Introduction to Solutions and Aqueous Reaction
Introduction to Solutions and Aqueous Reaction CHEM 101
Popular in Structural Chemistry, with Application to Chemistry of the Elements
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This 3 page Class Notes was uploaded by Piper Daniels on Tuesday November 10, 2015. The Class Notes belongs to CHEM 101 at University of Alabama - Tuscaloosa taught by Mrs. Leung in Fall 2015. Since its upload, it has received 16 views. For similar materials see Structural Chemistry, with Application to Chemistry of the Elements in Science at University of Alabama - Tuscaloosa.
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Date Created: 11/10/15
Chapter 9: November 5, 2015 Aqueous Reactions 1. Some ionic compounds and molecular acids dissociate and ionize respectively in H2 to form ions a. ionic compounds: solubility rules (see slide 9 from presentation) b. molecular acids: acid strength → strong acids 2. Precipitation Reactions: occurs when you take two solutions, mix them, and a solid is created; this solid is known as tprecipitate a. this solid must be insoluble in2 i. to determine this, go back to the solubility rules! 3. Ex: KI (aq) + Pb(NO32 ) To see if this reaction is possible and determine products: a. Are the reactants soluble in 2 Check the solubility rules, KIyes, lead nitrateyes b. If yes, dissociate them into ions. i. make sure to check the charges! K+ + Pb+ NO 1 3 c. Determine the possible products by combining the cation from one reactant and the anion from the other reactantNO + PbI 3 2 i. Make sure that this is reduced to the lowest whole number d. Ask yourself, is the product soluble or insoluble in water? i. If soluble, it is aqueous and they are ions in the soluNO.3q) ii. If insoluble, they will be solids and they will crash out of the solution (precipitate!)PbI2(s) e. Balance your equation. 2KI (aq) + Pb(NO ) (aq) → 2KNO (aq) + PbI (s) 32 3 2 4. So what physically just happened in the example 3? + a. Spectator ions: K and NO 3 i. are ions in solutions that are unchanged in the reaction ii. ions as reactants and ions as products iii. hence “spectators” ;) No Reaction 1. KI (aq) + NaCl (aq) → a. KIsoluble in water → K + b. NaClsoluble in water → Na + Cl c. KCl + NaI d. KI (aq) + NaCl (aq) → KCl (aq) + NaI (aq) i. no precipitates ii. this actually means that there is no reaction since there are no new precipitates Aqueous Reactions 1. Molecular equation: a balanced equation that shows the complete neutral formulas for each compound, even if they are ions in the solution a. 2KI (aq) + Pb(NO 32aq) → 2KNO 3(aq) + PbI2 s) b. No reaction: KI (aq) + NaCl (aq) → no reaction 2. Complete Ionic equations: a balanced chemical equation that shows all the species as they actually are in the solution a. all soluble compounds → written as ions → (aq) b. all insoluble compounds → written as a molecular formula → (s) 3. Net ionic equation: a balanced equation that shows only the species that actually changed during the reaction a. remove spectator ions from the complete ionic equation Acids and Bases + 1. Arrhenius acid: substances that produces protons (H ) when dissolved in water a. ex: HCl (aq) → H + (aq) + Cl (aq) b. HCl (aq) + H 2(l) → H3 (aq) + Cl (aq) i. H O is a hydronium ion (which is essentially the proton) 3 ii. chemists use the hydronium ion and proton interchangeably in H 2 and therefore write the initial example a 2. Arrhenius base: substance that produces hydroxide (OH ) when dissolved in water a. typically always a metal and a hydroxide ion b. ex: NaOH → Na + + OH c. NH 3is also a base in a solution of water i. NH 3 H2→ NH 4 + OH 3. Polyprotic acids: are acids with more than one ionizable proton, which are released sequentially + 2 a. ex: H2O4→ 2H + SO4 i. treat the acids like ionic compounds and dissociate them! ii. the two protons that are released makes it polyprotic b. HC HO IS AN EXCEPTION TO THE POLYPROTIC ACIDS 2 3 2 i. this is because only one of the hydrogens can be removed 4. Polyvalent base: are bases with more than one hydroxide 2+ a. ex: Ca(OH) 2aq) → Ca (aq) + 2OH(aq)