Chemistry past paper questions i got wrong

C

Define the term stereoisomersim

A molecule with the same structural formula but a different arrangement of atoms in space

The nitrogen lone pair accepts a proton

What is the name

State limitations of using Free radical substitution in organic synthesis

Substitutions can occur anywhere on the carbon chain(e.g. position 1 or 2)

Multiple substitutions could occur(e.g. di or tri if haloalkane is in excess)

Multiple termination steps so more than 1 organic product can form

Name electron donating groups (position,4,6)

OH,CH3,NH2

Name electron-withdrawing groups (position 3,5)

NO2,halogens,carbonyls(aldehydes,ketones,carboxylic acids)

Define a sigma bond

Direct overlap of orbitals between the bonding atoms

Define a pie bond

Sideways overlap of P orbitals between bonding atoms

What is a complex ion

A central metal ion surrounded by ligands

What are ligands

They are molecules/ions that can form dative covalent bonds with the transition metal ion by donating lone pairs of electrons

What are the assumptions when calculating the pH of weak acids

1) [HA]initial =[HA] eqm ( As the extent of the dissociation is small)

2) [H+] eqm = [A-] eqm ( because the acid dissociates in a 1:1 ratio)

How can optical isomerism occur in transition metals

3 bidentate ligands show optical isomerism.

2 bidentate ligands and 2 of the same monodentate ligands: trans (180 ) don’t, but cis (90) show optical isomerism

Chemical teting for halides

. Add nitric acid to remove carbonate ions

Add aqueous silver nitrate

add ammonia

Testing for sulphates

Add HNO3 to remove any carbonate ions

Add barium chloride/barium nitrate

White pp forms

Test for carbonates

Add HNO3

White ppt

Oxidising power of halogens and some reactions and colours

decreases as you go down group 7. Those higher up group 7 displace those below

Reducing power in halides and what is a reducing agent

increases as you go up the group. Reducing agents is a species which donates electrons and itslf is oxidised

Reaction of chlorine

Benefits and risk of chlorine used in water treatments

Acid-hydrogen Fuel cells

Alkaline-hydrogen fuel cells

What is the equivilance point

volume at which moles of acid = moles of base

What is the end point

the point during the titration when the indicator changes colour

Strong acid stong base ph curve

Strong acid-weak base ph curve

Weak acid strong base ph curve

Weak acid-weak base ph curve

Transition metals

Explain the use of 2 deuterated compounds in NMR spectroscopy

. CDCl3 is used as a solvent

. D2O is used to identify OH or NH protons

Explain why an electric heater is preferred over a bunsen burner (for this hydrolysis)

The ester (organic product) is flammable

Describe the purpose of reflux in this hydrolysis process

Allows volatile reactants to condense and return to the flask and react

Balance equation between sodium benzoate and HCl

Discuss why sodium benzoate dissolves in cold water while benzoic acid doesn’t

Recrysillisation (6)