Unit 5 Assessment 2-Benzoic Acid Synthesis

 Unit 5 Assessment 2-Benzoic Acid Activity Essay

п»їUnit 5 Assessment 2-Benzoic Acid Activity

Activity and Exploration of Benzoic Acid

The aims:

Produce benzoic acidity using benzaldehyde and hydrogen peroxide. Then simply remove a few impurities in the benzoic chemical p crystals.



Pipette (25 cm3)

Burette (50 cm3)

Retort stand


Conical flask (250 cm3)

Volumetric flask (250 cm3) and stopper

White-colored tile

Beakers (250 cm3)

Dropping pipette

Filter direct

Deionised normal water

Phenolphthalein indicator

Volumetric flask

Burning point experiment apparatus

Melting level apparatus



Bunsen burner


Filtering paper

Buchner channel

Conical flask


Benzaldehyde + hydrogen peroxide

Warmth mat


Conical flask



Litmus paper

TLC Research apparatus


UV light fixture




Observe glass


To get started on the test we added hydrogen peroxide (H2O2) to benzaldehyde (C7H6O) in a 1: 1 rate to form benzoic acid (C7H6OOH). We would this by heating the perfect solution is on a heat mantle and stirring using a thermometer, when the solution travelled clear and cool we all added focused hydrochloric chemical p to that until the blue litmus paper went red. When the benzoic acid is definitely solidifies, all of us filtered this off using a Buchner funnel and let it stay to dry inside the oven overnight. The day after benzoic acid deposits are placed in a container, after this we took the melting level of 3 samples of the crude benzoic acid crystals. We then took the melting level of the uric acid by using a burning point equipment, we after that found the typical temperature to get the elementary crystals. If the crystals dried we roughly took 1 ) 00g with the product and water to the crystals. All of us then warmed the mixture using a warmth mat, after it had cooled and removed we strained the solution once again using a Buchner funnel, and then we remaining it in the oven right away again to be dried the uric acid again. The subsequent day we-took the purified crystals to check for the melting level using a shedding point equipment, we took several results to you should find an average shedding point, we then wanted to check for the purity from the crystals therefore we out a small amount a side to get a titration. Firstly we started out with a well-balanced equation intended for the reaction, accompanied by placing the purified crystals right into a volumetric flask and then dissolving them in sodium hydroxide (NaOH) we placed a couple of drops of indicator in to the sodium hydroxide and loaded a flacon with benzoic acid, we all started the titration and recorded the results from the experiment to exercise the uric acid purity. We all then repeated the experiment two more times to find the mean typical titre. Benefits:

Crude Benzoic Acid

Crystals Mass

Empty Vial

21. 655g

Vial with Crystals

23. 053g

Crystal's weighs

1 ) 398g

Melting Point

1st Melting Stage

119 occitan

Second Shedding Point

119 oC

Third Melting Level

119 occitan

Average Shedding Point

119 oC

Deliver Percentage = (Actual Yield/Theoretical Yield) times 100

Yield Percentage = (0. 76g/3. 053g) x 90

Yield Percentage = twenty four. 89%

Genuine Benzoic Acid solution

Crystals Mass

Clear Vial

twenty one. 535g

Vial with Uric acid

22. 353g

Crystal's weighs about

0. 818g

Melting Stage

First Shedding Point

121 oC

Second Melting Point

120 oC

Third Melting Point

121 oC

Normal Melting Level

121 occitan

Recovery = (Mass of Purified benzoic/Mass of Primitive Benzoic) x 100 Restoration = (0. 818/1) x 100

Recovery = 81. 8%

When you compare the average burning point of crude benzoic acid and pure benzoic acid, it can be clear the fact that pure benzoic has a higher melting level. This increase in the melting point intended for the benzoic acid is most likely the result of the successful recrystallization, this process removed some impurities from the crude benzoic acidity, therefore increase the acids burning point (impurities decrease the melting point). Even so the pure benzoic acid still contained a lot of impurities since the burning points was not 123oC (benzoic acid real...

Bibliography: John Clark. (2007). THIN COATING CHROMATOGRAPHY. Available: http://www.chemguide.co.uk/analysis/chromatography/thinlayer.html. Previous accessed first Mar 2014.