Unit One Practice

Class Copy Unit One Practice 1. What is the formula of the ionic compound formed between Mg and Br? a) MgBr b) Mg2Br c) MgBr2 d) Mg2Br2 e) Mg2Br3 2. What is the formula of the ionic compound formed between Ca and P? a) HTe c) HiTe b) H₂Te d) HTe2 8. The correct formula for dinitrogen tetroxide is a) NO2 N2O4 c) N2O5 d) NO3 e) (N2O)4 a) Ca2P3 d) Ca₂P b) CaP e) Ca3P2 c) CasP10 3. What is the name of the SO32-ion? a) sulfate b) nitrate sulfite d) sulfur trioxide c) hydrogen sulfate 4. What is the correct formula and charge for the chromate ion? 4) CrO42- b) CrO4 d) Cr2O7 e) Cr3+ c) Cr2O72- 5. Which one of the following elements forms ions with two different valences? a) calcium b) arsenic iron d) fluorine 9. The correct name for S2Cl2 is a) sulfur dichloride b) sulfur(1) chloride c) sulfur(II) chloride disulfur dichloride e) sulfur chloride 10. The correct name for NO2 is a) nitrogen dioxide b) nitrite c) nitrogen oxide d) nitrogen(II) oxide e) nitrate 11. The molar mass of (NH4)2S is closest to: a) 50 g/mol 68 g/mol b) 82 g/mol d) 100 g/mol 6. The correct name for CCl4 is a) carbon (1) chloride b) carbon chloride carbon tetrachloride d) monocarbon chloride(IV) c) carbochlorinate 7. The correct formula for hydrogen telluride is 12. How many atoms are in 12 molecules of glucose, C6H12O6? a) 24 6 288 c) 2160 d) 7.22 x 1024 13. Calculate the number of atoms in 4.0 x 10-5 g of aluminum. a) 8.9 x 1017 4x10x6x1023 24x1018 -5 27 2.7 c) 6.5 x 1070 b) 4.6 x 1019 d) 3.8 x 1023 14. Which of the following samples contains the smallest number of atoms? a) 1 g H2 b) 1g 02 32 c) 1803 4 18 Ch 71 18. A compound consists of the following elements by weight percent: carbon-40.0% 40/12-3.5 oxygen 53.3% 53.3/14 3.5 hydrogen-6.7% 6.1/1=6.7 the The ratio of carbon oxygen: hydrogen in empirical formula is a) 1:2:1 b) 1:1:1 1:1:2 d) 2:1:2 15. What is the mass of one molecule of octane, CgH18? a) 114 g 6) 1.89 x 10-22 g c) 1.10 x 10-22 g d) 4.32 x 10-23 g 114 23 6x10 -23 19x10 19. An organic compound which has the empirical formula CHO has a molar mass of 232. Its molecular formula is: 16. What is the percent nitrogen (by mass) in ammonium carbonate, (NH4)2CO3? a) 14.53% 29.16% b) 27.83% d) 33.34% १७ 17. Of the following, the only empirical formula is a) N2F2 b) N2F4 c) H₂C2 HNF2 a) CHO c) C4H4O4 b) C2H2O2 CHO 2328 29 8 8 20. When CaSO4-y H2O is heated, all of the water is driven off. If 34.0 g of CaSO4 [molar mass = 136] is formed from 43.0 g of CaSO4-y H₂O, what is the value of y? a) 1 c) 3 2 d) 4 =,209 2 136+X 7914 = 28.44.2014 =35.9-225 16 Answers: 1. c 6. c 11. с 16. c 2. e 7. b 12. b 17. d 3. c 8. b 13. a 18. C 4. a 9. d 14. d 19. d 5. c 10. a 15. b 20. b Unit 1 Free Response 1- Write balanced chemical equations for the following (5 points each) a- aluminum nitrate reacts with magnesium hydroxide to form aluminum hydroxide and magnesium nitrate 2Al(NO3), Bong (OH)2 →2A1 (ort), mg (ny)2 b- When solid ammonium carbonate is heated it produces ammonia, carbon dioxide and water (NH4)2CO3 92NH₃ + CO₂ +₂O c- iron (III) sulfide reacts with sulfuric acid to form hydrogen sulfide gas and iron sulfate Fex S₃ +31tz sou 3 H₂S + Fe(504)3 2- Consider the following unbalanced reaction: (25 points) 3mol Ca3(PO4)2 +H2SO4-CaSO4 H3PO4 10.2 a- What masses of calcium sulfate and phosphoric acid can be produced from the reaction of a sample of calcium phosphate that contains 1.44 x 1025 atoms of oxygen with 1.00 Kg of sulfuric acid? b- If the actual amount of calcium sulfate produced is 396 grams and phosphoric acid is 190 grams, what is the percent yield for the reaction? 