4. A chemist mixes g of potassium permanganate, g of ethanol, and excess sulfuric acid. These chemicals react as follows:

Transcription

1 Chemistry 400 Miller Chapter 4 omework Problems 1. To the proper number of significant figures, if you have a g sample of sodium dichromate A....how many moles of sodium dichromate do you have? B....how many actual oxygen atoms (and not moles of atoms) do you have? C....how many grams of sodium atoms do you have? D....how many grams of chromium do you have? E....how many actual sodium ions (and not moles of ions) do you have 2. To the proper number of significant figures, if you have a g sample of ammonium phosphate A....how many moles of ammonium phosphate do you have? B....how many actual oxygen atoms (and not moles of atoms) do you have? C....how many grams of hydrogen atoms do you have? D....how many grams of phosphorus do you have? E....how many actual ammonium ions (and not moles of ions) do you have? 3. To the proper number of significant figures if you have a g sample of ammonium chromate A....how many moles of ammonium chromate do you have? B....how many moles of oxygen atoms do you have? C....how many actual hydrogen atoms do you have? D....how many grams of chromium do you have? E....how many protons do you have? 4. A chemist mixes g of potassium permanganate, g of ethanol, and excess sulfuric acid. These chemicals react as follows: 4 KMnO C 2 5 O SO 4 4 MnSO C 3 COO + 2 K 2 SO O Please report all of your answers for this problem to the correct number of significant figures. A. What mass of manganese(ii) sulfate is produced in this reaction, assuming that the reaction goes to completion? B. The chemist isolates g of acetic acid. Calculate the percent yield of acetic acid in this experiment. C. What mass of sulfuric acid is consumed in this reaction assuming that the reaction goes to completion? D. Assume that the reaction went to completion. ow many grams of excess reactant (either potassium permanganate or ethanol) are left over? 5. A chemist mixes g of potassium permanganate, g of ethanol, and excess sulfuric acid. These chemicals react as follows: 4 KMnO C 2 5 O SO 4 4 MnSO C 3 COO + 2 K 2 SO O Please report all of your answers for this problem to the correct number of significant figures. A. What mass of sulfuric acid is consumed in this reaction, assuming that the reaction goes to completion? B. The chemist isolates g of acetic acid. Calculate the percent yield of acetic acid in this experiment. C. What mass of acetic acid is produced in this reaction assuming that the reaction goes to completion? D. Assume that the reaction went to completion. ow many grams of excess reactant (either potassium permanganate or ethanol) are left over? 6. A student wishes to prepare a solution of ammonium sulfate. A. What mass of ammonium sulfate would be required to prepare ml of a 6.00 M solution? B. Suppose part of this solution is then diluted to prepare ml of M. What volume of the solution from part A is needed to prepare this more dilute solution? C. If you double the volume of the diluted solution from part B to 1,000 ml, what will the final molarity be? D. Complete the following sentence: When the volume of the solution is doubled in part C, the concentration of the solution (remains the same, is doubled, is halved). 21

2 7. A student wishes to prepare a solution of iron(iii) acetate. A. What mass of iron(iii) acetate would be required to prepare ml of a 1.00 M solution? B. Suppose part of this solution is then diluted to prepare L of M. What volume of water was added to the original solution to prepare the diluted solution (note: this question does not ask for the final volume of solution, but the volume of water added). Assume that the volumes of the solutions are perfectly additive. C. If you add an additional ml of water to the diluted solution from part B, what will the final molarity be? D. Complete the following sentence: When the volume of the solution is doubled in part C, the concentration of the solution is (remains the same, is doubled, is halved). 8. Many fertilizers contain ammonium phosphate as a source of phosphorus and nitrogen. A g sample of a fertilizer is dissolved in water and mixed with excess barium chloride solution, and the following reaction occurs: 2 (N 4 ) 3 PO 4 (aq) + 3 BaCl 2 (aq) Ba 3 (PO 4 ) 2 (s) + 6 N 4 Cl(aq) The product mixture is found to contain g of barium phosphate. Using this information, calculate the percentage by mass of ammonium phosphate in the fertilizer. 9. The combustion of liquid ethanol (C 2 5 O) produces carbon dioxide and water. After 4.62 ml of ethanol (density = g/ml) was allowed to burn in the presence of g of oxygen gas, 3.72 ml of water (density = 1.00 g/ml) was collected. Determine the limiting reactant, theoretical yield of 2 O and the percent yield for the reaction. 10. All of the lanthanide metals (La through Lu, elements 57 through 71) react with Cl to form compounds having either the formula MCl 2, MCl 3 or MCl 4 (where M represents the metallic element). Each lanthanide forms a single compound. A chemist has a g sample of a lanthanide, and she wishes to identify the metal. She reacts the metal with excess Cl and obtains g of product. Based on this information, identify the metal and write the chemical formula of the product. 11. All of the lanthanide metals (La through Lu, elements 57 through 71) react with Cl to form compounds having either the formula MCl 2, MCl 3 or MCl 4 (where M represents the metallic element). Each lanthanide forms a single compound. A chemist found a g sample of a lanthanide while walking in the eastern Sierras, and she wishes to identify which one it is. She reacts it with excess Cl and obtains g of the metal chloride. Based on this information, identify the two possible metals that it could be. Then, based on the fact that the sample was found in the mountains, determine which one of the metals it is g of vanadium (V) is mixed with g of bromine (Br 2 ). After the elements react, some bromine is left over, along with a single compound that contains the two elements. The excess bromine is removed and allowed to react with excess sodium sulfite and excess sodium hydroxide, producing a mixture that contains 2.93 g of sodium sulfate. The balanced equation for this second reaction is: 2 NaO + Na 2 SO 3 + Br 2 2 NaBr + Na 2 SO O Based on this information, determine the empirical formula of the compound that was formed when vanadium reacted with bromine g of vanadium (V) is mixed with g of bromine (Br 2 ). After the elements react, some bromine is left over, along with a single compound that contains the two elements. The excess bromine is removed and allowed to react with excess sodium sulfite and excess sodium hydroxide, producing a mixture that contains g of sodium sulfate. The balanced equation for this second reaction is: 2 NaO + Na 2 SO 3 + Br 2 2 NaBr + Na 2 SO O Based on this information, determine the empirical formula of the compound that was formed when vanadium reacted with bromine. 14. A mixture of 28.3 g of P and g Cl 2 reacts completely to form PCl 3 and PCl 5 as the only products. Find the mass of PCl 3 formed. 15. A mixture of 20.6 g of P and 79.4 g Cl 2 reacts completely to form PCl 3 and PCl 5 as the only products. Find the mass of PCl 3 formed. 22

