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Limiting reactant prob

Limiting reactant prob

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Limiting reactant prob

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  1. CHEMISTRYThe Central Science 9th Edition Limiting reactant prob Nitrogen monoxide can be prepared by the oxidation of ammonia by the following equation: NH3 (g) + O2 (g) ® NO (g) + H2O (g) If 45.7 g of NH3 and 52.5 g of O2 react together, how many g of NO will be formed? David P. White

  2. If 18.59 mol of H2 is burned in air, what is the theoretical yield (in mol) of H2O? If 7.50 mol H2O are formed, what is the percent yield?

  3. If 18.59 mol of H2 is burned in air, what is the theoretical yield (in mol) of H2O? H2 + O2 H2O If 7.50 mol H2O are formed, what is the percent yield?

  4. Chapter 4: All about Aqueous Solutions • Electrolytic Properties • Water is a poor conductor of electricity • Aqueous solutions of ions can conduct electricity. • Three types of solutes: • Strong electrolytes: (solute is all ions) • Weak electrolytes: (some ions, mostly molecules) • Non-electrolytes: (no ions, all molecules)

  5. Models of dissolution (figure 4.3) Ionic substance in water

  6. Molecularsubstancein H2O

  7. Ionization vs. dissociation Ions form in water in two ways Dissociation: ionic substance dissociates (separates) Ionization: molecular substance (no ions) reacts with water to form ions

  8. Strong and Weak Electrolytes • Strong electrolytes: • Exist as 100% ions, conducts electricity Nearly 100% • Weak electrolytes: • make a small % of ions when dissolved. • ions in equilibrium with the molecule. • Can be very soluble, just not ionized

  9. Compounds in Solution Ionic compounds are strong electrolytes Polyatomic ions remain intact as ions when dissolving in water Molecular compounds remain intact as moleculeswhen dissolving in water (non-electrolytes) no ions in solution = nothing to transport electric charge.

  10. Picture of strong electrolyte Strong acid: HCl(g) + H2O(l) H3O+(aq) + A-(aq)

  11. Picture of weak electrolyte Weak acid: HA(aq) + H2O(l) H3O+(aq) + A-(aq)

  12. Soluble vs. electrolyte Don’t confuse solubility and strong vs. weak electrolytes. Electrolyte means only that substance exists as ions in water

  13. Precipitation reactions Double replacement reaction: ions switch Special case of double replacement reactions also called exchange or metathesis A solid (precipitate) forms in these reactions ??How do we know what the precipitate will be??

  14. Precipitation Reactions

  15. Solubility rules to remember Soluble only means greater than 0.01 moles dissolve in 1 L of solution • All nitrates, acetates, ammonium and Group 1 salts are soluble • Solubility of chlorides, bromides and iodides(all soluble except Ag+ Pb2+ and Hg22+) • Hydroxides (all insoluble except rule 1, Ca, Sr, Ba) • What to know • Sulfates mostly soluble • Phosphates and carbonates (insoluble except rule 1)

  16. Net Ionic reaction Concept check Predict the products when NaOH (aq) is combined with HCl (aq), write a balanced chemical equation (including states of matter) Write the total ionic equation Write the net ionic equation

  17. Net ionic reactions • Molecular equation (or “complete” equation): all species listed like molecules with full formulas: • HCl(aq) + NaOH(aq) H2O(l) + NaCl(aq) • total ionic equation: lists all ions: • H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) H2O(l) + Na+(aq) + Cl-(aq)

  18. Cross out “spectators” or ions on both sides of the arrow (lazy bums that don’t react) • H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) H2O(l) + Na+(aq) + Cl-(aq) • Net ionic equation: lists unique ions, only those that react: • H+(aq) + OH-(aq)  H2O(l)

  19. Steps to write net ionic equations: • Write a balanced complete equation. • Dissociate any and only strong electrolytes. • Cross out spectators. • What’s left is the net ionic eq.

  20. These forms of compounds do not make ions • molecules • weak electrolytes • Water • gases • precipitates • Keep together, they don’t exist as ions in solution

  21. Concept check: What is the complete equation? NiCl2(aq) + 2AgNO3(aq) 2AgCl(s) + Ni(NO3)2(aq) What is the total ionic equation? What is the net ionic equation?

  22. A solution of lead (II) nitrate is mixed with a solution of sodium chloride. Write the balanced chemical equation, the total ionic equation, and the net ionic equation for the reaction

  23. Acids • Acid= substance that ionizes toform H+ in solution(HCl, HNO3, CH3CO2H, citric, vitamin C). • H+ also written as H3O+ (hydronium) • one acidic proton= _______________ • (HC2H3O2). • two acidic protons = _______________ • (H2SO4).

