A student prepared ethyne (C₂H₂) gas by dropping liquid A onto solid B and collecting the gas in test tubes over water - Leaving Cert Chemistry - Question 1 - 2019
Question 1
A student prepared ethyne (C₂H₂) gas by dropping liquid A onto solid B and collecting the gas in test tubes over water. The apparatus used is shown in the diagram.
... show full transcript
Worked Solution & Example Answer:A student prepared ethyne (C₂H₂) gas by dropping liquid A onto solid B and collecting the gas in test tubes over water - Leaving Cert Chemistry - Question 1 - 2019
Step 1
Identify the piece of apparatus labelled X
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
X is a dropping funnel, also known as a tap funnel, used for adding liquids to a reaction vessel.
Step 2
Identify liquid A
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Liquid A is water, also represented as H₂O.
Step 3
Identify solid B
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Solid B is calcium carbide, which has the chemical formula CaC₂.
Step 4
Describe what was observed when liquid A was dropped onto solid B
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
When liquid A (water) is added to solid B (calcium carbide), effervescence occurs, producing bubbles and a fizzling sound. White smoke and steam may also be observed due to the reaction.
Step 5
Why did the student not carry out any tests on the first few test tubes of gas collected?
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The student did not carry out tests on the first few test tubes because the gas collected initially may have contained impurities, which could interfere with the results.
Step 6
What was observed when bromine (Br₂) solution was added to a test tube of ethyne?
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
When the bromine solution was added to the test tube of ethyne, the brown (red, orange, yellow) color of the bromine fades and eventually disappears, indicating a reaction.
Step 7
What did the result of this test tell the student about the structure of the ethyne molecule?
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The result indicates that the ethyne molecule contains a double or triple bond, as it reacts with bromine to form a colorless product.
Step 8
Give the name or formula of another organic compound that you would expect to react in a similar way with bromine solution
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Another compound that would react similarly with bromine is ethene (C₂H₄) or any alkyne such as propyne (C₃H₄).
Step 9
What did the student observe when a lighting taper was inserted into a test tube of ethyne?
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The student observed a bright flame and a noticeable popping sound when a lighting taper was inserted into the test tube of ethyne, indicating combustion.
Step 10
Give a common use of ethyne gas
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Ethyne gas is commonly used in oxy-acetylene welding, a process for cutting and joining metals, as well as for ripening bananas.
Join the Leaving Cert students using SimpleStudy...
