Chemical Reactions 2014.notebook January 06, 2015 Chemical Reactions D. Knauss RRHS Jan 58:59 AM Chemical Reaction When one or more substances change into one or more new substances with different chemical and physical properties. Jan 58:59 AM Chemical Reaction (continued) Reactants yield Products Or Reactants Products Jan 58:59 AM 1 Chemical Reactions 2014.notebook January 06, 2015 Chemical Reaction (continued) Law of Conservation of Mass: Mass is neither created nor destroyed Jan 58:59 AM 5 Types of Chemical Reactions • • • • • Single Displacement (Single Replacement) Double Displacement (Double Replacement) Combustion Decomposition Synthesis (Combination) Jan 58:59 AM Balancing Chemical Reactions • 1. Write out the names for the reactants and the products (Word Equation) • 2. Write out the chemical symbols for the elements. • 3. Balance the chemical formulas (only subscripts i.e. H2O) (Skeleton Equation) • 4. Balance the chemical equation (only coefficients 3H2O ). (Balanced Equation) Jan 58:59 AM 2 Chemical Reactions 2014.notebook January 06, 2015 Sample Equation Word Equation Silver and Iodine react to form Silver Iodide Skeleton Equation Ag + I2 > AgI Balanced Equation 2Ag + I2 > 2AgI Jan 58:59 AM Single Displacement • An element in a compound is replaced by another Jan 58:59 AM Single Displacement Aluminum + Magnesium Chloride yields Jan 58:59 AM 3 Chemical Reactions 2014.notebook January 06, 2015 Answer Write out the reactants and products in word form (Word Equation) Aluminum + Magnesium Chloride yields Aluminum Chloride and Magnesium Write out element symbols and compounds Al + MgCl > AlCl + Mg Write out the charges for the ions Al + Mg+2Cl1 > Al+3Cl1 + Mg Balance the chemical formulas (Skeleton Equation) Al + MgCl2 > AlCl3 + Mg Check how many aluminums are in the reactants and the products Al + MgCl2 > AlCl3 + Mg Check how many magnesiums are in the reactants and the products Al + MgCl2 > AlCl3 + Mg Check how many chlorines are in the reactants and the products Al + 3MgCl2 > 2AlCl3 + Mg Check how many aluminums are in the reactants and the products 2Al + 3MgCl2 > 2AlCl3 + Mg Check how many magnesiums are in the reactants and the products (Balanced Equation) 2Al + 3MgCl2 > 2AlCl3 + 3Mg Jan 58:59 AM Double Displacement Reactions • Two compounds exchange cations or anions resulting in the formation of two new compounds. Jan 58:59 AM Double Displacement Reactions (continued) • One of the following must be true: • One product precipitates from solution with one dissolved in solution • One product leaves as a gas • One product is a molecular compound that separates from the ions as an intact molecule Jan 58:59 AM 4 Chemical Reactions 2014.notebook January 06, 2015 Balance the following Double Displacement Reaction • potassium iodide and magnesium oxide Jan 58:59 AM Write out the reactants and products in word form (Word Equation) Potassium Iodide and Magnesium Oxide react to form Potassium Oxide and Magnesium Iodide Write out element symbols and compounds KI + MgO > KO + MgI Write out the charges for the ions K+1I1 + Mg+2O2 > K+1O2 + Mg+2I1 Balance the chemical formulas (Skeleton Equation) KI + MgO > K2O + MgI2 Check how many Potassiums are in the reactants and the products 2KI + MgO > K2O + MgI2 Check how many Iodines are in the reactants and the products 2KI + MgO > K2O + MgI2 Check how many Magnesiums are in the reactants and the products 2KI + MgO > K2O + MgI2 Check how many Oxygens are in the reactants and the products (Balanced Equation) 2KI + MgO > K2O + MgI2 Jan 58:59 AM Combustion • Is the reaction of a carbon based compound with oxygen. • Always involves oxygen in the reactants and carbon dioxide and water in the products • C?H? O? + O2 > CO2 + H2O Jan 58:59 AM 5 Chemical Reactions 2014.notebook January 06, 2015 Balance the following Combustion Reaction • What is the balanced equation for the combustion of methane (CH4)? Jan 58:59 AM Answer Methane + Oxygen reacts to form Water + Carbon Dioxide (Word Equation) CH4 + O2 > H2O + CO2 (Skeleton Equation) Balance Carbon CH4 + O2 > H2O + CO2 Balance Hydrogen CH4 + O2 > 2H2O + CO2 Balance Oxygen CH4 + 2O2 > 2H2O + CO2 (Balanced Equation) Jan 58:59 AM Decomposition Reactions • A single compound is broken down into two or more elements Jan 58:59 AM 6 Chemical Reactions 2014.notebook January 06, 2015 Balance the following Decomposition Reaction • dihydrogen monoxide Jan 58:59 AM Answer Word Equation Dihydrogen monoxide yields Hydrogen and Oxygen Skeleton Equation H20 > H2 + O2 Balance Hydrogen H20 > H2 + O2 Balance Oxygen 2H20 > H2 + 2O2 Balance Hydrogen 2H20 > 2H2 + O2 Jan 58:59 AM Synthesis Reactions • Two or more substances react to form a single substance Jan 58:59 AM 7 Chemical Reactions 2014.notebook January 06, 2015 Balance the following Synthesis Reaction • magnesium and oxygen Jan 58:59 AM Answer Word Equation Magnesium and Oxygen react to form Magnesium Oxide Skeleton Equation Mg + O2 > MgO Balance Magnesium Mg + O2 > MgO Balance Oxygen Mg + O2 > 2MgO Balance Magnesium 2Mg + O2 > 2MgO Jan 58:59 AM Jan 69:06 AM 8
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