3 16. Titanium occurs in the magnetic mineral ilmenite (FeTiO 3 ), which is often found mixed up with sand. The ilmenite can be separated from the sand with magnets. The titanium can then be extracted from the ilmenite by the following set of reactions: FeTiO 3 (s) + 3 Cl 2 (g) + 3 C(s) 3 CO(g) + FeCl 2 (s) + TiCl 4 (g) TiCl 4 (g) + 2 Mg(s) 2 MgCl 2 (l) + Ti(s) Suppose that an ilmenite-sand mixture contains 22.8% ilmenite by mass and that the first reaction is carried out with a 90.8% yield. The second reaction is carried out with an 85.9% yield. If you start with 1.00 kg of an ilmenite-sand mixture, calculate the mass of: A. Ilmenite in the ilmenite-sand mixture B. TiCl 4 (g) produced in the first reaction C. Ti(s) produced in the second reaction 17. ydrochloric acid dissolves calcium carbonate to produce calcium chloride and carbon dioxide gas and another product. A. Write the balanced reaction for this process. Be sure to include phases for all species. B. An eggshell has an average mass of 5.5 g. Ninety-four percent of an eggshell is calcium carbonate. What mass of hydrochloric acid is required to dissolve an eggshell? What mass of carbon dioxide is produced? 18. A 28.1 g chunk of calcium metal reacts with 13.7 g of oxygen gas to make calcium oxide. A. Write the balanced reaction. B. Assume that the reaction went to completion, but that through the collection and purification processing only 24.3 g of calcium oxide are purified. What is the percent yield? C. Assume that the reaction went to completion. ow many grams of oxygen gas are left over? 19. Sulfuric acid dissolves aluminum to produce aluminum sulfate and hydrogen gas. A. Write the balanced reaction for this process. B. Suppose you wanted to dissolve an aluminum block with a mass of 15.2 g. What mass of sulfuric acid would you need? What mass of aluminum sulfate would you produce? What mass of hydrogen gas would you produce? 20. To be an electrolyte, whether strong, weak, or inert, a substance must. 21. Place the following lists of compounds into as many categories (boxes) as appropriate: A. NaCl, Cl, AgCl, C 3 C 2 O, AgNO 3, C 3 COO, 2, Fe(C 3 COO) 3, C 6 12 O 6, NaO, Fe(O) 3, 2 S, CaCO 3, N 4 NO 3, Li 3 PO 4, 2 CO 3, 2 SO 4, COO, LiO, N 3 B. NaNO 3, NO 3, PbCl 2, C 3 C 2 O, AgNO 3, C 3 COO, Fe(C 3 COO) 3, C 6 12 O 6, NaO, Fe(O) 3, 2 S, CaCO 3, (N 4 ) 3 PO 4, Li 3 PO 4, 2 CO 3, 2 SO 4, COO, CsO, N 3 C. NaC 3 COO, NO 3, PbBr 2, C 3 C 2 O, AgNO 3, C 3 COO, Fe(NO 3 ) 3, C 6 12 O 6, KO, Zn(O) 3, 2 S, CaCO 3, (N 4 ) 3 PO 4, Li 3 PO 4, 2 CO 3, 2 SO 4, COO, CsO, N 3, Na 2 SO 4 Strong acids. Strong electrolytes. Weak acids. Weak electrolytes. Strong bases. Nonelectrolytes. Insoluble. 23

