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Ch. 4 REACTIONS,SOLUTIONS

Ch. 4 REACTIONS,SOLUTIONS. Concentration [ ] dilution, molarity (moles/L) Replacement Rxns activity series, solubility. Electrolytes Reduction – Oxidation oxidation numbers. RXN: Acid-Base, Neutralization PPT; REDOX. TERMS. Solution. A homogeneous mixture of 2

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Ch. 4 REACTIONS,SOLUTIONS

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  1. Ch. 4 REACTIONS,SOLUTIONS Concentration [ ] dilution, molarity (moles/L) Replacement Rxns activity series, solubility Electrolytes Reduction – Oxidation oxidation numbers RXN: Acid-Base, Neutralization PPT; REDOX

  2. TERMS Solution A homogeneous mixture of 2 or more pure substances The substance that is dissolved in solution Solute Solvent The substance that does the dissolving

  3. MOLARITY --CONCENTRATION mols liter M Label moles of solute liter of solution [H+] [OH-] Concentration of ACID Symbol Concentration of BASE Brackets indicate CONCENTRATION

  4. DILUTION The terms used indicate: Mo; VoInitial – Original -- Beginning M1; V1; Mi; Viconcentration & volume Md; VdFinal – Diluted -- Ending M2; V2; Mf; Vf concentration & volume Equation: M1 * V1 = M2 * V2 A single solution (homogeneous mixture) of a known concentration needs to be diluted to a lower concentration. This is accomplished by adding a known quantity of water (distilled) to the original solution volume.

  5. Step #1: Identify the parts for equation Step #2: Set up and solve equation 650 ml 290.0 mL of a 0.560 M Fe(OH)3 solution is required to make a 0.250 M solution by dilution. What is the final volume. M1 = 0.560 M V1 = 290.0 M2 = 0.250 M V2 = X ml (0.560 M) (290.0 mL) = (X ml) (0.250 M) 0.250 M Notice: Dilution problems are not volume specific

  6. 1.25 L of H2O is added to 750 ml of 0.75 M HCl solution. What is the resulting molarity? Step #1: Identify parts for equation M1 = 0.75 M V1 = 750 ml So, final vol. is amount Start + Added M2 = X V2 = ??? or 2000.0 ml 2.0 L or 0.75 L Look at the problem, what does it say!!! Step #2: Set up & solve equation 1.25 L is added to …. (0.75 M) (0.75 L) = (X) (2.0 L) 2.0 L OR 0.28 M

  7. 752.0 g *1 mol . 1 208.3 g M = 3.6 moles 0.575 L Given mass & volume, find molarity Determine the M of 752.0 g Barium Chloride in 575 ml of solution. Step 1: Need to change 575 ml to 0.575 L Step 2: Find formula wt. of CMPD. BaCl2 = 208.3 g/mol Step 3 : Find moles of CMPD. 3.6 moles Step 4 : Find molarity of solution 6.3 M

  8. Using given concentration & volume, find moles Given molarity & volume, find moles & mass How many moles of NaCl are in 36.7 ml of a 0.256 M solution? Step 1: Need to change 36.7 ml to 0.0367 L Step 2: Convert M label to mols/L 0.256 mols 1 L Step 3 : Find moles of NaCl 0.0094 or 9.4*10-3 moles NaCl

  9. 0.55 g NaCl Multiply by MOLES Divide by MASS Continuing, next we need to find the MASS of NaCl in0 .0094 moles Step 1: find formula wt. of NaCl 58.5 g /mol Step 2 : Find mass

  10. PRACTICE PROBLEMS MOLARITY 1. What is the molarity of a solution containing 2.50 moles of KNO3 dissolved in 5.00 L? 2. How many moles of KCl are present in 100.0 mL of 0.125 M solution? DILUTION 1. What is the molarity of 50.0 mL of a 0.50 M NaOH solution after it has been diluted to 300.0 mL? 2. If 300.0 mL of water is added to 400.0 mL of a 0.400 M Na2CrO4 solution, what is the molarity of the resulting solution?

