Long Answer Questions: Ethanol and Ethanoic Acid

Medium Level (Application & Explanation)

Answer:

Ethanol (C₂H₅OH) is completely miscible with water because both ethanol and water can form strong hydrogen bonds with each other.
The -OH (hydroxyl) group in ethanol interacts effectively with water molecules, allowing them to mix in any proportion.
Ethanoic acid (CH₃COOH) is also soluble in water due to hydrogen bonding formed by its -COOH group.
However, at higher concentrations, ethanoic acid molecules tend to form dimers (pairs) due to hydrogen bonding between themselves more than with water.
This self-association reduces their tendency to mix endlessly with water.
Thus, ethanol remains miscible in all proportions, but ethanoic acid shows decreasing miscibility as its concentration increases, mainly because of molecular interactions.

Answer:

When ethanol is heated with concentrated sulphuric acid at 170°C, dehydration takes place.
In this reaction, ethanol loses a molecule of water to form ethene (C₂H₄).
The chemical equation:
$C_2H_5OH \xrightarrow{conc.H_2SO_4,\ \Delta} C_2H_4 + H_2O$
This shows that ethanol can act as a source of alkenes through loss of water, highlighting its alcohol nature.
The process is important industrially to produce ethene, which is used to manufacture plastics.
This reaction also illustrates that ethanol undergoes elimination reactions, a property common to alcohols.

Answer:

When ethanoic acid (CH₃COOH) reacts with sodium carbonate (Na₂CO₃), a salt, carbon dioxide gas, and water are formed.
The reaction:
$2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + CO_2 ↑ + H_2O$
Step 1: The acid reacts with the carbonate ion to release CO₂ gas (seen as bubbles).
Step 2: Sodium ethanoate (CH₃COONa), a soluble salt, is formed in solution along with water.
This reaction is used in labs to test for carboxylic acids; the rapid fizzing confirms acid presence.
It also helps in preparing sodium ethanoate for further chemical use.

Answer:

Denaturation means making alcohol unfit for human consumption by adding harmful or foul-tasting substances.
Ethanol for industrial use is denatured to prevent its misuse as a beverage.
Denaturants like methanol, pyridine, or copper sulphate are added.
These substances make ethanol toxic or bitter, without altering its usefulness for industry.
Denaturing saves tax, as the government heavily taxes drinking alcohol.
Thus, this process ensures public safety and proper regulation of ethanol use.

Answer:

Ethanoic acid is best known as the main ingredient in vinegar, used as a food preservative for pickles and condiments.
Its acidic nature prevents bacterial growth, making it ideal for food preservation.
In the chemical industry, it is used to manufacture acetates (like sodium acetate and cellulose acetate), important in making rayon and photographic films.
It acts as a starting material for dyes, perfumes, and plastics due to its reactivity with alcohols and other chemicals.
In medicine, diluted acetic acid is used as an antiseptic.
All these uses rely on its acidic and reactive carboxyl group.

Answer:

Ethanol in water is neutral and does not affect blue litmus paper; color remains blue.
Ethanoic acid in water ionizes to form H⁺ ions, making the solution acidic; blue litmus paper turns red.
Sodium carbonate in water forms carbonate ions, which are basic; blue litmus remains blue (or red litmus will turn blue).
This experiment shows that ethanol is neutral, ethanoic acid is acidic, and sodium carbonate is basic when dissolved in water.
The results help identify the nature of solutions using a simple litmus test.

Answer:

Ethanol burns cleanly in air, releasing energy, carbon dioxide, and water.
Its structure allows for easy ignition and controlled combustion, making it suitable as a biofuel in engines.
Ethanoic acid does burn, but its acidity is corrosive and can damage engine parts.
It has a higher boiling point and forms corrosive acidic vapors that can harm metallic and rubber engine components.
Ethanol is not acidic and is less likely to cause corrosion or residue build-up.
Thus, ethanol is fuel-friendly, whereas ethanoic acid is not, despite their similar elements.

Answer:

The mixture undergoes esterification, forming an ester and water.
The equation:
$CH_3COOH + C_2H_5OH \xrightarrow{conc.H_2SO_4} CH_3COOC_2H_5 + H_2O$
The product, ethyl ethanoate, has a fruity (pineapple-like) smell.
Concentrated H₂SO₄ acts as a dehydrating agent and catalyst.
This reaction is important in making artificial flavors and perfumes.
It demonstrates how simple chemicals can create pleasant aromas found in natural fruits.

Answer:

Test 1: Litmus Test
- Add the sample to water and dip blue and red litmus papers.
- Ethanol: No color change; solution is neutral.
- Ethanoic acid: Turns blue litmus red; indicates acidity.
Test 2: Reaction with Sodium Carbonate
- Add a small amount of sodium carbonate.
- Ethanol: No gas evolved.
- Ethanoic acid: Brisk effervescence observed due to carbon dioxide gas release.
These tests work because ethanoic acid is acidic, while ethanol is neutral and does not react with carbonates.

Answer:

Ethanol-blended petrol (like E10) contains about 10% ethanol and 90% petrol.
Ethanol is renewable; made from plants like sugarcane, it helps reduce the reliance on fossil fuels.
It burns more cleanly than pure petrol, producing less carbon monoxide and unburned hydrocarbons.
This reduces air pollution and greenhouse gas emissions.
However, challenges include the need for large land areas to grow biofuel crops, which can affect food production.
Also, modifying engines for higher ethanol ratios and managing water content in fuel are technical issues to solve for wide adoption.