SPM Form 5: Chemicals for Consumers (Checklist)

• Saponification: Alkaline hydrolysis of an ester where the ester is boiled with sodium hydroxide, NaOH or potassium hydroxide, KOH solution to produce an alcohol and a sodium or potassium salt of a carboxylic acid.
• Soap is not an effective cleansing agent in hard water but is only effective in soft water. Detergent is an effective cleansing agent in both hard water and soft water.  
• Soft water: Water that does not contain mineral salts such as magnesium salt or calcium salts.
• Hard water: Water that contain mineral salts.
• Food additives are substances added to food to preserve flavor or enhance its taste and appearance. Types of additives are preservatives, antioxidants, flavourings, stabilizers, thickening agents and food dyes (colourings).
• Medicines: a compound or preparation used for the treatment or prevention of disease, especially a drug or drugs taken by mouth. Types of modern medicines are analgesics, antibiotics, stimulants, antidepressant and antipsychotic. 

SPM Form 5: Carbon compounds (Checklist)

• Organic compounds: Carbon-containing compounds that can be obtained from living things.
• Inorganic compounds: Non-carbon-containing compounds that can be obtained from non-living things.
• Hydrocarbons: Compounds that contain only carbon and hydrogen. In a saturated hydrocarbon, all the bonds are single bonds. Alkane is another name for a saturated hydrocarbon. Unsaturated hydrocarbons are a hydrocarbon that contains one or more double or triple bonds are an unsaturated hydrocarbon. There are three types of unsaturated hydrocarbons alkenes, alkynes, and aromatic hydrocarbons.
• Alkanes: Hydrocarbons having the general formula C_nH_2n+2, where n = 1, 2
• Alkenes: Hydrocarbons that contain one or more carbon-carbon double bonds. They have the general formula C_nH_2n.      
• Alcohol: An organic compound containing the hydroxyl group -OH.
• Aldehydes: Compounds with a carbonyl functional group and the general formula RCHO, where R is an H atom, an alkyl, or an aromatic group.       
• Carboxylic acids: Acids that contain the carboxyl group -COOH.
• Esters: Compounds that have the general formula R’COOR, where R’ can be H or an alkyl group or an aromatic group and R is an alkyl group or an aromatic group.
• Homologous series: A series of compounds in which each member differs from the next by a specific number and kind of atoms.
• Esterification: A reaction between an alcohol and a carboxylic acid in the presence of concentrated sulphuric acid as a catalyst through boiling to produce an ester and water. e.g. reaction of ethanol, C₂H₅OH with ethanoic acid, CH₃COOH in the presence of concentrated sulphuric acid, H₂SO₄ produces ethyl ethanoate, CH₃COOC₂H₅ which is an ester with a pleasant fragrant smell.
• Fats: Solid triester of glycerol and mostly saturated fatty acids.
• Vulcanization of rubber:  A process whereby rubber is reacted with sulphur to enable the formation of cross-linkages by sulphur atoms between the rubber molecules through covalent bonds. Rubber can be vulcanized by dipping natural rubber sheets into disulphur dichloride solution in methylbenzene. Vulcanized rubber is hard whereas unvulcanized rubber is soft. Vulcanized rubber is more elastic than unvulcanized rubber.
• Coagulation of latex: A process of converting liquid latex to solid natural rubber by adding an acid. Coagulation of latex occurs rapidly when an acid is added to the latex. Latex does not coagulate when an alkali is added to the latex. Alkaline solutions contain hydroxide ions which neutralize the acid produced by bacteria. Hence, it prevents the latex from coagulating. 

Indicators and their colours in acid and alkaline solution

• An indicator is substances that have distinctly different colors in acidic and basic media. Many indicators are dyes which have been extracted from natural sources, for example litmus. 
• Methyl orange, a common indicator used in titrations is pink in an acid solution but changes to show a yellow colour in an alkaline solution. 
• Phenolphthalein is pale-yellow crystals; soluble in alcohol, ether, and alkalis, insoluble in water; used as an acid-base indicator (carmine-colored to alkalis, colorless to acids) for titrations. 

Electrolysis of molten lead (II) bromide

During the electrolysis of molten lead(II) bromide, PbBr₂, bromine gas, Br₂ is released at the cathode while the lead metal is formed at the anode.  

Pb²⁺ and Br^- ions are present in the molten lead(II) bromide, PbBr₂.  At the anode, bromide ions, Br^- are discharged by donating electrons to form bromine molecules, Br₂. At the cathode, each lead(II) ion, Pb²⁺ is discharged by accepting two electrons to form a lead atom.

Formation of hydrogen molecules

Hydrogen atom has one valency. To become stable with hydrogen atom, it needs one more electron, When 2 hydrogen atoms join, they share their electrons, on which, the share becomes 2 electrons, which is now a noble gas configuration, being shared between these 2 atoms.

H – H single bond [they share an electron pair (2 electrons)].

Summary of Laws of Thermodynamics

• First Law: In any process, the total energy of the universe remains constant.

Universe = system + surroundings.

• Second Law: In any spontaneous process, the overall entropy of the universe increases.
• Third Law: As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

Rules for figuring out oxidation numbers

• Atoms in elemental form have an oxidation number of zero.
• Single-atom (monoatomic) ions have an oxidation number equal to their charge.
• In a neutral compound, oxidation numbers add up to zero. In a charged compound, oxidation numbers add up to the compound’s charge.
• In compounds, oxygen usually has an oxidation number of –2, in which its oxidation number is –1.
• In compounds, hydrogen has an oxidation number of +1 when it bonds to nonmetals and an oxidation number of –1 when it bonds to metals.
• In compounds

Group 1 atoms (alkali metals) have oxidation number +1.

Group 2 atoms (alkaline earth metals) have oxidation number +2.

Group 3 atoms have oxidation number +3.

Group 17 atoms (halogens) usually have oxidation number –1.