Questions Related to Carbon & its Compounds

Formula: C₅H₁₀
Cyclopentane is a ring compound with five carbon atoms linked in a closed chain. Each carbon forms two bonds with neighboring carbon atoms and two bonds with hydrogen atoms.

     H   H
      \ /
  H - C   C - H
   |       |
  H C     C H
    \     /
      C
      |
      H

Each carbon (C) is surrounded by four dots or lines (representing shared pairs of electrons), showing covalent bonds with other carbons and hydrogens.

The two properties of carbon that lead to a huge number of carbon compounds are:

1. Catenation – Carbon atoms can join with each other to form long chains, branched chains, or rings.
2. Tetravalency – Each carbon atom can form four covalent bonds with other atoms like carbon, hydrogen, oxygen, or nitrogen.

A mixture of ethyne and air is not used for welding because it does not burn hot enough and can explode. When ethyne burns in pure oxygen, it gives a very hot flame that can melt metals, but with air, burning is incomplete and the flame is not hot enough for welding.

The conversion of ethanol to ethanoic acid is an oxidation reaction because oxygen is added to ethanol. During this process, ethanol (which contains fewer oxygen atoms) is converted into ethanoic acid (which contains more oxygen).

In simple terms, adding oxygen or removing hydrogen from a substance is called oxidation.

Oxidising agents are substances that add oxygen to other substances or remove hydrogen from them during a reaction. In doing so, the oxidising agent itself gets reduced.

Example:
Potassium permanganate (KMnO₄) and potassium dichromate (K₂Cr₂O₇) are common oxidising agents.

You can distinguish between an alcohol and a carboxylic acid using sodium carbonate or sodium hydrogen carbonate.

Experiment:

• Add a small amount of sodium carbonate (Na₂CO₃) or sodium hydrogen carbonate (NaHCO₃) to both liquids.
• If bubbles (effervescence) of gas appear, it means carbon dioxide (CO₂) is released — the substance is a carboxylic acid.
• If no bubbles form, the substance is an alcohol.

Reason:
Carboxylic acids react with carbonates to produce CO₂ gas, but alcohols do not.

Agitation is needed because it helps to loosen and remove dirt from clothes. When clothes move or rub against each other in water with soap, the dirt comes off the fabric and gets washed away, making the clothes clean.

Yes, you can check if water is hard using a detergent.

Take two test tubes, one with distilled water and one with the water to be tested. Add a little detergent to both and shake well. If foam forms easily, the water is soft. If little or no foam forms, the water is hard.

Soap has two parts — one part mixes with water and the other mixes with oil or dirt.
When soap is added to water, it breaks the dirt into small parts and forms bubbles called micelles.
These micelles trap the dirt, which is then washed away with water, cleaning the surface.

The bromine water test is used to differentiate them.
When bromine water is added to an unsaturated hydrocarbon, its orange colour disappears.
In contrast, saturated hydrocarbons do not decolourise bromine water.

Only unsaturated hydrocarbons (those with double or triple bonds) undergo addition reactions.
So, C₃H₆ (propene) and C₂H₂ (ethyne) undergo addition reactions.

Hydrogenation is the process in which hydrogen gas is added to unsaturated hydrocarbons (like vegetable oils) in the presence of a catalyst such as nickel or palladium to form saturated compounds.
Industrial application: It is used to convert vegetable oils into solid fats like margarine or vanaspati ghee.

Soap solution is basic because it is made from sodium or potassium salts of fatty acids. When tested with litmus paper, it turns red litmus paper blue, showing its basic nature. However, blue litmus paper remains unchanged, as bases do not affect it.

Hard water contains salts of calcium and magnesium. When soap is added to hard water, these salts react with soap to form an insoluble substance called scum. This scum does not dissolve in water and reduces the cleansing ability of soap.

Carbon and its compounds are used as fuels because they burn easily in air and release a large amount of heat and energy. They have high calorific value and produce clean flames when burnt completely. Examples include coal, petrol, diesel, and natural gas.

Micelle formation takes place when soap is added to water because soap molecules have two parts — one part attracts water (hydrophilic) and the other attracts oil or dirt (hydrophobic). In water, the soap molecules arrange themselves into spherical structures called micelles that trap dirt and oil inside.
Micelles are not formed in solvents like ethanol because ethanol can mix with both oil and water, so separate micelles are not needed.

Physical properties: Ethanol has a pleasant smell and is neutral in nature, while ethanoic acid has a strong vinegar-like smell and is acidic in nature.
Chemical properties: Ethanoic acid reacts with sodium carbonate to produce carbon dioxide gas, but ethanol does not. Ethanol burns with a blue flame, while ethanoic acid does not burn easily.

A homologous series is a group of organic compounds having the same functional group and similar chemical properties. Each member of the series differs from the next by a –CH₂– group.
For example, the alkane series — methane (CH₄), ethane (C₂H₆), and propane (C₃H₈) — form a homologous series.

In CH₃Cl, carbon shares its electrons with three hydrogen atoms and one chlorine atom. By sharing electrons, all the atoms become stable. This sharing of electrons to form bonds is called a covalent bond.

If the bottom of the vessel gets blackened while cooking, It means that the fuel is not burning completely due to insufficient supply of air, which causes the formation of black soot (carbon).