01 Ethene Gas

Summary

This educational video demonstrates the laboratory preparation of ethylene gas from ethanol. It outlines the necessary equipment, including a test tube with a sidearm and a Bunsen burner, and the use of aluminum oxide as a dehydrating agent. The script details the steps for heating, collecting ethylene, and conducting tests for unsaturation using acidified potassium permanganate and bromine water. It also explains how to identify ethylene gas through its bright blue flame test and the presence of carbon dioxide, verified by the milkiness of lime water.

Takeaways

• 🔬 The experiment involves the preparation of ethylene gas (C2H4) from ethanol.
• 🌡️ The process requires heating ethanol in the presence of aluminum oxide as a catalyst.
• 🧪 A test tube with a sidearm and a Bunsen burner are used for the reaction setup.
• 🔥 The aluminum oxide is heated to initiate the dehydration of ethanol to produce ethylene.
• 💧 Glass jars are used to collect the ethylene gas, and glass wool is used to support the ethanol inside the test tube.
• 🌬️ The initial bubbles produced are displaced air, not ethylene, which is collected once the air is displaced.
• 🧪 Lime water and acidified potassium permanganate are used to test for the presence of ethylene, indicating unsaturation by decolorization.
• 🔥 Ethylene gas burns with a bright blue flame, which is a characteristic test for its presence.
• 🌿 Bromine water is used to test for unsaturation, where ethylene gas decolorizes the bromine water due to the addition reaction across the double bond.
• ⚗️ The byproduct of the reaction is carbon dioxide, which is tested using lime water turning milky.

Q & A

What is the main reaction described in the script?

The main reaction described in the script is the preparation of ethene gas (C2H4) from ethanol (C2H5OH) through a dehydration process.

What is the role of ethanol in this reaction?

Ethanol serves as the starting material, which is dehydrated to form ethene gas and water.

What is the purpose of aluminum oxide in this reaction?

Aluminum oxide acts as a dehydrating catalyst to facilitate the removal of water from ethanol, leading to the formation of ethene.

Why is a tight-fitting Bunsen burner used in the reaction setup?

A tight-fitting Bunsen burner is used to ensure efficient heating of the reaction mixture and to prevent the escape of ethene gas.

What is the significance of glass wool in the reaction setup?

Glass wool is used to support the ethanol and prevent it from splashing out of the test tube during heating.

How is the presence of ethene gas confirmed in the script?

The presence of ethene gas is confirmed by testing for unsaturation using acidified potassium permanganate and bromine water, both of which should decolorize in the presence of ethene.

What is the purpose of the glass trough in the reaction setup?

The glass trough is used to collect ethene gas during the reaction, preventing it from escaping into the atmosphere.

Why is it important to remove the rubber tubing before moving the glass jar in the script?

Removing the rubber tubing before moving the glass jar prevents the formation of a vacuum inside the test tube, which could cause the test tube to shatter due to the contraction of gases upon cooling.

What is the test for the presence of carbon dioxide in the reaction?

The presence of carbon dioxide is tested by adding lime water to the reaction container; if carbon dioxide is present, the lime water will turn milky.

How is the ethene gas identified in the script?

Ethene gas is identified by its characteristic bright blue flame in a flame test.

Outlines

00:00

🔬 Preparing Ethane Gas from Ethanol

The video script describes a chemistry experiment to prepare ethane gas from ethanol. Ethanol, a two-carbon compound with hydroxyl groups, is dehydrated to form ethane and water. The setup includes a test tube with a sidearm, a Bunsen burner for heating, and a glass trough for gas collection. The reaction requires ethanol, aluminum oxide as a catalyst, and glass wool to support the ethanol. Indicators like lime water, acidified potassium permanganate, and bromine water are used to test for the presence of ethane gas, which is an unsaturated compound. The process involves heating the mixture to initiate the reaction and collecting the ethane gas in glass jars. The script also emphasizes safety measures, such as removing rubber tubing before moving the test tube to prevent shattering due to vacuum formation.

05:00

🧪 Testing for Unsaturation and Carbon Dioxide

This paragraph details the testing procedures to confirm the production of ethane gas and the presence of carbon dioxide as a byproduct. The tests for unsaturation include bubbling the collected gas through acidified potassium permanganate and bromine water, which should decolorize if ethane is present, indicating its unsaturated nature. The script also describes a flame test for ethane, where the gas burns with a bright blue flame, characteristic of ethane. Lastly, to verify carbon dioxide production, lime water is added to the container, which turns milky in the presence of CO2, confirming its presence. The script concludes with a step to decant the milky lime water into a test tube, visually demonstrating the presence of carbon dioxide.

