(a) Distinguish between molecular formula and structural formula
(b) List three factors that determine the ionization energy of an atom.
(c) State the two conditions necessary for the establishment of a chemical equilibrium
(d) Consider the following table
| Element | A | B | C |
| Ionization energy KJ mol\(^{-1}\) | 619 | 518 | 594 |
(d)(i) State which of the elements is the strongest reducing agent.
(ii) Give a reason for the answer stated in (d)(i)
(e) State Graham’s law of diffusion
(f) Consider the following salts: Mg(NO\(_{3}\))\(_{2}\), CaCO\(_{3}\), Na\(_{2}\)SO\(_{4}\). State which of the salts is/are:
(i) readily soluble in water:
(ii) insoluble in water.
(g) Classily each of the following products as addition polymer or condensation polymer:
(i) protein:
(ii) perspex:
(iii) nylon.
(h) Define atomic radius.
(i) Explain briefly why ethanol has a higher boiling point than propane even though they both have comparable molar masses.
(j) State three significance of the pH value in everyday life.
Explanation
(a) Molecular formula gives the actual number of each kind of atom in one molecule while structural formula is a graphical representation of a molecule of a compound which shows how the atoms are linked/bonded together OR Molecular formula gives the total number of atoms of each element in one molecule of a compound. while structural formula shows li arrangements/relative position of atoms/atoms and bonds in one molecule of a compound.
(b) Factors that Determine the ionization Energy of an Atom:
- Atomic radius/size of atom Nuclear charge.
- Shielding effect/screening effect.
- Electron configuration,-Penetration effect.
(c) Conditions Necessary for the Establishment of a Chemical Equilibrium
- The rates of the forward and backward reactions must be equal.
- \(\bigtriangleup\)G must be zero.
- The temperature must be constant
- System must be dynamic/ all reactant and product must be present.
- System must be closed.
(d) Consider the following table:
| Element | A | B | C |
| Ionization energy KJ mol\(^{-1}\) | 619 | 518 | 594 |
(i) Element B
Reason: Element B has the lowest ionization energy/ it loses electrons most easily.
(e) Graham's Law of Diffusion: Graham's law of diffusion states that the rate of diffusion of gas at the same temperature and pressure is inversely proportional to the square root of its vapor density/molar mass
(f)i. Salts that is/are readily soluble in water: - Mg(NO\(_{3}\))\(_{2}\), Na\(_{2}\)SO\(_{4}\)
(ii) Insoluble in Water - CaCO\(_{3}\)
(g) Product classification as addition polymer or condensation polymer:
(i) Protein - Condensation.
(ii) Perspex - Addition.
(iii) Nylon - Condensation.
(h) Define Atomic Radius:
- lt is defined as half the distance between the nuclei of any two close atoms in a molecule/or is a measure of the size of its atoms, the mean distance from the center of the nucleus to the boundary of the surrounding shells of electrons.
(i) Why ethanol has a higher boiling point than propane even though they both have comparable molar mass: - The intermolecular forces in ethanol are hydrogen bonds which are stronger than the van der Waal's forces in propane.
(j) Three Significance of pH Value in Everyday Life:
- Digestion of food.
- Determination of pH of soil/used in agriculture.
- Important role in the survival of animals (self-defense) existence of living beings.
- pH change as the cause of tooth decay.
- Treatment of water for public supply.
- reatment of industrial efluent/ liquid waste.
- ln pharmaceuticals.
- In medicine (to determine pH of body fluid/urine /blood).