Q2. * Preparation and properties of ethyne Flashcards
From what reaction is ethyne prepared?
Ethyne is prepared by the reaction of water with calcium carbide, CaC2
What is the formula for calcium carbide?
CaC2
What is CaC2?
Calcium carbide
What can calcium carbide also be called?
Calcium dicarbide
What can calcium dicarbide also be called?
Calcium carbide
How are the gases that contaminate hydrogen removed?
By bubbling the gas through acidified copper (II) sulfate
What chemicals are needed for this experiment?
5
Calcium carbide
Acidified copper (II) sulfate solution
Limewater
Bromine water
Acidified potassium permanganate solution
What is the first step of this experiment?
3
Set up the apparatus
Make sure to use a spatula when handling the calcium carbide and not to touch it with your fingers
Use only a few lumps of calcium carbide
Describe how you set up the apparatus
8
Place some calcium carbide lumps in the Buchner flask
Put a one-hole rubber stopper in the top of the Buchner flask
Connect the stopper to the dropping funnel and fill the funnel with water
Using a delivery tube connect the Buchner flask to the gas-washing bottle
Fill the gas-washing bottle with acidified copper sulfate solution
Stopper the gas-washing bottle with a two-hole rubber stopper
Using a delivery tube connect the gas-washing bottle to the has jar
Cover the gas jar with a gas-jar cover and place in a trough of water
Where is the calcium carbide placed?
In the Buchner flask
What is placed inside the Buchner flask?
Calcium carbide
What is attached to the Buchner flask?
2
A dropping funnel is attached to a one-hole rubber stopper at the mouth of the Buchner flask
A delivery tube leads from the upper side of the Buchner flask to the gas-washing bottle
What is the gas-washing tube filled with?
Acidified copper (II) sulfate solution
What is filled with acidified copper (II) sulfate solution?
The gas-washing bottle
What is attached to the gas-washing tube?
3
Two delivery tubes are connected
One delivery tube comes from the Buchner flask containing the calcium carbide - this tube must be underneath the surface of the acidified copper (II) sulfate solution
The second tube is connected to the gas jar and it must be above the surface of the acidified copper (II) sulfate solution
Where is the ethyne gathered?
At the space at the top of the gas jar
Where is the gas jar placed?
It is filled with water and placed in a trough of water
What gathers in the space at the top of the gas jar?
Ethyne
Why should no naked flame be brought anywhere near the gas preparation apparatus?
Because ethyne forms an explosive mixture with air
Why should you avoid handling the calcium carbide with your hands?
Because the calcium carbide could start a reaction with the moisture from your hands
What is the second step of this experiment, the apparatus has just been set up?
Double check that you have connected the gas-washing bottle correctly
What is the third step of this experiment, the gas-washing bottle connections have just been double checked?
Using the dropping funnel, add water slowly to the calcium carbide to maintain an even evolution of ethyne
What colour is the calcium carbide?
It is a grey-black or grey-brown colour
What four observations can be made when the water is added to the calcium carbide?
Fizzing takes place in the Buchner flask
A white solid is formed
Bubbles of as start to collect in the gas jar
The Buchner flask becomes warm
What causes the fizzing in the Buchner flask?
This is caused by ethyne gas being given off by the reaction in the flask
What reaction takes place in the Buchner flask?
CaC2 + 2H2O –> Ca(OH)2 + C2H2