  11. SINGLE REPLACEMENT A+B- + E0 ----- E+B- + A0 FORM: 2 reactants: 1 cmpd. & 1 element forms 2 products: 1 new cmpd. & 1 new element DOUBLE REPLACEMENT A+B- + X+Y- ----- A+Y- + X+B- FORM: 2 reactants: 2 compounds form 2 products: 2 new compds.

  12. SINGLE REPLACEMENT Reference used for rxn. occurring ACTIVITIES SERIES of METALS Electrochemical Series DOUBLE REPLACEMENT Reference used of rxn. occurring RULES of SOLUBILITY

  13. ACID + BASE ----- SALT + H2O Nitric Acid + Potassium Hydroxide --- ?????? DR HNO3(aq) + KOH (aq) --- KNO3 (aq) + H2O (l) Sulfuric Acid + Barium Hydroxide ----- H2SO4 (aq) + Ba(OH)2 (aq) --- BaSO4 (s) + H2O (l) 2

  14. Zinc + Copper II Sulfate ----- 1st is a reaction going to occur or not????? What type of RXN??? Which players will trade places???? We have an element plus a compound. Single Replacement Check the METAL REACTIVITY list ZnSO4 (aq) + Cu (s) Zn (s) + CuSO4 (aq) ---- BALANCED??? Look at relation between Zn & Cu Zn is more active then Cu, therefore, rxn. occurs

  15. SOLUTIONS AgNO3(aq) + NaCl (aq) ---- NaNO3(aq) + AgCl (s) Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) ----- Na+(aq) + NO3-(aq) + AgCl(s) Cl- Na+ NO3- Ag+ Na+ Ag+ Cl- NO3- Na+ Now, combine both solutions together. Ag+ Cl- NO3- Na+ Ag+ Na+ Ag+ Cl- Na+ NO3- Ag+ Cl- NO3- Na+ Ag+ Na+ What is the expected effect?????? NO3- Ag+ Cl- Cl- NO3-

  16. Silver + Sulfuric Acid -- ????? NR Ag (s) + H2SO4 (aq) -- Therefore, this is a “No RXN” CHECK, “Ag” active metal to replace “H” in an Acid ??? “Ag” is not an active enough metal to replace “H” in an Acid

  17. REDOX – Reduction/Oxidation LEO the lion says GER-r-r-r-r-r Lose Electron Oxidize Gain Electron Reduce RIG OIL Reduce Is Gain Oxidize Is Lose

  18. OXIDATION - REDUCTION “REDOX” Reduction: gain electron Oxidation: lose electron charge becomes more neg charge becomes more “+” H2(g) + O2(g) --------> H2O(g) Both H2 & O2 are diatomics: charge on each 0 In the cmpd. H is +1 & O is -2 H: from 0 to +1 charge, loses e-, oxidized (reducing agent) O: from 0 to -2 charge, gain e-, reduced (oxidizing agent)

  19. Ionic Reaction -- Ionic Equations Spector ions - not involved in reaction - no D in charge & state 3 diff types of equations for same reaction molecuar; total ionic; net ionic STATES: (aq): aqueous; soln (s): solid; precipitate (g): gas (l): liquid: H2O Type of rxn; molecular, total, net eqns; oxidized/reduced & agents; spectators Potassium carbonate reacts w/ strontium nitrate to yield ??????????

  20. Type: double replacement; precipitation Spectator: K+1 & NO3-1 Reduce, oxidize: none, not a redox rxn

  21. Barium hydroxide and hydrocyanic acid produces ??????? Type: DR; acid-base; neutralization Spectator: none, since HCN weak acid Reduce, oxidize: none, not a redox rxn

  22. Same reaction but with a strong acid instead Barium hydroxide and hydrochloric acid produces ??????? Type: DR; acid-base; neutralization Spector: Ba+2 & Cl-1, since HCl strong acid Reduce, oxidize: none, not a redox rxn