4 22. Write (i) the balanced overall reaction for each of the following reactions. Write (ii) the total ionic equation (TIE), and (iii) the net ionic equation (NIE) for each of the reactions that will occur when the following solutions are mixed. If there is a reaction, it will go to completion. If there is no reaction, write "No Reaction" for the NIE but still complete the balanced overall reaction and the TIE. A. aqueous solutions of silver nitrate and potassium chloride B. aqueous solutions of acetic acid and potassium hydroxide C. 2 SO 4 (aq) and Na 2 CO 3 (aq) D. aqueous solutions of potassium sulfite and nitric acid E. aqueous solutions of hydroiodic acid and lithium hydroxide F. aqueous solutions of potassium sulfate and calcium iodide G. aqueous solutions of potassium carbonate and nitric acid. aqueous solutions of ammonium carbonate and iron(iii) chloride 23. A chemist dissolves g of sodium hydroxide in water and dilutes the solution to the mark in a ml volumetric flask. A 1.00 ml sample of this solution is then transferred to a ml volumetric flask and diluted to the mark. A. What is the molarity of the sodium hydroxide in the final solution? B. What is the p of the final solution? 24. A chemist dissolves g of hydrochloric acid in water and dilutes the solution to the mark in a ml volumetric flask. A 1.00 ml sample of this solution is then transferred to a ml volumetric flask and diluted to the mark. A. What is the molarity of the hydrochloric acid in the final solution? B. What is the p of the final solution 25. A 12.0 g chunk of zinc is dropped into ml of M Cl. A. What is the concentration of zinc chloride? B. What is the mass of hydrogen gas produced? C. What is the concentration (molarity) of + in the solution? D. What is the p of the solution? 26. Assign oxidation numbers to each of the elements in the following compounds: A. P 2 O 5 B. N 2 O 4 C. SO 2 D. Fe(NO 3 ) 2 E. N 4 Cl F. C 3 C 2 O G. C 2 5 COO. C 3 COC 3 I. C 3 C 2 C Assign an oxidation number to each of the elements in the following reaction. Identify the element oxidized and the element reduced. Also identify the element that is the oxidizing agent and the reducing agent. 2 NO 3 (aq) + 3 Zn(s) (aq) 2 NO(g) + 3 Zn 2+ (aq) O(l) 28. Assign an oxidation number to each of the elements in the following reaction. Identify the element oxidized and the element reduced. Also identify the element that is the oxidizing agent and the reducing agent. 2 NO 2 (aq) + 4 Fe(O) 2 (s) O(l) 4 Fe(O) 3 (s) + N 2 O(g) + 2 O (aq) 29. Balance and assign oxidation numbers the following elements for the burning of glucosamine (pictured). Identify the element oxidized and the element reduced. Also identify the element that is the oxidizing agent and the reducing agent. More than one element may be oxidized or reduced. C O O C C O C C O C O N 2 + O 2 (g) CO 2 (g) + 2 O(g) + NO 2 (g) 24

5 30. List the 7 strong acids. 31. acids are (essentially) 100% ionized. acids are approximately % ionized. bases are soluble in water, have the ion in their formulas, and dissociate % into ions. bases are approximately % ionized. They are called amines and have nitrogen bonded to three other atoms and a lone pair of electrons. 32. Fill in the gaps in the following table: p [ + ] (mol/l) [O ] (mol/l) Acid/Base Sol'n? p: always 2 decimal places [ + ], [O ]: always 2 sig figs 1.9 x x Fill in the gaps in the following table: p [ + ] (mol/l) [O ] (mol/l) Acid/Base Sol'n? p: always 2 decimal places [ + ], [O ]: always 2 sig figs 1.9 x x An auto mechanic spills 88 ml of 2.6 M sulfuric acid solution from a rebuilt car battery. ow many milliliters of 1.6 M sodium bicarbonate must be poured on the spill to neutralize the sulfuric acid? 35. In an experiment, ml of silver nitrate of unknown concentration and ml of calcium chloride of unknown concentration are mixed together. A white precipitate forms. When 10.0 ml more calcium chloride is added, no more precipitate forms. The solution is then filtered and the precipitate is weighed to be 2.15 g. Then excess M sodium carbonate is added to the previous solution. Another precipitate forms. When it is filtered, the new precipitate weighs 2.33 g. What are the concentrations of the silver nitrate and calcium chloride solutions 25

6 36. A ml sample of aqueous solution contains an unknown amount of dissolved NaCl. Analysis of the solution can be accomplished through use of a precipitation reaction such as the one that would result from adding an aqueous solution of Pb(NO 3 ) 2. A. What is the chemical formula of the precipitate? B. Write the net ionic equation for this precipitation reaction. C. The precipitate can be recovered by filtration and then weighed. If the mass of precipitate recovered was grams, what was the concentration of Cl- ions in the original solution? 37. Determine the type of electrolyte. Also, list or draw all ion(s)/molecule(s) that would be present in each beaker if the substance was dissolved in water in the approximate ratios that they would be present. A. NaNO 3 B. C O 11 C. COO Type of electrolyte: Type of electrolyte: Type of electrolyte: 26