Exam 2 Worksheet Exam 2 Worksheet – Chemistry 102 Chapter 4 – Reactions in Aqueous Solutions 1. Assign the pictures (A, B, C, D, E, F, G, or H) to the solutions (in water) of iron(II) nitrate, iron(III) nitrate, cobalt(II) sulfate, lithium hydroxide, magnesium hydroxide, barium hydroxide, aluminum sulfate, aluminum sulfide, calcium sulfide, calcium sulfate, sodium sulfate, sodium sulfide, silver nitrate, silver chloride, lead(II) bromide and iron(III) hydroxide. The assignment of shapes/shading to cations or anions is arbitrary and water molecules are not shown (for clarity). A B C D E F G H 2. Describe how to test for the anions in solution. a. Phosphate versus chloride b. Sulfate versus acetate c. Hydroxide versus sulfide d. Carbonate versus bromide 3. Describe how to test for the cations in solution. a. Ag+ versus Mn2+ b. NH4+ versus Ca2+ c. Ba2+ versus Mg2+ d. Fe3+ versus K+ e. Pb2+ versus Na+ f. Pb2+ versus Ba2+ 4. Give the net ionic equation for the following combinations. If no reaction occurs, write no reaction. a. Lithium phosphate and iron(III) acetate b. Ammonium carbonate and aluminum nitrate c. Ammonia (a weak base) and nitric acid (a strong acid) d. Nitric acid and barium hydroxide (a strong base) e. Lead(II) sulfate and sodium chloride f. Barium hydroxide and magnesium sulfide 1 Exam 2 Worksheet g.
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Barium hydroxide and ammonium phosphate Barium hydroxide and hydrocyanic acid (a weak acid, HCN) Calcium chloride and silver sulfate Ammonium acetate and aluminum nitrate Strontium sulfate and calcium sulfide 5. What is the oxidation state for each element in the compounds? a. NaNO3 b. KClO4 c. NO2 d. NO e. SO2 f. FeSO4 g. CaCr2O7 h. AlPO4 i. Fe3O4 6. Identify the species oxidized and the species reduced in each reaction or if no oxidation/reduction reaction is occurring. For the oxidation/reduction reactions, identify the number of electrons transferred. a. 2H 2 ( g ) + O2 ( g ) → 2H 2 O ( l ) b. 2HCl ( aq ) + Zn ( s ) → H 2 ( g ) + ZnCl2 ( aq ) c. Fe2 O3 ( s ) + 3CO ( g ) → 2Fe ( l ) + 3CO2 ( g ) d. 2HNO3 ( aq ) + Ba ( OH )2 ( aq ) → 2H 2 O ( l ) + Ba ( NO3 )2 ( aq ) e. C ( s ) + O2 ( g ) → CO2 ( g ) f. Al3+ ( aq ) + 3OH − ( aq ) → Al ( OH )3 ( s ) g. Fe2 O3 ( s ) + 2Al ( s ) → 2Fe ( l ) + Al2 O3 ( s ) In answering items 7‐9, you will be given figure 4.14 in your textbook on the exam. 7. Predict whether a reaction will occur between the species in aqueous solution. If a reaction occurs, give the net ionic equation, give each half reaction, identify the species oxidized/reduced, and give the number of electrons transferred. a. Potassium chloride and fluorine to produce potassium fluoride and chlorine b. Potassium chloride and bromine to produce potassium bromide and chlorine c. Tin(II) chloride and magnesium to produce tin and magnesium chloride d. Aluminum nitrate and barium to produce aluminum and barium nitrate e. Aluminum nitrate and nickel to produce aluminum and nickel(II) nitrate f. Tin and steam g. Potassium and water h. Platinum and nitric acid i. Nickel and nitric acid 2 Exam 2 Worksheet j. Gold(III) chloride and hydrogen k. Iron(II) chloride and hydrogen 8. Of the sets, which species is a stronger reducing agent? Explain what this means (in general). a. Fe or Ni b. H2 or Cr c. Pt or Pb d. Mg or Ca e. F– or Cl– f. Br– or Cl– g. Zn or Na h. F–, Cl–, Br–, or I– 9. Of the sets, which species is a stronger oxidizing agent? Explain what this means (in general). a. H+ or Ni2+ b. Pt2+ or Au3+ c. Br2 or I2 d. Br2 or Cl2 e. Zn2+ or Sn2+ f. H+ or Ag+ g. F2, Cl2, Br2, or I2 h. Co2+ or Cd2+ 10. Use the balanced net ionic equation in the calculations listed. 2Co3+ ( aq ) + 3CO32- ( aq ) → Co 2 ( CO3 )3 ( s ) a. Combine 25.0 mL of 0.105 M cobalt(III) nitrate and 25.0 mL of 0.105 M ammonium carbonate. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 62.5%? iv. If the reaction is run again with 45.5 mL of 0.275 M of cobalt(III) nitrate and excess ammonium carbonate with a percent yield of 32.5%, what mass of cobalt (III) carbonate will experimentally be recovered? b. Combine 45.5 mL of 0.565 M cobalt(III) nitrate and 60.5 mL of 0.605 M ammonium carbonate. