Section 8.1 Understanding Reactions in Aqueous Solutions 1.To state 4 factors that cause chemical reactions to occur 2.To predict the products that form in a reaction between aqueous solutions of ionic compounds Objectives

Section 8.1 Understanding Reactions in Aqueous Solutions A. Predicting Whether a Reaction Will Occur Four driving forces favor chemical change. –Formation of a solid –Formation of water –Transfer of electrons –Formation of a gas

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in Which a Solid Forms Precipitation Reaction – a reaction in which a solid product forms Precipitate – a solid that forms as a result of a chemical reaction Example: Barium nitrate + potassium chromate Ba(NO 3 ) 2 (aq) + K 2 CrO 4 (aq)  products

Section 8.1 Understanding Reactions in Aqueous Solutions The ions separate and move around independently. B. Reactions in Which a Solid Forms What Happens When an Ionic Compound Dissolves in Water?

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in Which a Solid Forms What Happens When an Ionic Compound Dissolves in Water? Ba(NO 3 ) 2 (s)  Ba +2 (aq) + 2 NO 3 -1 (aq) K 2 CrO 4 (s)  2K +1 (aq) + CrO 4 -2 (aq) So, the reaction between aqueous solutions of barium nitrate and potassium chromate can be written as…

Section 8.1 Understanding Reactions in Aqueous Solutions Determine the possible products from the ions in the reactants. In our example K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq)  Products The possible ion combinations are B. Reactions in Which a Solid Forms How to Decide What Products Form

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in Which a Solid Forms How to Decide What Products Form Decide which is most likely to be the yellow solid formed in the reaction. K 2 CrO 4 (aq) reactant Ba(NO 3 ) 2 (aq) reactant The possible combinations are KNO 3 and BaCrO 4. –KNO 3 white solid –BaCrO 4 yellow solid

Section 8.1 Understanding Reactions in Aqueous Solutions Objective: 1.Identify the solid that forms in a precipitation reaction

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in which a solid forms Predicting Precipitates Soluble solid – solid that readily dissolves in water Insoluble solid or slightly soluble solid – little or no solid will dissolve in water Example: Ba (NO 3 ) 3 (aq) + K 2 CrO 4 (aq)  3 KNO 3 (aq) + BaCrO 4 (s)

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in Which a Solid Forms Using Solubility Rules

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in Which a Solid Forms Predicting Precipitates Using Solubility Rules –Soluble solid –Insoluble solid –Slightly soluble solid

Section 8.1 Understanding Reactions in Aqueous Solutions B. Reactions in Which a Solid Forms

Section 8.1 Understanding Reactions in Aqueous Solutions C. Describing Reactions in Aqueous Solutions Three types of equations: –Molecular (formula) equation  complete formulas of all reactants and products –Complete ionic equation  all strong electrolytes are shown as ions –Net ionic equation  only those components of the solution that undergo a change Spectator ion (those that remain unchanged)  not shown in the net ionic equation