Keywords

💡Ethanol

Ethanol is an organic compound with the chemical formula C2H5OH, commonly known as alcohol. In the video, ethanol serves as the starting material for the preparation of ethylene gas. It is described as having two carbons with an O-H bond, and the script mentions the process of dehydrating ethanol to produce ethylene, illustrating the chemical transformation central to the video's theme.

💡Ethylene

Ethylene, also known as ethene, is an unsaturated hydrocarbon with the formula C2H4. The video's main objective is to prepare ethylene gas from ethanol. Ethylene is characterized by a double bond between carbon atoms, making it an unsaturated compound, which is a key point in the script as it relates to the testing for unsaturation.

💡Dehydration

Dehydration in the context of the video refers to the chemical process of removing a water molecule from ethanol to form ethylene. This is a crucial step in the preparation of ethylene gas, as described in the script where aluminum oxide acts as a dehydrating agent to facilitate this reaction.

💡Aluminum Oxide

Aluminum oxide is a white powdery substance mentioned in the script as a catalyst for the dehydration of ethanol. It is a non-transition metal element used to dehydrate the alcohol, transforming it into ethylene. The script emphasizes the importance of having a very fine powder to increase the surface area for a better catalytic reaction.

💡Bunsen Burner

A Bunsen burner is a type of gas burner used in the video to provide heat for the reaction. It is essential for initiating the dehydration process of ethanol into ethylene, as described in the script where the aluminum oxide is heated to start the reaction.

💡Unsaturated Compound

An unsaturated compound is a term used in the video to describe compounds that contain double or triple bonds, such as ethylene. The script discusses testing for unsaturation using acidified potassium permanganate and bromine water, which are indicative of the presence of double bonds in the ethylene gas produced.

💡Acidified Potassium Permanganate

Acidified potassium permanganate is a chemical used in the video to test for the presence of unsaturated compounds like ethylene. When ethylene gas is bubbled through this solution, it causes the purple permanganate to decolorize, indicating the presence of a double bond, as demonstrated in the script.

💡Bromine Water

Bromine water is another chemical test mentioned in the video for confirming the production of ethylene. The script describes the process where ethylene gas, when bubbled through bromine water, causes decolorization due to the addition of bromine across the double bond, providing evidence of an unsaturated compound.

💡Lime Water

Lime water, or clear limewater, is used in the video to test for the presence of carbon dioxide, a byproduct of the reaction. The script describes how the lime water turns milky in the presence of carbon dioxide, indicating its production during the reaction.

💡Flame Test

A flame test is a qualitative analysis technique used in the video to identify certain metal ions based on the color of their flame when burned. The script mentions a bright blue flame as an indication of ethylene gas, which is consistent with the known flame test for sodium, suggesting the presence of ethylene.

Highlights

Preparation of ethylene gas from ethanol is described.

Ethanol's molecular structure with two carbons and an O-H bond is explained.

The reaction produces ethylene and water, maintaining molecular balance.

A test tube with a sidearm and a tight-fitting ball is used for the reaction apparatus.

Aluminium oxide is used as a dehydrating agent for the ethanol.

A Bunsen burner is used for heating the reaction mixture.

Glass jars are used for collecting ethylene gas.

Lime water, acidified potassium permanganate, and bromine water are used to test for unsaturation.

Glass wool is used to support the ethanol inside the test tube.

Ethanol is introduced into the test tube using a squeezy bottle.

Aluminium oxide is added to the test tube to create a larger surface area for the reaction.

The rubber tubing is removed to prevent melting during heating.

The reaction is initiated by heating the aluminium oxide, not the ethanol.

Displaced air is removed before collecting ethylene gas.

Ethylene gas is collected in glass jars and tested for unsaturation.

Acidified potassium permanganate decolorizes, indicating the presence of unsaturated gas.

Bromine water decolorizes when bubbled with ethylene gas, confirming unsaturation.

Ethylene gas burns with a bright blue flame, a characteristic test for its presence.

Lime water turns milky in the presence of carbon dioxide, indicating a byproduct of the reaction.