  24. Bases Bases • Bases = form OH-, or react with acids (NH3, Drano™, Milk of Magnesia™). • Metal hydroxides are strong bases:Ba(OH)2 Ba2+ + 2OH -

  25. Bases 2 Bases • Some molecules, like amines, are weak bases. • Weak bases ionize in water to make OH -

  26. Memorize strong acids and bases • Memorize 7 strong acids: • HCl, HBr, HI H2SO4, HNO3, HClO3, HClO4 • OR • Memorize the _________ common weak acids • Soluble hydroxides are strong bases

  27. Reactions of acids and bases • Neutralization: acid + base are mixed: • HNO3(aq) + KOH(aq)  ??? • Salt = ionic compound cation from base anion from acid. • Neutralization of acid with metal hydroxide produces water and a salt. • Acids + carbonates = CO2 and H2O

  28. Concept check • Which substance has the most ions form when dissolved in aqueous solution? • NaC2H3O2 • K2CO3 • Na3PO4

  29. Concept check Classify each of the following as a strong (1), weak (2) or non-electrolyte (3) When dissolved in water: NaCl (NH4)2CO3 C12H22O11 HF (weak acid) CH3OH

  30. Concept check: A solution of nickel (II) chloride is mixed with a solution of silver nitrate, a ppt forms. What is the complete equation? What is the total ionic equation? What is the net ionic equation?

  31. Concentration for calculations 20.0 mL * 0.0183 g/mL = 0.366 g cobalt (II) nitrate

  32. Concentration 2 Molarity = moles of solute= M Volume of solution (liters) Molarity, or number of moles per liter of solution Molarity can be used like a conversion factor

  33. Volume x moles = moles L Moles x L = volume (L) moles A 1.0 M (molar) NaCl solution has 1.0 mol or 58.5 g of NaCl dissolved in water to make 1.0 L

  34. 1. Measure mass 14.58 g 3. Fill volumetric flask to known volume 0.2500 L To make a 250.0 mL solution of 1.00 molar NaCl 2. Dissolve in some water 4. M = moles/L 14.58 g x 1 mol/58.54 g x 1/0.2500 L = 1.000 mol/L

  35. Pour ½ in each beaker 0.20 L of2.0 Msolution: 0.20 L x 2.0 mol/L = 0.40 moles total in each beaker: 0.10 L of 2.0 M solution: 0.10 L x 2.0 mol/L = 0.20 moles Same conc, fewer particles

  36. 0.10 L x 2.00 mol/L = ______________ Pour 0.10 L H2O into beaker 0.10 L of solution + 0.10 L H2O = 0.20 L 0.20 moles = _____ 0.20 L new solution Same # of moles, but more dilute

  37. What is molarity if 0.450 mol of NaCl is dissolved to make 0.3500 L of solution? What is molar concentration when 3.18 g of NaNO3 is dissolved to make 150.0 mL of solution?

  38. Molarity, moles/L What is molar concentration when 3.18 g of NaNO3 is dissolved to make 150.0 mL of solution? 3.18 g NaNO3 x 1 mol/84.99g = 0.0374 mol 0.0374 mol/0.1500L =

  39. Molarity, moles/L How many g of potassium sulfate are required to make 235.0 mL of 0.152 M solution?

  40. Molarity, moles/L How many g of potassium sulfate are required to make 235.0 mL of 0.152 M solution?

  41. The mole highway From mass To Moles With g/mole ratio or M To mass With g/mole ratio or M From Moles mole mole Use mole ratio from equation

  42. How many g of lead (II) iodide can be made by mixing 25.0 mL of 0.230 M potassium iodide with 25.0 mL of 0.140 M lead (II) nitrate? Write molecular and net ionic equations. Draw a mental model.

  43. 0.879 M H2SO4 is added to 45.0 mL of 0.100 M NaOH, until the acid is just completely neutralized. How many mL of H2SO4 were added?

  44. pH is a measure of the acidity of a solution pH is calculated as pH = - log10[H+] or [H+] = 10-pH What is pH of solution if [H+] = 1.35*10-4 M? -log 0.000135 = ______(use 2 decimals) What is [H+] if pH = 4.25? pH scale

  45. Figure 16.5

  46. H2O(l) + H2O(l) H3O+(aq) + OH−(aq) • “auto-ionization” of water 55.6 M Water treated like a molecule (very few ions)

  47. Oxidation and reduction Some reactions are a transfer of e- Mg(s) +2HCl(aq)  MgCl2(aq) + H2(g) Write net ionic equation: Mg(s) +2H+(aq)  Mg2+(aq) + H2(g)

  48. Oxidation and reduction • Mg(s) +2H+(aq)  Mg2+(aq) + H2(g) • In the above rxn, Mg(s) loses e-, H+ gains e- • Oxidized: atom, molecule, or ion becomes more positively charged. • Reduced: atom, molecule, or ion becomes less positively charged.

  49. Figure 4.13

  50. Activity series • Some metals are easily oxidized (lose e–), others are not. • Activity series: list of metals in decreasing ease of oxidation. • Metals higher on the activity series are more active lose e– more easily. • Any metal can be oxidized by the ions of elements below it.