| Monday February 5, 2024 Day 20 Limiting & Excess Reactants ... Actual Theoretical and Percent Yield . |
|
| Textbook Readings: 4.3 Limiting Reactant, Theoretical Yield, and Percent Yield |
Course Lectures 3.3 pdf Video* Calcs. with Chemical Equations |
| Limiting, Excess and Percent Yield |
Limiting Reactant Practice Problem |
Objectives 1. Given moles and/or grams of multiple reactants, determine which reactant(s) is limiting which reactant(s) is excess. 2. Determine how much of the excess and limiting reactants are left over when the reaction is finished. 3. Predict product amounts based on limiting reactant calculations. 4. Use actual yields and theoretical yields to determine percent yield values. |
Limiting Reactant Advanced Problem |
Homework Problems (You must show all work including mole ratios for credit) 20.1 Use the balanced "equation" below as you answer the questions that follow. 1 Frame + 2 Wheels → 1 Bicycle a. Given 12 frames, how many bicycles could theoretically be built? b. Given 29 wheels, how many bicycles could theoretically be built? c. Given 12 Frames and 29 wheels, how many bicycles can thoeretically be built? d. Which "reactant" (referring to part d) is in excess? Which is Limiting? e. How many excess parts are left over once bicycle construction is no longer possible? f. 10 bicycles are actually made. Compare this to the theoretical number as a percentage. 20.2 Use the balanced chemical equation below to answer the questions that follow. CO(g) + 2 H2(g) → CH3OH(l) a. Given 12 moles of CO, how many moles of CH3OH could be made? b. Given 29 moles of H2, how many moles of CH3OH could be made? c. Given 12 moles of CO and 29 moles of H2, how many moles of CH3OH could theoretically be made? d. Which reactant (referring to part d) is in excess? Which is Limiting? e How much (mols) of the excess reactant is left over once the reaction is complete? f. 10 moles of CH3OH are actually created. Compare this to the theoretical value as a percentage. 20.3 2.55 grams of aluminum and 6.80 grams of chlorine gas are reacted according to the following chemical reaction: 2 Al(s) + 3 Cl2(g) → 2 AlCl3(s) a. How many moles of each reactant are initially present? b. How many moles of AlCl3 could be made if all of the aluminum is consumed? c. How many moles of AlCl3 could be made if all of the chlorine is consumed? d. Limiting reactants always predict the lesser product amount. Identify which reactant is the limiting reactant and which is the excess reactant. e. Use the limiting reactant product prediction to determine the mass of AlCl3 that should be theortically produced. f. If 6.78 grams of AlCl3 are actually produced, what is the percent yield? g. What mass of each reactant is left over when the reaction is complete? 20.4 Hydrogen gas can be produced by reacting methane gas with water vapor according to the following balanced reaction: CH4(g) + H2O(g) → CO(g) + 3 H2(g) a. If 10.0 grams of methane are reacted with 10.00 grams of water, what is the maximum mass of hydrogen gas that can be produced? (i.e. what is the theoretical yield) b. If 1.88 grams of H2 are actually collected, what is the percent yield? c. What is the mass of excess reatant that is left over once the reaction is complete? 