SCH3U
Lab Activity: Complete and Incomplete Combustion of Ethyne
Name:__________________
Date of Lab:_____________
Partner’s Name:__________
Date Due: ______________
[C-1]
Hydrocarbons are covalently bonded compounds and are often used as fuels. You probably recognize some of the more
familiar names such as methane, propane, butane and octane. In this activity you will produce a hydrocarbon called ethyne
(acetylene), which is often used, in welding torches. When it combines with oxygen it produces a very hot flame that can melt
certain metals. When acetylene combusts in excess pure oxygen it produces carbon dioxide and water. This is called
complete combustion. However, if there is not enough oxygen supplied during combustion carbon monoxide and carbon soot
can be produced as well as carbon dioxide and water. This is called incomplete combustion.
In this activity you will react calcium carbide, CaC 2 , with water to produce ethyne gas. Calcium hydroxide is also produced in
this reaction. You will collect different amounts of ethyne gas in different test tubes and then light it on fire so that a
combustion reaction occurs. You should observe both complete and incomplete combustion in this lab.
Purpose
The purpose of this lab is to______________________________________________________________________________
____________________________________________________________________________________________________
________________________________________________________________________________________________[C-1]
Prediction
____________________________________________________________________________________________________
________________________________________________________________________________________________ [I-2]
Materials
Wooden splints
Tweezers/ scoopula
Rubber stoppers
3 test tubes with no cracks or tape
1 400 mL beaker
Tap water
Calcium carbide pieces
matches
Safety
List all safety precautions should you take when igniting a gas in a test tube. [C-2]
List all safety precautions should you take when working with heated glass. [C-2]
List all safety precautions should you take when working with calcium carbide. [C-3]
Observations
Table 1:
Sample
[C-9]
1
Amount of
Ethyne / Air
1/1
2
1/2
3
1/10
Observations
Diagram of Observations
after Gas Test
Discussion Questions
1. Write the BALANCED, including the states, chemical reaction for the production of ethyne, C2H2 , from CaC2 and
water.
[I-3]
2. What did you observe as the amount of oxygen in each test tube increased?
[I-2]
4. a) In which tube(s) did complete combustion occur? Explain how you know.
[I-2]
b) Write the BALANCED chemical equation for the complete combustion of ethyne, including the states.
[I-3]
5. a) In which test tube(s) did incomplete combustion occur? Explain how you know.
[I-2]
b) Write the BALANCED chemical equation for the incomplete combustion of ethyne, including the states.
[I-3]
6. Ethyne is covalently bonded. Draw the Lewis structure and structural formula to show the bond arrangement in this
molecule. [C-4]
Application
7. Give two sources of error that you think could have effected your dependent variable. Make sure to explain how. [A2]
8. Describe some applications of acetylene in industry.
[A-2]