Test for Carboxylic Acids
Summary
TLDRThis educational video explores carboxylic acids, organic compounds found in citrus fruits and vinegar, and demonstrates various tests to identify them. It categorizes acids into aliphatic and aromatic, showcasing examples like formic, acetic, benzoic, citric, and tartaric acids. The video conducts tests including the litmus test, sodium bicarbonate reaction, ester formation, and a fluorescein test specific to dicarboxylic acids. It also acknowledges the support of Patreon backers in facilitating these experiments.
Takeaways
- 🔬 Carboxylic acids are organic compounds with the COOH functional group.
- 🍇 Carboxylic acids occur naturally in citrus fruits like grapes and green apples.
- 🧪 Vinegar is a dilute solution of acetic acid, which is a type of carboxylic acid.
- 📦 The video presents samples of carboxylic acids, including formic acid and acetic acid.
- 🌿 Aromatic carboxylic acids like benzoic acid are also discussed, with a link to a synthesis video in the description.
- 🍊 Citric acid is highlighted as commonly found in grocery stores, and tartaric acid is noted in tamarind fruit.
- 🧪 The litmus test is demonstrated to show the acidic property of carboxylic acids, turning blue litmus paper red.
- ⚗️ The sodium bicarbonate test produces a carboxylate salt and carbon dioxide, observed as effervescence.
- 🍸 The ester test involves a reaction between carboxylic acid and alcohol to produce esters with a fruity smell.
- 🌈 The fluorescein test is a special confirmatory test for dicarboxylic acids, resulting in a red color and green fluorescence under UV light.
- 🙏 The video creator thanks their Patreon supporters for helping to fund the materials needed for these experiments.
Q & A
What are carboxylic acids?
-Carboxylic acids are organic compounds characterized by the presence of the -COOH functional group. They occur naturally in citrus fruits and are exemplified by acetic acid found in vinegar.
How are carboxylic acids classified?
-Carboxylic acids are classified into aliphatic and aromatic acids based on their structure.
What is the difference between aliphatic and aromatic carboxylic acids?
-Aliphatic carboxylic acids are those with an open chain structure, like formic and acetic acids. Aromatic carboxylic acids have a benzene ring in their structure, such as benzoic acid.
What is the purpose of the litmus test in the context of carboxylic acids?
-The litmus test is used to demonstrate the acidic property of carboxylic acids. When carboxylic acid is dropped onto blue litmus paper, it turns red.
How does the sodium bicarbonate test work with carboxylic acids?
-In the sodium bicarbonate test, carboxylic acids react with sodium bicarbonate to produce a carboxylate salt and release carbon dioxide, which is observed as effervescence.
What is the ester test and how is it performed?
-The ester test involves reacting a carboxylic acid with an alcohol in the presence of concentrated sulfuric acid and heat to produce an ester, which has a fruity smell. This is done by mixing the acid with alcohol, adding sulfuric acid, and then heating the mixture.
What is the purpose of the fluorescein test for carboxylic acids?
-The fluorescein test is a confirmatory test for dicarboxylic acids. It involves the reaction of the dicarboxylic acid with resorcinol and concentrated sulfuric acid to form fluorescein, which shows green fluorescence under ultraviolet light.
Why is the fluorescein test specific to dicarboxylic acids?
-The fluorescein test is specific to dicarboxylic acids because it relies on the reaction of two carboxylic acid groups with resorcinol to form the fluorescent compound fluorescein.
What precautions are taken during the ester test?
-During the ester test, the mixture is not directly sniffed to avoid inhaling the volatile compounds. Instead, the air above the beaker is gently wafted towards the nose to detect the fruity smell.
How is the alkalinity of the solution checked after the fluorescein test?
-The alkalinity of the solution after the fluorescein test is checked using red litmus paper, which turns blue in an alkaline solution.
What is the final observation when testing for fluorescein under normal white light?
-Under normal white light, the presence of fluorescein shows a green fluorescence in the reflected light, and the transmitted light appears deep red.
Outlines
🧪 Chemistry of Carboxylic Acids
The script introduces carboxylic acids, organic compounds with the COOH functional group, found in nature like citrus fruits and vinegar. It explains the division into aliphatic and aromatic acids and presents examples such as formic, acetic, benzoic, citric, and tartaric acids. The video demonstrates various tests for carboxylic acids, including the litmus test, which turns blue litmus paper red, indicating acidity; the sodium bicarbonate test, where the acid reacts to produce a carboxylate salt and releases carbon dioxide; and the ester test, where the acid reacts with alcohol to form esters with a fruity smell. A special test for dicarboxylic acids, the fluorescein test, is also mentioned.
🔬 Testing Carboxylic Acids: The Fluorescein Test
The script details the fluorescein test for dicarboxylic acids, using phthalic acid as an example. It describes the process of dehydrating phthalic acid with sulfuric acid to form phthalic anhydride, which then reacts with resorcinol to produce fluorescein. The test involves adding sodium hydroxide to make the solution alkaline, which is confirmed by the change of red litmus paper to blue. The presence of fluorescein is indicated by green fluorescence under normal light and deep red transmitted light. The script concludes with a demonstration of fluorescein's bright green fluorescence under ultraviolet light, confirming the presence of dicarboxylic acids.
Mindmap
Keywords
💡Carboxylic Acids
💡Functional Group
💡Aliphatic Acids
💡Aromatic Acids
💡Acetic Acid
💡Litmus Test
💡Sodium Bicarbonate Test
💡Ester Test
💡Fluorescein Test
💡Resorcinol
💡Phthalic Acid
Highlights
Carboxylic acids are organic compounds with the COOH functional group.
