Chemistry 2023 Jamb Examination

Soap and detergent molecules consist of two distinct parts: a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail.
The hydrophilic head dissolves in water, while the hydrophobic tail attaches to grease and oil. This dual nature allows soap and detergents to emulsify oils, forming micelles that can be rinsed away with water.

The solubility product constant (K\(_{sp}\)) expresses the equilibrium between a sparingly soluble ionic compound and its ions in a saturated solution.
It is used to determine the concentration of ions at equilibrium and predict whether a precipitate will form under given conditions.
It does not measure total solubility but the product of ionic concentrations at equilibrium.

Temporary hardness in water is mainly due to the presence of dissolved bicarbonates of calcium and magnesium. Boiling converts these bicarbonates into insoluble carbonates, which precipitate out, thereby removing the hardness.
Filtration, sedimentation, and chlorination do not remove hardness as effectively as boiling does.

Carbon dioxide (CO\(_2\)) is a greenhouse gas that absorbs infrared radiation emitted by the Earth's surface and re-emits it, trapping heat in the atmosphere.
This process contributes to global warming and climate change. Although CO\(_2\) makes up a small fraction of the atmosphere, its impact on temperature regulation is significant.

Faraday's constant (F) represents the electric charge carried by one mole of electrons. It is approximately 96,485 coulombs per mole (C/mol).
This constant is essential in electrochemistry for calculating quantities like charge, current, and time during electrolysis processes. It relates directly to Avogadro’s number and the elementary charge of an electron.

According to Boyle’s Law, the pressure of a gas is inversely proportional to its volume when temperature is constant.\[P_1V_1 = P_2V_2\]Given: \(P_1 = 2\,atm\), \(V_1 = 1.5\,L\), \(P_2 = 4\,atm\), find \(V_2\).\[V_2 = \dfrac{P_1V_1}{P_2} = \dfrac{2 \times 1.5}{4} = 0.75\,L\]Therefore, the new volume of the gas is 0.75 litres.

Stainless steel is primarily composed of iron and chromium, often with small amounts of nickel and carbon. Chromium provides corrosion resistance by forming a thin, protective oxide layer on the surface of the metal.
This property makes stainless steel durable and ideal for use in cookware, medical instruments, and construction materials.

In the gaseous state, particles are far apart and move randomly at high speeds with significant kinetic energy. The forces of attraction between them are very weak, allowing gases to expand and fill any container.
This property distinguishes gases from solids and liquids, where particles are more closely packed.

In this redox reaction, zinc (Zn) loses electrons to form Zn\(^{2+}\), while copper ions (Cu\(^{2+}\)) gain electrons to form copper metal (Cu).
The substance that donates electrons is the reducing agent. Therefore, Zn acts as the reducing agent because it undergoes oxidation by losing electrons.

To balance the equation Fe\(_2\)O\(_3\) + CO → Fe + CO\(_2\):
Each molecule of Fe\(_2\)O\(_3\) contains two Fe atoms and three oxygen atoms. Carbon monoxide (CO) provides the oxygen needed to form carbon dioxide (CO\(_2\)).
Balancing gives:\[Fe_2O_3 + 3CO → 2Fe + 3CO_2\]This means three molecules of CO reduce one molecule of Fe\(_2\)O\(_3\) to produce two atoms of Fe and three molecules of CO\(_2\).