Ethanoic Acid Titration

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Concentration of Ethanoic Acid in Vinegar

Date: 09/08/2012

Aim:

To determine the concentration of ethanoic acid in commercial vinegar using titrations.

Materials:

1x 25.0mL pipette

1x 250mL volumetric flask

1x 250mL waste beaker

1x 50.0 mL burette

1x Burette clamp

1x Pipette pump

1x Funnel

1x Retort stand

1x Small glass pipette

1x White tile

4x 100mL conical flasks

Commercial vinegar

Demineralised water

Paper towels

Phenolphthalein indicator

Standard sodium hydroxide solution  (0.1M)

Water

Method:

A burette, a 25.0 mL pipette, four conical flasks, a plastic funnel, a 250mL beaker and a 250mL volumetric flask were rinsed with water. They were visually inspected for any solids. It was then rinsed twice with demineralised water.

The burette, retort stand, burette clamp and a white tile were set up for the titration.  

The 250mL beaker was rinsed with a small amount of standard sodium hydroxide solution twice, and was then used to collect about 200mL of the solution in the beaker.

The outside of a pipette was dried, and was later rinsed twice with the commercial vinegar.

The commercial vinegar was diluted by pipetting 25.0mL of the vinegar into a 250mL volumetric flask. The mark was later met with demineralised water by using a small glass pipette for accuracy. The 250mL volumetric flask was then mixed thoroughly by shaking it with inversion and swirling.

The 25.0mL pipette was rinsed thoroughly with demineralised water. It was then rinsed with the diluted vinegar solution.

25.0mL of the diluted vinegar solution was pipetted into each 100mL conical flask with 4 drops of phenolphthalein indicator.

The burette and plastic funnel were rinsed with the sodium hydroxide solution.

The burette was filled with the standard sodium hydroxide solution using the plastic funnel. The meniscus was adjusted to zero and the funnel was removed from the burette.

25.0mL of the diluted vinegar with the standard sodium hydroxide solution was titrated until the indicator first changed its colour to light pink. The colour lasted for approximately 5-10 seconds after the swirling. And the final result was noted.

Steps 9-10 were repeated until all the conical flasks have been titrated. This provided 3 concordant results.

Cleaned up, and then calculated the precise concentration of the ethanoic acid in the commercial vinegar by using stoichiometry.

Results:

Table 1: OBSERVATIONS- Titration  readings

        

Calculations of the concentration of ethanoic acid

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NaOH + CH3COOH  CH3COONa + H2O      

             

 mol

           

 = 0.0020 mol

Mole ratios

 mol

                          n(CH3COOH)= 0.0020 mol

Convert n(CH3COOH) to c(CH3COOH)

             

   

 

   

Convert diluted c(CH3COOH) to undiluted c(CH3COOH)

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