A group of students prepared a sample of ethanolic (acetic) acid, CH₃COOH, in the school laboratory as follows - Leaving Cert Chemistry - Question 1 - 2008
Question 1
A group of students prepared a sample of ethanolic (acetic) acid, CH₃COOH, in the school laboratory as follows.
A solution of ethanol, C₂H₅OH, in water was added in... show full transcript
Worked Solution & Example Answer:A group of students prepared a sample of ethanolic (acetic) acid, CH₃COOH, in the school laboratory as follows - Leaving Cert Chemistry - Question 1 - 2008
Step 1
Make a rough sketch of any one of these arrangements of apparatus in your answer-book and clearly indicate the direction in which the water should flow through the condenser.
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
In your sketch, ensure to include
The condenser pointing downwards
Water inlets at the bottom and outlets at the top
Label the direction of water flow as 'in' at the bottom and 'out' at the top.
Make sure the apparatus is neatly labeled for clarity.
Step 2
Explain why small pieces of glass or pumice stone were added to the reaction flask at the start of the experiment.
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
Small pieces of glass or pumice stone are added as nucleation sites. They provide surfaces for bubbles to form, which helps prevent bumping and ensures smooth boiling. This promotes safety and efficiency during the reaction.
Step 3
What colour was produced as the ethanol reacted with the sodium dichromate(VI)?
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 color produced during the reaction was orange. This is due to the reduction of the orange sodium dichromate(VI) to green chromium(III) ions as ethanol is oxidized.
Step 4
Why was it important to reflux the reaction mixture?
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
Refluxing the reaction mixture is crucial because it ensures that the reaction goes to completion, maximizes the yield, and allows for the efficient transfer of heat while preventing loss of solvent through evaporation.
Step 5
Why was the solution of ethanol and water added in small portions?
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 ethanol and water solution was added in small portions to control the reaction rate and ensure that the exothermic reaction does not become too violent. It also helps to prevent excessive heating, which could lead to safety hazards.
Step 6
What colour was produced when the ethanolic acid was distilled?
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
The solution produced during the distillation of ethanolic acid was green. This color indicates the presence of chromium(III) ions formed from the reduction of sodium dichromate during the previous reaction.
Step 7
If a diluted solution (5-6% w/v) of ethanoic acid (acetic acid) is used in food preservation and as a flavouring agent. What is the common name of this solution?
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 common name of this solution is vinegar. It is widely used for culinary purposes and food preservation due to its acidic properties.
Join the Leaving Cert students using SimpleStudy...
