CHEM-113. Problem Set I. Chapter 3 PDF

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CHEMISTRY-113. CHAPTER 3. PROBLEM SET I. 1. A sample of ammonia has a mass of 45.5 g. How many molecules are in this sample? a) 2.67 molecules b) 2.74 x 1025 molecules c) 2.25 x 1023 molecules 1.61 x 1024 molecules d) e) 9.02 x 10–16 molecules 2. How many moles of hydrochloric acid are contained in a 52.6-g sample of this acid? a) 0.693 mol b) 1.44 mol c) 89.1 mol d) 52.2 mol e) 2.89 mol 3. What is the molar mass of propanol (C3H7OH)? a) 59.09 g/mol b) 36.07 g/mol c) 60.09 g/mol d) 30.03 g/mol e) 149.04 g/mol 4.

Roundup, an herbicide manufactured by Monsanto, has the formula C3H8NO5P. How many moles of molecules are there in a 304.3-g sample of Roundup? a) 0.5556 b) 2.203 c) 1.800 d) 16.91 e) none of these

5. Calculate the molar mass of calcium perchlorate. a) 254.98 g/mol b) 222.98 g/mol c) 279.06 g/mol d) 179.61 g/mol e) 238.98 g/mol 6. What is the molar mass of Ca3(PO4)2? a) 310.18 g/mol b) 87.05 g/mol c) 278.18 g/mol d) 215.21 g/mol e) 166.02 g/mol 7.

How many oxygen atoms are there in 3.80 g of Ca3(PO4)2?

8. What is the mass of a 6.267-mol sample of sodium hydroxide? a) 40.00 g b) 250.7 g c) 150.4 g d) 6.382 g e) 0.1567 g 9. How many atoms of hydrogen are present in 3.18 g of ammonia? a) 1.12 x 1023 b) 6.33 x 1023 c) 5.74 x 1024 d) 3.37 x 1023 10. What is the molar mass of cryolite (Na3AlF6)? a) 209.9 g/mol b) 185.3 g/mol c) 210.0 g/mol d) 104.2 g/mol e) 68.97 g/mol 11. NaHCO3 is the active ingredient in baking soda. How many grams of oxygen are in 0.42 g of NaHCO3? a) 0.080 g b) 0.015 g c) 5.00 x 103 g d) 0.027 g e) 0.24 g 12. A substance contains 35.0 g nitrogen, 5.05 g hydrogen, and 60.0 g of oxygen. How many grams of hydrogen are there in a 179-g sample of this substance? a) 9.03 g b) 897 g c) 18.1 g d) 5.05 g e) 35.4 g 13. How many grams of potassium are in 21.9 g of K2CrO7? a) 3.54 g b) 1.120 g c) 7.07 g d) 78.2 g e) 43.8 g 14. Chloric acid, HClO3, contains what percent hydrogen by mass? a) 1.92% b) 20.0% c) 18.9% d) 1.19% e) 4.20% 15. An oxide of iron has the formula Fe3O4. What mass percent of iron does it contain? a) 0.72% b) 28% c) 30% d) 70% e) 72% 16. The mineral mimetite has the formula Pb5(AsO4)3Cl. What mass percent of oxygen does it contain? a) 38.70 % b) 16.34 % c) 50.32 % d) 12.90 % e) 1.08 %

17. Ammonium sulfate, (NH4)2SO4, contains what percent nitrogen by mass? a) 42.4% b) 10.6% c) 21.2% d) 13.7% e) none of these 18. Adipic acid contains 49.32% C, 43.84% O, and 6.85% H by mass. What is the empirical formula? a) C 3 H5 O 2 b) C 3 H3 O 4 c) C2HO3 d) C 2 H5 O 4 e) C3HO3 19. Vitamin C contains the elements C, H, and O. It is known to contain 40.9% C and 4.58% H by mass. The molar mass of vitamin C has been found to be about 180 g/mol. The molecular formula for vitamin C is: a) C 2 H3 O 2 b) C 3 H4 O 3 c) C 4 H6 O 4 d) C 6 H8 O 6 e) C14H18 20. A compound composed of sulfur and fluorine is found to contain 25.24% by mass of sulfur. If the molar mass of the compound is 254.11 g/mol, what is its molecular formula? a) S3F8 b) S2F8 c) SF5 d) S2F5 e) S2F10...