  23. Aluminum metal & manganese II sulfate produce aluminum sulfate & manganese metal Type: Single Replacement; Oxidation Reduction Spectator: SO4-2 Oxidize Reduce Red. Agent Ox. Agent Al (0 ---> +3) Al Mn (+2 ---> 0) Mn

  24. -2 0 -2 +4 -2 +2 +5 Oxidized: Reduced: Oxidizing Agent: Reducing Agent: OXIDATION NUMBERS IA:+1 IIA: +2 IIIA: +3 PO4-3: sum “P” charge + “O” charge = -3 -2 +1 -2 + 1 = -1 OH-1: O = H = P + 4(-2) = -3 P = +5 Carbon monoxide reacts with diiodine pentaoxide yields iodine & carbon dioxide 5 CO (g) + I2O5(s) -------> I2(s) + 5 CO2(g) C +2 ---> +4; loss 2e- I+5 ---> 0; gain 5 e- I C

  25. +2 gain 2 e- loss 2 e- 0 +4 -2 -2 C (s) + CO2(g) -------> 2 CO (g) Oxidized Reduced Red. Ag Ox. Ag C (s) C in CO2 C (s) CO2 0 ----> +2 +4 ----> +2

  26. +5 +5 gain 1 e- loss 2 e- -2 -2 -2 -2 0 +2 +4 +1 +1 Balance REDOX Sn (s) + HNO3(aq) -------> Sn(NO3)2(aq) + NO2(g) + H2O (l) Oxidized Reduced Red. Ag Ox. Ag Sn (s) N in HNO3 Sn (s) N 0 ----> +2 +5 ----> +4

  27. PRACTICE PROBLEMS 1. Calcium Acetate (aq) + Aluminum Sulfate (aq) ------ write and balance the molecular, total ionic, & net ionic equations reduced? oxidized????? 3 Ca(C2H3O2)2(aq) + Al2(SO4)3 (aq) ----> 3 CaSO4 (s) + 2 Al(C2H3O2)3 (aq) 3 Ca+2 + 6 C2H3O2-1 + 2 Al+3+ 3SO4-2 ----> 3 CaSO4 (s) + 2 Al+3 + 6 C2H3O2-1 Ca+2(aq) + SO4-2(aq) ----> CaSO4 (s) NOT a redox rxn

  28. ELECTROLYTES: Subst. that produces ions when in H2O; conducts electrical current 1. All ionic subst. ARE 2. Most covalent ARE NOT; acids ARE DISSOCIATE: Completely separates into ions ionic cmpds STRONG ELECTROLYTE: Ionize completely in H2O NaCl (aq) ---------> Na+1 (aq) + Cl-1(aq) H2SO4(aq) ---------> 2 H+1 (aq) + SO4-2(aq)

  29. Partially ionize in H2O WEAK ELECTROLYTE: HC2H3O2(aq) <---------> HC2H3O2(aq) + H+1 (aq) + C2H3O2-1(aq) NONELECTROYLTE: Not produce ions in H2O usually dissolves as whole molecule unit C2H8(aq) ---------> C2H8(aq) STRONG WEAK NON All ionic cmpds No ionic cmpds Covalent Molecules Strong Acids Weak Acids -non-acids HCl HBr HI Weak Bases -not contain NH3 HNO3 H2SO4 NH3 HClO3 HClO4 Strong Bases -1A metal hydroxides -2A heavy metal hydroxides: Ca, Ba, Sr

  30. COMPOSITION REACTIONS FORM: A0 + B0 ----- A+B- 2 reactants form 1 product DECOMPOSITION REACTIONS FORM: A+B- ----- A0 + B0 1 reactants breaks apart into 2 or more product SINGLE REPLACEMENT 2 reactants: 1 cmpd. & 1 element forms 2 products: 1 new cmpd. & 1 new element FORM: A+B- + E0 ----- E+B- + A0 DOUBLE REPLACEMENT FORM: A+B- + X+Y- ----- A+Y- + X+B- 2 reactants: 2 compounds form 2 products: 2 new compds.

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