equilibrium in practicals Flashcards
A common experiment is working out the equilibrium constant is …,,.
esterification reaction. Ethanol and
ethanoic acid are mixed together with a sulphuric acid catalyst
Method
Part 1
steps
Preparing the equilibrium mixture
1 Use burettes to prepare a mixture in boiling tube of carboxylic acid, alcohol, and dilute sulfuric acid.
2 Swirl and bung tube. Leave the mixture to reach equilibrium for one week
Method
Part 1 step 1
1 Use burettes to prepare a mixture in boiling tube of carboxylic acid, alcohol, and dilute sulfuric acid.
method
part 1
step 2
2 Swirl and bung tube. Leave the mixture to reach equilibrium for one 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.
step 1 part 2
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.
step 7 part 2
7 Repeat the titration until you obtain a minimum of two concordant titres.
step 6 part 2
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.
step 5 part 2
5 Set up the burette with sodium hydroxide solution..
step 4 part 2
4 Add 3 or 4 drops of phenolphthalein indicator to the conical flask.
step 2 part 2
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
.
step 3 part 2
3 Use the pipette to transfer 25.0 cm3 of the diluted equilibrium mixture to a 250 cm3 conical flask.
Haber process conditions
T= 450oC, P= 200 – 1000 atm, catalyst = iron
haber process and methanol from CO2
Low temp gives good yield but slow rate:
compromise temp used
High pressure gives good yield and high rate: too
high a pressure would lead to too high energy costs
for pumps to produce the pressure
co to methanol
T= 400oC, P= 50 atm, catalyst = chromium and zinc
oxides
contact process
T= 450oC, P= 1 or 2 atm, catalyst = V2O5
Low temp gives good yield but slow rate: compromise moderate temp used
High pressure only gives slightly better yield and high rate: too high a pressure would lead to too high energy costs for pumps to produce the pressure
hydration of ethene
Low temp gives good yield but slow rate: compromise temp used
High pressure gives good yield and high rate: too high a pressure would lead to too high energy costs for pumps to produce the pressure
High pressure also leads to unwanted polymerisation of ethene to poly(ethene)
condition of hydration of ethene
T= 300oC, P= 70 atm, catalyst = conc H3PO4
catalyst in the reaction
In all cases catalysts speeds up the rate, allowing a lower temp to be used (and hence lower energy costs), but have no effect on position of equilibrium
high pressure equipment
In all cases high pressure leads to too high energy costs for pumps to produce the pressure and too high
equipment costs to have equipment that can withstand high pressures.
