1. Chemistry 2 Molecular Quantities J Young

2. A chemical change: any change in which a new substance is formed. Evidence of a Chemical Change:  Release of energy as heat  Release of energy as light  Change in colour  Formation of a gas  Change in odour…

3. 1.Neutralization: Acid(H) + Base(OH)  salt + H(OH) 2.Combustion: AB + oxygen  CO 2 + H 2 O 3.Synthesis: A + B  AB 4.Decomposition: AB  A + B 5.Single displacement: A + BC  AC + B 6.Double displacement: AB + CD  AD + CB

4. –A + B  AB where A and B represent elements –The elements may form ionic compounds, like… –Sodium metal and chlorine gas combine to form sodium chloride. –2Na + Cl 2  2NaCl Sodium added to chlorine gas Synthesis reactions are also known as FORMATION reactions. Two or more reactants (usually elements) join to form a compound.

6. Decomposition reactions are the opposite of synthesis reactions. –A compounds breaks down into two or more products (often elements). –AB  A + B where A and B represent elements 1. Ionic compounds may decompose to produce elements, like the following: Table salt, sodium chloride, can be broken down into sodium metal and chlorine gas by melting salt at 800ºC and running electricity through it. 2NaCl  2Na + Cl 2

7. (c) McGraw Hill Ryerson 2007 See page 260

8. Types: Decomposition Example: NaCl General: AB  A + B  Cl Na Cl + Na

9. Types: Decomposition Example 2HgO  O Hg O OO + General: AB  A + B

10. 2. Covalent compounds may decompose into elements, like the following: By running electricity through water, the water molecules decompose into hydrogen and oxygen gases. 2H 2 O  2H 2 + O 2 DECOMPOSITION REACTION: http://www.youtube.com/wa tch?v=NddwtXEA_Ak

11. Single replacement reactions replace one element from a compound with another element. –A compound and an element react, and the element switches places with part of the original compound. A + BC  B + AC where A is a metal, or A + BC  C + BA where A is a non-metal

13. Types: Single displacement Example: Zn + CuCl 2  Zn Cl Cu + General: AB + C  AC + B Cl Zn Cu +

14. 1. When A is a metal: Aluminum foil in a solution of copper(II) chloride produces solid copper and aluminum chloride. 2Al + 3CuCl 2  3Cu + 2AlCl 3 2. When A is a non-metal: When fluorine is bubbled through a sodium iodide solution, iodine and sodium fluoride are produced. Fl 2 + 2NaI  I 2 + 2NaF SINGLE REPLACEMENT: http://www.youtube.com/watch?v=hKtynbVtMKc

15. (c) McGraw Hill Ryerson 2007 Double replacement reactions swap elements between 2 compounds that react together to form two new compounds. –Two compounds react, with elements switching places between the original compounds. AB + CD  AD + CB See page 262

16. (c) McGraw Hill Ryerson 2007 See page 262

17. Types: Double displacement Example: MgO + CaS General:AB + CD  AD + CB S O  Mg Ca + O S Mg Ca +

18. (c) McGraw Hill Ryerson 2007 –When potassium chromate and silver nitrate react, they form a red precipitate, silver chromate, in a solution of potassium nitrate. –K 2 CrO 4 + 2AgNO 3  Ag 2 CrO 4 + 2KNO 3 silver chromate Two solutions react to form a precipitate (solid) and another solution. Ionic solution + ionic solution  ionic solution + ionic solid. AB + CD  AD + CB DOUBLE REPLACEMENT: http://www.youtube.com/watch?v=opY3FLrPTa4

19. (c) McGraw Hill Ryerson 2007 Neutralization reactions occur when an acid (most compounds starting with H) and a base (most compounds ending in OH) react to form a salt and water. Neutralization reactions are a type of double replacement. Acid + base  salt + water HOH HX + MOH  MX + H 2 O where X and M are elements See page 263

