02 Ethyne Gas

Summary

This educational video demonstrates the preparation of ethyne gas in a laboratory setting. The process begins with calcium carbide and deionized water in a flask, generating ethyne gas and calcium oxide. To purify the gas, copper sulfate and sulfuric acid are used. The gas is collected over water and tested for unsaturation using potassium permanganate and bromine water, which decolorize in the presence of ethyne. The video concludes with a flame test to confirm the presence of ethyne, showcasing a successful experiment.

Takeaways

• 🔬 The experiment demonstrates the preparation of ethyne gas, which consists of two carbon atoms triple-bonded with two hydrogens.
• 🧪 Calcium carbide reacts with water to produce ethyne gas and calcium oxide as a by-product.
• 💧 Deionized water is used in the reaction to ensure purity of the ethyne gas produced.
• 🌐 The setup includes a doctor flask, dropping funnel, and a gas collection jar to facilitate the reaction and collection of ethyne gas.
• 🔄 Copper sulfate and sulfuric acid are used to remove impurities from the ethyne gas.
• 🔬 The presence of an unsaturated compound is confirmed through the decolorization of potassium permanganate and bromine water.
• 🔥 A flame test is conducted to definitively test for the presence of ethyne gas, which burns with a distinctive flame.
• 🧑‍🔬 Safety precautions are emphasized, such as wearing a lab coat and conducting the experiment in a fume hood.
• ⏱️ The reaction is initiated by adding water to the calcium carbide in the flask, and the gas is collected once the air is displaced.
• 📝 The script provides a detailed step-by-step guide for conducting the experiment, including the use of specific chemicals and apparatus.

Q & A

What is the main objective of the practical described in the script?

The main objective of the practical is to prepare ethyne gas.

What is the molecular structure of ethyne gas?

Ethyne gas has a molecular structure with two carbons bonded by a triple bond and each carbon is also bonded to a hydrogen atom.

What are the chemicals used to produce ethyne gas in the practical?

Calcium carbide and deionized water are used to produce ethyne gas.

Why is copper sulfate mixed with sulfuric acid used in the preparation?

Copper sulfate mixed with sulfuric acid is used to remove impurities from the ethyne gas.

What is the purpose of the beehive in the apparatus setup?

The beehive is used to displace water and collect the ethyne gas.

How is the ethyne gas collected in the practical?

Ethyne gas is collected by filling glass jars with water, inverting them in a water trough, and then connecting them to the gas outlet of the reaction flask.

What is the purpose of the flame test in the practical?

The flame test is used to confirm the presence of ethyne gas by observing the color of the flame.

What is the significance of the decolorization of bromine water in the practical?

The decolorization of bromine water indicates the presence of an unsaturated compound, as ethyne gas reacts with bromine, causing the solution to lose its color.

Why is it important to remove the displaced air before collecting ethyne gas?

It is important to remove the displaced air before collecting ethyne gas to ensure that the collected gas sample is pure and not contaminated with air.

How is the reaction initiated between calcium carbide and water?

The reaction is initiated by allowing water to drop onto the calcium carbide in the flask, which produces ethyne gas and calcium oxide as a by-product.

What safety precautions are mentioned in the script during the practical?

The script mentions wearing a lab coat and conducting the flame test in a fume cupboard as safety precautions.

Outlines

00:00

🔬 Preparing Acetylene Gas in a Lab

The video script describes a laboratory procedure for producing acetylene gas. The setup involves a doctor flask with a dropping funnel and a delivery tube leading to a collecting jar. Calcium carbide is used as the solid reactant, and deionized water is added to react with the calcium carbide to generate acetylene gas and calcium oxide as a by-product. To purify the gas, copper sulfate mixed with sulfuric acid is used to remove impurities. The process begins with adding calcium carbide to the flask and then slowly introducing water to initiate the reaction. The initial gas bubbles are displaced air, which is not collected. Once the air is cleared, the acetylene gas is collected in glass jars that have been filled with water to displace the gas. The video also mentions the importance of conducting a flame test to confirm the presence of acetylene, which is indicated by a distinctive flame color.

