Mixed Exam Style Questions Flashcards
When adding dilute NH3 to halogens which ones are left as residue
AgBr and AgI
How do you work out rate when given time (80s) and half life is first order
Ln 2 / 80s
What is the standard enthalpy change of atomisation of bromine?
1/2 Br (l) —> Br (g)
Explain Delta H and delta S
Delta H decreases when exothermic reaction from gas to solid.
Delta H decreases when endothermic reaction from solid to gas
Entropy increases when gas (as less order)
Entropy decreases when solid (as more order)
What does non polar mean
Symmetrical in shape
Explain how temperature increases rate
As temperature increases, more particles have more kinetic energy above activation energy so more successful collisions
Explain the term enthalpy change of formation
Enthalpy required to form one mole of a compound from its elements under standard conditions
Explain the term entropy
Entropy is the measure of discordance in a system
What is the formula for free energy change (delta G)
Delta G = Delta H - T delta S
Explain why the first ionisation energies of Helium and beryllium are higher than first ionisation energy of lithium
Helium - outer electrons are in a closer shell to the nucleus , so greater nuclear attraction
Beryllium - outer electrons are in the same shell and there is greater nuclear charge
Explain why the first ionisation energy of Be is higher than the first ionisation energy of B
Be has an electron in the 2s sub shell and has a lower energy level compared to Boron
What happens to rate of hydrolysis
Bond length increases so rate of hydrolysis is faster
C-F > C-I
RBr is hydrolysed faster because the C-CL bond enthalpy is greater
What is meant by the term structural isomer
Same molecular formula but different structural formula
What is meant by the term stereoisomers
Stereoisomer is the same structural formula but atoms are arranged in different space
How could you test for the presence of carbonyl
Add 2-4 DNP and if orange or yellow precipitate formed then carbonyl is present.
Measure the melting point and compare with data sheet to see what carbonyl
Describe a chemical test that would identify an aldehyde?
Add tollens reagent and if aldehyde is present then silver mirror precipitate will form.
What reagents are used for NO2 to go to NH2?
Sn/Hcl
How to confirm the presence of the phenol group
Indicator and observe acidity
No reaction with carbonate
13 C NMR compound J,K, L
J - 6 environments
K - 5 environments
L - 8 environments
Why is there a large difference in boiling point between NH3 and NH4NO3
NH3 is simple molecular
NH4NO3 is ionic, ionic bonds are stronger than intermolecular bonds so more energy required to break the bonds.
determine enthalpy of hydration when everything is negative
Hydration = lattice enthalpy + solution - (hydration) §
