xxxxx

UNIVERSITI TEKNOLOGI MARA(UITM),
SHAH ALAM CAMPUS,
40450 SHAH ALAM,

SELANGOR DARUL EHSAN.

AS250 : BACHELOR OF SCIENCE (HONOURS)
TEXTILE SCIENCE AND FASHION TECHNOLOGY

CHM 412: ORGANIC CHEMISTRY

EXPERIMENT 5B
REACTIONS OF CARBON COMPOUNDS

Prepared by :

Name : NURNASUHA BINTI JUNAIDI

Student ID : 2019495438

Group : AS2503B

Name : NUR AIN IZZATI BINTI IMRAN

Student ID : 2019461554

Prepared for:
DR MOHD FIRDAUS KASIM

EXPERIMENT 5(B)

REACTIONS OF CARBOXYL COMPOUNDS

Objective

To study the reactions of carboxylic acids (ethanoic acid and benzoic acid).

Theory

Organic acids are weaker than minerals acid such as hydrochloric acid (HCl) and sulphuric
acid (H2SO4). The organic acid has functional group of –COOH and general formula of
RCOOH, where can be an alkyl or aryl even H.

Solubility of the organic acid in water or polar solvent depending on the size of the R group
and number of -COOH group, the bigger the R group less soluble the acid in water, but
increasing the number of -COOH group will increase the solubility in water. –COOH group is
important because it also involve in the formation of hydrogen bonding for carboxylic acids.

In this experiment the two carboxylic acids use are ethanoic acid and benzoic acid. Ethanoic
acid is liquid, while benzoic acid is solid at room temperature. Aliphatic carboxylic acids can
be obtained from oxidation of primary alcohols. Aromatic carboxylic acid such as benzoic acid
can be obtained from oxidation of benzaldehyde or methylbenzene at certain conditions.

Chemicals

I. Ethanoic acid,
II. benzoic acid,
III. dilute NaOH(aq),
IV. dilute HCl(aq),
V. conc. NaHCO3,
VI. conc. H2SO4,
VII. ethanol,
VIII. NaHCO3 solution,
IX. iron (III) chloride solution,
X. dilute NH4OH(aq).

Apparatus

I. 5-10 test tubes
II. One 250 ml beaker
III. Two 100 ml beakers
IV. Blue and red litmus papers
V. Hot plate
VI. Waterbath

Procedure

1) SOLUBILITY

1. 0.5 g or half of small spatula of benzoic acid will dissolved with 2 ml of water in a test
tube.

2. The solution will tested with blue litmus paper. Explain your observations.
3. The test were repeated using ethanoic acid.

KEEP THESE TEST TUBES TO COMPARE IN EXPERIMENT 2

2) ACID-BASE REACTION

1. 2 ml of dilute NaOH(aq) to 0.5 g or half of small spatula of benzoic acid was added
in a test tube and its solubility observed as compare to its solubility in water AS IN
EXPERIMENT .Dilute HCl (aq) slowly added until the solution is acidic to
BLUE litmus paper.

2. Observed the reaction.

3) ESTERIFICATION

1. Using a hot plate, a mixture of 2 ml of ethanol, 2 ml of ethanoic acid and 5 drops of
concentrated H2SO4 (as a catalyst) were boiled in a small beaker for one minute, and
added in 2ml of dilute NaHCO3(aq).

Figure 1. A mixture of 2 ml of ethanol, 2 ml of ethanoic acid and 5 drops of concentrated H2SO4 (as a
catalyst) were boiled in a small beaker

2. The reaction mixture poured into 20 ml of cold water in another small beaker.
3. The test repeated using 2 g or 2 of small spatula benzoic acid.

QUALITATIVE TEST FOR ETHANOATE AND BENZOATE SALTS

1. To 3 ml dilute NaOH(aq), ethanoic acid was until the solution is acidic to blue litmus
paper. A few drops of iron (III) chloride solution were dropped.

2. 0.5 g or half of small spatula of benzoic acid were dissolved in 2 ml of hot water.
Dilute NH4OH(aq) were added until the solution is basic to red litmus paper.
The excess NH4OH(aq) solution on a water bath by moving in and out the test tube
AND FACING AWAY FROM YOU AND YOUR FRIENDS. WHEN NO MORE
AMMONIA SMELL RELEASE, a few drops of iron (III) chloride solution was added.

