Most singular ions, Na⁺...

Only NH₄⁺ applicable

Most molecular/compound ions, NO₃^-...

Cl^-, Br^-,I^-, O^2-

Soluble Anions

NO₃^-, Cl^-, Br^-, I^-, SO₄^-2

Insoluble with

Ag⁺ Pb⁺² ...

Insoluble Anions

OH^- S^-2 CO₃^-2 PO₄^-3

Soluble with

Na⁺ K⁺ NH₄⁺(except OH^-) Ba⁺(only OH^-)

1 ppm = 1 mg/dm³

= 1 x 10^-3 g of substance

1 dm³ of solution

    actual    

theoretical

x 100%

1. XXX reactants not pure

2. Loss of XXX products during transfer

3. XXX side reaction occurs

4. XXX reaction does not reach completion.

           Molecular Mass of Desired Product         

Sum of Molecular Mass of all reactants/products

x 100

1. Enthalpy of Products < Enthalp of Reactants

2. -ve Enthalpy Change

3. High Temperature

4. Heat lost to surroundings

5. Bonds formed

[image]

1. Enthalpy of Products > Reactants

2. +ve Enthalpy Change

3. Lower Temperature

4. Gain from surroundings

5. Bonds broken

[image]

Keywords

1 mole of compound

From its elements

Standard states at 298K and 1 atm

1 mole of substance

Burns completely in oxygen

at 298K and 1 atm

1 mole of water is formed

From neutralisation of 1 acid by 1 alkali

at 298K and 1 atm

1 mole of separate gaseous atoms

From element in its standard state

at 298K and 1 atm

Break 1 mole of covalent bond

in gaseous molecules

Experimental method to find Enthalpy Change

Calorimeter

- M x C x ΔT

- Only use mass of solution and solution's C as substance/powder etc. have negligible C and M

1. Heat lost to calorimeter.

2. Assumption density and specific heat capacitry of solution same as water.

1. Reduces heat lost.

2. Inert/ Does not react with most chemicals.

3. Does not absorb much heat.

4. If use beaker, ΔH will decrease.

Black solid - Carbon, formed due to incomplete combustion

Experimental of Combustion < Theoretical

1. Heat lost to surroundings

2. Some heat goes to beaker instead

3. Incomplete combustion due to inadequate O₂

4.Condition of products not standard (water vapour, endothermic reaction)

Resolutions

1. Use shields

2. Use copper tin

3. No shields

To ensure all XXX have completely reacted

OR

To ensure all XXX have neutralised completely (if neutralisation)

If using enthalpies of formation,

1. Arrows go up

2.  Elements as middle part

If using enthalpies of combustion,

1. Arrows go down

2. Combustion products as middle part

Why XXX reaction cannot be determined directly but calculated through Hess's Law?

(Alkene to alkane)

C_nH_2n + H₂ -> C_nH_2n+2

1. Reaction cannot be conducted in lab due to H₂ being flammable

2. Ethane etc. may undergo combustion

3. Reaction rate is too slow.

Bonds broken +ve

1. Compare strength of bonds

2. Understand struscture and bonding

3. Calculate ΔH_f and ΔH_reaction
using Hess's Law

1. Constant stirring of water to ensure even temperature

2. Use screen/coppertin/polystyrene board/lid etc to prevent heat loss

3. Use more accurate apparatus (thermometers that read up to 0.1, use pipetter not measuring cylinder...)

4. Take temperature every 30s...

        Uncertainty of Error     

Value of measurement

x 100

Reliability : repeat experiment and get average value

Accuracy :

1. Use precise instruments

2. Use larger volume/mass...

Isotopes

1.Same Chemical properties

2.Different Physical properties

1. same amount of electrons/electronic configuration

2. Masses are different

1. Vaporisation (gaseous atoms to move through instrument)

2. Ionisation (bombarded by high energy electrons and 1 electron is knocked out of atom)

3. Acceleration (Electric field)

4. Deflection (Magnetic field according to m/z ratio)

5. Detection (shows how many ions of each m/z ratio in sample)

1. Archeology - Radiocarbon dating using C-14

2. Geographical - Detect oil composition

...

