Lecture 9 7/13

Today’s Agenda Types of Reactions – Synthesis – Decomposition – Single displacement – Double displacement – Combustion Review conversions with moles

Synthesis Reactions What does synthesis mean? It is a reaction where elements come together to form a compound – What we have been doing the last couple weeks 2Na (s) + Cl 2 (g)  2NaCl (s) Once elements from an ionic bond, they become ions.

Decomposition Reactions What does decomposition mean? A compound breaking down into its elements. – The opposite of a synthesis reaction. 2KCl (s)  2K (s) + Cl 2 (g) Sometimes compounds with 3 types of atoms will not completely decompose!

Single Displacement Reactions Always a reaction between a compound and an element. The metals in the reaction are switched. – One replaces another. This only occurs if the one doing the replacing is more reactive. 2FeCl 3 + 3Mg  3MgCl 2 + 2Fe

Single Displacement Reactions How do you determine which metal is more reactive? – The Activity Series! 1.Alkali Metals Most Reactive 2.Alkaline Earth Metals 3.Most Transition Metals 4.Hydrogen 5.Cu, Ag, Au, Pt, and Hg Least Reactive

Single Displacement Reactions The metals are not only switched, sometimes the compound reacts with a nonmetal so that the nonmetals are switched. – We will only be looking at the halogens The more electronegative the halogen, the more reactive it is. 2KI (s) + Cl 2 (g)  2KCl (s) + I 2

Double Displacement Reactions Always a reaction between two compounds – Don’t worry about the activity series. – The two cations switch place. These are the reactions that produce a precipitate (solid). – If the products are both aqueous (aq), no reaction occurs. WHY??? There needs to be a solid in the products in order for a reaction to occur.

Double Displacement Reactions 2NaOH (aq) + MgCl2 (aq)  Mg(OH)2 (s) + 2NaCl (aq) Reaction NaCl (aq) + KI (aq)  NaI (aq) + KCl (aq) No Reaction

Combustion AKA Burning Something reacts with Oxygen to produce Carbon Dioxide and Water. – Always CH 4 (g) + O 2 (g)  CO 2 (g) + H 2 0 (g) Is there a reaction similar to this in Biology???

Next Class Homework 7 and 8 are due! Quiz 5 Review Day Final on Wednesday! – Cumulative Tomorrow I will be in study hall. Monday or Tuesday I will have an extra review which will give you a little extra credit on the exam.