Alcohols and carboxylic acids Flashcards
What is the general formula for alcohols?
CnH2n+1OH
What are the physical properties of alcohols?
Volatile liquids at room temperature and pressure
Down the homologous series, as molecular size increases
- solubility in water decreases (higher percentage of C-H bonds)
- stronger intermolecular forces of attraction –> boiling point increases
What chemical reactions do alcohols undergo?
Combustion and oxidation
How can ethanol be produced?
Fermentation of glucose
C6H12O6 (aq) –> 2 C2H5OH (aq) + 2 CO2 (g)
What are the conditions for fermentation of glucose?
- 37 degrees
- presence of yeast
- absence of oxygen
What is the experimental set-up for fermentation of glucose?
- glucose solution is mixed with yeast in connical flask
- Flask is immersed in water bath and kept at 37 degrees for a few days
- Dilute aqueous solution of ethanol is produced. Pure ethanol can be obtained via fractional distillation.
Why is limewater included in the experimental set-up for production of ethanol?
Limewater serves as a air-lock and prevents oxygen from entering the set-up. Also allows us to check if fermentation is taking place.
Why must temperature be kept at 37 degrees?
If temperature is too high, enzymes in yeast will denature.
What is the general formula for carboxylic acids?
CnH2n+1COOH (n = no. of carbons -1)
What are the chemical properties of carboxylic acids?
They are weak acids that ionize partially in aqueous solution.
CH3COOH <–> CH3COO- + H+
Undergo
- MASH
- CASWC
- ABSW
How is ethanoic acid produced?
Ethanol can be oxidised by potassium manganate (VII) into ethanoic acid. Potassium manganate (VII) will turn colourless.
Ethanol can be oxidised into ethanoic acid by oxygen and bacteria in air.
C2H5OH (aq) + O2(g) –> CH3COOH (aq) + H2O (l)
