Types of Chemical Reactions

1. Types of Chemical Reactions Section 11.2

2. Classifications of Chemical Reactions 5 classifications: Combination, decomposition, single-replacement, double-replacement, and combustion Allows us to predict products Combination- synthesis reaction- two or more substances combine to form a single substance. Product is always a single compound A + B ? AB

3. Synthesis or Combination Reaction

4. Classifications of Chemical Reactions Decomposition- a single compound is broken down into two or more products Products will be 2 or more elements and/or compounds AB ? A + B Products of binary decomposition The constituent elements of the compound In other words, the elements that made up the compound are the products of the reaction.

5. Decomposition Reaction

6. Classifications of Chemical Reactions Single replacement/displacement- One element replaces another element in a compound Products will be a different compound and a different element A + BC ? B + AC Either the metal replaces the metal OR the nonmetal replaces the nonmetal Use an activity series to determine if a reaction will actually occur! Activity Series- lists metals in order of decreasing reactivity Used to predict which metals will replace which other metals in a reaction More reactive (higher) solid metal can replace a less reactive aqueous metal

7. Single Displacement Reaction

8. Activity Series

9. Classifications of Chemical Reactions Nonmetals can also replace nonmetals in replacement reactions The activity of halogens decreases going down a group, so F can replace any of the others Double replacement reactions an exchange of positive ions between two reacting compounds Products will be 2 new compounds. Usually : One product is a precipitate, a gas, or a molecular compound (covalent) AB + CD ? AD + CB

10. Double Displacement

11. Classification of chemical reactions Combustion reactions- An element or compound reacts with oxygen to produce energy as heat and light. ALWAYS has O2 as a reactant Often involve hydrocarbons Products will usually be CO2 and H2O- if combustion is complete If combustion is incomplete: Soot and carbon monoxide form, so products would be C and CO

12. Combustion Reaction

13. Predicting the products 1) Identify the likely reaction type based on the reactants: Synthesis- often 2 elements Decomposition- 1 compound Single displacement- 1 compound & 1 element Double displacement- 2 compounds Combustion- O2 is a reactant

14. Predicting the products 2) Use the information in your notes about likely products to help you determine the products Synthesis- put the 2 elements together-look at the charges and use the crisscross method Decomposition- pull the compound apart- for us, it will usually be the 2 elements that make up the compound Pay attention to the diatomics

15. Predicting Products 2) continued Single Displacement- look at the activity series or halogens on the periodic table to see if the element can replace one of the elements in the compound If the reaction occurs, find the charges of the each of the elements. Trade the places of the metals OR trade the places of the nonmetals Write the new formula of the compound using the crisscross method Eliminate the charge from the new lone element and write it alone.

16. Predicting products 2) Continued Double displacement- trade the cations of the compounds- look at your formula cheat sheet to help you do this. You must pay attention to charge of your ions and use the crisscross method to write the formula. Look at your solubility table on the back of your periodic table to determine which product is solid (the insoluble one is the solid) and which is aqueous Be sure to indicate state of matter for every compound in double displacement reactions If both are aqueous (soluble), no reaction occurs. If one product is water, a reaction DOES occur. Water is a liquid

17. 2) Continued Combustion- products will be CO2 and H2O if you started with a substance containing C and H. Product will be a combination of the element and oxygen if an element was burned. (if you burn an element, the reaction is also a synthesis reaction, so you can follow the directions for synthesis)

18. Predicting Products 3) Balance the equation.