20.5 With the addition of heat, NaHCO3 undergoes the following reaction: 2 NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g) a. If the reaction is know to have an 88.5% yield and 23.9 grams of Na2CO3(s) were actually collected as product, what mass of NaHCO3 was originally present? b. What are the masses of CO2 and H2O actually produced? Click and Drag below for answers 20.1 a. 12 bikes b. 14. bikes c. 12 bikes could be built (too many wheels) d. Frames are limiting Wheels are in excess e. 12 bikes requires 24 wheels leaving 29 - 24 = 5 wheels left over f. 83.3 % 20.2 a. 12.0 moles of CH3OH b. 14.0 moles of CH3OH c. 12.0 moles CH3OH d. CO is limiting. H2 is in excess e. 12 moles of CH3OH requires 24 moles of H2 leaving 29 - 24 = 5 moles H2 left over f. 83.3% 20.3 a. 0.094509 molsAl 0.0959016 mol Cl2 b. 0.094509 molsAlCl3 c. 0.063934 molsAlCl3 d. 0.063934 molsAlCl3 e. 8.5250 grams AlCl3 f. 78.944 % g. 0.8245 g of Al left over 20.4 a. 3.3569 gH2 theoretically yield b. 56.0 % c. 1.09 g CH4 left over 20.5 a. 42.809 grams NaHCO3(s) b. 9.9239 g CO2 4.06237 g H2O |
|
| Tuesday February 6, 2024 Day 21 . Solution concentration and solution stoichiometry This is really important stuff! :) |
|
| Textbook Readings: 4.4: Solution Concentration and Solution Stoichiomentry |
Course Lectures 3.4 pdf Video* Solutions: Molarity, Dilution and Titrations |
| Objective 1. For any solution, determine molarity (M) moles or Liters given any two of the three variables 2. Determine solution concentrations after dilution. 3. Determine additional water volume required to reduce a solution's concentration to a new level. 4. From titration data, determine unknown acid or base concentrations |
Solutions: Molarity, Dilution and Titrations |
Homework Problems (As always, you must show all work for credit) 21.1 For each of the following, determine the number of moles of substance present. a. 1.0 liter of 0.50 molar sucrose solution b. 0.50 Liter of 3.0 M NaCl solution c. 750. mL of 1.50 M CaCl2 solution d. 33.5 mL of 0.050 M HCl solution 21.2 How many grams of CaCl2 would be required to make 125 mL of 0.350 M solution? 21.3 150. mL of distilled water is added to 500. mL of 0.45 M NaOH solution. a. How many moles of NaOH are initially present? b. How many moles of NaOH are present after the addition of distilled water? c. What is the final volume of the solution after dilution? d. Use "b" and "c" to determine the NaOH concentration after dilution. 21.4 Acid dilution is always performed by adding acid to water (and not the other way around). This is to more carefully control the heat that is released during the dilution process. What is the concentration of a solution formed by slowly adding 10.0 mL of 12.0 M H2SO4 to 500. mL of distilled water? 