05:00

🧪 Testing for Unsaturated Compounds and Acetylene Gas

This part of the script focuses on testing for unsaturated compounds using potassium permanganate and bromine water. The procedure involves bubbling the acetylene gas through a solution of potassium permanganate, which should decolorize if an unsaturated compound is present. The script also describes a method to check the decolorization effect by comparing it with a control test tube. The decolorization of the potassium permanganate solution indicates the presence of an unsaturated compound, such as acetylene. Additionally, the script describes a test with bromine water, where the acetylene gas is bubbled through it, causing a reaction that leads to decolorization due to the addition of bromine across the triple bond of acetylene. The script concludes with the preparation of a sample of acetylene gas for a flame test, which is a definitive test for the presence of acetylene, confirmed by the gas producing a specific flame color when ignited.

Keywords

💡Ethane gas

Ethane gas is a colorless, flammable gas with the chemical formula C2H6. It is a simple alkane and is a major component of natural gas. In the video, the preparation of ethane gas is the main theme, where the process involves a chemical reaction between calcium carbide and water.

💡Calcium carbide

Calcium carbide is a chemical compound with the formula CaC2. It is used in the video to produce ethane gas through a reaction with water. Calcium carbide is a common industrial chemical used in the production of acetylene and other chemicals.

💡Triple bond

A triple bond is a chemical bond between two atoms involving six shared electrons, three pairs of electrons being shared between the two atoms. In the context of the video, the model of ethyne gas (acetylene) is described as having a triple bond between two carbon atoms.

💡Apparatus

Apparatus refers to the set of equipment and instruments used in a scientific experiment or procedure. The video describes the setup of an apparatus consisting of a flask, a dropping funnel, and a collecting jar, which is used to generate ethane gas.

💡Deionized water

Deionized water is water that has had almost all of its mineral ions removed, thus making it a high purity water source. In the video, deionized water is used in the chemical reaction to produce ethane gas, indicating the need for a pure water source to avoid contamination.

💡Copper sulfate

Copper sulfate is a compound with the chemical formula CuSO4. It is used in the video to remove impurities from the ethane gas. Copper sulfate is often used as a fungicide and in water treatment processes.

💡Sulfuric acid

Sulfuric acid is a strong mineral acid with the molecular formula H2SO4. In the video, it is mixed with copper sulfate to form a solution that helps in purifying the ethane gas by removing impurities.

💡Flame test

A flame test is a chemical test used to identify certain metal ions based on the color they impart to a colorless flame. In the video, a flame test is mentioned as a definitive test to confirm the presence of ethane gas, which would burn with a characteristic flame.

💡Decolorization

Decolorization is the process of removing color from a substance. In the context of the video, it refers to the reaction of ethane gas with bromine water, where the bromine water's color fades as the gas reacts with it, indicating the presence of an unsaturated compound.

💡Unsaturated compound

An unsaturated compound is a chemical compound containing one or more double or triple bonds between atoms. The video discusses the use of a test to check for unsaturated compounds, which is relevant because ethane gas, being a simple alkane, does not have any double or triple bonds.

Highlights

Introduction to the preparation of ethyne gas with a model of its molecular structure.

Description of the apparatus setup, including a doctor flask, dropping funnel, and collecting jar.

Use of calcium carbide as the solid chemical to produce ethyne gas.

Deionized water is used in the preparation process to ensure purity.

The necessity of copper sulfate and sulfuric acid to remove impurities from the ethyne gas.

Procedure for adding chemicals into the flask, including calcium carbide and deionized water.

Explanation of the gas collection process and the importance of removing air from the apparatus.

Observation of the reaction as calcium carbide reacts with water to produce ethyne gas and calcium oxide.

Demonstration of the decolorization test using potassium permanganate to confirm the presence of an unsaturated compound.

Use of bromine water to test for the presence of a triple bond in the ethyne gas.

Observation of the decolorization of bromine water as ethyne gas reacts with it.

Preparation for the flame test to definitively identify the presence of ethyne gas.

Safety precautions taken during the flame test, including the use of a fume hood and a lighter.

Successful production of ethyne gas confirmed by the characteristic flame test.