5) REACTION WITH BICARBONATE
1. 1ml of ethanoic acid was added to 3 ml concentrated NaHCO3 in a test tube slowly.

2. Observed if there is any fizziness/effervescence/bubbles.
3. The test repeated with using benzoic acid.

Result a) Benzoic acid
A. Solubility
Observations

Figure 2. 0.5 ml enzoic acid with 2ml of water.

When 0.5ml benzoic acid dissolved with 2ml of water,
the solution becoming white preticipate with some
bubbles.

Figure 3. reaction after several minutes

After several minutes, white preticipate forms at the
bottom of test tube. It is slightly soluble in water.

Figure 4. Changes in litmus paper

Litmus paper blue turn to red
b) Ethanoic acid

Figure 5. Ethanoic acid with water.
Ethanoic acid with water dissolved well.

Discussion Figure 6. Reaction after several minutes

After several minutes, the bubbles form on top of test
tube .ethanoic acid soluble in water.

a) Benzoic acid
C6H5COOH + H20 = C6H5COO-H + H20
b) Ethanoic acid
CH3COOH + H2O ⇌ CH3COO- + H3O+
a) Benzoic acid
Benzoic acid has low solubility in room-temperature
water because the bulk of the molecule is non-polar. At
higher temperatures, solubility increases.

In acidic solution, the solubility will be partially but if
acid dissolved in alkaline solution ,it will more soluble.
Benzoic also have low solubility in room temperature
and dissolved well in hot temperature.

c) Ethanoic acid.
Ethanoic acid is a typical weak acid. It reacts with water
to produce hydroxonium ions and ethanoate ions. The
reaction of carbonate with an acid will creates strongly
bubbling reaction .

B) ACID BASE REACTION a) Benzoic acid
Observation

Figure 7. 2ml NaOH with benzoic acid

The 2ml NaOH and benzoic acid in test shows that
benzoic acid did not soluble in Naoh

Figure 8. Addition of dilute HCL in beaker

The addition of dilute HCL giving small bubbles in test
tube

Figure 9. Result on litmus paper

It turn red litmus paper to blue.
b) Ethanoic acid

Figure 10. 2ml NaOH with ethanoic acid

2ml NaOH with ethanoic acid make the solution are
soluble.Hot solution are formed

Figure 11. Solution clear

The solution remains clear

Figure 12. Result on litmus paper

It turn the red litmus paper to blue.
To compare with experiment 1, we can see from
solubility, benzoic acid with water, it gives slightly
soluble. However, in acid base reaction, it giving
insoluble when benzoic acid react with Naoh.
While solubility test for ethanoic acid, it giving soluble
when ethanoic acid react with water. It also soluble
with NaOH.

conclusion a) Benzoic acid
C6H5COOH(s)+ NaOH(aq)→C6H5COONa(aq) + H2O(l)

C6H5COONa(aq)+ HCl(aq)→NaCl(aq)+ C6H5COOH

b) Ethanoic acid
CH3COOH(aq) +NaOH-(aq) CH3COONa (aq) +OH-

CH3COONa(aq) + HCl(aq) → NaCl(aq) +
CH3COOH(aq)

a) Benzoic acid
since benzoic acid is acidic and NaOH is a strong alkali
containing an active metal (sodium), it displaces one
H-atom from benzoic acid to produce sodium benzoate
and water. Formation of benzoate ions increase its
solubility. After the addition of HCl, benzoic acid is
formed again but it is insoluble. The increase in
concentration of H+ions will shift the position of
equilibrium of dissociation of benzoic acid to the left,
causing benzoic acid hardly soluble in acidic medium

b) Ethanoic acid
NaOH can react with ethanoic acid to form sodium
ethanoate ions which is soluble in sodium hydroxide
solution. After the addition of HCl, ethanoic acid was
formed again, thus causing red litmus paper turns to
blue

3) ESTERIFICATION a) Benzoic acid
Observations

Figure 13. Reaction white precipitate

White precipitate forms and produces fruity smell. The
solution insoluble

b) Ethanoic acid

Figure 14. The addition of 20ml cold water.

After added the mixture into 20ml of cold water, it is soluble
and produces fruity smell

Equations a) Benzoic acid

b) Ethanoic acid

Conclusions/explanat a) Benzoic acid

ion The solution is insoluble because of the properties benzoic

acid. When benzoic acid insoluble, white participate form.

