Chemistry RR mistakes

KHCO3 decomp eqn

2KHCO3(s)→K2CO3(s)+CO2(g)+H2O(g)

Enthalpy change of atomisation

Enthalpy change when 1 mole of gaseous atoms is formed from its elements under standard conditions

Lattice enthalpy

Energy change when one mole of an ionic solid is formed at 298K and 1 atmosphere from its isolated gaseous ions

First electron affinity

Energy released when 1 mole of electrons is added to one mole of gaseous atoms to form 1 mole of gaseous 1- ions

Hydration energy

Energy change when 1 mole of gaseous ions are dissolved in sufficient water to give an infinitely dilute solution under standard conditions

Enthalpy change of Solution

Energy change when 1 mole of ionic solid dissolves in sufficient water to give an infinitely dilute solution under standard conditions

Mneumonics for solubility down group for sulphates and hydroxides

HOILE and SOD - H (SHydLE)

Lithium flame test

Crimson red

Sodium (Na⁺)

Yellow / orange (persistent)

Potassium (K⁺)

Lilac

Calcium (Ca²⁺)

Brick-red / orange-red

Strontium (Sr²⁺)

Crimson / red

Barium (Ba²⁺)

Apple-green / pale green

Copper (Cu²⁺)

Blue-green

Ca²⁺ (NaOH / NH₃(aq))

Precipitate: White | Excess behavior: NO

Cr³⁺ (NaOH)

Precipitate: Green gelatinous | Excess behavior: YES (dark green solution)

Cr³⁺ (NH₃(aq))

Precipitate: Green gelatinous | Excess behavior: NO

Cu²⁺ (NaOH / NH₃(aq))

Precipitate: Blue | Excess behavior: YES (NH₃ only: deep blue solution)

Pb²⁺ (NaOH / NH₃(aq))

Precipitate: White | Excess behavior: YES (NaOH only)

Zn²⁺ (NaOH / NH₃(aq))

Precipitate: White | Excess behavior: YES (both NaOH and NH₃)

PbI2

Yellow ppt

Acid added to buffer

A- + H+ --> HA; Conjugate base removes added acid and shifts eq to HA.

Base added to buffer

H+ + OH- --> H2O; Eq shifts right to replace H+ minimising rise in pH

Order of reaction

The power to which the concentration of a reactant is raised in the rate equation

1st order eqn

T1/2 = (ln2)/k

Alternate Kc eqn

Kc = Kstab * Ksp

Rate Determining Step (RDS)

The slowest step in a multi step reaction

Relation between rate constant and temperature

Proportional

Standard cell potential

Potential difference between two cells under 298K, 101kPa, and 1 molar solns

O2 formed at anode

4OH− → O2 + 2H2O + 4e-

Thermochemical evidence for kekule

Enthalpy of hydrogenation is less than three times that of cyclohexene

Nitration of benzene conditions

50-60C and conc H2SO4

Hydrogenation of benzene conditions

Heat, nickel/platinum catalyst

Nucleophilic substitution to cyanide

KCN/HCN ethanolic reflux

Hydrolysis of acyl chlorides

Produces a carboxylic acid and HCl gas

Why benzene doesn't undergo simple addition with bromine like ethene

Ring electrons are spread out and very stable, meaning it cannot polarize the bromine molecule on its own.