5.1.2 how far Flashcards
preparing an equilibrium mixture
working out equilibrium constant for esterification reaction
ethanol + ethanoic acid > ethyl ethanoate + h2o
use burettes to prepare a mixture in boiling tube of carboxylic acid, acid and dilute H2SO4
swirl and bung tube. leave to reach equil for 1 week
Part 2 Titrating the equilibrium mixture
1 Rinse a 250 cm3 volumetric flask with distilled water.
Use a funnel to transfer the contents of the boiling tube into the flask. Rinse the boiling tube with water and add
the washings to the volumetric flask.
2 Use distilled water to make up the solution in the volumetric flask to exactly 250 cm3
. Stopper the flask, then invert and shake the contents thoroughly.
3 Use the pipette to transfer 25.0 cm3 of the diluted equilibrium mixture to a 250 cm3 conical flask.
4 Add 3 or 4 drops of phenolphthalein indicator to the conical flask.
5 Set up the burette with sodium hydroxide solution..
6 Add the sodium hydroxide solution from the burette until the mixture in the conical flask just turns pink. Record
this burette reading in your table.
7 Repeat the titration until you obtain a minimum of two concordant titres.
partial pressures and kp
work out moles
mole fraction (moles/total moles of all)
multiply by pressure
kp = p(prod) / p(react)
effect of temperature on equilibrium and Kc
increasing, shifts to endothermic direction e.g. to left, decreasing Kc as there are fewer products
effect of concentration on equilibrium and Kc
increasing conc on left shifts equil to right, lowering conc of reactants and increasing conc of products
new concentrations would restore equilibrium to same value of Kc
effect of catalysts on equilibrium and Kc and Kp
no effect on value of Kc or Kp or position of equil as they speed up both forward and backward rates by same amount
effect of pressure on equilibrium and Kc
increasing shifts to side with fewer moles
position of equilibrium moves
kc value stays the same
Effect of pressure on position of equilibrium and Kp
changes position of equil but Kp stays constant as only varies with temperature