However, fruity smell present because of reaction between

carboxylic acid and alcohol still occur.

b) Ethanoic acid
Reaction of ethanoic acid with ethanol will form ester which
is ethyl ethanoate. Ethyl ethanoate is the causes of fruity
smell are present.

4) QUALITATIVE TEST FOR ETHANOATE AND BENZOATE SALTS

Observations a) Ethanoic acid

Figure 15. Result on litmus paper

The solution is acidic, and turn litmus paper to red.

Figure 16. The addition of iron III chloride

Adding iron III chloride, solution turn to slightly orange

b) Benzoic acid

Figure 17. Result on litmus paper

The addition of NaOH until solution turn red litmus paper
to blue. The benzoic not fully dissolved maybe due to the
water that did not hot.

Figure 18. Result after addition of iron III chloride

After addition iron III chloride, it turns to creamy
precipitate.

Equations a) Benzoic acid
C6H5COOH + H20  C6H6COO + H30

C6H5COOH + NH4OH  C6H5COONH4 + H20

3C6H5COON4 + FECI3  Fe(C6H5COO)3 +3NH4CI

b) Ethanoic acid
CH3COOH + H20  CH3COO + H30

CH3COOH + NH4OH  CH3COONH4 + H20

CH3COOH + FECI3  FE(CH3COO)3 + HCI
Conclusions/explanation a) Ethanoic acid

blue litmus turn to red indicate the solution is acidic. When
iron III chloride added into the solution, the colour turn
slightly orange. It because iron III chloride is an indicator
in this experiment. It used to test carboxylic acids liberate
carbon dioxide gas form aqueous solution of carbonated
and hydrogen carbonates.

c) Benzoic acid
Red litmus paper turn to blue indicate that solution is acid.
Benzoic acid is weak acid, when NH4OH was added, the
solution will become acid. However, benzoic acid partially
dissolved which causing the solution become precipitate.
As the creamy colour happen because of iron III chloride

5) REACTION WITH BICARBONATE

Observations a) Benzoic acid

Figure 19. 1 ml ethanoic acid with NaHCO3

It formed white small bubbles on the top of solution.
It do not produce any sound. It also continuously
react.

b) Ethanoic acid

Figure 20. 1ml of benzoic acid with NaHCO3

It showed the present of continuously small bubbles

when NacHo3 was added into test tube. It giving

hissing sound during reaction.

Equations a) Benzoic acid
2 C6H5 COOH + Na2CO3  2 C6H5COONa +

CO2 +H2O

b) Ethanoic acid
NaHCO3 + CH3COOH CH3COONa + H2O +

CO2

Conclusions/explanation a) Benzoic acid

It will give acid-base reaction. The two moles

of benzoic acid reacts with sodium carbonate

to give two moles of sodium benzoate as the

product along with carbon dioxide (which

causes brisk effervescence) and water as the

byproducts. The caron dioxide will giving

bubble effect on the test tubes.

b) Ethanoic acid
They react because concentrated NaHCO3 is
a base and ethanoic acid is an acid dissolved
in water. When an acid and a base is mixing
in a solvent, which in this case is the water,
usually the acid transfers hydrogen to the base
to form a new compound. In this case, the new
compound is called carbonic acid, which then
decomposes to water and carbon dioxide gas.
Formation of carbon dioxide will give bubble in
solution. It also produced brisk effervescence

Questions

1. Which is more acidic, ethanoic acid or benzoic acid? Explain your answer briefly
Benzoic acid is more stronger than ethanoic acid because the strength of an
acid is determined by it ease to lose a proton/H+ ion. If an acid can easy to
removed a proton, than it said to stronger. In benzoic acid, if it lose proton, the
left behind will be benzoate anion. This anion established well by resonance. In
ethanoic, if it lose proton, the ethanoate anion formed is not too much stable.
Ethanoic has lesser tendancy to lose proton compared benzoic acid.

References

1. https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemist
ry__The_Central_Science_(Brown_et_al.)/04._Reactions_in_Aqueous_Solution/
4.3%3A_Acid-Base_Reactions

2. https://chem.libretexts.org/Courses/Sonoma_State_University/SSU_Chem_335
B/Material_for_Exam_1/Chapter_22%3A_Carboxylic_Acids_and_Their_Derivati
ves%E2%80%94_Nucleophilic_Acyl_Substitution/22.10_Reactions_of_Carboxy
lic_Acids

3. http://www.docbrown.info/page04/OilProducts10b.htM