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 62.5%? c. Combine 45.5 mL of 0.565 M cobalt(III) acetate and 60.5 mL of 0.605 M potassium carbonate. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 62.5%? 3 Exam 2 Worksheet d. Combine 6.55 mL of 2.35 M cobalt(III) chloride and 10.5 mL of 2.35 M sodium carbonate. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 62.5%? 11. Use the balanced net ionic equation in the calculations listed. Ag + ( aq ) + Cl− ( aq ) → AgCl ( s ) a. Combine 37.5 mL of 0.0755 M silver nitrate and 47.5 mL of 0.0755 M calcium chloride. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 44.5%? iv. If the reaction is run again with 30.5 mL of 0.145 M calcium chloride and excess silver nitrate with a percent yield of 77.7%, what mass of silver chloride will experimentally be recovered? b. Combine 37.5 mL of 0.0755 M silver acetate and 47.5 mL of 0.0755 M calcium chloride. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 44.5%? c. Combine 37.5 mL of 0.0755 M silver acetate and 97.5 mL of 0.0755 M aluminum chloride. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 44.5%? d. Combine 37.5 mL of 0.0755 M silver nitrate and 97.5 mL of 0.0755 M iron(II) chloride. i. What is the limiting reactant? ii. What is the theoretical yield in mass of the precipitate? iii. What is the experimental yield if the percent yield is 44.5%? 12. Determine the concentration of all ions in solution in number 11 when the reaction is over. Assume the experiment yield is equal to the theoretical yield. 13. If the percent yield is 75%, what ions will increase in concentration in number 11? 14. If the percent yield is 75%, what ions will not increase in concentration in number 11? 15. What is the concentration of all ions in the solutions after mixing? a. Combine 45.5 mL of 0.455 M sodium acetate and 50.0 mL of 0.255 M sodium phosphate. b. Combine 45.5 mL of 0.455 M sodium acetate and 50.0 mL of 0.255 M sodium phosphate to a final volume of 125 mL. c. Combine 13.5 mL of 1.25 M lithium carbonate and 22.5 mL of 0.955 M lithium sulfate. 4 Exam 2 Worksheet d. Combine 13.5 mL of 1.25 M lithium carbonate and 22.5 mL of 0.955 M lithium sulfate to a final volume of 50.0 mL. e. Combine 27.5 mL of 0.205 M iron(III) nitrate and 42.5 mL of 0.195 M magnesium nitrate. f. Combine 27.5 mL of 0.205 M iron(III) nitrate and 42.5 mL of 0.195 M magnesium nitrate to a final volume of 85 mL. Chapter 5 – Gases 1. What is the density of the gases at STP? a. Dinitrogen tetroxide b. Sulfur trioxide c. Nitrogen d. Helium 2. What is the density of the previous gases when the temperature is 265ºC and under 1.978 atm of pressure? 3. What the density of the previous gases when the temperature is –15.5ºC and under 0.198 atm of pressure? 4. What is the volume of the gases? a. 14.5 mol of carbon dioxide under 0.675 atm of pressure at –10.0ºC. b. 14.5 g of carbon dioxide under 0.675 atm of pressure at –10.0ºC. c. 98.0 g of argon under 9.09 atm of pressure at 450 ºC. d. 98.0 g of neon under 9.09 atm of pressure at 450 ºC. e. 6.75 mol of sulfur dioxide under 2.40 atm of pressure at 100 ºC. f. 4.5 × 1024 particles of carbon monoxide under 4.56 atm of pressure at 550.0 ºC. 5. How will the previous volumes change if the gas was changed to hydrogen? 6. What is the pressure of the gases? a. 14.5 mol of carbon dioxide in a 250 L container at 440.0ºC. b. 14.5 g of carbon dioxide in a 250 L container at 440.0ºC. c. 98.0 g of argon in a 55.0 L container at 450 ºC. d. 98.0 g of neon in a 55.0 L container at 450 ºC. e. 0.675 mol of sulfur dioxide in a 17.6 L container at 300 ºC. f. 4.5 × 1024 particles of carbon monoxide in a 350 L container at 50.0 ºC. 7. How will the previous pressures change if the gas was changed to hydrogen? 8. How will the previous pressures change when the volume is reduced by 50% (keeping everything else constant); when the temperature is reduced by 50% (keeping everything else constant)? 