Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Unit 22 – Assignment 1 – P1 & P2

Results
Mass of filter paper: 1
...
99g
Mass of dried crystals of product: 2
...
05
N of CuSO4 = 0
...
05 * 159
...
975g

Percentage yield = (actual / theoretical) x 100
= (2
...
975) x 100
= 31%

Calculating the percentage purity of hydrated copper(II) sulfate:

1
...

3
...

5
...
1 x 12
...
00124
0
...
0062
0
...
2232
(0
...
32%

Percentage yield = (actual yield/theoretical yield) x 100

Theoretical = n = mass/mr = 2/138 = 0
...
0145 x 180 = 2
...
161/2
...
36 x 100 = 236%

Percentage mass = (overall weight / mass of two tablets) x 100
= (0
...
543) x 100
= 11
...
Firstly, the solution is heated in an evaporating basin;
therefore allowing the solvent to evaporate, which leaves a saturated solution
...
The crystals are then collected and dried
...

Filtration - Passing a solid and liquid mixture through filter paper gets rid of the solvent and allows
excess solvent to evaporate
...
The fine, porous material of the filter
paper does not allow the solid, insoluble particles to go through
...


Determining the percentage purity of aspirin:
Titration – To determine the volume that has been consumed when the endpoint (the point at which
the titration is complete) is reached, a calibrated burette must be used to add the titrant
...
It is also when
the solution permanently changes colour; this is due to an indicator
...
This point is identified from the first faint pink colour that persists in
the solution being titrated
...
There is a
slight difference between the change in indicator colour and the actual equivalence point of the
titration
...
It leaves the solid residue behind
...
It isolated the
product
...

Drying – This is carried out to remove water from a compound
...
A desiccator
can also be used to absorb any moisture and keeping the product dry, from the evaporated solvent,
from the surrounding air
...
This is either
done by converting the substance into an insoluble form or by changing the composition of the
solvent to decrease the solubility of the substance in it
...
This causes the purity to decrease
whilst causing the analysis to be inaccurate
...
An effective technique

is that called homogeneous precipitation, in which the precipitating agent is synthesized in the
solution instead of adding mechanically
...
It leaves the solid residue behind
...
It isolated the product
...
Firstly, the solution is heated in an evaporating basin;
therefore allowing the solvent to evaporate, which leaves a saturated solution
...
The crystals are then collected and dried
...

Evaporation - Evaporation is used to separate a soluble solid from a liquid
...
During evaporation, the water evaporates away leaving solid crystals
behind
...
Then the
volume of the solution would be decreased
...
Once the water has been evaporated, the solid crystals
are left behind
...
It leaves the solid residue behind
...
It isolates the product
...
Crystallisation is normally
done from a hot concentrated solution
...
The solid crystals will become bigger, as the solution is too
concentrated for the solute to remain dissolved at the temperature
...
When cooling the hot,
concentrated solution, more crystals form
...

Re-crystallisation – Reactions will often yield impure products which need to be purified by recrystallisation
...
The technique of re-crystallisation dissolving the product in
the minimum amount of a hot solvent, hot filtration to remove any insoluble impurities and then
allowing crystals of the purified product to form
...
Firstly, the hot solvent is added to the compound
...
Then, the solution is
filtered while is it hot through a warmed filter funnel
...
As
the temperature of the solution decreases, the solubility of the compound also decreases
...
the
compound can then be collected by filtration and dried
...
If the glassware was not
washed or dried properly and

---