21.5 How many mL of distilled water must be added to 250. mL of 1.30 M KOH solution to lower its concentration to 0.500 M KOH? 21.6 Acid/base titrations involve slowly adding the base to the acid OR the acid to the base until a color change (a.k.a. the "endpoint") is achieved. Knowing the concentration of one, and the volumes of both, the concentration of the unknown can be calculated. Consider the following balanced strong acid/strong base NEUTRALIZATION reaction: NaOH(aq) + HCl(aq) → H2O(l) + NaCl(aq) If it takes 23.5 mL of 0.50 M NaOH to neutralize 50.0 mL of HCl, answer the following questions. a. How many moles of NaOH were required to neutralize the acid? b. Use the HCl/NaOH mole ratio to convert moles of NaOH (part a) into moles of HCl. c. Use moles of HCl (part b) and the initial volume of HCl to determine it's initial concentration with the correct number of significant figures. 21.7 75.0 mL of sulfuric acid (H2SO4) is titrated with 0.250 M KOH. 2 KOH(aq) + H2SO4(aq) → 2 H2O(l) + K2SO4(aq) If 12.55 mL of KOH was required to reach the endpoint, what was the sulfuric acid's initial concentration? 21.8 125.0 mL of phosphoric acid (H3PO4) is titrated with 0.0500 M NaOH. NaOH(aq) + H3PO4(aq) → H2O(l) + Na3PO4(aq) (UNBALANCED) If 1.23 mL of NaOH was required to reach the endpoint, what was the phosophoric acid's initial concentration? Click and Drag below for answers 21.1 a. 0.50 moles of sucrose b. 1.5 molNaCl c. 1.125 molCaCl2 d. 0.001675 molHCl 21.2 4.86 gramCaCl2 21.3 a. 0.225 molNaOH b. 0.225 molNaOH c. 0.650 L d. 0.346 MNaOH 21.4 0.23529 M 21.5 400. mL of water must be added (Final total solution volume = 650. mL) 21.6 a. 0.01175 molsKOH b. 0.01175 molHCl c. 0.235 MHCl (3 SF) 21.7 0.020916 MH2SO4 21.8 0.000164 MH3PO4 |
|
| Wednesday February 7, 2024 Day 22 Solutions and Precipitation Aqueous Reaction: Molecular, Ionic and Total Ionic Equations |
|
| Textbook Readings: 4.5: Types of Aqueous Solutions and Solubility 4.6: Precipitation Reactions 4.7: Representing Aqueous Reactions: Molecular, Ionic, and Complete Ionic Equations |
Course Lecture 4.1 pdf Video* Electrolytes and Solubility 4.2 pdf Video* Molecular total and net ionic Equations 4.3 pdf Video* Barium hydroxide and Sulfuric Acid titrations |
| What Happens when Stuff Dissolves |
Electrolytes and
Solubility |
| Molecular, Total and Net Ionic Equations |
Barium hydroxide and Sulfuric Acid
titrations |
| Objectives 1. Identify ionic salts as soluble or insoluble 2. Know how to identify electrolytes and non-electrolytes 3. Identify ion combination that likely produce insoluble ionic solids 4. Identify aqueous species in chemical equations and re-write them as separate ions. 5. Write total ionic equations denoting solid or liquid products with correct subscript (aq) or (l) 6. Know how to identify spectator ions and cancel in total ionic equation 7. Write the total ionic and total molecular equations corresponding to a specific molecular reaction |
|
Homework Problems. NOTE: For solubility rules that will appear on all exams click HERE. 22.1 Which of the following would form an aqueous electrolye solution when mixed with distilled water? a. MgBr2 b. glucose...C6H12O6 c. Na2SO4 d. Sr(OH)2 e. CO2 f. AgCl g. PbCl2 h. CaCO3 22.2 For each of the following, determine the ions that are present and in what ratio. a. NaCl (aq) b. Pb(NO3)2(aq) c. CaSO4(aq) d. NH4Cl(aq) e. AgNO3(aq) f. CuI2(aq) g. HNO3(aq) h. Fe2(SO4)3(aq) 22.3 For each of the following, identify the ions that are initially present. a. Ca(NO3)2(aq) + Na2CO3(aq) → b. KI(aq) + Pb(NO3)2(aq) → c. NaCl (aq) + AgNO3 (aq) → d. Ba(NO3)2(aq) + Na2SO4(aq) → e. NaCH3COO(aq) + KCl(aq) → f. MgSO4(aq) + NaOH(aq) → g. Ba(OH)2(aq) + H2SO4(aq) → 22.4 For each of the partial reactions described above, examine the ions and decide which cations and anions will form an insoluble precipitate. Write the charge balanced chemical formula for the solid that forms. 