Random Markscheme Shit

Question 1

Compare and contrast acid and alkaline ester hydrolysis

Answer 1

-both lead to the formation of an alcohol
-acid hydrolysis is reversible, alkali hydrolysis is irreversible
-acid hydrolysis produces the carboxylic acid and alkali produces the carboxylate ion (that needs to be protonated to form the acid)
-acid acts as a catalyst and alkali acts as a reactant

Question 2

Why does phenol requires milder reaction conditions than benzene for electrophilic substitution

Answer 2

-the lone pair on the oxygen atom is donated into the pi cloud of delocalised electrons as it overlaps with it
-this increases the electron density of the benzene ring making it more susceptible to electrophilic attack

Question 3

How do u determine a suitable indicator from a titration curve

Answer 3

-the indicator needs to change colour in the vertical section of the curve
-choose and indicator with a pH range that lies within the vertical region of the titration curve

Question 4

Explain how the region on a titration curve before the vertical region acts as a buffer

Answer 4

-contains a large reservoir of acid and its conjugate base (name the ions present)
-the base (name it) will react with added acid (write the equation)
-the acid (name it) will react with added base (write equation)

Question 5

PH of the salt formed from a weak acid and strong base

Answer 5

Around 9

Question 6

PH of salt formed from a weak acid and weak base

Answer 6

Around 7

Question 7

PH of salt formed from strong acid and strong base

Answer 7

Around 7

Question 8

PH of salt formed from a strong acid and weak base

Answer 8

Around 5

Question 9

How can you use data of the concentration of a reactant at given times to determine that a reaction is neither zero nor first order

Answer 9

-not zero order if the rate is not constant
-not first order if the half life is not constant (time taken from concentration to half isn’t equal)

Question 10

Describe how to draw distillation apparatus

Answer 10

-heat source, round bottomed flask with reaction mixture, anti-bumping granules sealed at the top with a thermometer going in thats within the still head (make super clear that the thermometer is stuck within some sealed glass tubing)
-diagonally downwards condenser with water jacket drawn around it and water going in at the bottom and out of the top
-collection vessel that isn’t sealed with a little tap for pressure release before the liquid hits the flask (goes around the bend)

Question 11

Explain why during recrystallisation you leave the filtrate to cool and then carry out filtration under a reduced pressure

Answer 11

-leave to cool because the product is less soluable in cooler solvent than hot solvent so will crystallise out and soluable impurities will remain dissolved in solution
-filter under reduced pressure to remove more soluable impurities faster