5 Exam 2 Worksheet 9. What is the temperature of the gases? a. 14.5 mol of carbon dioxide in a 250 L container under 0.195 atm of pressure. b. 14.5 g of carbon dioxide in a 250 L container under 0.195 atm of pressure. c. 98.0 g of argon in a 55.0 L container under 1.25 atm of pressure. d. 98.0 g of neon in a 55.0 L container under 1.25 atm of pressure. e. 0.675 mol of sulfur dioxide in a 17.6 L container under 2.245 atm of pressure. f. 4.5 × 1024 particles of carbon monoxide in a 350 L container under 345 mmHg of pressure. 10. How will the previous temperatures change if the gas was changed to hydrogen? 11. How will the previous temperatures (in number 9) change when the volume is reduced by 50% (keeping everything else constant); when the pressure is reduced by 50% (keeping everything else constant)? 12. What is the mass of the gas under the conditions? a. 2.5 L of carbon dioxide under 0.195 atm of pressure at 156 ºC. b. 2.5 L of carbon monoxide under 0.195 atm of pressure at 156 ºC. c. 55.0 L of argon under 1.25 atm of pressure at –90.0 ºC. d. 55.0 L of neon under 1.25 atm of pressure at –90.0 ºC. e. 17.6 L of sulfur dioxide under 0.245 atm of pressure at 98 ºC. f. 35.0 L of carbon monoxide under 3.45 atm of pressure at 10 ºC. 13. What is the molar mass of the gases in a 45.5 L container? a. 12.5 g of a gas under 0.970 atm of pressure at 460 ºC. b. 45.6 g of a gas under 0.705 atm of pressure at 335 ºC. c. 65 g of a gas under 0.506 atm of pressure at 87.0 ºC. d. 32.5 g of a gas under 0.875 atm of pressure at 625 ºC. e. 65.5 g of a gas under 1.025 atm of pressure at 56.7 ºC. f. 45.5 g of a gas under 1.56 atm of pressure at 32.1 ºC. 14. Estimate whether the molar masses of the gases determined in number 13 will increase or decrease with the changes. a. The volume of the container increased from 4505 L to 85.5 L. b. The temperature increased by 25%. c. The pressure reduced by 10%. 15. What are the gases in number 13 from these possibilities: the noble gases, the molecular elements, CO2, SO2, CO, SO3, COS, NH3, H2O, CH4, NO, N2O, NO2, CH2O? 16. Using the balanced chemical reaction, determine: 4 NH 3 ( g ) + 6 NO ( g ) → 5 N 2 ( g ) + 6 H 2O ( l ) 6 Exam 2 Worksheet a. The mass of water produced from 2.35 L of ammonia under 1.56 atm of pressure at 105 ºC and excess nitrogen monoxide. b. The mass of water produced from 2.35 L of nitrogen monoxide under 1.56 atm of pressure at 105 ºC and excess ammonia. c. The volume of nitrogen produced when 3.4 L of ammonia is consumed under STP. d. The volume of nitrogen produced when 3.4 L of nitrogen monoxide is consumed under STP. e. The total volume of gases consumed when 45.0 g under water is produced at STP. f. The volume of nitrogen produced under STP when 45.0 g of water is also produced. g. Combine 1.25 atm of ammonia and 10.0 g of nitrogen monoxide in a 10.0 L rigid container at 55 ºC and determine the following: i. The limiting reactant. ii. The theoretical yield of water. iii. The partial pressure of the reactant in excess. iv. The partial pressure of nitrogen. v. The experimental yield if the reaction only goes 75%. vi. The partial pressure of all gases if the reaction only goes 75%. vii. The partial pressure of all gases (at 100% completion) if the phase of water is a gas. viii. The partial pressure of all gases if the phase of water is a gas and the reaction only goes to 75% completion. ix. Under what conditions will the partial pressure of the gases be unaffected by reaction completion percentage (does a condition exist?). 17. Using the balanced chemical reaction, determine: 4C3 H 5 N3O9 ( l ) → 12CO2 ( g ) + 6 N 2 ( g ) + 10 H 2O ( g ) + O2 ( g ) a. The total pressure of gases produced when 125 g of nitroglycerine (C3H5N3O9) is reacted at 575 ºC in a 55 gallon drum. Assume the volume of the liquid to be zero and the container to be filled with 1 atm of inert gas (like helium) prior to reaction. b. The total volume of gases produced in an open container (assume pressure constant at 1 atm) when 125 g of nitroglycerine is reacted at 575ºC. c. The partial pressures of all gases in scenario (i) if the reaction goes to 100% completion. d. If 12.5 g of nitroglycerine is found once the reaction is over (in scenario number 1), what are the partial pressures of