AP EAMCET cheat sheet

Chemistry

• Mole concept: n=mass/molar mass; N=nN_A with N_A=6.022×10²³ mol⁻¹; molarity M=n/V(L); use stoichiometric coefficients to convert moles of one species to another.

• Gas laws: ideal gas PV=nRT with R=8.314 J mol⁻¹ K⁻¹; Dalton law P_total=ΣP_i; Graham law r₁/r₂=√(M₂/M₁); van der Waals equation (P+an²/V²)(V−nb)=nRT accounts for attractions and finite molecular volume.

• Thermodynamics: ΔH=ΔU+Δ(PV); Hess law allows enthalpy changes to be added; ΔG=ΔH−TΔS; a constant-temperature and constant-pressure process is spontaneous when ΔG<0, and equilibrium occurs at ΔG=0.

• Equilibrium: K_p=K_c(RT)^Δn for gases; Le Chatelier shift opposes imposed changes in concentration, pressure, or temperature; pH=−log[H⁺]; at 25°C pH+pOH=14; buffer pH≈pK_a+log([salt]/[acid]).

• Electrochemistry: Nernst equation at 298 K is E=E°−(0.05916/n)logQ; one faraday F=96485 C mol⁻¹; charge Q=It; conductance depends on ion concentration and mobility.

• Chemical kinetics: rate law expresses rate=k[A]^m[B]^n; first-order half-life t₁/₂=0.693/k and is independent of initial concentration; Arrhenius equation k=Ae^(−E_a/RT).

• Periodic trends: atomic radius generally decreases across a period and increases down a group; ionization enthalpy generally increases across a period and decreases down a group; electronegativity increases across a period and decreases down a group, with noble-gas and subshell exceptions.

• Coordination chemistry: coordination number equals donor atoms bonded to the central metal; common geometries are linear for 2, tetrahedral or square planar for 4, and octahedral for 6; ligands are ordered by the spectrochemical series.

• Organic chemistry: IUPAC naming selects the longest chain and lowest locants; Markovnikov addition places H on the carbon with more hydrogens; SN1 proceeds via carbocation with racemization, while SN2 is concerted with inversion; aromatic electrophilic substitution is directed by activating or deactivating groups.