General chem

effect of concentration on equilibrium

if we increase reactants equilibrium will favour the forwards reaction to use up any extra reactants. if we increase products equilibrium will favour the reverse reaction to use up extra products. opposite applies for a decrease in concentration.

effect of concentration on rates of reaction

concentration is the number of particles within a given volume. increasing concentration means more particles which means more frequent successful collisions and reaction rate will increase.

effect of temperature on rate of reaction

temperature is a measurement of the kinetic energy of particles. when temperature increases particles gain more kinetic energy and move faster resulting in more frequent collisions and more particles have enough energy to overcome the activation energy barrier meaning more frequent successful collisions

effect of temperature on equilibrium

increase in temperature will favour the endothermic reaction (positive delta H heat absorbed) in order to use up the heat energy. a decrease in temperature will favour the exothermic reaction (negative delta H energy released) to produce more heat energy.

effect of catalyst on equilibrium

a catalyst has no effect on equilibrium position, the catalyst will speed up both the forwards and backwards reaction, this means the reaction reaches equilibrium faster but equilibrium position and kc are unchanged.

effect of catalyst on rate of reaction

catalysts increase the rate of reaction by providing an alternative path way with a lower activation energy. this means that more particles will have enough energy to over come the activation energy barrier, resulting in an increased frequency of successful collisions.

effect of surface area on rate of reaction

decreasing particle size will increase surface area. increasing surface area means more particles are exposed and available for collision therefore more frequent successful collisions.

effect of changing pressure/ volume on equilibrium

increase im pressure will favour the reaction that produces the least amount of gas moles. decrease in pressure will favour the reaction that produces the most amount of gas moles. pressure increases if the volume container of a given reaction decreases and vise versa.

Kc and changes to equilibrium

equilibrium constant Kc is unchanged by changes in concentration, pressure, and catalyst. the only factor that will change Kc is temperature.

how does Kc change in temperature (if in endothermic reaction)

when temperature increases equilibrium will favour the forwards reaction to absorb extra heat. this increases the concentration of products and decreases the concentration of reactants so Kc increases. when temperature decreases equilibrium will favour the reverse reaction so the concentration of products decreases and the concentration of reactants increases, so Kc decreases.

how does Kc change in temperature (if in exothermic reaction)

when temperature increases equilibrium will favour the backwards reaction to absorb extra heat. this increases the concentration of products and decreases the concentration of reactants so Kc decreases. when temperature decreases equilibrium will favour the forwards reaction so the concentration of products decreases and the concentration of reactants increases, so Kc increases.

alkene to alcohol

addition reaction using H2O/H+

alkene to alkane

addition reaction using H2/Ni/ or Pt

alkene to polymer

addition reaction using high heat, pressure, or catalyst

alkene to haloalkane

addition reaction using HBr or HCl

alkene to dihaloalkane

addition reaction using Br2 or Cl2

alkene to diol

addition reaction usiing KMno4/H+

alkane to haloalkane

substitution reaction using Br2/ uv light

haloalkane to amine

substitution reaction using NH3 (alc or conc) and heat

haloalkane to alcohol

substitution reaction using KOH( aq) or NaOH (aq)

alcohol to haloalkane

substitution reaction using PCl3/PCl5/SOCl2

haloalkane to alkene

elimination reaction using KOH(alc)

alcohol to alkene

elimination reaction using H2SO4 (conc) and heat

alcohol to carboxylic acid

oxidation reaction using Mno4-/H+

carboxylic acid to amine

neutralisation using KOH or NaOH

what happens to alkenes in orange bromine water

2 layers form as orange bromine water rapidly decolourises

what happens to alkane in orange bromine water

2 layers from an orange bromine water remains orange or brown unless UV light is added, it is a slow reaction

solubility in organic

all hydrocarbons (alkane, alkene, alkynes) are all insoluble in water and form two layers. short chain carbons (1-4) alcohols, amines, and carboxylic acids are soluble in water and form one layer because. like dissolve like polar molecules dissolve in polar substances like water and non polar molecules dissolve in non polar substances like cyclohexane.

solubility in polarity

solubility is when the attraction between solute and solvent is stronger than the attraction within solute and within solvent. for molecules like dissolves like, polar molecules in water and non polar in cyclohexane. ionic substances will dissolve in water because the attraction between the ions and the polar water molecules is strong enough to overcome the ionic bonds and the water molecule bonds.

