elements in a compound.
$ratio_i$
Simplified mole ratio for element i
$n_i$
Moles of element i (mol)
$n_{min}$
Smallest number of moles among the elements (mol)
Worked example and calculator

Gases

Ideal Gas Law
$PV = nRT$
Relates pressure, volume, amount, and temperature of an ideal gas.
$P$
Gas pressure (atm)
$V$
Gas volume (L)
$n$
Amount of substance (mol)
$R$
Universal gas constant ≈ 0.0821 (L·atm/(mol·K))
$T$
Absolute temperature in Kelvin (K)
Worked example and calculator

Acids and bases

pH Calculation
$\text{pH} = -\log[H^+]$
Measures acidity or basicity of a solution.
$pH$
pH value (0-14 scale)
$[H⁺]$
Concentration of H⁺ ions (mol/L)
Worked example and calculator
pOH Calculation
$\text{pOH} = -\log[OH^-]$
Measures hydroxide ion concentration.
$pOH$
pOH value
$[OH⁻]$
Concentration of OH⁻ ions (mol/L)
Worked example and calculator
pH-pOH Relationship
$\text{pH} + \text{pOH} = 14$
Sum of pH and pOH always equals 14 at 25°C.
$pH$
pH value
$pOH$
pOH value
Worked example and calculator

Nuclear decay and energy

Half-Life
$N = N_0(\frac{1}{2})^{t/t_{1/2}}$
Time for half of a substance to decay or be eliminated.
$N$
Amount remaining after time t
$N_0$
Starting amount
$t$
Time that has passed (time units)
$t_half$
Time for half to decay (time units)
Worked example and calculator
Gibbs Free Energy
$\Delta G = \Delta H - T\Delta S$
Determines spontaneity of a reaction.
$ΔG$
Change in Gibbs free energy (J/mol)
$ΔH$
Change in enthalpy (J/mol)
$T$
Absolute temperature (K)
$ΔS$
Change in entropy (J/(mol·K))
Worked example and calculator

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Matter and atoms

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Chemistry Formula Sheet

These are the formulas a high school chemistry course uses: density and the mole, solutions, composition, gases, acids and bases, half-life, and energy.

Each formula shows what its letters stand for and their units. Open any one for a worked example and a calculator, or print the sheet to keep beside your lab notes.

Density and the mole

Density Formula

\rho = \frac{m}{V}

Density is mass per unit volume: how much matter is packed into a space.

$\rho$: Mass per unit volume (g/mL or kg/m³)
$m$: Amount of matter (g or kg)
$V$: Space occupied (mL or m³)

Worked example and calculator

Mole Conversion

n = \frac{m}{M}

Converts between grams and moles using molar mass.

$n$: Number of moles (mol)
$m$: Mass of the substance (g)
$M$: Mass of one mole of the substance (g/mol)

Worked example and calculator

Solutions

Molar Concentration

C = \frac{n}{V}

Moles of solute per liter of solution.

$C$: Molarity (mol/L (M))
$n$: Amount of solute (mol)
$V$: Volume of solution (L)

Worked example and calculator

Dilution Formula

M_1V_1 = M_2V_2

Relationship between concentration and volume before and after dilution.

$M_1$: Starting molarity (M)
$V_1$: Starting volume (L)
$M_2$: Final molarity (M)
$V_2$: Final volume (L)

Worked example and calculator

Composition

Percent Composition

\% = \frac{m_{element}}{m_{compound}} \times 100

Mass percentage of an element in a compound.

$%$: Percentage by mass (%)
$m_element$: Mass of the element (g)
$m_compound$: Total mass of compound (g)

Worked example and calculator

Empirical Formula

\text{ratio}_i = \frac{n_i}{n_{min}}

Simplest whole number ratio of elements in a compound.

$ratio_i$: Simplified mole ratio for element i
$n_i$: Moles of element i (mol)
$n_{min}$: Smallest number of moles among the elements (mol)

Worked example and calculator

Acids and bases

pH Calculation

\text{pH} = -\log[H^+]

Measures acidity or basicity of a solution.

$pH$: pH value (0-14 scale)
$[H⁺]$: Concentration of H⁺ ions (mol/L)

Worked example and calculator

pOH Calculation

\text{pOH} = -\log[OH^-]

Measures hydroxide ion concentration.

$pOH$: pOH value
$[OH⁻]$: Concentration of OH⁻ ions (mol/L)

Worked example and calculator

pH-pOH Relationship

\text{pH} + \text{pOH} = 14

Sum of pH and pOH always equals 14 at 25°C.

$pH$: pH value
$pOH$: pOH value

Worked example and calculator

Nuclear decay and energy

Half-Life

N = N_0(\frac{1}{2})^{t/t_{1/2}}

Time for half of a substance to decay or be eliminated.

$N$: Amount remaining after time t
$N_0$: Starting amount
$t$: Time that has passed (time units)
$t_half$: Time for half to decay (time units)

Worked example and calculator

Gibbs Free Energy

\Delta G = \Delta H - T\Delta S

Determines spontaneity of a reaction.

$ΔG$: Change in Gibbs free energy (J/mol)
$ΔH$: Change in enthalpy (J/mol)
$T$: Absolute temperature (K)
$ΔS$: Change in entropy (J/(mol·K))

Worked example and calculator

Density and the mole

Density Formula

Mole Conversion

Solutions

Molar Concentration

Dilution Formula

Composition

Percent Composition

Empirical Formula

Gases

Ideal Gas Law

Acids and bases

pH Calculation

pOH Calculation

pH-pOH Relationship

Nuclear decay and energy

Half-Life

Gibbs Free Energy

Learn these formulas

Other formula sheets

Density and the mole

Density Formula

Mole Conversion

Solutions

Molar Concentration

Dilution Formula

Composition

Percent Composition

Empirical Formula

Gases

Ideal Gas Law

Acids and bases

pH Calculation

pOH Calculation

pH-pOH Relationship

Nuclear decay and energy

Half-Life

Gibbs Free Energy

Learn these formulas

Other formula sheets