22.5 Write the total ionic equation for each of the reactions above. ...all ions that don't form a precipitate must appear as individual ions ...The reaction must be balanced using only coefficients 22.6 For each of the total ionic equations you determined in 22.5, cancel out all ions that appear identically on both sides of the . This is the net ionic equation. Clean up and write the net ionic equation for each reaction (Remember you must always use "aq" and "s" in your answer) 22.7 Record the total Molecular equation for each of the above reactions. Click and Drag below for answers 22.1 a. Soluble: forms a conductive electrolyte solution b. Soluble: Molecular...doesn't form a conductive electrolyte solution c. Soluble: forms a conductive electrolyte solution d. Slightly Soluble since Sr relatively large ion...forms a weakly conductive electrolyte solution e. Relatively insoluble: Molecular...doesn't form a conductive electrolyte solution f. Insoluble: Doesn't dissolve in distilled water and solution is non-conductive g. Insoluble: Doesn't dissolve in distilled water and solution is non-conductive h. Insoluble: Doesn't dissolve in distilled water and solution is non-conductive 22.2 a. 1 Na+ ion and 1 Cl- ions b. Pb2+ and 2 NO3- ions c. 1 Ca2+ ion and 1 SO42- ion d. 1 NH4+ ion and 1 Cl- ion e. 1 Ag+ ion and 1 NO3- ion f. 1 Cu+2 ion and 2 I- ions g. 1 H+ ion and 1 NO3- ion h. 2 Fe3+ ions and 3 SO42- ions 22.3 a. Ca2+(aq) + 2 NO3-(aq) + 2 Na+(aq) + CO32-(aq) → b. K+(aq) + I- (aq) + Pb 2+(aq) + 2 NO3-(aq) → c. Na+(aq) + Cl- (aq) + Ag+(aq) + NO3-(aq) → d. Ba2+(aq) + 2 NO3-(aq) + 2 Na+(aq) + SO42-(aq) → e. Na+(aq) + CH3COO-(aq) + K+(aq) + Cl- (aq) → f. Mg2+(aq) + SO42-(aq) + Na+(aq) + OH-(aq) → g. Ba2+(aq) + 2 OH-(aq) + 2H+(aq) + SO42-(aq) → 22.4 a. Ca2+ and CO32- combine to form CaCO3(s) precipitate b. Pb 2+ and two I- combine to form PbI2(s) precipitate c. Ag+ and Cl- combine to form AgCl(s) precipitate d. Ba2+ and SO42- combine to form BaSO4(s) precipitate e. No precipitate forms. f. Mg2+ and two OH- combine to form Mg(OH)2(s) precipitate g. Ba2+ and SO42- combine to form BaSO4(s) precipitate .....AND...... H+ and OH- combine to form liquid water H2O(l) 22.5 a. Ca2+(aq) + 2 NO3-(aq) + 2 Na+(aq) + CO32-(aq) → 2 NO3-(aq) + 2 Na+(aq) + CaCO3(s) b. 2 K+(aq) + 2 I- (aq) + Pb 2+(aq) + 2 NO3-(aq) → 2 K+(aq) + 2 NO3-(aq) + PbI2(s) c. Na+(aq) + Cl- (aq) + Ag+(aq) + NO3-(aq) → Na+(aq) + NO3-(aq) + AgCl(s) d. Ba2+(aq) + 2 NO3-(aq) + 2 Na+(aq) + SO42-(aq) → 2 Na+(aq) + 2 NO3-(aq) + BaSO4(s) e. Na+(aq) + CH3COO-(aq) + K+(aq) + Cl- (aq) → Na+(aq) + CH3COO-(aq) + K+(aq) + Cl- (aq) f. Mg2+(aq) + SO42-(aq) + 2 Na+(aq) + 2 OH-(aq) → 2 Na+(aq) + SO42-(aq) + Mg(OH)2(s) g. Ba2+(aq) + 2 OH-(aq) + 2H+(aq) + SO42-(aq) → BaSO4(s) + 2 H2O(l) 22.6 a. Ca2+(aq) + CO32-(aq) → CaCO3(s) b. 2 I- (aq) + Pb 