Transcripts

[Music]

in his practical here today we're going

to prepare ethan gas so here is the

model of ethyne gas two carbons bonded

by a triple bond with two hydrogens

later end so north prepared etang gas

you need to apparatus here I have in

front to me a doctor flask with a

dropping form and addrational head into

a collecting jar so first of all in

order to do this practical look at the

chemicals the solids were going to make

the Etan gas out of is calcium carbide

which I'll be putting in today okra

flask I'm going putting deionized water

in here into the dropping funnel and

then when you're preparing etang gas a

lot of impurities so in order to remove

that impurities you need a certified

copper sulfate so I have a copper

sulfate mixed with sulfuric acid

institution here I'll be adding this

into the threshold bottle I got pour the

copper sulfate in my rationale bottle

roughly 3/4 filled and then if I put my

dress on head in here make sure to clamp

it up put the Thresher headed to the

solutions so sure that you go to the

bottom of the container and then the

tube because the bottom to entertainer

the other end of this rubber tubing must

be connected on to my book nor flask so

I put your rubber on to your book the

flask and now we've got all the

apparatus complete so addition of

chemicals into the container the Bhakra

flask I click on my calcium carbide the

calcium carbide comes in large lumps so

put that in the bottom of my container

again it doesn't really matter how much

you add in possibly 20 or 30 grams and

for a funnel back on the top of the

container and I'm using deionized

deionized water so here I have a beaker

of the ionized water make sure the top

is closed before you start

now reactors ready to go and now we want

where we're going to connect glass we're

gonna get our beehive into our water

trough there's a beehive and our rubber

tubing goes into the end of the beehive

and the gas is going to come out or

beehive and be connected in our glass

jars so with the glass jars I've got

these previously filled full of water to

move the water trough and slide the

glass off the bottom and your apparatus

is ready for collection however if I

fill the glass here now if I start

reaction at this start stage I've got

air in all of these voids inside here

that air will be displaced into a glass

jar so remove the tube until you're

ready to collect its gas and then we're

ready to start reaction okay so can I

open the tap here the water is going to

drop down to cut some carbide the CHC to

producing Etan gas and calcium oxide as

a by-product

so I going to gently let some water into

the container and we'll start to see

bubbles then produce really quickly this

actually bubbles of gas comic artists

tube this bubble is the displaced air

that's in the container so we don't

collect the first few drops of gas now

that all the displaced air is gone I can

now collect the ethane gas for the flame

tests like breathing wadding the

knee-high boot you see the bubbles

coming up here

it's placing the water downwards so now

my glass jar is full of a defy gas I

will now be able to my flame tests on

the efi gas which is the definitive test

to see what I've got neat I'm present or

not before we actually do the flame test

I'm first of all I'm going to do the

demonstration of the check to see

whether I've got an unsaturated compound

so remember this is it check to see

we've got an unsaturated compound not to

check for eaten gas to check for eaten

gas is solely the flame test for tests

we use some test tubes so into test tube

one I'm going to put a simple magnet and

properly certified potassium pregnant

there's purple solution here

it's also advisable to have a test test

tube as well so you can sit short a

color before you do the reaction

that's my detachment magnet test Edition

is now ready now then with bromine water

again is my test solution I'm gonna put

it into a test you add the Roman water

test you and another solution

I'll get a test solution ready as well

so I can see the corner before hunter

stop controlling water for 400 so in

this decolorization practical you Bobble

eaten gas true the Siddha five

attachment magnet the magnet the magnet

ease in the macro magnet goes from plus

seventy plus 2 and it gets decolorized

so open your present test you to tube

into it and if you have an unsaturated

compound you will get the chlorination

of potassium for magnet very gently

and probably the eat on gas to

detachment wagon it as the eat on gas

reacts with the magnetic it'll torrent

colorist let that continue for a while

I see the advantage now of having the

before color ready you can see if this

is decolorizing in front of our eyes

here test to is a decolorization of

roaming water but here absent bromine

water I'm going to bubble my gas shoot

the roaming water the action of slow

down so I need to add some more water

so my gas there's an additional reaction

occurring the bromine is adding across

to the triple bond and putting drawings

onto the compound and this should

decolorize a solution this takes a

little bit longer go through but again

as a reaction proceeds we can look at a

test solution and you can see the

decolorization is occurring now what I'm

going to do is take out my gas jar so

I'm going to snip this glass disk

underneath before a little jar out of

the water and now we've got my sample of

eaten gas for the flame test so

professor if the fume cupboard

always make sure your lighter is list

before you remove the glass disk

so we see the [ __ ] flame definitely we

have produced a tying us