CHAPTER 4 AQUEOUS REACTIONS AND SOLUTION STOICHIOMETRY: Electrolyte-a compound that conducts electricity in the melt or in solution (water)

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1 CHAPTER 4 AQUEOUS REACTIONS AND SOLUTION STOICHIOMETRY: Electrolyte-a compound that conducts electricity in the melt or in solution (water) STRONG ELEC. 100% Dissoc. WEAK ELEC..1-10% Dissoc. NON ELEC 0% Dissoc.

2 Classes of compounds that are Strong Electrolytes, DISSOCIATE COMPLETELY -SOLUBLE IONIC CPDS. -STRONG ACIDS

3 -STRONG BASES SOLUBLE IONIC CPDS. and STRONG ACIDS and BASES DISSOCIATE COMPLETELY AND BEHAVE AS STRONG ELECTROLYTES. WEAK ACIDS and BASES UNDERGO ONLY PARTIAL DISSOCIATION (equilibrium) AND EXIST AS MOLECULAR CPDS. Methods of Writing Rx. -Molecular -Total Ionic

4 -Net Ionic (MOST IMP.) Metathesis Reactions (swap) AX + BY AY + BX -PRECIPITATION -ACID + BASE -GAS FORMING -OXIDATION-REDUCTION (non-metathesis) PRECIPITATION RX- A Rx that results in the formation of an insoluble ionic cpd.,

5 termed a precipitate. Write balanced net ionic equations for the following. NaCl(aq) + AgNO 3 (aq)

6 Ba(NO 3 ) 2 (aq) + Na 2 SO 4 (aq) Fe(ClO 4 ) 2 (aq) + Na 3 PO 4 (aq) NaBr(aq) + CuSO 4 (aq) SOLUBILITY RULES (Table 4.1) (summary below) -All IA and NH 4 + salts soluble -All NO 3 -, ClO 4 -, C 2 H 3 O 2 - sol. -All Ag +, Hg +, Pb 2+ salts insol. -All Cl -, Br -, I - soluble -SO 4 2- soluble ex. Ca, Sr, Ba -CO 3 2-, PO 4 3-, S 2-, O 2-, OH - insol. (PRIORITY)

7 SPECTATOR ION- an ion that is present in solution but that is not involved in the net Rx. They are not shown in the net ionic equation. AX + BY AY + BX ACID - a substance that when dissolved in water increases the concentration of H +, H 3 O + STRONG ACID WEAK ACID HCl, HBr, HI all others HNO 3, H 2 SO 4 HF, HClO 4, HClO 3 H 3 PO 4

8 monoprotic acid HX diprotic acid H 2 X triprotic acid H 3 X BASE - a substance that when dissolved in water increases the concentration of hydroxide, OH - STRONG BASE WEAK BASE IA MOH all other Li-Cs M(OH) x IIA M(OH) 2 and NH 3 Ca, Sr, Ba SOLUBLE IONIC CPDS. and

9 STRONG ACIDS and BASES DISSOCIATE COMPLETELY AND BEHAVE AS STRONG ELECTROLYTES. WEAK ACIDS and BASES UNDERGO ONLY PARTIAL DISSOCIATION (equilibrium) AND EXIST AS MOLECULAR CPDS. -ACID + BASE Reaction NEUTRALIZATION-a Rx between an acid and a base SALT - an ionic cpd. in which the cation comes from a

10 base and the anion comes from an acid. Give examples of neutralization reaction of HCl with NaOH and Ba(OH) 2 H + (aq) + OH - (aq) H 2 O and of HF with NaOH and Ba(OH) 2 HF(aq) + OH - (aq) H 2 O + F - (aq) AX + BY AY + BX

11 -PRECIPITATION -ACID + BASE -GAS FORMING Gas Forming Rx normally involves Rx of a carbonate (CO 3 2- ), hydrogen carbonate (HCO 3 - ), or sulfide (S 2- ) with an acid to produce a gas, carbon dioxide (CO 2 ) or hydrogen sulfide (H 2 S). Give equations for reaction of sodium carbonate (aq) and nickel sulfide (s) with HCl

12 AX + BY AY + BX -PRECIPITATION -ACID + BASE -GAS FORMING TYPES OF REACTIONS Metathesis (swap) AX + BY AY + BX -PRECIPITATION -ACID + BASE -GAS FORMING -OXIDATION-REDUCTION ion + element

13 ion + element salt + element salt + element Oxidation-Reduction Rx REDOX Rx-A Rx involving transfer of one or more electrons from one reactant to another. 2Ag + (aq) + Cu(s) 2Ag(s) + Cu 2+ (aq)

14 Oxidation- Loss of electrons from an atom, ion, or molecule (increase in oxidation number) Reduction- Gain of electrons for an atom, ion, or molecule

15 (decrease in oxidation number) Remember that oxidation and reduction always take place together Oxidation Number-an arbitrary number assigned to each atom in a species by a series of rules Rules for Assigning Oxidation Numbers p137.

16 Determination of OX # -Atoms of a pure element have an ox # of zero -the sum of the ox # for all of the atoms of a species is equal to the charge on the species -for monatomic ions the ox # equals the charge -F in cpds is -1 -H is +1 when combined with nonmetals and -1 when combined with metals -O is normally -2

17 Oxidation of metals by 1)Acids 2) Salts Use the activity series (Table 4.5) to predict the outcome of the following reactions. Fe + Cu 2+ Ni + H + Cu + Ag + Cu + H +

18 A metal on the activiy series

19 is oxidized by ions beneath it. Metals above hydrogen dissolve in acid (those beneath it do not) SOLUTION STOICHIOMETRY Molarity, M-the # of moles of solute per liter of solution. Determine the concentration of HCl (36.5 g/mol) if 1.00 g of it is dissolved in 250. ml of solution.

20 What is the concentration of the solution prepared by diluting 5.00ml of the above solution to 100. ml Calculate the mass of NaOH (40.0 g/mol) in 50.0ml of a 2.00M solution Titration-a quantitative procedure in which two reactants in solution are allowed to react completely with one another.

21 Equivalence Point- the point

22 in a titration at which one reactant has exactly consumed the other Indicator- a substance that indicates the end point (close to the equivalence point) of a titration by a change in a physical property such as color Calculate the voume of.159m NaOH that would be required to neutralize a) 25.0 ml of.100m HCl b) 25.0 ml of.100m H 2 SO 4

23 How many ml of.100m HCl are required to react with 1.00 g of NaOH (40.0 g/mol) Na 2 CO 3 (106g/mol)?

Chapter 4. Reactions in Aqueous Solution

Chapter 4. Reactions in Aqueous Solution 4.1 General Properties of Aqueous Solutions A solution is a homogeneous mixture of two or more substances. A solution is made when one substance (the solute) is