2+(aq) → PbI2(s) c. Cl- (aq) + Ag+(aq) → AgCl(s) d. Ba2+(aq) + SO42-(aq) → BaSO4(s) e. No Reaction. All ions cancel out. f. Mg2+(aq) + 2 OH-(aq) → Mg(OH)2(s) g. Ba2+(aq) + 2 OH-(aq) + 2H+(aq) + SO42-(aq) → BaSO4(s) + H2O(l) 22.7 a. CaNO3(aq) + Na2CO3(aq) → CaCO3(s) + 2 NaNO3(aq) b. 2 KI (aq) + Pb(NO3)2(aq) → PbI2(s) + 2 KNO3(aq) c. NaCl (aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq) d. Ba(NO3)2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaNO3(aq) e. No Reaction occurs f. MgSO4(aq) + 2NaOH(aq) → Mg(OH)2(s) + Na2SO4(aq) g. Ba(OH)2(aq) + 2H2SO4(aq) → BaSO4(s) + H2O(l) |
|
| Thursday February 8, 2024 Day 22 REDOX and other reaction types |
|
| Textbook Readings: 4.8: Acid-Base and Gas-Evolution Reactions 4.9: Oxidation-Reduction Reactions |
Course Lectures 4.4 pdf Video* Oxidation Reduction (REDOX) reactions |
| Types of Chemical Reactions |
Oxidation-Reduction Reactions |
| Gas Evolution Reactions |
Acid/Base Neutralization Reactions |
| Objectives 1. Identify chemical reactions as one or more of the following 9 types: ... Synsthesis ... Decomposition ... Combustion ... Single Replacement ... Double Replacement ... REDOX ... Acid/Base Neutralization ... Gas Evolution ... Precipitation 2. For REDOX reactions: ...assign oxidation states (numbers) to all elements ... use oxidation states to identify oxidation: loss of an electron and increase in oxidation number ... use oxidation states to identify oxidation: gain of an electron and decrease in oxidation number ... identify the "oxidation agent" and the "reducing agent" 3. For Gas Evolution reactions correctly predict the gaseeous products: CO2 SO2 H2S NH3 |
|
Homework Problems (The videos above will be very useful when answering these questions) 23.1 For each of the following , identify the reaction's type(s). a. 4 HNO3(aq) + Cu(s) → Cu(NO3)2(aq) + 2 H2O(l) + 2NO2(g) b. Cu(NO3)2(aq) + 2NaOH(aq) → Cu(OH)2(s) + 2NaNO3(aq) c. Cu(OH)2(s) → CuO(s) + H2O(l) d. CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l) e. CuSO4(aq) + Zn(s) → ZnSO4(aq) + Cu(s) f. CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g) 23.2 Determine the oxidation states (numbers) for each element in the following species a. Zn(s) b. ZnO(s) c. H2O(l) d. H2(g) e. CO32-(aq) f. PO43-(aq) g. NH4+(aq) h. Fe2+(aq) i. Al2O3(s) j. CrSO4(s) k. Sn(NO3)2(s) l. NaHCO3(aq) 23.3 For each of the following REDOX reactions: 1. Assign oxidation states (numbers) to all elements (reactants AND product species) 2. Determine which elements are being oxidized and reduced. 3. Identify the oxidizing and reducing agents. a. Mg(s) + Fe2+(aq) → Mg2+(aq) + Fe(s) b. Ba(s) + Cl2(g) → BaCl2(s) c. Ca(s) + O2(g) → CaO2(g) d. 2 HNO3(aq) + Zn(s) → H2(g) + Zn(NO3)2(aq) 23.4 Complete each of the following gas evolution reactions: a. CaCO3(s) + HCl(aq) → b. MgSO3(s) + HCl(aq) → c. Li2CO3(aq) + HNO2(aq) → d. Na2SO3(aq) + H3N(aq) → Click and Drag below for answers (ON = "Oxidation Number or oxidation state) 23.1 a. Gas Evolution, REDOX b. Precipitation, Double Replacement, c. Decomposition, Precipitation d. Double Replacement e. Single Replacement, REDOX, Precipitation f. Double replacement, Gas Evolution 23.2 Determine the oxidation