Past Paper Improvements Flashcards
Explain why the lattice enthalpy of sodium oxide is more exothermic than that of potassium oxide
The ionic radius of a sodium ion is smaller than that of a potassium ion, therefore there is a greater attraction between the ions
Explain how Haemoglobin transports oxygen around the body
VERY IMPORTANT
Oxygen coordinately / datively bonds with the Fe²⁺ ion. When required, Oxygen is replaced by water or carbon dioxide in a ligand substitution reaction.
What colour is CrO₄²⁻ ?
Yellow
Why may someone use a much smaller concentration than usual when doing a titration?
By decreasing the concentration, you must increase the titre so that the same amount of substane is put into the solution. This leads to a smaller percentage error/uncertainty in your titration
What is the most important thing when writing a Kp expression?
DO NOT USE SQUARE BRACKETS:
You must write it with p(A) instead for partial pressures.
Is the equivalence point always neutral?
NO
For strong acid-weak base or weak acid-strong base titrations the equivalence point is not neutral
When have you reached the equivalence point?
When [HA] = [OH⁻]
Not when concentration of hydrogen = concentration of base!!!!!
What is the most important thing in organic synthesis questions?
Consider the reactions of ALL functional groups. For example, in the alkaline hydrolysis of an ester which contains a bromo group somewhere in its structure, not only will the ester be broken down in the alkaline hydrolysis reaction but the bromo group will also react in a nucleophilic substitution reaction.
VERY IMPORTANT
A polymer is formed from 200 molecules of 4-hydroxybenzoic acid, What is the Mr of the polyester?
24,018
What should you always remember when working with fragments in mass spectra?
THEY ARE POSITIVE IONS
Describe in terms of orbital overlaps, the similarities and differences between the kekule model and the delocalised model of benzene
- Similarities: They both have the sideways overlap of P orbitals creating a pi bond system above and below the plane of the ring
- Differences: Kekule has alternating pi bonds between carbon atoms, with each pi bond localised between two carbon atoms. Whereas the delocalised model has a pi ring system where 6 electrons are delocalised into a pi bond
Name this molecule
3-methylbut-2-enal
These 2 substances are reacted with bradys reagent, how can you distinguish between the 2 compounds formed?
Test the melting points and compare to known values
Why does reactivity increase down group 2?
Atomic radius increases and there is more electron shielding. Therefore the nuclear attraction decreases on the valence electrons and so ionisation energy decreases and less energy is required to remove electrons
MUST MENTION ENERGY
What happens when Cu²⁺(aq) and KI(aq) react?
You form CuI(s) and I₂(aq)
