lab 2 complete.docx - Determination of Acetic Acid...

Determination of Acetic Acid Concentration in Vinegar
Using Titration
Pre-laboratory Question
1. Write the balanced equation for the neutralization of acetic acid by sodium hydroxide.
CH
3
COOH (aq) + NaOH (aq)  CH
3
COONa (aq) + H
2
O (l)
2. The Food and Drug Administration (FDA) mandates that all vinegar sold in the United
States must have a minimum concentration of 4% acetic acid by mass. Calculate the
minimum molarity of acetic acid in vinegar according to this standard. Assume the
density of vinegar is the same as for water.
M = mass / (molar mass x Volume)
40 g /60.04-g/mol x 1 L
M = 0.666 mol/L
3. Calculate the mass of NaOH required to make 0.40 L of a 0.50 M solution 0.40 L NaOH
x 0.50 mole = 0.200 moles
4. Read through the laboratory procedures and then diagram the procedures using
illustrations and/or a flow chart to describe the steps. Ensure that your diagrams are
labeled with quantities and descriptions.
1
©2014, Carolina Biological Supply
Company

Place the 10mL graduated
cylinder on the electronic
balance.
Place the 10mL graduated
cylinder on the electronic
balance.
1
1
Tare the balance.
Tare the balance.
2
2
Dispense ~5 mL of vinegar
into the graduated cylinder
with a plastic pipet
Dispense ~5 mL of vinegar
into the graduated cylinder
with a plastic pipet
3
3
Record the exact mass of the
vinegar in Data Table 1
Record the exact mass of the
vinegar in Data Table 1
4
4
Transfer the vinegar into the
clean 25 mL Erlenmeyer flask
Transfer the vinegar into the
clean 25 mL Erlenmeyer flask
5
5
Add two drops of
phenolphthalein to the
vinegar
Add two drops of
phenolphthalein to the
vinegar
6
6
Transfer approximately 10 mL
of 1 M Sodium Hydroxide
(NaOH) to the small cup. This
solution wil be used to fill the
syringe.
Transfer approximately 10 mL
of 1 M Sodium Hydroxide
(NaOH) to the small cup. This
solution wil be used to fill the
syringe.
7
7
Fill the syringe with 1 M
NaOH solution. Try to
minimize the amount of air in
the syringe.
Fill the syringe with 1 M
NaOH solution. Try to
minimize the amount of air in
the syringe.