Carboxylic acids occur naturally in citrus fruits like grapes and green apples.
Vinegar is a dilute solution of acetic acid, which is a type of carboxylic acid.
Carboxylic acids can be subdivided into aliphatic and aromatic acids.
Formic acid and acetic acid are examples of aliphatic carboxylic acids.
Benzoic acid is the simplest aromatic carboxylic acid.
Citric acid is commonly found in grocery stores.
Tartaric acid is found in fruits like tamarind.
Heparic acid is excreted through urine with increased consumption of phenolic products.
The litmus test is used to demonstrate the acidic property of carboxylic acids.
Sodium bicarbonate test produces carboxylate salt and carbon dioxide from carboxylic acids.
Ester test involves the reaction of carboxylic acid with alcohol to produce esters.
Fluorescein test is specific for dicarboxylic acids.
Phthalic acid is used in the fluorescein test to confirm the presence of dicarboxylic acids.
Resorcinol is used in the fluorescein test along with concentrated sulfuric acid.
Fluorescein is formed by the reaction of phthalic anhydride with resorcinol.
The fluorescein test solution turns alkaline, indicated by blue litmus paper.
Fluorescein exhibits green fluorescence under normal white light and deep red transmitted light.
Under ultraviolet light, fluorescein shows bright green fluorescence.
The video acknowledges Patreon supporters for their financial contributions to the experiments.
Transcripts
[Music]
the following video is for academic
purposes only
it demonstrates the various tests for
carboxylic
acids
carboxylic acids are organic compounds
with the cooh
functional group they occur naturally in
citrus fruits
like grapes and green apple vinegar is a
dilute solution of acetic acid which is
also a carboxylic acid
here we have few samples of carboxylic
acids
they can be subdivided into aliphatic
and aromatic acids
here i have formic acid in this beaker
and in the glass bottle i have acetic
acid
now for some aromatic carboxylic acids
the simplest one is the benzoic acid
and i have a synthesis video of benzoic
acid you can check the
description for the link and this is
citric acid
citric acid is commonly available in
grocery stores
this is tartaric acid tartaric acid is
seen plenty in the fruit
tamarind and this is heparic acid which
is normally excreted through urine when
you have an increased consumption of
phenolic products like
fruit juices and wine these are the
various tests for the carboxylic acid
the litmus test sodium bicarbonate test
ester test and fluorescein test which is
specific for dicarboxylic acids that are
compounds with 2coh functional group
let's start with the litmus test
when carboxylic acid is dropped on a
blue litmus paper
it turns red it indicates that the
compound have acidic property
sodium hydrogen carbonate or sodium
bicarbonate test
we have taken three milliliters of
saturated solution of sodium hydrogen
carbonate in the test tube
into that we add few milliliters of the
carboxylic acid
carboxylic acid behave like any other
acid
producing the specific carboxylate salt
and carbon dioxide is released which is
observed as the
brisk effervescence
the next test is the ester test
for that we take a clean and dry test
tube
and into that we add one milliliter of
the carboxylic acid
then i add equal volume that is one ml
of ethyl alcohol then we mix the
compounds by shaking
now add three to four drops of
concentrated
sulphuric acid into the test tube and
mix the test tube well
now we place the test tube in hot water
bath
for few minutes what's happening here is
carboxylic acid reacts with alcohol
in acidic medium to produce fruity
smelling compounds called esters
the contents of the test tube is then
poured into 30 milliliters of cold
distilled water the fruity smell of a
stir could be identified by gently
wafting the air from the beaker to the
nose
do not directly put your nose in the
beaker
now for the special test there is the
fluorescent test which is a confirmatory
test for dicarboxylic acids like talic
acid and succinic acid
for this test i am using phthalic acid
we need hundred milligram of phthalic
acid
200 milligram of resource in all three
dots of concentrated sulphuric acid
and hundred milliliter of five molar
sodium hydroxide
we start by taking a clean and dry test
tube and then we add hundred milligrams
of phthalic
acid
next we add 200 milligrams of resource
in all
the amount of resulcinol should be
roughly double the amount of phthalic
acid sociometrically
after that we shake the contents to mix
them evenly
now we add three drops of concentrated
sulphuric acid over it
do not add too much of acid
now we gently heat the chest tube over
the bunsen burner flame
the compound melts and attains a deep
red color
what's happening here is stalic acid
gets dehydrated by the presence of
sulfuric acid to form phthalic
anhydride which then reacts with
resource synol to form fluorescein
now pour the contents to 5 molar sodium
hydroxide solution
i tried to pour my contents but it
immediately got solidified
so instead i added sodium hydroxide into
the test tube
either way we want the resultant
solution to be alkaline
we can test whether our resultant
solution is alkaline or not by using a
red litmus paper
and in this case it is alkaline as it
turned blue now this solution has a high
concentration of fluorescein in it
now to test the presence of fluorescein
on passing the normal white light
the reflected light shows a green
fluorescence and the transmitted light
is deep red in color
in the presence of ultraviolet right add
some fluorescein into distilled water
and observe the bright
green fluorescence by this we conclude
the test for carboxylic acids
i would like to take this opportunity to
thank my patreon supporters who have
financially supported me
so that i could get the materials
required for doing all these experiments
thank you so much for watching this
video if you loved the contents of this
video
do subscribe to the channel and hit on
the bell button so that you will get the
notifications of my new videos
also join my discord server i will put a
link to that in the description
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