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Types of Chemical Reactions. A chemical equation describes a chemical change. The Law of Conservation of Mass says that the number and kind of atoms going INTO a chem. rxn must be the same as the number and kind of atoms coming OUT.
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A chemical equation describes a chemical change. • The Law of Conservation of Mass says that the number and kind of atoms going INTO a chem. rxn must be the same as the number and kind of atoms coming OUT. • Balancing an equation makes it obey the Law of Conservation of Mass. Review
Types of Reactions • Chem. rxns are often separated into different categories.
Types of Chemical Reactions The five types of chemical reactions we will discuss are: Synthesis Decomposition Single Displacement Double Displacement Combustion
Synthesis Reactions Two or more substances combine to form one substance. The general form is A + X AX Example: 2Mg + O2 2MgO
Decomposition Reactions One substance reacts to form two or more substances. The general form is AX A + X Example: 2H2O 2H2 + O2
Single Displacement Reactions A metal replaces a metal ion (or H+) in a cmpd. The general form is A + BX AX + B A nonmetal replaces a nonmetal ion in a cmpd. The general form is Y + BX BY + X
Single Displacement Reactions Examples: Ni + AgNO3 Nickel replaces the metallic ion Ag+. The silver becomes free silver and the nickel becomes the nickel(II) ion. Ni + 2AgNO3 2Ag + Ni(NO3)2
Double Displacement Reactions Ions of two compounds exchange places with each other. The general form is: AX + BY AY + BX
Double Displacement NaOH + CuSO4 The Na+ and Cu2+ switch places. Na+ combines with SO42- to form Na2SO4. Cu2+ combines with OH- to form Cu(OH)2 2NaOH + CuSO4 Na2SO4 + Cu(OH)2
Combustion Reaction When a substance combines with oxygen, a combustion reaction results. Combustion Reaction: A fuel reacts with oxygen to produce oxides of the fuel’s elements. The combustion reaction may be burning of a fuel.
Combustion Reaction When hydrocarbon compounds are burned in oxygen, the products are water and carbon dioxide. CH4 + 2O2 CO2 + 2H2O
Combustion Reactions Combustion reactions release light and heat. Natural gas, propane, gasoline, etc. are burned to produce heat energy. Most of these organic reactions produce water and carbon dioxide. If any elements are present in the fuel besides C and H, the reaction will also produce oxides of those elements.
Practice Classify each of the following reactions: H2 + Cl2 2HCl Synthesis Ca + 2H2O Ca(OH)2 + H2 Single displacement
Practice 2CO + O2 2CO2 Synthesis 2KClO3 2KCl + 3O2 Decomposition
Practice CH3SH + 3O2 CO2 + 2H2O + SO2 Combustion Zn + 2HCl ZnCl2 + H2 Single replacement
Predicting the Outcomes of Chemical Reactions • Predicting Single Displacement Outcomes • Need activity series handout. • Any metal on the activity series is capable of displacing any metal ion below it. • Metals cannot displace more active metals. • If a metal is placed in contact with a compound that has a more active metal, no reaction will occur. • A halogen can displace any halogen beneath it. • Example: Cl2 can displace Br-1 ions and I-1 ions from compounds, but it cannot displace F-1 ions.
Predicting the Outcomes of Chemical Reactions • Predict whether a chem. rxn will occur in each of the following cases, and if it does, what products it will form. • Mg + Cu(NO3)2 ??? • Mg is higher than Cu on the activity series. • Mg will displace Cu from Cu(NO3)2. • The expected products are Mg(NO3)2 and Cu. • Mg + Cu(NO3)2 Mg(NO3)2 + Cu • Fe + AlCl3 ??? • Fe is lower than Al on the activity series. • There will be no chemical reaction.
Predicting the Outcomes of Chemical Reactions • Would you expect each of the following chemical reactions to occur as written? • Li + NaCl LiCl + Na • 2Al + 3CuCl2 2AlCl3 + 3Cu • Ni + Zn(NO3)2 Ni(NO3)2 + Zn • Mg + 2HBr MgBr2 + H2 • F2 + 2KBr 2KF + Br2 • I2 + 2KBr 2KI + Br2
Predicting the Outcomes of Chemical Reactions • Predicting Double Displacement Outcomes • Need solubility rules handout. • A dbl displacement reaction will occur if at least one of its products is insoluble.
Predicting the Outcomes of Chemical Reactions • Predict whether a chem. rxn will occur in each of the following cases, and if it does, what products it will form. • NaOH + Cu(NO3)2 ??? • Two possible products: NaNO3 and Cu(OH)2 • NaNO3 is soluble, but Cu(OH)2 is not. • This reaction will proceed. • KCl + Fe(NO3)3 ??? • Two possible products: KNO3 and FeCl3 • KNO3 and FeCl3 are both soluble. • There will be no chemical reaction.