explanation questions Flashcards
compare the acidities of alcohol, phenol, carboxylic acid and acyl chloride
acyl chloride > carboxylic acid > phenol > alcohol
alcohol:
- e- donating alkyl group
- negative charge on alkoxide ion is intensified
- less stable, less H+ dissociated
phenol:
- negative charge on O delocalises into benzene ring
- negative charge on phenoxide ion dispersed
- more stable, more H+ dispersed
carboxylic acid:
- negative charge on carboxylate ion delocalises over O-C-O bond
- even more stable than phenoxide ion, more H+ disperse
acyl chloride:
- RCOCl + H2O –> RCOOH + HCl
When acyl chloride is added to water, hydrolysis takes place to give HCl as a product.
HCl is a strong acid that fully dissociates, giving the most amount of H+
compare the basicities of amine, amide and phenylamine
amine > phenylamine > amide
dependent on the availability of lp of e-
amine:
- e- donating alkyl group, lp of e- more available for donation
- most basic
phenylamine:
- lone pair of e- on N delocalises into benzene ring, less available for donation
- less basic than amine
amide:
- lone pair of e- delocalises over O-C-N bond, not available for donation
- least basic (neutral)
compare the ease of hydrolysis between halogenoalkane, halogenoarene and acyl chloride
acyl chloride
- carbonyl C atom is highly electron deficient, as it is attached to 2 electronegative atoms, Cl and O
- most susceptible to nucleophilic attack
halogenoalkane
- carbonyl C atom only attached to 1 electronegative atom, Cl
- less e- deficient than the carbonyl C in acyl chloride
- less susceptible to nucleophilic attack
halogenoarene
- lp of e- delocalises into benzene ring
- partial double bond character in C-Cl
- more energy required to overcome strong C-X bond
compare the ease of bond breaking of a C-X bond
C-Cl > C-Br > C-I
- down the group, atomic radius increases
- orbital overlap between C and Cl, C and Br and C and I becomes less effective down the group
- bond strength decreases from C-Cl, C-Br, C-I
- energy required to overcome C-X bond decreases from C-Cl, C-Br, C-I
what is the trend of reducing power of group 2 metals down the group
trend in IE, extent of oxidation, E value, reducing power
TEER
- down the group, no. of proton increases, NC increases
- no. of e- shells increases, shielding effect increases
- valence e- further away from the nucleus, less strongly attracted to the nucleus
- less energy required to remove two valence electrons from atom (1st and 2nd IE decreases)
- extent of oxidation is greater
- E value more -ve down the group
- reducing power of group 2 metals increases
what is the trend of thermal stability of group 2 carbonates/nitrates/hydroxides down the group
ICPWT
- Down the group, ionic radius of group 2 ions increases
- since charge density is proportional to charge/ionic radius, charge density decreases
- polarising power of cation decreases
- weakening of C-O bond to lesser extent
- thermal stability of group 2 carbonates increases down the group
what is the trend in volatility of group 17 elements?
SIA + volatility
- non polar simple covalent molecules with id-id interations
- down the group, no. of electrons increases, strength of id-id interaction increases
- more energy required to overcome increasing strength of id-id interaction
- volatility of halogens decreases down the group/mp and bp increases down the group
what is the trend of the reactivity of group 17 elements as oxidising agents
E values, likeliness of reducation, oxidising power
ELO
- down the group, E values become less +ve
- less likely of X2 to be reduced to X-
- oxidising power of halogens decreases down the group
what is the trend on thermal stability of group 17 hydrides
- down the gropup, atomic radius increases from F to I
- valence orbital larger and more diffuse
- less effective orbital overlap between 1s orbital of H and p orbital of halogen
- H-X bond energy decreases down the group
- thermal stability decreases down the group
