AQA A2 Chemistry

My revision cards for A2 chemistry - will be updated as I go through the topics!

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Acids and Bases 1

Acid - Proton Donor (H+) - Ex. NH4+, H30+

Base - Proton Acceptor - Ex. CO3-, NO3-

Both an acid and a base - CH3COOH, HClO4 (No Charge)

Ionisation is the removal of electrons from the outer shells forming a positive ion.When an acid molecule dissloves aqueous solution it undergoes an ionisation. We call this dissociation.

HCl(s) + (aq) -----------> H+(aq) + Cl-(aq)

HCl <-------> H+ + Cl- (HCl is the congugate acid, Cl- the congugate base.)

HCl(g) + H20(l) -----------> H30+ (aq) + Cl- (aq)

^Oxonium Ion H30+

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Acids and Bases 2

Strength is a measure of dissociation. A strong acid is highly dissociated. Concentration of an acid is the amount of mols per unit.

Strong acids Ka >1 Ka = dissociation constant

Weak acids Ka <1 Kw = Ionic product of water (Use Kw to get H+)

Calculate pH

1) 0.5M HCl - HCl <-------> H+ + Cl (ASSUME FULL DISSOCIATION)

so [Cl-] = 0.5 moldm-3, pH = -log10 [H+], pH = -log10 [0.5] = 0.3

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Naming Organic Compounds

A root tells us the longest unbranched hydrocarbon chain or ring (e.g 1=meth, 2=eth, 3=prop). The syllable after the root tells us whether there are any double bonds. ane means no double bond (ethane) .ene means there is a double bond (ethene). -yne means there is a triple bond (propyne).

Prefixes and suffixes describe the changes that have been made to the root. Prefixes are added at the beginning of the root (e.g chloroethane) Side chains are shown as a prefix, these are often called alkyl groups. Suffixes are added at the end of the root (e.g ethanol)

Reactive groups of atoms attached to a hydrocarbon chain are called functional groups. They are named by using a suffix or prefix. Some functional groups have a prefix and a suffix. E.g alcohol has the suffix -ol and the prefix hydroxy. The suffix is only used if it is the only functional group.

Compounds are named alphabetically, so bromo is written before iodo. In chemical names, numbers are separated by commas and a hyphen is placed between words and numbers

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Isomers are compounds with the same molecular formula but a different arrangement of atoms in space.

Stereoisomerism is where two or more compounds have the same structural formula. They differ in the arrangement of bonds in space.

- E-Z Isomerism

- Optical isomerism

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