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Objectives. To state 4 factors that cause chemical reactions to occur To predict the products that form in a reaction between aqueous solutions of ionic compounds. A. Predicting Whether a Reaction Will Occur. Four driving forces favor chemical change. Formation of a solid
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Objectives • To state 4 factors that cause chemical reactions to occur • To predict the products that form in a reaction between aqueous solutions of ionic compounds
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
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(NO3)2 (aq) + K2CrO4 (aq) products
B. Reactions in Which a Solid Forms • What Happens When an Ionic Compound Dissolves in • Water? • The ions separate and move around independently.
B. Reactions in Which a Solid Forms • What Happens When an Ionic Compound Dissolves in • Water? • Ba(NO3)2(s) Ba+2(aq) + 2 NO3-1(aq) • K2CrO4 (s) 2K+1(aq) + CrO4-2(aq) So, the reaction between aqueous solutions of barium nitrate and potassium chromate can be written as…
B. Reactions in Which a Solid Forms • How to Decide What Products Form • Determine the possible products from the ions in the reactants. • In our example • K2CrO4(aq) + Ba(NO3)2(aq) Products • The possible ion combinations are
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. • K2CrO4(aq) reactant • Ba(NO3)2(aq) reactant • The possible combinations are KNO3 and BaCrO4. • KNO3 white solid • BaCrO4 yellow solid
Objective: • Identify the solid that forms in a precipitation reaction
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 (NO3)3(aq) + K2CrO4 (aq) 3 KNO3 (aq) + BaCrO4(s)
B. Reactions in Which a Solid Forms • Using Solubility Rules
B. Reactions in Which a Solid Forms • Using Solubility Rules • Predicting Precipitates • Soluble solid • Insoluble solid • Slightly soluble solid
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