Solutions, Molarity, Solubility, Electrolytes And Non Electrolytes

Page 1 Ch. 8 Sol'n /Molarity, Solubility, Electrolytes & 4.5 Rxn Types: Precipitation Rxns, Acid Base reactions, gas evolution rxns, Redox Rxns (oxidation-Reduction Rxns), Combustion Rxns (incl. Comp. Analysis) PPT Rxn Na⁺ PO₄³⁻ Ni²⁺ Cl⁻ Question: If Na⁺ (sodium) Phaphate and Nickel (II) Chloride are mixed together in aqueous sol'n, will a precipitation rxn occur? Write the complete molecular, complete ionic, and net ionic equations. Possible Products: NaCl (aq) Ni₃(PO₄)₂(s) ← percipitate CM: 2Na₃PO₄(aq) + 3NiCl₂(aq) → 6NaCl(aq) + Ni₃(PO₄)₂(s) CI: 6Na⁺(aq) + 2PO₄³⁻(aq) + 3Ni²⁺(aq) + 6Cl⁻(aq) → 6Na⁺(aq) + 6Cl⁻(aq) + Ni₃(PO₄)₂(s) NI: 2PO₄³⁻(aq) + 3Ni²⁺(aq) → Ni₃(PO₄)₂(s) Acid/Base Rxn (aka Neutralization Rxns) (2 reactons/2 products) ↳ occur when an acid is added to a base forming – 2 compounds: H₂O(water)(l) & a "salt" ↳ "the ionic compound formed from "the back of the acid & the front of the base"." 3 definitions that chemists use to define Acid & Base Arrhenious definitions ← CHEM 101 Bronsted-Lowry { CHEM 102 Lewis definitions ↳ always (aq) except exceptions Arrhenious - An acid is a molecular (NM/NM) compound that produces one or more Hydrogen cations (H⁺) in aqueous sol'n. (protons) HCl(aq) Page 2 how? HCl(aq) → H⁺(aq) + Cl⁻(aq) ↳ just one proton; loses an e⁻ by dissociating (falls apart) Acids can be monoprotic or polyprotic one H⁺ released releases more than one H⁺ ↳ ex HF, HC₂H₃O₂, HBr ↳ ex: H₂CO₃, H₂SO₄, H₃PO₄ Dissociation Rxn for H₂CO₃(aq) → H⁺(aq) + HCO₃⁻(aq) H₂CO₃ ... HCO₃⁻(aq) → H⁺(aq) + CO₃²⁻(aq) Aside: H⁺(free proton) will always attach to a neighboring H₂O molecule!! [Diagram of H₂O + H⁺ → H₃O⁺] ← called the hydronium ion Acids: 2 categories ← has nothing to do w/ [ ] ↳ all other acids are considered "weak" Strong Acids vs Weak Acids [Box with list: HCl, HBr, HI, HNO₃, H₂SO₄, HClO₄] fully dissociate in H₂O ex: HBr → H⁺ + Br⁻ 100% dissociate Strong electrolyte conducts electricity Only partially dissociate in H₂O ex: HC₂H₃O₂ ⇌ H⁺ + C₂H₃O₂⁻ 1-5% dissociate doesn't produce as much electricity, weak electrolyte [Box with list: LiOH, NaOH, KOH, Ca(OH)₂, Ba(OH)₂] Arrhenious definitions: Base: A compound that produces one or more hydroxide ions (OH⁻) in aqueous sol'n how? by dissociating ex KOH(aq) → K⁺(aq) + OH⁻(aq) loses an e⁻ gains an e⁻ Strong Bases vs Weak Bases Group 1/or 2 metal hydroxides NH₃, NH₄OH Page 3 [Diagram showing a beaker of HI(aq) labeled "acid" and a beaker of KOH(aq) labeled "Base" being combined into a third beaker. Products? H₂O(l), KI(aq)] Question: Write CM, CI, & NI Equations for the rxn between nitric acid and calcium hydroxide. CM: HNO₃(aq) + Ca(OH)₂(aq) → H₂O(l) + Ca(NO₃)₂(aq) balance: ↳ 2HNO₃(aq) + Ca(OH)₂(aq) → 2H₂O(l) + Ca(NO₃)₂(aq) Start w/ the salt when balancing CI: 2H⁺(aq) + 2NO₃⁻(aq) + Ca²⁺(aq) + 2OH⁻(aq) → 2H₂O(l) + Ca²⁺(aq) + 2NO₃⁻(aq) NI: 2H⁺(aq) + 2OH⁻(aq) → 2H₂O(l) or H⁺(aq) + OH⁻(aq) → H₂O(l) The NI equation for all acid-base rxns is the same! Question: Write CM, CI, NI equations for the rxn between phosphoric acid and Lithium Hydroxide. CM: H₃PO₄(aq) + LiOH(aq) → H₂O(l) + Li₃PO₄(aq) H₃PO₄(aq) + 3LiOH(aq) → 3H₂O(l) + Li₃PO₄(aq) CI: 3H⁺(aq) + PO₄³⁻(aq) + 3Li⁺(aq) + 3OH⁻(aq) → 3H₂O(l) + 3Li⁺(aq) + PO₄³⁻(aq) NI: 3H⁺(aq) + 3OH⁻(aq) → 3H₂O(l) Page 4 Molarity Practice Question: Which Solution Contains more mols of KCl? → more particles [150.0mL OF 1.75M] or 80.0mL of 3.0M 0.150L x (1.75M / 1L) = 0.2625M 0.0800L x (3.0M / 1L) = 0.24 What is the [ ] of 650.0mL of solution containing 63g magnesium chloride? 650.0mL -> 0.650L M=mol/L MgCl₂ 63g x (1mol / 92.21g) = 0.6617mol = 1.0M How many grams of Calcium Hydroxide is required to make 80.0mL of a 2.5M solution? Ca(OH)₂ 80.0mL x (1L / 1000mL) x (2.5mol / 1L) x (74.09g / 1mol) = 15g