states (numbers) for each element in the following species a. ONZn= 0 b. ONZn = +2 ONO = -2 c. ONH = +1 ONO = -2 d. ONH = 0 e. ONO = -2 ONC = +4 f. ONO = -2 ONP = +5 g. ONH = +1 ONN = -3 h. ONFe+2 = +2 i. ONAl= +3 ONO = -2 j. ONCr= +2 ONO = -2 ONS = +6 k. ONSn= +2 ONO = -2 ONN = +5 l. ONNa= +1 ONO = -2 ONC = +4 NH = +1 23.3 a. Mg(s) ON = 0 .... Mg2+(aq) ON = +2 Oxidation, Mg(s) is reducing agent Fe2+(aq) ON = 2+ .... Fe(s) ON = 0 Reduction, Fe2+(aq) is oxidizing agent b. Ba(s) ON = 0 .... BaCl2(s) ONBa = +2 Oxidation, Ba(s) is reducing agent Cl2(g) ONCl = 0 .... BaCl2(s) ONCl = -1 Reduction, Cl2(g) is oxidizing agent c. Ca(s) ON = 0 .... CaO2(g) ONCa = +4 Oxidation, Ca(s) is reducing agent O2(g) ONO = 0 .... CaO2(g) ONO = -2 Reduction, O2(g) is oxidizing agent d. HNO3(aq) ONH = +1 .... H2(g) ONH = 0 Reduction, HNO3(aq) is oxidizing agent Zn(s) ONO = 0 .... Zn(NO3)2(aq) ONZn = +2 Oxidation, Zn(s) is reducing agent 23.4 a. CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g) b. MgSO3(s) + 2 HCl(aq) → MgCl2(aq) + H2O(l) + SO2(g) c. Li2CO3(aq) + 2 HNO2(aq) → 2 LiHNO2(aq) + H2O(l) + CO2(g) d. 3 Na2SO3(aq) + 2H3N(aq) → 2Na3N(aq) + 3 H2O(l) + 3 SO2(g) |
|
| Friday February 9, 2024 Day 24 Gases and Pressure |
|
| Textbook Readings: 5.1: Water & Wells: Atmospheric Pressure at Work 5.2: Pressure: The Result of Particle Collisions |
Course Lectures 5.1 pdf Video* Gas Pressure |
| Gas Pressure: The Basics |
Measuring Gas Pressure and Atmospheric
Pressure |
| Objectives: 1. List the names of the four main gases in our atmosphere and their approximate percent abundances. 2. Describe why inflated ballons don't expand indefinitely and burst. 3. Describe the operation of a simple water pump and how water is lifted out of a well. 4. Describe the operation of a manometer and how it measures gas pressure. 5. Use a manometer to measure gas pressure 6. Convert gas pressures between torr, mmHg kPa, and atmospheres (atm). 760 mmHg = 760 torr = 1 atm (exact) = 101.325 kPa (exact) |
|
Homework Problems 24.1 What are the 4 main components (...and abundances) of the atmosphere we breath? 24.2 In your own words, explain why an air filled balloon doesn't expand indefinitely? 24.3 People sometimes mistakenly say that a water pump "lifts" water out of a well. In your own words, provide the correct explanation for how water is removed from the well using this type of pump. 24.4 Manometers are used to measure gas pressures. Examine this manometer and provide the gas's pressure in mmHg, torr, kPa and atmosphere (atm) units. 24.5 Manometers are used to measure gas pressures. Examine this manometer and provide the gas's pressure in mmHg, torr, kPa and atmosphere (atm) units. Click and Drag below for answers 24.1 Nitrogen (N2) 78% Oxygen (O2) 21% Argon (Ar) 1% Carbon Dioxide (CO2) <1% 24.2 Balloons don't continue to expand because of the atmosphere around them that pushes inward and balances the outward expansion. 24.3 This type of pump lowers the air pressure in the pipe so that it no longer balances atmospheric pressure that can now push the water UP the pipe. 24.4 897 mmHg, 897 torr, 1.18 atm, 1.20 × 102 kPa 24.5 713.5 mmHg, 713.7 torr, 0.9391 atm, 95.15 kPa |
|