Balanced equation: (COOH) 2 +2NaOH →(COONa) 2 + 2H2 O
The quantities and concentrations of any reagents used:
The volume of sodium hydroxide: x (between 7-9cm3)
The volume of the ethandioic acid: 250cm3
The concentration of the sodium hydroxide which before the dilution: 1.00mol/dm3
The concentration of the ethandioic acid: 2g/dm3
The volume of the water, which needs to mix with the sodium hydroxide: unknow
Preparation:
Planning a dilution:
Ethandioic was approx 2g/dm3 , sodium hydroxide was 1.0mol/dm3
Because of the equation:
(COOH) 2 +2NaOH →(COONa) 2 + 2H2 O
The sodium hydroxide needs to be diluted to give a titration, which has matched solution, i.e. in which 25cm3 pipette will react with approx 25cm3 from the burette
Ethandioic: 2g/dm3 is of concentration 2/126=0.01587mol/ dm3
I.e. approx 0.016 mol/ dm3
To match this solution the ethandioic needs to be approx 0.032-mol/ dm3
The volumetric flask used for dilution has volume 250 cm3, let the volume required be v
Because we know that:
V1×C1=V2×C2
Where C1=the concentration of the concentrated solution
V1=the volume of the concentrated solution
C2=the concentration of the dilute solution
V2=the volume of the dilute solution
So, v×c=v×c
V×1=250×0.032
V=8.00 cm3
The volume used for dilution is 7.00 cm3 to 9.00 cm3
Method:
1.Set up the apparatus, use a clamp to fix the burettes, one is on the left and one is on the right.
2. Put the funnel on the burette 1, and then pour the sodium hydroxide into the burette 1, and read the number carefully with the white tile behind, pour it very carefully until it will nearly reach 0.00 cm3.if it is over the line, open the valve to regulate the solution until it exactly reaches the line of 0.00 cm3 and then remove the funnel before you read the number.
3.Burette the solution and pour it into a 250 cm3-graduated flask.
4. Pour the water into the graduated flask until the solution level is point on the
250cm3 line and shake it as much as possible (30 times).
5. Pour this solution into the burette 2, as the same as in step 2.
6. Pipette 25cm3 of ethandioic acid into a conical flask. (Use the filler safely) .You must be very careful with the solution when you use a pipette. Look if there is some gas in the pipette, because it will affect the result and make it smaller.
7. Add 5 drops of phenolphthalein in the conical flask, now the colour of the solution is colourless.
8. Titrate with the diluted sodium hydroxide from the second burette. You must pour the solution very carefully, because you don’t know when the solution will change colour. Firstly put the white tile under the conical flask to see the colour more clearly and then titrate it very slowly. Shake the conical flask very often and see if the solutions change the colour after some drops. When the colour has changed to pink, you’ve got the result. Record it.
Repeat the titration as many times in order to get two results which agree to within
0.1 cm3.because it will make the results more accurate.
Titration of ethandioic acid with diluted sodium hydroxide.
Show that results you used to obtain this value of the volume of diluted sodium hydroxide by placing a tick under the readings used.
References:
The Internet.
and textbook