Types of Chemical Reactions Synthesis, Combustion, Decomposition and Replacement
You can think of atoms as people getting together as couples... Analogy One person A couple Switching partners Chemical Reaction An ion or element A compound A replacement reaction
The Get Together
Synthesis
Decomposition
Decomposition
Single Replacement Reactions
Single Replacement Reactions
Double Replacement Reaction
Double Replacement Reaction
Combustion
Combustion
How does this analogy break down? People in Relationships People can switch partners whenever they want We usually just think about one partner and one couple People don t assume different states of matter People aren t swimming in water Chemical Reactions The ions or elements in a compound switch partners according to rules In chemistry, we usually are dealing with billions of particles reacting at once In double replacement reactions, there will be a change of state (a solid, liquid, or gas is formed) Displacement reactions generally happen in aqueous solutions
Let s look at the reactions in more detail Synthesis Decomposition Single-Replacement Double-Replacement Combustion
Combustion What are some types of combustion you are familiar with? Every cell in your body is carrying out combustion
Combustion Oxygen combines with a metal, non-metal, or compound Creates a metal oxide, non-metal oxide, or 2 or more oxides Releases energy heat, light Can be a slower process too
Synthesis 2 or more reactants combine to make a product A B AB
Decomposition A compound breaks down into two or more substances
Single Replacement A metal replaces a hydrogen A metal replaces another metal We use an activity series to predict which metals are stronger and can knock out other metals from compounds
Activity Series The most active metals are at the top. These will replace metals below them. The halogens are also listed in order of most active at the top to least active at the bottom. More active elements replace less active elements in single replacement reactions
Single Replacement Examples 2 AgNO3 + Cu Cu(NO3)2 + 2 Ag Fe + Cu(NO3)2 Fe(NO3)2 + Cu Zn + 2HCL ZnCl2 + H2
Double Replacement Reactions Produces a precipitate, liquid or gas All four of the ions switch partners Aqueous solution
Double Replacement Examples AgNO3(aq) + KCl(aq) AgCl(s) + KNO3(aq) CaCO3(aq) + 2 HCl(aq) CaCl2(aq) + H2O(l) + CO2(g) HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq)
Steps to determine type of reaction Write the chemical equation How to identify a reaction Be systematic it will help you identify the reaction type and the products! Determine what is happening in the reaction Use the table to identify the type of reaction Check your answer by comparing the chemical equation to the generic equation
Example: Identifying a reaction How to identify a reaction Example: Solid calcium oxide and carbon dioxide gas react to produce solid calcium carbonate CaO (s) + CO2 (g) CaCO3 (s) 2 compounds are reacting to form one compound This is a synthesis reaction A + B AB
Summary The main types of reactions Combustion reaction with oxygen Synthesis two compounds or elements getting together Decomposition One compound splitting up Replacement Another ion moves in Replacement Reactions: 2 types Single replacement a stronger cation steps in and replaces a weaker anion Double replacement 2 cations switch places, forming a precipitate, a liquid, or a gas
You try it! Work on these examples together in pairs. Write the reaction Balance the equation Classify the reaction Be prepared to present your results on the board! Magnesium and Hydrochloric acid form Magnesium Chloride and Hydrogen Carbon Dioxide and Water form Carbonic Acid (H2CO3) Silver Nitrate and Sodium Chloride form Silver Chloride and Sodium Nitrate Heating sodium bicarbonate (NaHCO3) releases water and carbon dioxide and sodium carbonate
You try it! Magnesium and Hydrochloric acid form Magnesium Chloride and Hydrogen: Mg + HCl MgCl + H2 (skeleton equation) 2Mg + 2HCl 2MgCl + H2 (balanced equation) Single replacement (reaction type) Carbon Dioxide and Water form Carbonic Acid (H2CO3): CO2 + H2O H2CO3 (skeleton equation) CO2 + H2O H2CO3 (it s already balanced!) Synthesis (reaction type)
You try it! Silver Nitrate and Sodium Chloride form Silver Chloride and Sodium Nitrate AgNO3 + NaCl AgCl + NaNO3 (skeleton equation) AgNO3 + NaCl AgCl + NaNO3 (already balanced) Double replacement (reaction type) Heating sodium bicarbonate releases water and carbon dioxide and sodium carbonate NaHCO 3 Na 2 CO 3 + H 2 O + CO 2 (skeleton equation) 2NaHCO 3 Na 2 CO 3 + H 2 O + CO 2 (balanced equation) Decomposition (reaction type)