Transcripts

[Music]

the reaction we're going to do now is

the preparation of 18 gas this involves

having ethanol ethanol consists of two

carbons with an old-age bond here all

the whites represent hydrogen's I was

going to turn each ethanol into 18

that's the structure of eighteen and

water what that reaction then involves

if you look on the right hand side

you've got the same molecules as on the

left hand side so we're going to get our

ethanol remove the water molecule from

that I left behind with an ET molecule

eighteen because as a double bond is an

unsaturated compound the reaction

apparatus for this is a test tube with a

sidearm a very tight fitting ball it's

imperative a very tight fitting form in

this particular practical and then a

Bunsen burner for heating aluminium

oxide and here I've got my glass trough

to collect 18 gas and I'd want to

collect the eating gas in these glass

jars here the chemicals required for

this practical are ethanol which will be

dehydrating so I put I've taken the

ethanol here and put it into a squeezy

bottle we will be using aluminium oxide

to dehydrate the alcohol so here's a

Lamia oxide and you can see from the

petri dish in front of us

it's a white powder non-transition metal

element then the test to see whether we

have it in gas produced are using lime

water acidified potassium permanganate

and bromine water we also need some

glass wool to support the ethanol before

we start the dehydration reaction the

first thing in this particle is pulling

the ethanol into the test tube so here

are my adult in my squeezy bottle are

nothing to stoichiometrically

just adding about 25% for the volume of

the test you pull that now

my ethanol's now be introduced now

ethanol is now on the inside of this

test tube so what I want to do is take

make sure that ethanol is removed by

putting in my glass wool that's gonna

take the ethanol down off the side of

the tube then using your spatula let's

drive inside the test tube

ice of course the alcohol might you now

I want to add my dehydrating catalyst my

aluminium oxide so have my aluminium

oxide my white powder allomere oxide

it's a very finely divided powder I put

my annum innum oxide on the inside of

the test tube now as much as possible

because the more surface area available

better the catalytic reaction that

happens so again I'm not doing this

stoichiometrically I'm just adding in

minim oxide no to create a larger

surface area as possible you may notice

I removed the rubber from the clamp

because this test shoot is very hot so

in order to stop the rover from melting

I've actually taken it away

he's a very tight bomb in order to stop

the e-team gas from escaping so all of

my tests you ain't going to get that

bonus tight as possible the normal

reaction is ready to go next part of

this reaction is the heating of the

Delirium oxide to start dehydrating the

ethanol into e-team so I have my glass

jar ready to receive the gas both the

first few bubbles of gas that are

produced are going to be the displaced

air is in the test tube and in the

rubber tubing but first of all have to

be displaced once i've displaced all

that air i can then start collecting my

eating gas and i have my my trough on my

glass y'all ready we're catching up take

your gas

so next procedure is to light the Bunsen

burner

now we've got our Bunsen burner lit

we're gonna start heating the other

medium oxide notice I'm eating the

aluminum oxide and not the ethanol and

we can already see bubbles of gas come

out the tube that is not product that is

displaced air so let that happen

rope while I mostly decided we've got

the volume of gas start to collect our

gas at this stage we will have 18 gas

coming out of the tube so put into my

beehive and then put my glass jar on top

of the Beehive and we can see bubbles of

gas oriented glass jar that's 18 gas is

now being collected oil a glass jar is

filling of eating gas you prepared to

test for the unsaturation to test for

unsaturation are bobbing the solution

true roaming water we want to fill to

test ships full of Brawley water one

connect us to control we can test and

likewise I have pacified potassium

permanganate

I'll fill two trips again one the test

ship wanted to experiment on and one is

to control will allow for the brought

the eating gas to the acidified

potassium magnet and if we have an on

such a gas you should notice the

attachment Magnus is decolorizing

you see the gas bubbles bubbling true

and then when you compare that to

control we can see decolorization

has occurred therefore proving it's an

unsaturated compound second test for D

saturation is the decolorization

of bromine water so here I have my

solution of bromine water and I'm going

to bubble eating gas through the bromine

water and the bromine is adding across

double bond so decolorizing the solution

so if we compare that to a test tube to

the control we can see the color ization

has occurred so proving we produce an

unsaturated gas i've now collected the

eating gas in the glass jar I can move

the glass jar and put the coverslip

myelinated and we're going to be doing

the flame tests to see that we've got 18

gas produced it's very important at this

stage to remove the rubber tubing before

you move the roof on some burner if we

remove the Bunsen burner first what

happens is the gasses inside the test

you contract so causing a vacuum inside

the apparatus drawing the water from the

rubber tubing in the test tube and it

has you can shatter so the test for

eating gas is a burns in a bright new

messin flame so always light your

lighter before you remove the cover slip

and then white gas i will notice burning

with a bright blue messin flame the

bipod out of the reaction would be

carbon dioxide in order to check the

presence of carbon dioxide i'm going to

add some lime water into the container

answers carbon dioxide present the lime

water will turn milky shake this up

so we should notice how the lime water

is turning milky and just a short that

milkiness i will decant that into a test

tube so if you see the milky color of

the lime water so proving the presence

of carbon dioxide