Background Knowledge Flashcards
Draw the graphs if rate against concentration for 0 order, 1st order and 2nd order
See notes page 47 rev book
0 = straight line across
1st = straight line through origin
2nd = curve upwards
Draw the graphs of 0 order, 1st order and 2nd order for concentration against time
See notes page 48 rev book
0 = straight line going down
1st = downwards curve
2nd = deeper downwards curve
What is an acidic buffer made up of and what is an alkaline buffer made up of
Weak acid and its salt
Weak base and its salt
What is the definition of a buffer
A solution which resists changes in pH upon addition of small amounts of acid or alkali
What is the equation for pH (both normal and Henderson-Hasselbalch)
See unit 1 notes
What is the equation and value of kw
(H+)(OH-)
1x10^-14
What is the equation of pkw
-log(kw)
What is the equation for Ka and pka
(H+)^2 ➡️ or (H+)(A-)
————
(HA)
-log(Ka)
Draw the titration curves for a strong acid and strong base, weak acid strong base, strong acid weak base and a weak acid weak base
See pg 54 rev book
What colour is the precipitate when an aldehyde or ketone is added to 2,4-dinitrophenylhydrazine
Yellow/orange
Why is excess aldehyde/ketone added to 2,4-dinitrophenlyhydrazine rather than the other way round
The solid 2,4-dinitrophenylhydrazone is soluble in propanone and other aldehydes and ketones
What are the requirements of a solvent
Impurities have to be either insoluble in the solvent or very soluble - so they either do not dissolve or stay dissolved even when the filtrate is cooled
Draw the diagram for suction filtration
See pg 58 rev book
What is the colour change for Fehling’s solution test
Write the half equation
Blue to red precipitate
Cu^2+ ➕ e- ➡️ Cu^+
What is the colour change for Tollens’ reagent
Write the half equation
Colourless to silver mirror
Ag^+ ➕ e- ➡️ Ag
Why is sulfuric acid used in an esterification reaction
Catalyst
Removes water - shifts equilibrium to the right - more Ester formed
Why are acyl chlorides better for esterification than carboxylic acids
No catalyst needed
Irreversible
Reaction goes to completion
What is a nitrating mixture made from
Concentrated sulfuric acid and concentrated nitric acid
Why is the base line in chromatography drawn in pencil
Not soluble in the solvents used
Why are iodine crystals used as a locating agent for TLC
The iodine vapour can adhere to the spots and mark them
What are the standard conditions for the standard electrode
25°C (298K)
100kPa (1atm)
1 mol dm^-3 concentration if ions for the solution
Why is a high resistance voltmeter used when determining electrode potentials
Measure voltage but not allow any current to flow
How do you make a salt bridge
Filter paper soaked in a concentrated solution of potassium chloride or potassium nitrate
Write the equation for the formation of aspirin
See notes page 82 rev book
Why is suction filtration preferred to gravity filtration
Faster and gives a drier product
Why is phosphoric acid used in the production of aspirin
Acts as a catalyst
Why is water added afterwards in the formation of aspirin
To hydrolyse any remaining ethanoic anhydride
How do you test the purity after producing aspirin and what is observed if there are/aren’t impurities
Add a solution if iron(III) chloride
A purple colour will be observed
If no impurities then it will remain yellow/orange
