Chem Summary

The Mole ( $n$ ): SI unit for amount of substance. $\text{Avogadro's number}$ ( $N_A$ ) is $6,02 \times 10^{23}\,mol^{-1}$ .
Molar Mass ( $M$ ): Mass in grams of one mole ( $g\,mol^{-1}$ ).
Central Equation: $n = \frac{m}{M}$ .
Molar Volume ( $V_m$ ): One mole of any gas occupies $22,4\,dm^3$ at $\text{STP}$ ( $0\,^{\circ}\text{C}$ and $101,3\,kPa$ ). Equation: $n = \frac{V}{V_m}$ .
Concentration ( $c$ ): Amount of solute per volume. Equation: $c = \frac{n}{V}$ or $c = \frac{m}{M \times V}$ . Units: $mol\,dm^{-3}$ .
Stoichiometry: Involves balanced equations and mole ratios. Includes identifying limiting reagents, $\text{percentage yield}$ ( $\frac{\text{actual}}{\text{theoretical}} \times 100$ ), and $\text{percentage purity}$ ( $\frac{\text{pure}}{\text{total}} \times 100$ ).

Intramolecular Bonds: Covalent (sharing electrons), Ionic (electron transfer), and Metallic (positive kernels in a sea of delocalised electrons).
Molecular Shapes: Determined by symmetry and bond angles ( $\text{Linear}$ $180^{\circ}$ , $\text{Angular}$ $104,5^{\circ}$ , $\text{Trigonal planar}$ $120^{\circ}$ , $\text{Trigonal pyramidal}$ $107,8^{\circ}$ , $\text{Tetrahedral}$ $109,5^{\circ}$ ).
Intermolecular Forces (IMF): $\text{London forces}$ (all molecules), $\text{dipole-dipole forces}$ (polar molecules), and $\text{hydrogen bonding}$ ( $H$ bonded to $N$ , $O$ , or $F$ ).
Physical Properties: Boiling and melting points depend on the energy required to overcome IMF. Stronger IMF leads to higher boiling points.

Enthalpy Change ( $\Delta H$ ): $\Delta H = E_{\text{products}} - E_{\text{reactants}}$ . $\text{Exothermic}$ ( $\Delta H < 0$ ) releases heat; $\text{Endothermic}$ ( $\Delta H > 0$ ) absorbs heat.
Activation Energy ( $E_a$ ): Minimum energy required to form the $\text{activated complex}$ and start a reaction.
Collision Theory: Effective collisions require correct orientation and enough kinetic energy ( $E_k \ge E_a$ ).
Factors Affecting Rate: Nature of reactants, surface area, concentration, pressure (gases), temperature, and $\text{catalysts}$ (which lower $E_a$ for both directions).
Maxwell-Boltzmann Distribution: Shows the spread of kinetic energies. Higher temperature shifts the peak right and flattens the curve.

Dynamic Equilibrium: Occurs in a closed system when forward and reverse reaction rates are equal.
Equilibrium Constant ( $K_c$ ): Ratio of products to reactants. Equation: $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$ . Only temperature changes $K_c$ . Solids and pure liquids are omitted.
Le Ch\u00e2telier\u2019s Principle: If a stress (temperature, pressure, concentration) is applied, the system shifts to counteract it.
Industrial Processes: $\text{Haber-Bosch}$ ( $NH_3$ ), $\text{Contact}$ ( $H_2SO_4$ ), and $\text{Ostwald}$ ( $HNO_3$ ).

Lowry-Br\u00f8nsted Model: Acid (proton donor), Base (proton acceptor). Includes $\text{conjugate acid-base pairs}$ and $\text{amphoteric substances}$ (e.g., $H_2O$ , $HCO_3^-$ ).
Strength: $\text{Strong acids}$ (e.g., $HCl$ , $H_2SO_4$ , $HNO_3$ ) ionise completely. $\text{Strong bases}$ (Group 1 hydroxides) dissociate completely.
Auto-ionisation of Water: $K_w = [H_3O^+][OH^-] = 1 \times 10^{-14}$ at $25\,^{\circ}\text{C}$ .
pH Scale: $pH = -\log([H_3O^+])$ . $\text{Neutral}$ at $25\,^{\circ}\text{C}$ is $pH = 7$ .
Hydrolysis: Reaction of salt ions with water. Salts from strong acid + weak base are acidic; weak acid + strong base are basic.
Titrations: Used to find concentrations via $\frac{c_a V_a}{c_b V_b} = \frac{n_a}{n_b}$ . Indicators chosen by $\text{equivalence point}$ $pH$ .

Redox: $\text{Oxidation}$ (loss of $e^-$ ), $\text{Reduction}$ (gain of $e^-$ ). $\text{Reducing agent}$ is oxidised; $\text{oxidising agent}$ is reduced.
Galvanic Cells: Spontaneous; converts chemical to electrical energy. $\text{Anode}$ ( $-$ ) is site of oxidation; $\text{Cathode}$ ( $+$ ) is reduction.
Electrolytic Cells: Non-spontaneous; uses electrical energy. $\text{Anode}$ ( $+$ ) is oxidation; $\text{Cathode}$ ( $-$ ) is reduction.
Standard Electrode Potential ( $E^0_{\text{cell}}$ ): $E^0_{\text{cell}} = E^0_{\text{cathode}} - E^0_{\text{anode}}$ . Calculated using the $\text{Standard Hydrogen Electrode}$ as reference ( $0,00\,V$ ).
Faraday's Laws: $q = It$ and $q = nF$ ( $F = 96\,500\,C\,mol^{-1}$ ).

Homologous Series: $\text{Alkanes}$ , $\text{alkenes}$ , $\text{haloalkanes}$ , $\text{alcohols}$ , $\text{carboxylic acids}$ , and $\text{esters}$ .
Isomerism: $\text{Chain}$ , $\text{positional}$ , and $\text{functional}$ isomers (same molecular formula, different structure).
Reaction Types: $\text{Combustion}$ ( $\text{exothermic}$ ), $\text{Substitution}$ (saturated), $\text{Addition}$ (unsaturated), $\text{Elimination}$ , and $\text{Esterification}$ (acid-catalysed).
Tests: Bromine water determines unsaturation (alkenes decolourise it rapidly).