Reactions in Aqueous Solutions Unit 4: Reactions in Aqueous Solutions Day 1: Gummy Bear Death and Precipitation Reactions

Warm Up Balance the following equations for sending a gummy bear to it’s death: ___KClO3 ⟶ ___ KCl + ___KClO4 ____KClO4 ⟶ ____ KCl + ____O2 ____O2+___C6H12O6 ⟶ ___CO2+___H2O 4 1 3 2 1 2 6 1 6 6 4, 1, 3 1, 1, 2 6, 1, 6, 6 ⟶

Agenda Gummy Bear Death (Outside) Lecture Notes Practice Problems Discussion: What would make this class better? What would you like to see me do differently to help you be more successful?

Pour the two solutions together. Observe what happens Pour the two solutions together. Observe what happens. Discuss with people at your table why this happens.

Lecture Notes Topics: What’s Important? Definitions: Electrolyte (strong vs. weak) Non-electrolyte Dissociate Precipitate Solubility ( and guideline table) Metathesis Reactions Types of Equations: Molecular Complete ionic Net ionic Neutralization Strong Acids vs. Strong Bases

Lecture Notes Topics: What’s Important? Processes How to identify strong vs. weak electrolytes How to predict precipitates How to predict metathesis reactions How to write a molecular equation How to write a net ionic equation How to write a neutralization reaction

What do I need to memorize and what do I need to just practice with? Memorize Practice Definitions Table 4.1, p. 129 Solubility Guidelines Table 4.2, p. 134 Activity Series, p. 144 Table 4.3, p. 135 Steps for Molecular Eq Molarity equation Steps for Net Ionic Eq Dilution equation Steps for Neutralization

Solutions Solutions are defined as homogeneous mixtures of two or more pure substances. The solvent is present in greatest abundance. All other substances are solutes. When water is the solvent, the solution is called an aqueous solution.

Aqueous Solutions Substances can dissolve in water by different ways: Ionic Compounds dissolve by dissociation, where water surrounds the separated ions. Molecular compounds interact with water, but most do NOT dissociate. Some molecular substances react with water when they dissolve.

Aqueous Solutions https://www.youtube.com/watch?v=xdedxfhcpWo&safe=active

Electrolytes and Nonelectrolytes An electrolyte is a substance that dissociates into ions when dissolved in water. A nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so.

Electrolytes A strong electrolyte dissociates completely when dissolved in water. A weak electrolyte only dissociates partially when dissolved in water. A nonelectrolyte does NOT dissociate in water.

Give it some thought Which solute will cause the light bulb to glow most brightly if it was dissolved in water, CH3OH, NaOH, or CH3COOH?

Solubility of Ionic Compounds Not all ionic compounds dissolve in water. A list of solubility rules is used to decide what combination of ions will dissolve.

(See Solubility Rules) Aqueous Solutions Soluble Compounds (See Solubility Rules) Electrolytes Strong Weak Non-Electrolytes All soluble ionics Strong Acids Weak acids Weak bases Molecular compounds

Precipitation Reactions When two solutions containing soluble salts are mixed, sometimes an insoluble salt will be produced. A salt “falls” out of solution, like snow out of the sky. This solid is called a precipitate.

Predicting Precipitation Reactions Identify ions present in the reactants Consider the cation-anion combinations Use Solubility table to determine if these combinations are soluble or insoluable

Which of these are soluble? (NH4)2S, CaCO3, NaOH, Ag2SO4, Pb(CH3COOH)2

Predict the identity of the precipitate… When MgCl2 and CaS are mixed. Write the balanced equation.

Predict the identity of the precipitate… When solutions of Fe2(SO4)3 and LiOH are mixed. Write the balanced equation.

Yes or No? Will a precipitate form when Ba(NO3)2 and KOH are mixed?

Discussion What would make this class better? What would you like to see me do differently to help you be more successful?