Chemical Equations and Reactions By: Erica, Brittany, Dana

5 Types of Chemical Reactions There are 5 different types of reactions: Synthesis Decomposition Single replacement Double replacement Combustion They are used to predict the products of specific reactions

Synthesis Two or more elements or compounds combine to make one compound A+B AB Example: 2Mg+O₂ Combine elements Mg and O to make one compound 2Mg+O₂2MgO

Practice Synthesis Synthesis C+O₂ S₈+8O₂

Practice Synthesis Synthesis C+O₂CO₂ S₈+8O₂8SO₂

Decomposition A compound is broken down into 2 or more elements or compounds ABA+B Examples: 2H₂O Break down the compound 2H₂O 2H₂O2H₂+O₂

Practice Decomposition 2HgO CaCO₃

Practice Decomposition 2HgO2Hg+O₂ CaCO₃Ca+CO₂

Single Replacement One part of a compound switches places with an element, forming a new compound A+BCAC+B Examples: Fe+CuSO₄ Switch compounds Fe and Cu Fe+CuSO₄Cu+FeSO₄

Practice single replacement 2Na+2H₂0 Mg+2HCl

Practice single replacement 2Na+2H₂02NaOH+H₂ Mg+2HClH₂+MgCl₂

Double Replacement Parts of 2 compounds switch places to form 2 new compounds AB+CDAD+CB Examples: 2KI+Pb(NO₃)₂ Elements K and Pb Switch places 2KI+Pb(NO₃)₂2KNO₃+PbI₂

Practice Double Replacement FeS+2HCl HCl+NaOH

Practice Double Replacement FeS+2HClH₂S+FeCl₂ HCl+NaOHNaCl+H₂O

Combustion Any hydrocarbon burned in oxygen to form carbon dioxide and water Examples of combustion are burning of natural gas, propane, gas, and wood Example: CH₄+O₂ CO₂+H₂O Methane is burned in oxygen and creates carbon dioxide and water

Practice Combustion Combustion 2H₂+O₂ C₃H₈+5O₂

Practice Combustion Combustion 2H₂+O₂2H₂O C₃H₈+5O₂3CO₂+4H₂O

Activity Series A list of elements used to help predict whether or not a reaction will occur The elements are organized according to the ease with which the elements undergo certain chemical reactions In a single replacement reaction, an element can replace any element lower than it on the series

How about Zn + CaCl₂  ? How about Cu+ AgNO3  ? Will this reaction occur? Zn + HCl  ? How about Zn + CaCl₂  ? How about Cu+ AgNO3  ?

How about Zn + CaCl₂  ? How about Cu+ AgNO3  ? Will this reaction occur? Zn + HCl  ? Yes, Hydrogen is lower than Zinc on the activity series. Therefore, Zinc will combine with Chlorine, and Hydrogen will separate from Zinc. Zn + 2HCl  ZnCl₂ + H₂ How about Zn + CaCl₂  ? How about Cu+ AgNO3  ?

How about Zn + CaCl₂  ? How about Cu+ AgNO3  ? Will this reaction occur? Zn + HCl  ? Yes, Hydrogen is lower than Zinc on the activity series. Therefore, Zinc will combine with Chlorine, and Hydrogen will separate from Zinc. Zn + 2HCl  ZnCl₂ + H₂ How about Zn + CaCl₂  ? Will not occur How about Cu+ AgNO3  ? Will occur

Balancing Equations Equations should be balanced because the Law of Conservation of Matter states that mass can not be lost or gained in a chemical reaction. Therefore, the total mass of the reactants must equal total mass of the products

Balancing Decomposition of H₂O Water  hydrogen + oxygen H₂O  H₂ + O₂ because hydrogen and oxygen exist as diatomic molecules There are two H molecules and one O molecule in the reactants There are two H molecules and two O molecules in the products This is not balanced

Balancing Decomposition of H₂O H₂O  H₂ + O₂ 2 H₂O  H₂ + O₂ Now there are more H molecules on the reactant side 2 H₂O  2 H₂ + O₂ Now there are 4 H molecules on each side and 2 O molecules on each side Now it’s balanced! 

Writing and Balancing Practice methane + oxygen  carbon dioxide + water CH₄+ O₂  CO₂+ H₂O CH₄+ 2 O₂  CO₂+ 2 H₂O Try this! Zinc + hydrochloric acid  zinc chloride + hydrogen Zn + HCl  ZnCl₂ + H₂ Zn + 2 HCl  ZnCl₂ + H₂

Writing and Balancing Practice Try this! Iron sulfide + hydrochloric acid Yield Hydrogen sulfide + iron (III) chloride FeS+HCl  H₂S + FeCl₂ FeS+2 HCl  H₂S + FeCl₂

Sources http://www.jesuitnola.org/upload/clark/refs/ solu_act.htm (activity series)