2023 - JAMB Chemistry Past Questions and Answers - page 5

The contact process is used for the industrial production of sulfuric acid (H2SO4). In this process, sulfur dioxide (SO2) is oxidized to form sulfur trioxide (SO3), which is then dissolved in water to produce sulfuric acid. This is a crucial step in the large-scale production of sulfuric acid, an essential industrial chemical used in various processes such as the manufacture of fertilizers, detergents, and chemicals.

The highest entropy change is generally associated with the transition from a more ordered state to a more disordered state.

In this case, the transition from a liquid to a gas (Option A: Liquid → Gas) involves an increase in disorder because gas particles are more randomly distributed and have greater freedom of movement compared to liquid particles.

Therefore, the process of a substance changing from a liquid to a gas typically results in the highest entropy change among the given options.

An electrovalent bond, also known as an ionic bond, is formed when there is a transfer of electrons from one atom to another.

In the case of sodium chloride (NaCl), sodium (Na) donates an electron to chlorine (Cl), resulting in the formation of ions (Na+ and Cl-) that are held together by electrostatic forces.

This transfer of electrons leads to the creation of oppositely charged ions, and the attractive force between them forms the electrovalent or ionic bond. In contrast, options (CO2), (H2O), and (CH4) involve covalent bonds where electrons are shared between atoms.

Faraday's constant is the amount of charge (in coulombs) carried by one mole of electrons. It is approximately equal to 96,485 coulombs per mole.

This constant is commonly used in electrochemistry to relate the amount of electric charge to the number of moles of electrons involved in a redox reaction. 

The question asks for the alkane with a straight-chain structure. * **Butane (C4H10)** and **Pentane (C5H12)** can exist in straight-chain forms. * **Isobutane (C4H10)** has a branched-chain structure. * **Cyclopentane (C5H10)** is a cyclic alkane, and thus, does not have a straight-chain structure. Therefore, the correct answer is Butane and Pentane. However, only Butane is provided as an option.

When a substance is oxidized, it loses electrons. Oxidation is a process in which a substance loses electrons, and the term "LEO" (Loses Electrons Oxidation) is often used to remember this concept.

"Loses electrons," is the correct description of the oxidation process. In contrast, gaining oxygen atoms or gaining electrons is associated with reduction, not oxidation. Losing protons (H+ ions) is not a typical aspect of oxidation.

To calculate the molar mass of water (H2O), we need to sum the atomic masses of its constituent atoms. * Hydrogen (H) has an atomic mass of approximately 1 g/mol, and there are two hydrogen atoms in water. Thus, the mass contribution from hydrogen is 2 x 1 g/mol = 2 g/mol. * Oxygen (O) has an atomic mass of approximately 16 g/mol, and there is one oxygen atom in water. Thus, the mass contribution from oxygen is 16 g/mol. Therefore, the molar mass of water is 2 g/mol (from hydrogen) + 16 g/mol (from oxygen) = 18 g/mol.

When alkanoic acids react with alcohols in the presence of an acid catalyst, the process is known as esterification. This reaction results in the formation of esters and water.

When a reaction is reversed, the equilibrium constant (Kc) becomes the reciprocal of the original value.

If the original equilibrium constant for a reaction is K, then for the reversed reaction, the new equilibrium constant (K') is equal to 1/K.

The organic compound responsible for the characteristic aroma of fruits is an ester.

Esters are often formed by the reaction between carboxylic acids and alcohols, and they contribute to the fruity and pleasant smells in many fruits.