Today's Daily Quiz is Live — Test your knowledge & improve your rank
|

Top Chemistry Formulas

Important chemistry formulas and equations.

1
Moles and Mass
Number of moles (n) = Mass (m) / Molar mass (M)

Calculate the amount of substance in moles.

View Explanation
2
Molarity
Molarity = Moles of Solute / Volume of Solution in Litres

Calculate the molar concentration of a solution.

View Explanation
3
Ideal Gas Equation
P × V = n × R × T

Relate pressure, volume, amount and temperature of an ideal gas.

View Explanation
4
Number of Particles
N = n × Nₐ

Calculate particles from the number of moles.

View Explanation
5
pH
pH = -log₁₀[H⁺]

Calculate pH from hydrogen ion concentration.

View Explanation
6
Boyle Law
P₁V₁ = P₂V₂

Relate pressure and volume at constant temperature for a fixed amount of gas.

View Explanation
7
Avogadro Number Relation
1 mole = 6.022 × 10²³ particles

Relate moles to number of particles.

View Explanation
8
Molar Volume at STP
1 mole of gas at STP = 22.4 L

Volume occupied by one mole of ideal gas at STP.

View Explanation
9
Molality
Molality = Moles of solute / Mass of solvent in kg

Calculate molality of a solution.

View Explanation
10
Gay Lussac Law
P₁ / T₁ = P₂ / T₂

Relate pressure and temperature at constant volume.

View Explanation
11
Combined Gas Law
P₁V₁ / T₁ = P₂V₂ / T₂

Combine Boyle’s, Charles’ and Gay-Lussac’s laws.

View Explanation
12
pOH and pH Relation
pH + pOH = 14 (at 25°C)

Relate pH and pOH of aqueous solutions.

View Explanation
13
Buffer pH (Henderson-Hasselbalch)
pH = pKa + log([Salt]/[Acid])

Calculate pH of an acidic buffer.

View Explanation
14
Half Life First Order
t½ = 0.693 / k

Find half-life of a first-order reaction.

View Explanation
15
Equilibrium Constant Kc
Kc = [Products] / [Reactants] (with stoichiometric powers)

Write the expression for concentration equilibrium constant.

View Explanation
16
Density
Density = Mass / Volume

Calculate mass per unit volume.

View Explanation
17
Mass Percentage
Mass % = (Mass of Component / Total Mass) × 100

Calculate mass percentage in a mixture or solution.

View Explanation
18
Dilution Formula
M₁V₁ = M₂V₂

Calculate concentrations during dilution.

View Explanation
19
Percentage Yield
Percentage Yield = (Actual Yield / Theoretical Yield) × 100

Calculate the efficiency of a chemical reaction.

View Explanation
20
Empirical Formula
Mole Ratio = Mass Percentage / Atomic Mass; then simplify to the smallest whole-number ratio

Determine the simplest whole-number ratio of atoms in a compound.

View Explanation
21
Mole Fraction
Xᵢ = nᵢ / Σn

Calculate the mole fraction of a component.

View Explanation
22
Charles Law
V₁/T₁ = V₂/T₂

Relate gas volume and absolute temperature at constant pressure.

View Explanation
23
Reaction Rate
Average Rate = -Δ[Reactant]/Δt = Δ[Product]/Δt

Calculate average reaction rate from concentration change.

View Explanation
24
Normality
Normality = Number of gram equivalents / Volume of solution in litres

Calculate normality of a solution.

View Explanation
25
Graham Law of Diffusion
r₁ / r₂ = √(M₂ / M₁)

Compare rates of diffusion of two gases.

View Explanation
26
First Order Rate Constant
k = (2.303 / t) log([A]₀ / [A])

Calculate rate constant for a first-order reaction.

View Explanation