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10 CHEMISTRY 20 Simple Composition (Formation) and Simple Decomposition Reactions! (sc aka f) elements combine to form one single product! (sd) reactant breaks down to form pure elements from the periodic table! all elements are in the state found on the periodic table at SATP, unless otherwise given! ionic compounds are always solid! molecular compounds have states that are memorized, are common, or are given eg: aluminum and oxygen react to produce an oxide coating on the aluminum metal.! Identify reactants and products:!! Al + O > AlO! Write out proper formulas:!!! Al + O > Al 2 O 3! Balance the atoms on both sides:! 4Al + 3O > 2Al 2 O 3! Identify the states of matter:!! 4Al (s) + 3O 2(g) > 2Al 2 O 3(s) eg: Calcium phosphate decomposes into pure elements.! Identify reactants and products:!! CaSO > Ca + S + O! Write out proper formulas:!!! CaSO > Ca + S 8 + O 2! Balance the atoms on both sides:! 8CaSO > 8Ca + S O 2! Identify the states of matter:! 8CaSO 4(s) -----> 8Ca (s) + S 8(s) + 16O 2(g) Write the chemical reaction for each of the following situations. 1. Potassium reacts with bromine in a single composition reaction. 2. Sulfur combines with oxygen in a reaction which produces sulfur trioxide. 3. The product of a simple composition reaction is barium phosphide. 4. Sulfuric acid can decompose into its elemental forms. 5. Iron (III) hydroxide can decompose into three different elements. 6. After decomposition occurs the result is production of phosphorus and lead. 7. When ammonium benzoate breaks down, the result is a bit tricky to balance!!!!!! 8. Gold reacts with oxygen from the air, producing an oxide coating on jewelry. 9. Hydrogen and sulfur react in a sulfur refining plant, producing sour gas. 10. Ethanol can be formed from a composition reaction. 11. Tin reacts with chlorine. 12. Sucrose can produce pure elements from a form of decomposition reaction. BE SURE TO INCLUDE ALL STATES OF MATTER AND BALANCE REACTIONS

11 CHEMISTRY 20 Single and Double Replacement Reactions! (sr) an ionic compound (or water) reacts with an element! (dr) two ionic compounds react! ionic reactants are almost always dissolved in water (aqueous).! pure elements are in their SATP state, unless otherwise specified.! solubility of ionic compounds, as products, is determined by the solubility table, at SATP! like charged ions always replace like charges, like charges never join together. (ie. + replaces + and - replaces -)! in converting atoms to multivalent ions, use the top (most common) ion unless otherwise specified.! in sr and dr rxns water is best written as HOH (think of it as H + and OH ) rather than H 2 O eg: Solutions of potassium hydroxide and barium nitrate react to form a precipitate.! KOH + Ba(NO 3 ) > KNO 3 + Ba(OH) 2! NOTE: negative ions exchanged places! KOH (aq) + Ba(NO 3 ) 2(aq) > KNO 3 + Ba(OH) 2! NOTE: Ionic reactants are dissolved in solution (aqueous)! KOH (aq) + Ba(NO 3 ) 2(aq) > KNO 3(aq) + Ba(OH) 2(s)! NOTE: According to the solubility table, nitrates form soluble compounds.!! According to the solubility table, hydroxide with barium has low solubility.! 2KOH (aq) + Ba(NO 3 ) 2(aq) > 2KNO 3(aq) + Ba(OH) 2(s)! NOTE: Balance the compounds, balancing the whole ions where possilbe.!! DO NOT use the number one as a coefficient in balancing. eg: Bromine will react with aluminum sulfide, resulting in a color change.! Br 2 + Al 2 S > AlBr 3 + S 8! NOTE: negative ions exchanged places! Br 2(l) + Al 2 S 3(aq) > AlBr 3 + S 8! NOTE: Ionic compounds are dissolved in solution (aqueous)! Br 2(l) + Al 2 S 3(aq) > AlBr 3(aq) + S 8(s)! NOTE: According to the solubility table, bromide forms a soluble compound.!! Sulfur, as a pure element, forms a solid.! 24Br 2(l) + 8Al 2 S 3(aq) > 16AlBr 3(aq) + 3S 8(s)! NOTE: Balance the compounds, balancing the whole ions where possible.!! Balance the largest coefficient first. Write the complete chemical reactions for the following examples. 1. A piece of magnesium metal reacts with a solution of lithium sulfide. 2. A sample of iron will react with a nickel (II) sulfate solution, resulting in a color change. 3. Fluorine gas is bubbled through a potassium iodide solution. 4. A small piece of lithium is dropped into water. 5. A piece of copper is dropped into a silver nitrate solution. 6. Silver nitrate and chromium (II) bromide will react to form a solid. 7. Benzoic acid can be neutralized by adding a solution of barium hydroxide. 8. A lead (II) nitrate solutiion will react when mixed with a sodium iodide solution. 9. Strontium hydroxide can be used to neutralize stomach acid (hydrochloric acid). 10. Scrap iron reacts with copper(ii) sulfate solution. 11. Copper, when placed in a sulfuric acid solution, will produce gas bubbles. 12. Gold (III) chloride and sodium hydroxide will react easily 13. Manganese and water, when placed in the same beaker, will turn litmus paper blue.

12 Combustion Reactions See page 103 of the text for additional examples and notes. In general: substance + oxygen --> common oxide(s) If the burning substance contains:! C it produces CO2(g)! H it produces H2O(g)! S it produces SO2(g)! N it produces NO2(g)! a metal it produces the metal s common oxide Steps: a)! Use the chart above to predict the products.! Example: C2H2S2(l) reacts with oxygen to produce CO2(g) and H2O(g) and SO2(g) because it contains C, H, and S. b)! Balance all the atoms other than oxygen first. c)! Count oxygen atoms on the product side. d)! Balance oxygen atoms on the reactant side last. Note:! Fractional coefficients for oxygen are permitted in combustion reactions.! Watch for oxygen within the substance burning (ie. methanol) when balancing.! The combustion of metals can also be classified as formation. Example: Sucrose is burned. C12H22O11(s) + O2(g) ---> CO2(g) + H2O(g) Note: CO2(g) and H2O(g) are produced as the substance burning contains C and H atoms Balance atoms other than oxygen first: C12H22O11(s) + O2(g) ---> 12CO2(g) + 11H2O(g) Count oxygen atoms on the product side: Carbon dioxide: 12 2 = 24 water: 11 1 = 11 Total = = 35 Balance oxygen atoms on the reactant side: Total must be 35 O atoms. Sucrose has 11 O atoms, leaving 24 for O2(g). Each O2(g) molecule has 2 atoms, so the coefficient is 24 2 = 12. C12H22O11(s) + 12O2(g) ---> 12CO2(g) + 11H2O(g) Practice reactions: 1. Methane is burned in a furnace. 2. A welding torch burns acetelyne, C2H2(g). 3. Propane is burned in a barbecue. 4. C4H6S2(s) is burned. 5. A magnesium ribbon is burned. 6. Urea, which is used as a fertilizer, and has the formula CH4N2O(s), is burned.