Classification of Chemical Reactions: a Taxonomy Approach

What in Taxonomy?

Can we use Taxonomy to help Identify chemical reactions and predict the products formed?

What creatures are these even? On Your Own: Identify each organism List the physical traits that IMMEDIATELY helped you determine their identity Predict at least 3 behaviors that would be observed in the wild for each organism based on the fact that you know what kind of animal it is. Reflect: Why is quickly predicting the behavior of animal helpful? This Photo by Unknown Author is licensed under CC BY-SA This Photo by Unknown Author is licensed under CC BY-SA

1 fish, 2 fish…wut? On Your Own: list the DIFFERENCES between the two fish shown As A Team: guess at the identity of each fish (based on the traits listed) As A Team: use the Internet to confirm your guesses Discussion #1: what were the key details that helped you distinguish between the two fish? Discussion #2: if you were fishing, why might being able to tell the difference between similar-looking fish be important? This Photo by Unknown Author is licensed under CC BY This Photo by Unknown Author is licensed under CC BY-NC This Photo by Unknown Author is licensed under CC BY-SA

What in the whale do elephants and fish have to do with chemistry? 1 Being able to quickly identify the type of chemical reaction represented or observed in the lab is a CRITICAL SKILL 2 Chemical reactions are represented multiple ways Words Chemical formulas in a balanced equation Particulate drawings By experimentation

REACTIONS B. HCl (g) C. Al (s) + Br2 (s) D. HCl (aq) + Mg (s) A. Pb(NO3)2 (aq) + KI (aq) B. HCl (g) C. Al (s) + Br2 (s) D. HCl (aq) + Mg (s) E. KClO3 (s) F. C3H8 (g) + O2 (g) Have students work together to accomplish the following tasks for each reaction: 1) list the physical traits of each reaction (e.g. physical state, type of compound) 2) make a prediction about the product(s) *conservation of mass!!! 3) predict the type of reaction (based on what they already know or have read This Photo by Unknown Author is licensed under CC BY-NC

Acid or Base Ionization 1) acids release H+ to form H3O+ and a conjugate base 2) Bases REACT with H2O to form a conjugate Acid and OH- The anion (conjugate base) and cation (conjugate acid) of the parent acid and base are formed. This Photo by Unknown Author is licensed under CC BY This Photo by Unknown Author is licensed under CC BY This Photo by Unknown Author is licensed under CC BY-NC-SA

Types of Chemical Reactions: Acid Base Neutralization The anion of the base and the hydrogen cation from the acid react to produce water in the net ionic equation. A soluble salt is also produced In the case of carbonates (CO32-), bicarbonates (HCO31-), sulfites(SO32-) and sulfides (S2-), neutralization reactions lead to the production of gases. This Photo by Unknown Author is licensed under CC BY-NC-SA Types of Chemical Reactions: Acid Base Neutralization

Type of Chemical Reaction: Oxidation-Reduction (redox) Change in oxidation number occurs in the reactants to give products that are different in both oxidation number and chemical identity This Photo by Unknown Author is licensed under CC BY-NC-SA

All Kinds of Redox Reactions Combination (synthesis)* *not all combination reactions are redox reactions Decomposition **Combustion Disproportionation Displacement Hydrogen displacement Metal displacement Halogen displacement All of the reactions listed can be found on pages 137-141. You need to KNOW all of the redox reactions **It turns out that creepers undergo a type of redox reaction… This Photo by Unknown Author is licensed under CC BY-NC-ND

Redox Reactions: Quick Reference Combination (synthesis): 2 or more elements or molecules COMBINE to form 1 product. Change in oxidation number MAY occur. Decomposition: 1 molecule BREAKS down into 2 or more elements or molecules. Change in oxidation number ALWAYS occurs. Combustion: a molecule or substance combines with oxygen to produce heat and light. Combustions that only form 1 product are also combination reactions with redox. Disproportionation: an element in a substance undergoes oxidation and reduction to give different products containing atoms of the element with differing oxidations numbers Displacement: an ion or atom in a compound is replaced by an ion or atom of a different element Hydrogen displacement: H2 is produced when a reactive metal oxidizes H+ from water or acid Metal displacement: a more reactive metal is oxidized to a cation while reducing a less reactive metal to its elemental state Halogen displacement: a more reactive elemental halogen reduces a halide anion You should go through the text in the book (pgs 137-144) and annotate your notes (or this slide) with examples of each type of redox reaction

Quick Reference Notes Combination Decomposition Combustion Disproportionation

Quick Reference Notes Displacement Hydrogen Displacement Metal Displacement Halogen replacement

A reaction by any other name is still a Double Displacement Reaction…or. . . Precipitation Reactions…or…Double Replacement…or…Metathesis Reactions 2 ionic compounds in solution “switch partners” NO change in oxidation number occurs! Solubility rules help determine if a solid product (precipitate) will be formed (see handout or pg 122) May produce gases in there are carbonates (CO32-) present Acid base neutralizations are a type of double displacement reaction, but are generally NOT a precipitation reaction UNLESS an insoluble salt forms This Photo by Unknown Author is licensed under CC BY-NC-SA

REACTIONS B. HCl (g) C. Al (s) + Br2 (s) D. HCl (aq) + Mg (s) A. Pb(NO3)2 (aq) + KI (aq) B. HCl (g) C. Al (s) + Br2 (s) D. HCl (aq) + Mg (s) E. KClO3 (s) F. C3H8 (g) + O2 (g) Have students use what they have now learned about the different types of reactions to revise their earlier work This Photo by Unknown Author is licensed under CC BY-NC

YOUR TURN Discuss with your group (no more than 3 people) how you could organize all of the information presented about the different types of chemical reactions into a visual aid for easy reference (5-6 minutes) What is the best way to apply visual support, organization, and elaboration to help manage the material? Apply what you have discussed to your personal study time…especially the HW assignement