all gases? e. If the inert gas in the container was not helium initially, but nitrogen, how does this affect the partial pressures of all gases if the reaction in part (i) goes to 100% completion? Use: 4NH3 ( g ) + 5O2 ( g ) → 4NO ( g ) + 6H 2 O ( l ) for numbers 18‐20 18. What is the partial pressure of all substances given the percent yields when a 4.50 L flask containing 820 mmHg atm of ammonia is opened to a 3.50 L flask containing 1450 mmHg of 7 Exam 2 Worksheet oxygen? The reaction was carried out of a constant temperature of 45.0ºC with the partial pressure of water at 45.0ºC of 71.88 mmHg. a. A percent yield of 0% b. A percent yield of 25% c. A percent yield of 50% d. A percent yield of 75% e. A percent yield of 100% 19. What is the partial pressure of all substances given the final pressures when a 4.50 L flask containing 820 mmHg atm of ammonia is opened to a 3.50 L flask containing 1450 mmHg of oxygen? What is the percent yield? The reaction was carried out of a constant temperature of 45.0ºC with the partial pressure of water at 45.0ºC of 71.88 mmHg. a. A final pressure of 672 mmHg b. A final pressure of 729 mmHg c. A final pressure of 875 mmHg d. A final pressure of 995 mmHg 20. What is the partial pressure of all substances at 67.5% yield when a 4.50 L flask containing 820 mmHg atm of ammonia is opened to a 3.50 L flask containing 1450 mmHg of oxygen? The reaction was carried out of a constant temperature of 245.0ºC so water will also be in the gas phase. 21. What is the root‐mean‐square speed of the (ideal) gases at these temperatures? a. Helium at 250 K b. Helium at 450 K c. Nitrogen at 250 K d. Nitrogen at 450 K e. Methane at 250 K f. Methane at 450 K 22. Of each set, which gas will diffuse faster and by what factor? a. Helium or argon b. Argon or nitrogen c. Nitrogen or oxygen d. Oxygen or carbon dioxide e. Carbon dioxide or methane 23. Helium gas effuses through a porous barrier in 225 s. a. How long will it take for argon to effuse through the same barrier? b. How long will it take for carbon dioxide to effuse through the same barrier? c. What is the molar mass of a gas if it takes 615 s to effuse through the same barrier? If this gas contains 53% oxygen, what is the gas? d. What is the molar mass of a gas if it takes 160 s to effuse through the same barrier? What is this gas? 8 Exam 2 Worksheet e. What is the percent of nitrogen to oxygen gas if the mixture effuses through the same barrier in 605 s? f. What is the percent of methane to ethane if the mixture effuses through the same barrier in 505 s? Chapter 6 – Energy Relationships in Chemical Reactions 1. What is the heat evolved when 12.25 g of the substances decrease in temperature from 75ºC to 55ºC? a. Diamond (c = 6.113 J⋅K−1⋅mol−1) b. Iron (c = 25.10 J⋅K−1⋅mol−1) c. Brass (c = 0.38 J⋅g−1⋅ºC−1) d. Water (c = 4.18 J⋅g−1⋅ºC−1) e. Zinc (c = 25.40 J⋅K−1⋅mol−1) f. Graphite (c = 8.527 J⋅K−1⋅mol−1) g. Gold (c = 25.42 J⋅K−1⋅mol−1) 2. What are the heat capacities of the substances in #1 as J⋅g−1⋅ºC−1 (unless already are)? 3. What is the final temperature of the substances in #1 when 125.5 g samples (of each) evolve 2.50 kJ of heat (initial temperature = 90ºC)? 4. What is the final temperature of the substances in #1 when 125.5 g samples (of each) absorb 2.50 kJ of heat (initial temperature = 10ºC)? 5. If 655 g of the following samples are immersed in 2.5 L of water (assume the density of water = 1.00 g⋅mL−1) initially at room temperature (25 ºC) and each sample is initially at 815 ºC, determine the final temperature of both water and substance. a. Diamond b. Iron c. Brass d. Zinc e. Graphite f. Gold 6. A 0.500 kg block of ice at −15.0 ºC initially is placed in a square room with a wall length of 8.00 feet. If the final temperature of both the water and room are 20.0 ºC, determine the initial temperature of the room. (Assume all heat in the water is absorbed from the room’s air which will behave as an ideal gas ending at a constant pressure of 1 atm). Average molar mass of air is 28.9 g⋅mol−1, cair = 1.0 J⋅g−1⋅ºC−1, cice = 2.06 J⋅g−1⋅ºC−1, cliquid water = 4.18 J⋅g−1⋅ºC−1, and ΔHfus = 6.00 kJ⋅mol−1. 9