1. TITRATION OF A LACTIC ACID IN A SAMPLE OF MILK
CH3-CHOH-COOH

2. SCOPE :
The scope of this laboratory experiment is to determine the amount of lactic acid presents in a sample in order to determine the degree of acidity.

3. MATERIALS : NaOH solution with a known titre (0.4 N) Becker
Burette with sensibility 0.1ml and 50 ml capacity with its support
250 ml of fresh milk
phenolphthalein

4. METHODOLOGY:
We rinse the burette with titrant (NaOH), we take a known quantity of milk and we add the indicator (phenophthalein).
Then we begin to titrate our test substance by adding a more or less large amount of titrant (it depends on the color variation of the indicator.
We proceed with this methodology until the color variation is constant for more than 30 seconds and very evident.
We write down the volume of titrant used to reach our equivalent point. We’ll need it for theoretical calculations.

5. TABLE AND CALCULATIONS :
mole of lactic acid = 4,3*10^-3 [liters]*0,1001[mole/liters]=4,3*10^-4 [mole]
gr of lactic acid = 4,3*10^-4[mole] * 90,08 [gr/mole] = 3,88*10^-2[gr]

6. CONCLUSIONS:
Our sample of milk contains 1,55 gr/l of lactic acid and the S.H. degree > 6 indicates that it’s a good preservation milk.

7. IV A I.I.S CHEMICAL SPECIALIZATION
TEAM :
ALBRA INVA
CARUSO ANDREA
BENTIVOGLIO TECLA
MANGANI ILARIA
CINCI RACHELE