(a) (i) State the important points put forward in Dalton’s atomic theory.
(ii) How does the theory explain the law of multiple proportion?
(b) (i) Name three commercially useful products that may be obtained by chemical transformation of vegetable oils.
(ii) With the aid of equations, describe the chemical reaction involved in the transformations stated in (b)(i).
(c) Certain properties of Beryllium (Be) and its compounds differ from those of Magnesium (Mg) and its compounds, but rather resembles those of Aluminium and its compounds. Explain briefly why this is so.
(d) Write balanced equation for the reaction between iodine and aqueous sodium trioxothiosulphate(VI).
a)
(i) The important points put forward in Dalton's atomic theory are:
- All matter is made up of tiny, indivisible particles called atoms.
- Atoms of the same element are identical in size, mass, and other properties.
- Atoms of different elements have different properties.
- Atoms can neither be created nor destroyed in a chemical reaction, only rearranged.
- Compounds are formed when atoms of different elements combine in fixed ratios.
(ii) The theory explains the law of multiple proportion by stating that when two elements combine to form more than one compound, the ratios of the masses of one element that combine with a fixed mass of the other element are ratios of small whole numbers.
b)
(i) Three commercially useful products that may be obtained by chemical transformation of vegetable oils are soap, biodiesel, and margarine.
(ii) The chemical reactions involved in the transformations stated in (b)(i) are:
- Soap: Vegetable oil + Sodium hydroxide → Soap + Glycerol
- Biodiesel: Vegetable oil + Methanol → Biodiesel + Glycerol
- Margarine: Vegetable oil + Hydrogen gas → Margarine + Water
c) Beryllium (Be) and its compounds differ from those of Magnesium (Mg) and its compounds, but rather resemble those of Aluminium and its compounds because:
- Beryllium has a smaller atomic size and higher ionization energy than magnesium, which makes it more similar to aluminium in terms of electronic structure and chemical behavior.
- Beryllium forms covalent bonds more readily than magnesium, while magnesium forms primarily ionic bonds. This makes beryllium more similar to aluminium, which also tends to form covalent bonds.
d) The balanced equation for the reaction between iodine and aqueous sodium trioxothiosulphate(VI) is:
I2 + 2Na2S2O3 → 2NaI + Na2S4O6
This reaction is a redox reaction, in which iodine is reduced to iodide ions and trioxothiosulphate(VI) is oxidized to tetrathionate ions. Sodium ions are spectator ions and do not participate in the reaction. The reaction is commonly used as a titration to determine the concentration of iodine in a sample.
a)
(i) The important points put forward in Dalton's atomic theory are:
- All matter is made up of tiny, indivisible particles called atoms.
- Atoms of the same element are identical in size, mass, and other properties.
- Atoms of different elements have different properties.
- Atoms can neither be created nor destroyed in a chemical reaction, only rearranged.
- Compounds are formed when atoms of different elements combine in fixed ratios.
(ii) The theory explains the law of multiple proportion by stating that when two elements combine to form more than one compound, the ratios of the masses of one element that combine with a fixed mass of the other element are ratios of small whole numbers.
b)
(i) Three commercially useful products that may be obtained by chemical transformation of vegetable oils are soap, biodiesel, and margarine.
(ii) The chemical reactions involved in the transformations stated in (b)(i) are:
- Soap: Vegetable oil + Sodium hydroxide → Soap + Glycerol
- Biodiesel: Vegetable oil + Methanol → Biodiesel + Glycerol
- Margarine: Vegetable oil + Hydrogen gas → Margarine + Water
c) Beryllium (Be) and its compounds differ from those of Magnesium (Mg) and its compounds, but rather resemble those of Aluminium and its compounds because:
- Beryllium has a smaller atomic size and higher ionization energy than magnesium, which makes it more similar to aluminium in terms of electronic structure and chemical behavior.
- Beryllium forms covalent bonds more readily than magnesium, while magnesium forms primarily ionic bonds. This makes beryllium more similar to aluminium, which also tends to form covalent bonds.
d) The balanced equation for the reaction between iodine and aqueous sodium trioxothiosulphate(VI) is:
I2 + 2Na2S2O3 → 2NaI + Na2S4O6
This reaction is a redox reaction, in which iodine is reduced to iodide ions and trioxothiosulphate(VI) is oxidized to tetrathionate ions. Sodium ions are spectator ions and do not participate in the reaction. The reaction is commonly used as a titration to determine the concentration of iodine in a sample.
