(a) State the conditions necessary for the cracking of long-chain hydrocarbons to produce more gasoline....
(a) State the conditions necessary for the cracking of long-chain hydrocarbons to producemore gasoline.
(b) Statetwo reasons why metallic objects are electroplated
(c) (i) Explainbriefly why calcium oxide cannot be used to dry hydrogen chloride gas.
(ii) State one drying agent for hydrogen chloride gas.
(d) Concentrated trioxonitrate (V) acid was added to a solution of iron (II) tetraoxosulphate (VI) and the mixture heated. The mixture turned from pale green to yellow with the evolution of a brown gas. Explainbriefly these observations.
(e) (i) Write the equation for the reaction between zinc oxide and
- dilute tetraoxosulphate (VI) acid,
- sodium hydroxide solution.
(ii) State which property of zinc oxide is shown by the reaction in(e)(i).
(f) Two isotopes of chlorine are \(^{35}_{17}\)Cl and \(^{37}_{17}\)Cl State one:
- similarity;
- difference between the isotopes.
(g) State thetwo products formed when chlorine water is exposed to sunlight.
(h) Consider the reaction represented by the following equation:
State the:
- species that is undergoing oxidation;
- oxidizing agent.
(i) What is meant bycarbon-12 scale?
(j) Statetwo properties of a chemical system in equilibrium.
Explanation
(a) - high temperatures / stated temperature of 500\(^o\)C or more
- catalyst
(b) - To prevent corrosion/rusting/tarnishing
- To make them shiny/for decoration purpose/beautify/attractive
- To make surface harder/thicker
- To make more resistant to chemicals
- To make it durable
- To reduce friction/abrasion
(c) (i) Because calcium oxide is basic and hydrogen chloride is acidic ,they will react
to form salt and water.
(ii) - Fused CaCl\(_2\)
- (Conc) H\(_2\)SO\(_4\) (do not accept dil H\(_2\)SO\(_4\))
- Silica gel
- Phosphorus(V) oxide/P\(_2\)O\(_5\)
(d) Conc. HNO\(_3\) is a strong oxidizing agent. It oxidizes pale green Fe\(^{2+}\) ions to yellow Fe\(^{3+}\) ions(1) and itself reduced to nitrogen (IV) oxide.
(e) (i) I. ZnO(s) + H\(_2\)SO\(_{4(aq)}\) \(\to\) ZnSO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\)
II. ZnO\(_{(s)}\) + 2NaOH\(_{(aq)}\) \(\to\) Na\(_{2}\) Zn(OH)\(_{4 (aq)}\)
OR
ZnO + 2NaOH \(\to\) Na\(_2\)ZnO\(_2\) + H\(_2\)O
(ii) Amphoterism / Amphoteric properties
(f) (i) Same number (17) of protons / same number (17) of electrons/same atomic number
(ii) Difference in mass numbers / different number of neutrons / 35Cl has 18 neutrons and 37Cl has 20 neutrons
(g) - HCl / hydrochloric acid
- O\(_2\) / Oxygen
&nbs