A group of students prepared ethano l (C2H5OH) by slowly adding a mixture of ethanol (C2H5OH) and an oxidising agent in water, to hot aqueous sulphuric acid - Leaving Cert Chemistry - Question 1 - 2005
Question 1
A group of students prepared ethano l (C2H5OH) by slowly adding a mixture of ethanol (C2H5OH) and an oxidising agent in water, to hot aqueous sulphuric acid. The app... show full transcript
Worked Solution & Example Answer:A group of students prepared ethano l (C2H5OH) by slowly adding a mixture of ethanol (C2H5OH) and an oxidising agent in water, to hot aqueous sulphuric acid - Leaving Cert Chemistry - Question 1 - 2005
Step 1
Identify this solid and state its purpose.
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 solid material is identified as pumice stones or porcelain pieces. Its purpose is to prevent bumping during the reaction.
Step 2
Identify a suitable oxidising agent for this preparation.
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
A suitable oxidising agent for this preparation is sodium dichromate or potassium permanganate.
Step 3
What is the colour of the mixture in the dropping funnel at the start?
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 colour of the mixture in the dropping funnel at the start is yellow, matching the oxidising agent used.
Step 4
What is the colour of the mixture in the reaction flask as the reaction proceeds?
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
The colour of the mixture in the reaction flask changes to green as the reaction proceeds, due to the reduction of the permanganate.
Step 5
Why is it important to distill off the ethanol as it is produced?
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
It is important to distill off the ethanol as it is produced to prevent excessive oxidation and avoid the production of ethanoic acid.
Step 6
Why is it not necessary to keep heating the reaction flask during the addition?
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
It is not necessary to keep heating the reaction flask during the addition because the reaction is exothermic, generating sufficient heat.
Step 7
Why is the receiving vessel cooled in ice-water?
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 receiving vessel is cooled in ice-water to condense the ethanol vapor effectively and to maintain a lower temperature.
Step 8
What colour is the solid produced when a mixture containing a few drops of Fehling’s solutions (No 1 and No 2) and ethanol is heated?
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
The solid produced is brick red, indicating the presence of copper(I) oxide.
Join the Leaving Cert students using SimpleStudy...