20. (c) McGraw Hill Ryerson 2007 1. Sulfuric acid is used to neutralize calcium hydroxide: H 2 SO 4 + Ca(OH) 2  CaSO 4 + 2H 2 O 2. Phosphoric acid helps to neutralize the compounds that cause rust, such as iron(II) hydroxide. H 3 PO 4 + 3Fe(OH) 2  Fe 3 (PO 4 ) 2 + 6H 2 O See page 263 NEUTRALIZATION: http://www.youtube.com/watch?v=_P5hGzA6Vb0

21. (c) McGraw Hill Ryerson 2007 Combustion reactions occur when a compound or element react with oxygen to release energy and produce an oxide. –Also sometimes referred to as hydrocarbon combustion. C X H Y + O 2  CO 2 + H 2 O where X and Y represent integers See page 264 METHANOL + oxygen: http://www.youtube.com/watch?v=98JuJ-G1qXY&feature=related

22. (c) McGraw Hill Ryerson 2007 1. Natural gas (methane) is burned in furnaces to heat homes. »CH 4 + O 2  CO 2 + 2H 2 O + energy 2. An acetylene torch is used to weld metals together. »2C 2 H 2 + 5O 2  4CO 2 + 2H 2 O + energy 3. Carbohydrates like glucose combine with oxygen in our body to release energy. »C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy See page 264 Acetylene torch

23. (c) McGraw Hill Ryerson 2007 See page 265 Take the Section 6.1 Quiz MOVIE TO REVIEW: http://www.bcscience.com/bc10/pgs/videos_013_chemical_reactions.html

24. Combustion Reactions Rapid oxidation of fuel source All process reboilers and heaters Auto ignition of pyrophoric materials like Iron Sulfide

25. Neutralization Reactions Boiler feed water treatment Waste water treatment facility Chloride traps – reformer Caustic Scrubbers in many units.

26. Exothermic and Endothermic Exothermic reactions. – Give off energy, mainly heat. – Reaction will sustain itself, continuing until all reactants are gone. – Accelerates. More heat, more reaction. More reaction, more heat. Endothermic reactions – Requires energy input, mainly heat – Reaction will discontinue with loss of energy source

27. Examples of Exothermic and Endothermic Hydrotreating reactions are exothermic – DHDS Unit – Hydrocracker – NHDS Unit – Isom Reforming reactions are endothermic

28. Solutions and Concentrations Characteristics of solutions Percent-by-weight solutions pH measurement Homogeneous solutions

29. Homogeneous Solutions Crude oil. – Evenly mixed solution of hydrocarbons from methane to asphalt. – Each type of molecule has its own properties. Boiling point. Vapor pressure. Melting point. – Refineries are based on the physical properties of hydrocarbons.

30. Oxidation and reduction in terms of oxygen transfer Definitions Oxidation is gain of oxygen. Oxidizing agents give oxygen to another substance or remove hydrogen from it. Reduction is loss of oxygen. Reducing agents remove oxygen from another substance or give hydrogen to it. Oxidation and reduction in terms of electron transfer This is easily the most important use of the terms oxidation and reduction at A' level. Definitions Oxidation is loss of electrons. Reduction is gain of electrons. Source: http://www.chemguide.co.uk/inorganic/redox/definitions.html Reduction Oxidation (Redox) 1

31. Oxidation and reduction in terms of hydrogen transfer These are old definitions which aren't used very much nowadays. The most likely place you will come across them is in organic chemistry. Definitions Oxidation is loss of hydrogen. Reduction is gain of hydrogen. Notice that these are exactly the opposite of the oxygen definitions. For example, ethanol can be oxidized to ethanal: Reduction Oxidation (Redox) 2

32. Oxidation and reduction in terms of electron transfer This is easily the most important use of the terms oxidation and reduction at A' level. Definitions Oxidation is loss of electrons. Reduction is gain of electrons. The equation shows a simple redox reaction which can obviously be described in terms of oxygen transfer. CuO + Mg  Cu + MgO Reduction Oxidation (Redox) 3

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