Atomic Radii

1.Decrease across Period

2.Increase down Group

1. More protons but electrons in same energy level/shells, force of attraction increase

2. More protons but electron in higher energy levels, outermost electrons more shielded, force of attraction decreases

Remove 1 mole of electrons

From 1 mole of gaseous atoms

to form 1 mole of gaseous positive ions

1. Distance from nucleus (atomic radii)

2. Nuclear charge (number of protons)

3. Shielding effect (by inner shell electrons)

Trends in first ionisation energy

1. Increase across period

2. Decrease down the group

1. Atomic radius smaller, Nuclear charge increases, Negligible shielding as all in same shell, FOA ↑

2. Atomic radius increase but cancelled off by increase in number of protons, but shielding effect increase, FOA decrease

1 mole of electrons

Added to 1 mole of atoms

In gaseous state

First EA

1. Increase across period

1. To form an attraction between incoming electrons and nucleus

2. Repulsion between incoming electron and negative ion

1. Neatly arranged

2. Very high melting & boiling pt. - large amount of energy to overcome strong electrostatic attractions and separate ions

3. Hard but brittle - Any dislocation=layers moving=repulsion occurs=splits crystal

4. Good electrical conductivity in molten or aqueous state only - solid=ions held strongly by lattice, liquid/molten=mobile ions & conduction takes place

5. Very high density - higher than water but lower than typical metals

6 Na⁺ ion around each Cl^- ion

OR

Cubic structure with alternate Na⁺ and
Cl^- ions

Size of cation

1. < size of atom

Size of Anion

1. > Size of Atom

2. Increases down the group

1. Same number of electron shell but p/e ratio decreases, Effective nuclear charge decreases, expansion of electron cloud

2. Number of protons increases, but electrons in higher/outer shell, more shielding, FOA decreases

Ions with same number of electrons

H^- Li⁺ Be²⁺ B³⁺   - 2 electrons in each ion

1 mole of ionic compound

formed from gaseous ions under standard conditions

1. larger ionic charge = larger lattice energy

2. smaller sum of ionic radii=larger lattice energy

Cations - larger charge= higher polarising power

 - smaller redius = higher polarising power

Anions - larger radius= higher polarisability

-higher charge, smaller radius

-more polarising

-able to distort electron cloud to a greater extent

Covalent Bonding

1. Ionic radius

2. Ionic charge

3. Valence electrons (number of delocalised electrons)

Physical properties of Giant Metallic Lattices

1. V.high melting and boiling pt.

2. Good malleability and ductility

3. Good electrical conductivity in both solid and molten states

4. V.high density

1. Strong electrostatic attractions between cations and delocalised electrons

2. Ions and delocalised electrons move around each other, will not break as cations still surrounded by electrons

3. Delocalised electrons free to move and can conduct electricity when a potential difference is applied

4. Higher than water and ionic compound

1. Structural - same molecular formula but different structure

2. Geometrical -restricted rotation of Carbon-Carbond double bond(C=C)

- Both C atoms of C=C must have 2 different groups/atoms

Cis/trans isomers

- must have at least 1 same group of atoms each side

Cis - same group of atoms at same side of C=C

Trans - Groups at different sides

Limits - When all different groups, don't work

Use mass instead (group with higher mass is used)

E- Different

Z - Same

1. C_nH_2n+2

2. Only single bonds

3. 4 H bonds to every C atom

4. Saturated Hydrocarbon

1. Higher = not so pure, lower boiling/melting point

2. Middle area purest

3. Lowest= bitumen, Highest=Gas,

Gas<Petrol<Chemicals<Aircraft fuel<Central Heating fuel<Lube<Power Station/Ship fuel<Candles and grease<Road

Use of high temperature or catalyst to break large hydrocarbon to smaller molecules of alkane/alkene

C-C bonds broken

(Can also occur when no oxygen present)

E.g of catalyst zeolite Al₂O₃

1. Small chain of alkane allow for use as fuel

2. Small chain of alkene for use in polymer production

1. Combustion of alkanes

2. Free radical substitution (E.g with Cl₂) (must have UV)

1. Homolytic

2. Heterolytic

1. C_nH_2n

2. C=C

3. Unsaturated hydrocarbon

4. More reactive than alkane

5. Can form cis-trans (E/Z) isomers

1. Overlap of 2 s-orbitals

2. Overlap of 2 p-orbitals (one end to another end)

3. Overlap of one s-orbital and p-orbital

1. Combustion

2. Electrophilic addition

3. Oxidation

4. Polymerisation

Markovnikov's rule

(My understanding of it)

Add few drops of Bromine water, Br₂ to alkene.

It will be decolourised from brown to colourless.

[image]

1. Polyethene - food wrap

2. Polypropene - yogurt tubs

3. Polybutene - Rubber piping

4. Polychloroethen (PVC) - Cable insulation

      -Make flexible using plasticizer to allow chains to slide

5. Polytetrafluoroethene (Teflon) - Non-stick coating on frying pan

6. Polyphenylethen (Polystyrene) - Foam packaging, polystyrene cup

1. Use non-renewable resources (from crude oil)

2. High-energy production costs

3. Non-biodegradable - landfill problem

4. Does not burn easily (requires extremely high heat)

1. Reducing

2. Recycling

3. Burn waste (Produces energy)

4. Feedstock (Convert waste to hydrocarbon)

5. Biodegradable polymers (made from natural polymers - starch, cellulose)