PAPER 5 chemistry emergency!

[Youme&I]

Paper 53 November 2010 .
Question 2(c)

http://www.xtremepapers.me/CIE/Internat ... _qp_53.pdf

I drew the graph already.. however I dont know how to suggest an error in the conduct of the experiment which causes the anomalous result?

Can anybody tell me what to suggest? ASAP

 

[workinghard]

i dont wanna go through da ppr but i ve solved it
can u tell me in short wat it is bout???????????/ question lmean!
ll help u den!!!!

 

[Youme&I]

i dont wanna go through da ppr but i ve solved it
can u tell me in short wat it is bout???????????/ question lmean!
ll help u den!!!!

Here you go :

2) When a solute is added to two solvents, A and B, which do not mix, some of the solute
dissolves in each of the solvents and an equilibrium is set up between the two solvents.
At equilibrium the ratio of the two concentrations is a constant known as the Partition
Coefficient, K.
concentration in solvent A
concentration in solvent B = K
An experiment was carried out to determine K for succinic acid, HO2
CCH2
CH2
CO2
H,
between water (boiling point 100 °C) and diethyl ether, (C2
H5
(
2
O, (boiling point 35 °C).
• 100 cm3
of distilled water and 100 cm3
of diethyl ether were transferred to a conical
flask.
• A sample of succinic acid was added, the flask was stoppered and the mixture thoroughly
shaken until all of the solid had dissolved.
• A 10.0 cm3
sample of the water layer was removed and titrated with 0.10 mol dm–3
aqueous sodium hydroxide using phenolphthalein as an indicator.
• A 25.0 cm3
sample of the diethyl ether layer was removed and a small amount of water
added. This was then titrated with 0.020 mol dm–3
aqueous sodium hydroxide using
phenolphthalein as an indicator.
• The experiment was repeated using the same volumes of water and diethyl ether but
decreasing masses of succinic acid.

Q. Circle on the graph any point(s) you consider to be anomalous. For any point circled on the graph suggest an error in the conduct of the experiment that
might have led to this anomalous result.

Fyi I understand the part circling jus the anamalous result. ~

 

[musa]

if the abnomalities are below the line then the reason may be suggestedas that the concentration in the layer of succenic acid is low might be because the titration was stopped before it reached the end point
similiarly if abnomility is above the line it mean the sucsenic acid is greater it means the sample was over titrated mean acsess base was added even after reaching end point

 

[diwash]

here if u have plotted concn of succinic acid in the aqueous layer in X axis and concn of succinic acid in ether layer in Y axis then
the gradient of the graph is the (concentration of succinic acid in ether layer)/ (concentration of succinic acid in aqueous layer)
...
if the point lies up the line
the ratio ( gradient) is slightly higher than expected...
so u can write the ratio of concn succinic acid in ether layer to concn of succinic acid inaqueous layer is slightly higher than expected.
.....
if the point lies down the line
the ratio ( gradient) is slightly lower than expected...
so u can write the ratio of concn succinic acid in ether layer to concn of succinic acid inaqueous layer is slightly lower than expected.
....
any valid reason regarding the position of the points is acceptable

 

[zahraahmed]

http://notezone.net/cambridgechem/chemi ... sis%5D.pdf can sum1 go in dix page 11 n do solve n gimme answers plzzzz i cant able to slove it n it might cum for exam help mee!!!!