Chemistry ms

Solubility of group 2 hydroxides

enthalpy of lattice and enthalpy of hydration both become less exothermic down the group

enthalpy of lattice changes faster and more

the enthalpy of solution becomes more exothermic

SOLUTION = HYDRATION - LATTICE

solubility of group 2 sulfates

enthalpy of lattice and hydration both become less exothermic down the group

enthalpy of hydration changes faster and more

enthalpy of solution becomes more endothermic and thus sulfates are more insoluble down the group

why you can see different colors from different compounds

Δ E value is different

different wavelengths of visible light absorbed/ different complimentary color seen

why you can see colors from compoounds

d-d splitting occurs

electron is excited/promoted to higher energy level

wavelengths of visible light absorbed and complimentary color seen

method for heterogenous catalyst

Adsorption of reactant molecules

weakening of bonds in the reactant molecules

desorption of products

enthalpy of hydration differences

talk about high charge of ions

talk about ionic/atomic radius (both link to charge density but no mark for charge density anymore)

whichever one has the higher charge density will have stronger attractive forces to the water molecules

definition of entropy

the number of arrangements of particles and of the energy of the system

change in thermal stability of Group 2 hydroxides and carbonates

both increase down the group

radius of cation increases (M2+) as there are more shells

so OH- polarised less and thus stronger

drawing the cells (what to remember)

Voltmeter, salt bridge

the one with the higher E goes on the right

higher E = easier to reduce

if no metal in the half cell use Pt

all ions go in the solution

why buffer solution resists changed in pH

when base is added acid in buffer solution react with it forming the conjugate base (mention equations)

vice versa when more acid is added (mention equations)

ligand

species that uses its donates/shares its lone pair to form dative covalent bonds (1 or more) with the central metal ion

how to make 250cm³ solution in paper 5 (replace water with correct solvent)

add small amount of distilled water to dissolve the solid in the beaker completely then transfer solution to volumetric flask

rinse beaker (with the correct solvent) and transfer washings into 250cm³ volumetric flask (repeat 2-3 times)

fill up to the calibration (250cm³) line with distilled water and invert the flask multiple times to mix

transferring less than 25cm³ and more than 25cm³

use pipette for less than and burette for more than

use beaker to contain solution not measuring cylinder

order of reaction

the power to which a reactant is raised to in the rate equation

electron affinity

when 1 mol of electrons are added to 1 mol of gaseous atoms to form 1 mol of gaseous 1- anions in standard conditions and their standard states

transition metal

element that forms 1 or more stable ions with incomplete/partially filled d-orbitals

why transition metals are able to form complex ions

they have vacant 3d orbitals and thus are able to form dative bonds with ligands by accepting their lone pair

why transition metals have variable oxidation states

the d and s subshells have similar energy

general trend in first electron affinity of halides

more endothermic down the group

due to shielding from inner subshells

causing less attraction between the nucleus and the incoming electron

buffer solution

solution which resits changed in pH when small amounts of acid or base are added to it

optically active

can roate plane polarised light in opposite directions

E cell

the potential difference between 2 half cells in an electrode compared to the standard hydrogen electrode at 298K, 1atm, 1moldm^-3

electrode potential

the potential difference when a half cell is connected to the standard hydrogen electrode at 298K, 1atm and 1moldm^-3

why salt bridge is needed

to complete circuit and to maintain charge balance

how alpha and pi bonds form + hybridisation of benzene

all atoms in ring are sp2 hybridised

alpha formed from end on end orbital overlap

pi formed from side on side orbital overlap

Kpc

the ratio of the concentration of a solute between 2 immiscible solvents at equilibrium

why magnitude of lattice enthalpy decreases (reverse for increases)

size of cation increases (down group)

while charge remains the same so charge density decreases

so weaker attractive forces between the ions

increase in temp on gibbs free

as temp increases Tchangein S becomes bigger

makes reaction more feasible as change in G is negative (use math for this part this is only if both are positive

why some complex ions are colourless

no 3d electrons (mention oxidation state)

so can not absorb light/wavelengths of light IN VISIBLE SPECTRUM

coordination number

the number of dative bonds being formed by the central metal ion

Kstab

the equilibrium constant for the formation of a complex ion in a solvent from its constituent ions or molecules

gas liquid chromatography solvents

mobile = N2

stationary = non - volatile liquid

retention factor

time substance stays in the collumn/mobile phase