Chemistry 10 Dr. Scholefield Chapter 6 Worksheet Homework is not collected or graded, but should be worked on seriously every week. Mole Quantities, Particle Quantities and Mass 1. What is the numeric value of the mole? 1 mole = What is this value also known as? 2. A balloon contains 2.58 x 1024 molecules of methane, CH4. How many moles of methane are in this balloon? 3. An engagement ring contains 3.97 x 104 μmoles of gold. How many individual gold atoms are in this ring? 4. Exactly how is the formula mass of a substance different from its molar mass? 5. Calculate the molar masses of each of the following substances (don’t forget your units): a. silicon (in its natural state) b. phosphorus pentachloride c. lithium sulfite 6. Why does 1 mole of silicon have a different mass from 1 mole of phosphorus pentachloride (see 5a and 5b)? Don’t they both consist of the same number of particles? 7. What is the mass (in grams) of 0.121 moles of phosphorus pentachloride? 8. A rock contains 3.64 kg of lithium sulfite. How many moles of lithium sulfite are in this rock? 9. What is the mass (in grams) of 4.78 x 1024 atoms of silicon? 10. Aspartame (C14H18N2O5) is an artificial sweetener marketed as Nutra-Sweet. A packet of Nutra-Sweet is found to contain 500. mg of aspartame. How many individual molecules of aspartame are in this packet?Formulas as Conversion Factors 11. How many individual P atoms are found in 1.76 x 1022 molecules of tetraphosphorus trisulfide? 12. How many moles of O are in 0.575 moles of calcium perchlorate? 13. How many individual C atoms are found in 308 grams of benzene, C6H6? 14. What mass (in grams) of Na is found in 10.84 moles of sodium oxide? Percent Composition of Compounds 15. Calculate the mass percent of each element in aluminum bicarbonate, Al(HCO3)3. 16. Arrange the following compounds in order of increasing mass % of phosphorus: H3PO4, P4O10 and PCl3. 17. When 54 grams of a compound containing the elements N and O (only) is analyzed, it is found to contain 40 grams of O. What mass of N would be found in a 2.36 gram sample of this same compound? 18. What is the mass (in grams) of hydrogen in 253 grams of propane, C3H8?Empirical and Molecular Formulas 19. When a 34.61 gram sample of a “chromium oxide” compound is analyzed, it is found to contain 21.43 grams of Cr, the remainder being O. (a) Determine this empirical formula of this compound, and (b) state whether the chromium ions in this compound have a +3, +4 or a +6 charge. 20. Aspirin has a percent composition of 60.00% C, 4.48% H and 35.53% O. Determine its empirical formula. 21. The compound benzene is determined to have an empirical formula C1H1. If the true molar mass of benzene is 78.0 g, what is the true chemical formula of benzene? 22. Adipic acid is used in the manufacture of nylon. When a 68.4 g sample of adipic acid is analyzed it is found to consist of 33.8 g C, 4.7 g H and 29.9 g O. a. What is the empirical formula of adipic acid? b. If the molar mass of adipic acid is 146 grams, what is the true molecular formula of adipic
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