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Homework: Atoms, Molecules, and Ions

Homework: Atoms, Molecules, and Ions.
Assigment 1: Foundations: Atoms, Molecules, and Ions 1. 1 A 47. 3-mL sample of ethyl alcohol (ethanol) has a mass of 37. 32 g. What is its density? 1. 2 If 116 g of ethanol is needed for a chemical reaction, what volume of liquid would you use? The density of ethanol is 0. 789 g/mL 1. 3 Battery acid is 40. 0% sulfuric acid, H2SO4, and 60. 0% water by mass. Its density is 1. 31. Calculate the mass of pure H2SO4 in 100. 0 mL of battery acid. 1. 4 How many moles of atoms does 136. 9 g of iron metal contain? 1. 5 A stack of 500 sheets of typing paper is 1. inches thick. Calculate the thickness, in inches and in miles, of a stack of typing paper that contains one mole (Avogadro’s number) of sheets (1 inch = 2. 54 cm) 1. 6 Compounds containing sulfur and oxygen are serious air pollutants; they represent the major cause of acid rain. Analysis of a sample of a pure compound reveals that it contains 50. 1% sul- fur and 49. 9% oxygen by mass. What is the simplest formula of the compound? 1. 7 A 20. 882-gram sample of an ionic compound is found to contain 6. 072 grams of Na, 8. 474 grams of S, and 6. 336 grams of O.
What is its simplest formula? 1. 8 Hydrocarbons are organic compounds composed entirely of hydrogen and carbon. A 0. 1647-gram sample of a pure hydrocarbon was burned in a C-H combustion train to produce 0. 4931 gram of CO2 and 0. 2691 gram of H2O. Determine the masses of C and H in the sample and the percentages of these elements in this hydrocarbon. 1. 9 A 0. 1014-g sample of purified glucose was burned in a C-H combustion train to produce 0. 1486 g of CO and 0. 0609 g of H2O. An elemental analysis showed that glucose contains only carbon, hydrogen, and oxygen.
Determine the masses of C, H, and O in the sample and the percentages of these elements in glucose. 1. 10 Phosphorus, P4, burns with excess oxygen to form tetraphosphorus decoxide, P4O10. In this reaction, what mass of P4 reacts with 1. 50 moles of O2? 1. 11 What mass of CO2 could be formed by the reaction of 16. 0 g of CH4 with 48. 0 g of O2? Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU 19 -Le Thanh Tong, Hanoi, Vietnam. Email: [email protected] com 1. 12 What is the maximum mass of Ni(OH)2 that could be prepared by mixing two solutions that contain 25. g of NiCl2 and 10. 0 g of NaOH, respectively? NiCl2 + NaOH — > Ni(OH)2 + NaCl 1. 13 A 15. 6-gram sample of C6H6 is mixed with excess HNO3. We isolate 18. 0 grams of C6H5NO2. What is the percent yield of C6H5NO2 in this reaction? 1. 14 Phosphoric acid, H3PO4, is a very important compound used to make fertilizers. It is also pres- ent in cola drinks. H3PO4 can be prepared in a two-step process. Rxn 1: P4 +O2 — > P4O10 Rxn 2: P4 O10 +H2O — > H3PO4 We allow 272 grams of phosphorus to react with excess oxygen, which forms tetraphosphorus decoxide, P4O10, in 89. % yield. In the second step reaction, a 96. 8% yield of H3PO4 is obtained. What mass of H3PO4 is obtained? 1. 15 2. 00 grams of ammonium sulfate was dissolved in distilled water and made up to 250 mL in a volumetric flask. A 25. 0 mL portion of this solution was boiled with 50. 0 mL of 0. 100 M sodium hydroxide solution until no more ammonia gas was evolved. Then excess sodium hydroxide in the resulting solution required for neutralization, 24. 30 mL of HCl 0. 100M. Calculate the percentage purity of the sample. 1. 16 Write the correct formulae/ions for:

Potassium sulfite:………………. Dinitrogen pentoxide:……………. Nitrorous acid: ………………… Sodium hyperchlorite…………… Chloric acid………………… Hydride ion:………………… Coprous ions: ……………… Mercuric ion………………… 1. 17 In acidic solution, dichromate ion will oxidize ferrous ion to ferric ion and form chromate (III) ion. What volume of 0. 100 M dichromate ion is required to oxidize 60. 0 mL of 0. 250 M of ferrous ion? Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU 19 -Le Thanh Tong, Hanoi, Vietnam. Email: [email protected] com

Homework: Atoms, Molecules, and Ions

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