25 @1.44×10 alax Imolo 6x1023 Imal Co, puy,03×10 smo10 2 3 mol H2SO4 1000/98 = 10.2 ml 3 mol X 3H2S04= 9 hare 10.2. X Caso 9 mol X 136=1224gno. Casoy 4ml x 98=588 H3804 396 1224 = 32.490 190 588 = 32.476 ( Unit One FRQ Practice Problem vs. Exercise An exercise is a calculation or other task where you know what to do. You are doing repeated examples to build up your skill, your speed, and your experience. A problem is a situation in which you do not know what to do. So... what do you do when you do not know what to do? Read the problem, read it again, read it again, calculate a few things, read it again, and hopefully things fall into place. You learn to solve problems by solving problems. You add ideas to your "bag of tricks." 1982 B Water is added to 4.267 grams of UF. The only products are 3.730 grams of a solid containing only uranium, oxygen and fluorine and 0.970 gram of a gas. The gas is 95.0% fluorine, and the remainder is hydrogen. (a) From these data, determine the empirical formula of the gas. F = 95/19=5 H = 51,25 HF (b) What fraction of the fluorine of the original compound is in the solid and what fraction in the gas after the reaction? UF = 352. •970 HF X に 20 =,0485mlF 4.267 X 6F 352 UF6 0728 mol F 0485 10729 = 66.77. in gas,, 33. 370 solid. (c) What is the formula of the solid product? 01212 ml 4 0728F-.0485 = .0243F: 4617 4.267 352 10121 ml 4F 0121 4 x 2385 enol : 2.885gm 4. 3.732.885-461738330 .024 nol 0 16 UFO2 Divide.012 Note: There is also a part (d) that we would not yet know how to do. Stoichiometry 1. Sodium reacts with water to form sodium hydroxide and hydrogen gas. How many grams of He can be produced from 11.5 g of sodium? 2. Hydrochloric acid reacts with calcium hydroxide to produce water and calcium chloride. How many grams of HCl are required to react with 10.0 g of calcium hydroxide? 3. Nitrogen reacts with hydrogen to make ammonia. How many grams of ammonia can be produced from 2.00 g of hydrogen? 4. Potassium chlorate decomposes when heated to give oxygen gas and potassium chloride. How many grams of oxygen gas can be obtained in this way starting with 1.226 g of KCIO? 5. Phosphorus trichloride is made when white phosphorus (P4) reacts with chlorine gas. How many grams of phosphorus are required to produce 5.49 g of phosphorus trichloride? 6. Ethene gas (CH4) burns in oxygen to form carbon dioxide and water. How many grams of ethene must be burned to produce 200 g (to the nearest gram) of carbon dioxide? 7. Magnesium metal reacts with sulfuric acid in a displacement reaction. How many grams of hydrogen gas will be produced when 4.05 g of magnesium reacts completely? Limiting reagents in stoichiometry 8. Aluminum and sulfuric acid react in a displacement reaction. If 5.0 g of Al and 45 g of sulfuric acid are used, what mass of hydrogen is collected? What is the limiting reagent? 9. A student prepares hydrogen bromide gas by reacting sodium bromide with phosphoric acid. Sodium phosphate is a by-product. If 24.3 g of sodium bromide is used with 100.0 g of phosphoric acid, how many grams of hydrogen bromide gas can be collected? What is the limiting reagent?