Some+Simple+Patterns+of+Chemical+Reactivity

__Combination Reaction__ – When **two or more** substances react to form **one** product ★ When a combination reaction occurs between a metal and nonmetal the product will be an ionic solid

A + B → AB

Example of Combination Reaction: CaO(s) + SO2(g) ---> CaSO3(s) The reaction of calcium oxide with sulfur dioxide to form calcium sulfite.

__Decomposition Reaction__ – When **one** substance undergoes a reaction to produce **two or more new** substances ★ Many compounds go through a decomposition reaction when they are heated

AB → A + B

Example of a Decomposition Reaction: 2KClO3 → 2KCl + 3O2 The decomposition of Potassium Chlorate to produce Potassium Chloride and Oxygen.

**Single Replacement Reaction**: Occurs when a compound reacts with a single element and the element raplaces one part of the original compound AX + B ® A + BX This reaction will only occur when A is more reactive than B. A and B must either both be metals, making X an anion or both halogens, making X a cation.

Ex: 2AgNO3(aq) + Zn(s) → 2Ag(s) + Zn(NO3)2(aq) In this example, the zinc replaces the silver in silver nitrate.

Occurs when two ionic compounds react and the cations switch their anions. AX + BY ® AY + BX In this kind of reaction, a precipitate, a gas or a slightly ionized compound will be formed. Solubility Rules for Precipitates: __ Mainly Water Soluble __ Nitrates Acetates except AgCH3COO Chlorates Chlorides except AgCl, Hg2Cl2, PbCl2 Bromides except AgBr, PbBr2, Hg2Br2, HgBr Iodides except AgI, Hg2I2, HgI2, PbI2 Sulfates except BaSO4, PbSO4, Hg2SO4, CaSO4, Ag2SO4, SrSO4 All alkali metal and ammonium cations
 * Double Replacement Reaction**:

__Mainly Water Insoluble__ (All become soluble when paired with an alkali metal or ammonium) Carbonates Chromates except CaCrO4, SrCrO4 Hydroxides except Ba(OH) 2, Sr(OH) 2, Ca(OH) 2 Phospahtes Sulfites Sulfides except when paired with an alkaline earth metal

Ex: (NH4) 2S + Pb(NO3) 2 ® PbS + 2NH4NO3 In this example the ammonium and lead swith places. The ammonium cation is always soluble so the ammonium nitrate is aqueous and the sulfide anion is always insoluble so the lead sulfide is a precipitate.

-rapid reactions that produce a flame -most involve O 2 from the air as a reactant
 * Combustion Reactions **

Hydrocarbons are compounds that only contain carbon and hydrogen Ex. CH 4 and C 2 H 4

-when hydrocarbons combust in air they react with O 2 to form CO 2 and H 2 O

-the amount of O 2 used and of CO 2 and H 2 O produced, depends on the composition of the hydrocarbon present, as the hydrocarbon is the limiting reactant Ex. C 3 H 8 (g) + O 2 (g) à CO 2 (g) + H 2 O (g) C 3 H 8 (g) + O 2 (g) à  3 CO 2 (g) + H 2 O (g) C 3 H 8 (g) + O 2 (g) à 3CO 2 (g) + 4 H 2 O (g) C 3 H 8 (g) + 5 O 2 (g) à 3CO 2 (g) + 4H 2 O (g)

-the state of the H 2 O, gas or liquid, depends on the conditions of the reaction. Water vapor is formed at high temperatures in an open container

-oxygen-containing derivatives of hydrocarbons also produce CO 2 and H 2 O when combusted Ex. 2CH 3 OH + 3O 2 à 2CO 2 + 4H 2 O  -if there is an insufficient quantity of O 2  present, carbon monoxide (CO) is produced along with CO 2. If the quantity of O 2 <span style="font-family: 'Times New Roman'; font-size: 12pt; mso-ansi-language: EN-US; mso-bidi-language: AR-SA; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US;">is severely restricted, small particles of carbon will be produced. Only //complete// combustion produces CO <span style="font-family: 'Times New Roman'; font-size: 8pt; mso-ansi-language: EN-US; mso-bidi-language: AR-SA; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US;">2 <span style="font-family: 'Times New Roman'; font-size: 12pt; mso-ansi-language: EN-US; mso-bidi-language: AR-SA; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US;">. However, unless otherwise stated, take combustion to mean //complete// combustion.

Works Cited [] [] [] [] Chemistry: The Central Science Ninth Edition, Brown, LeMay, Bursten, Burdge Hon. Chem Notes