Question Library

The pressure exerted by an individual gas in a mixture is known as its partial pressure

There are several wastewater treatment methods based on biotechnology that are used worldwide. It includes Activated Sludge, Oxidation Ponds, Tricking Filters, Bio-filters and Anaerobic treatment. All the methods are part of the biological wastewater treatment and use microbes to treat organic waste in sewage.

- The boiling points of alkanes increase with increasing number of carbons. This is because the intermolecular attractive forces, although individually weak, become cumulatively more significant as the number of atoms and electrons in the molecule increases. - However; branched alkanes normally exhibit lower boiling points than unbranched alkanes of the same carbon content. This occurs because of the greater van der Waals forces that exist between molecules of the unbranched alkanes

The reaction between ethyne (C₂H₂) and hydrogen (H₂) is a hydrogenation reaction, specifically an addition reaction where hydrogen atoms add across the triple bond of ethyne, breaking the triple bond to form a C=C first, i.e ethene. Then on further reaction, the C=C reacts with H\(_2\), breaking the C=C to form a C-C bond. i.e ethane (C₂H₆). C\(_2\)H\(_2\) \(^{H_2}_{→}\) X \(^{H_2}_{→}\) Y. C\(_2\)H\(_2\) \(^{H_2}_{→}\) C\(_2\)H\(_4\) \(^{H_2}_{→}\) C\(_2\)H\(_6\)

- heavy chemicals are produced and handled in large lots and are often in a crude state. - Some examples of bulk chemicals are ammonia, sulfuric acid, and sodium hydroxide - Fine chemicals are single, pure and complex chemicals that are only produced in small amounts

Boyle's law states that the pressure (p) of a given quantity of gas varies inversely with its volume (v) at constant temperature; i.e., in equation form, pv = k, a constant. ...

- The most common apparatus used in volumetric determinations are the pipette,buret, measuring cylinder, volumetric and conical (titration) flask. - A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity.

The model of an atom put forward by Ernest Rutherford in 1911 on the basis of experiments on the scattering of alpha particles. The model consisted of a very dense positively charged nucleus, with electrons orbiting round the nucleus.

The atomic mass is written as superscript = proton number + neutron number - Atomic mass of Cu is 64 = 29 + 35 - Atomic mass of Zn is 65 = 30 + 35 Proton number is written as subscript

Its electronic configuration in ground state is 1s2 2s2 2p6 3s2 3p6 4s1 3d5.

The method of collecting a gas produced by a chemical reaction will depend on its solubility and its density.

Uses of electrolysis: Electrolysis is used in the extraction of metals from their ores. It is used for refining certain metals such as copper and zinc. Electrolysis is used for the manufacture of chlorine. Electrolysis is used for electroplating many things we use every day.

This periodic table shows the valences of element groups.

Kipp's apparatus is a laboratory apparatus specially designed for producing small amount of gases and is used to produce usually hydrogen sulfide.

(a) \(_2^4He\) has its outermost / Valence shell fully filled with electrons / has maximum number of electrons in its outermost shell / duplet thus more stable whereas \(_4^9Be\) has incomplete filled outermost / valence shell hence less stable. (b) (i) 1H - 2 electrons / zero 3Li - 2 electrons (ii) 1H - it accepts one electron / donates one electron 3Li - it loses an electron to have a duplet shell (c) - nearness to raw material / feed stock - nearness to markets - labour supply - transportation - availability of power supply - government policy - away from residential areas - storage facilities for raw materials - source of water supply - conducive climate (d) - saves money / the plant does not have to operate for long to produce - reduces energy / reaction proceeds at a much lower temperature - no undesirable products are formed / catalyst is specific in action (e) From the equation: 8 moles of Cl\(_2\) reacts with 1 mole turpentine 1 mole of Cl\(_2\) = 71 g 8 moles = 8 x 71 = 568 g \(\frac{21.3}{568}\)g will react with 21.3 x 136 = 5.1 g OR 8 moles of Cl\(_2\) reacts with 1 mole turpentine 8 moles of Cl\(_2\) = 8 x 71 = 568 g 21.3 g of Cl\(_2\) = \(\frac{136}{71 \times 8}\) x 21.3 = 5.1 g OR Mole of Cl\(_2\) = \(\frac{21.3}{71}\) = 0.3 mole 8 moles Cl\(_2\) \(\to\) 136 g C\(_{10}\)H\(_{16}\) 0.3 mole Cl\(_2 \) = \(\frac{136}{8}\) x 0.3 = 5.1 g (f) Cracking is the breaking down of long chain hydrocarbons into smaller molecules by the action of heat and / or in the presence of a catalyst. (g) - nuclear charge - atomic size - electron configuration (h) Carbohydrates are molecules / organic compounds consisting of carbon, hydrogen and oxygen atoms usually with hydrogen and oxygen atoms in the ratio of 2:1. (i) Sugar Starch - monosaccharides / low molar Mass - polysaccharides / high molar mass - single units of specific molecules - long chains of single sugar molecule/ subunits linked together - general formula C\(_x\)H\(_{2y}\)\(O_y\) - general formula (C\(_6\)H\(_{10}\)O\(_5\))n - crystalline - amorphous / non crystalline - soluble in water - insoluble in water (j) (i) H\(_2\)CO\(_{3(aq)}\) \(\to\) H\(^+\)\(_{(aq)}\) + HCO\(_{3(aq)}\)\(^{-}\) OR H\(_2\)CO\(_{3(aq)}\) \(\to\) 2H\(^{+}\)\(_{ (aq) }\) + CO\(_{3(aq)}^{2-}\) OR H\(_2\)CO\(_{3 (aq)}\) + H\(_2\)O\(_{(l)}\) \(\to\) H\(_3\)O\(^+\)\(_{(aq)}\) + HCO\(_{3 (aq)}^-\) H\(_2\)CO\(_{3 (aq)}\) + 2H\(_2\)O\(_{(l)}\) \(\to\) 2H\(_3\)O\(^+\)\(_{(aq)}\) + CO\(_{3 (aq)}^{2+}\) (ii) CH\(_3\)COOH\(_{(aq)}\) + H\(_2\)O\(_{(l)}\) \(\to\) CH\(_3\)COO\(^-_{(aq)}\) + \(H_3\)O\(^{+}\)\(_{(aq)}\) OR CH\(_3\)COOH\(_{(aq)}\) \(\to\) CH\(_3\)COO\(^-_{(aq)}\) + H\(^+_{(aq)}\)