ions

ions, ionic bonds (electrostatic attraction), strong

metals

metal atoms and delocalised electrons, metallic bonding, strong

molecular

molecules, intermolecular forces, weak

3D covalent network

atoms, covalent bonds, strong

melting point

how much heat energy is required ro trn a solid to liquid. the stronger the bonds of a molecule are the higher the melting point as to be because it requires more heat energy to break the bonds

brittle

ionic solids are brittle. the ionic bonds in ionic solids are directional, when force is applied like charged ions line up and repel causing bonds to break and the ionic solid to shatter.

malleable

metals are malleable (can be hammered into shape) and ductile (can be drawn into a wire) metallic bonding is non directional meaning when force is applied the layers of atoms slide over each other without breaking the metallic bonds

polar bonds

when a non metal bonds to a non metal electrons are shared in a covalent bond. if these electrons are not shared evenly a bond dipole forms where 1 atom is slightly negative and the other is slightly positive.

polar molecules

a polar molecule is one with a permanent dipole. for a molecule to be polar it must have bond dipoles that do not cancel. all trigonal pyrimid and bent molecules are polar

base shape

the base shape of a molecule is determined by the total number of negative electron regions around the central atom. because electron regions are negative they will maximise separation to minimise repulsion the bond angle is determined by the total number of electron regions.

actual shape

actual shape is determined by the bonded or non-bonded regions

tetrahedral

tetrahedral shapes have four negative electron regions and bond angle of 109.5 as well as four bonded regions

bent

bent has two bonding regions and a bond angle of 109.5 as well as two non-bonding regions

linear

liner has two electron regions and no non-bonding regions as well as a bond angle of 180

trigonal planar

trigonal planar has three negative electron regions and three bonded regionds as well as a bond angle of 120

trigonal pyramid

trigonal pyramid has four negative electron regions and only three bonded regions. it has a bond angle of 109.5

VSEPR

valence shell electron pair repulsion theory is the idea that electron regions are negatively charged and will arrange themselves as far apart as possible to minimise repulsion.

metallic bonding

can be described as the attraction between delocalised electrons and the nuclei of neighbouring metal atoms. metallic bonding is strong and non-directional.

covalent bonding

sharing of electrons between non metal atoms.

ionic bonding

metal and non metal ionic bonding is the electrostatic forces.

exothermic

heat energy released products have less energy than reactants, negative enthalpy change

endothermic

heat energy absorbed products have more energy than reactants positive enthalpy change.

ionic solids

metal and non metal atoms arranged in a 3d lattice shape held together by strong electrostatic attractions

markovnikovs rule

when an asymmetric alkene (eg propene) undergoes addition with an asymmetric reagent (eg Hx or H2O) there are two products. the c atom in the carbon to carbon double bond which has the most H atoms attached will gain the H atoms and the C atom with the least H atoms will gain the halogen (this forms the major product.)

saytzeffs rule

elimination of H2O or Hx from an alcohol or haloalkane will give two products. the carbon either side of the carbon in the carbon to carbon single bond with the least H atoms will gain the double bond and form the major product

addition polymerisation

in addition polymerisation carbon to carbon double bond is broken in order for new carbon to carbon single bonds to form between monomers forming long repeating chains called polymers

geometric isomers

have carbon to carbon double bonds that prevent rotation, each carbon in the double bond has a different group attached to it.

structural isomers

structural isomers have the same molecular formula but different structural formula.

Kc

Kc = [products]/[reactants]

strong acids

the strength of an acid is determined by the extent to which is dissociates into ions in solution. strong acids fully dissociate into ions (shown by a single arrow) and form a solution with a high concentration of ions (that will conduct well)

weak acids

weak acids only partially dissociate in solutions (shown by a double arrow) and will form solutions with a low concentration of ions (bad conductors)

amphioprotic substances

able to act as both an acid and act as a base

conjugate acid base pairs

differ by a single proton (H+)

salts

salts are ionic solids, in solution with water they completely dissociate into ions. sometimes one of their ions can accept or donate proton H+. this results in a solution that is weakly acidic or basic

what is pH

pH is a measure of the concentration of H3O+ ions in solution the more H3O+ ions the lower the pH