Chapter 7 Types of Reactions

Example of redox reaction where electrons transfer.

Zn (s) +Fe^2+ (aq) --> Zn^2+ (aq) + Fe (s). The 2+ is a superscript indicating charge of ion.

What do the following abbreviations indicating states of reactions stand for: (aq) (s) (l) (g)

(aq)- aqueous *water solution (s)- solid (l)- liquid (g)- gas

Redox reactions are those in which: (three requirements)

- A substance reacts with elemental oxygen - A metal reacts with a non-metal - More generally, one substance transfers electrons to another substance.

Example of redox reaction with elemental oxygen.

2 Mg(s) + O2(g) --> 2MgO2

How do you identify a a precipitation reaction?

A solid is formed as a product. (s) I.e. 2KI(aq) + Pb(NO3)2(aq) --> PbI2(s) + 2KNO3(aq). The important thing to note is not the reaction itself but the change from two aqueous reactants to one aqueous product and one solid product. The solid forming indicates a precipitation reaction.

Example of redox reaction where metal reacts with a non-metal.

Ca(s) + Cl2(g) --> CaCl2 (s) Calcium: metal. Chlorine: non-metal

What ways can you classify reactions?

Chemical reactions can be classified as: Precipitation reactions, acid-base reactions, gas evolution reactions, and oxidation-reduction reactions. A different model for classifying chemical reactions classifies reactions as: synthesis, decomposition, single-displacement, and double- displacement. Sometimes a reaction is a synthesis reaction and also a redox reaction. Since they are different classification systems, some overlap exists.

Name the type of reaction: 2HgO(s) --> 2 Hg (l) + O2 (g)

Decomposition Reaction

Name the type of reaction: HCl(aq) + NaOH(aq) --> H20 (l) + NaCl(aq).

Double displacement.

What is the acronym to understand the relationship between gaining and losing electrons and oxidation and reduction?

OIL RIG

Single-Displacement Reactions

One element displaces another in a compound. A + BC --> AC + B

What does the acronym mean?

Oxidation is loss (of electrons) , Reduction is gain (of electrons).

Name the type of reaction: Na2CO3(aq) + CuCl2(aq) --> CuCO3(s) + 2NaCl(aq).

Precipitation reaction. (a solid is formed in the products and no solid exists in the reactants.)

Name the type of reaction: C(s) + O2(g) --> CO2 (g)

Redox. (reacts with elemental oxygen.)

What does Redox stand for?

Reduction - Oxidation.

Synthesis/combination Reaction

Simple substances combine to form more complex substances. A + B --> AB

Name the type of reaction: Mg(s) + 2 HCl(aq) --> MgCl2(aq) + H2(g)

Single displacement

Name the type of reaction: 2 Na(s) + Cl2 (g) --> 2NaCl (s).

Synthesis Reaction

Double-Displacement Reactions

Two elements or groups of elements in two different compounds exchange places to form two new compounds. AB + CD --> AD + BC

Decoposition reaction

a complex substance decomposes to form simpler substances. AB --> A + B