2. What is the total mass (amu) of hydrogen in each of the molecules? (a) CH 4. (b) CHCl 3. (c) C 12 H 10 O 6. (d) CH 3 CH 2 CH 2 CH 2 CH 3

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1 Chem 180- Spring 2019 HW Ch 3 Name: Note: I used the problem numbers from the book, so they don t start at 1. Stay within the space provided, so keep your answers and explanations brief. (I have learned in lab that some of you write much more than you need to!) 2. What is the total mass (amu) of hydrogen in each of the molecules? (a) CH 4 (b) CHCl 3 (c) C 12 H 10 O 6 (d) CH 3 CH 2 CH 2 CH 2 CH 3 4. Determine the molecular mass (amu) of the following compounds: (a) (b) (c) (d) 8. Compare 1 mole of H 2, 1 mole of O 2, and 1 mole of F 2. (a) Which has the largest number of molecules? Explain why. (b) Which has the greatest mass? Explain why. 1

2 10. Which contains the greatest number of moles of oxygen atoms: 1 mol of ethanol (C 2 H 5 OH), 1 mol of formic acid (HCO 2 H), or 1 mol of water (H 2 O)? 12. Calculate the molar mass (g) of each of the following compounds: (a) hydrogen fluoride, HF (b) ammonia, NH 3 (c) nitric acid, HNO 3 (d) silver sulfate, Ag 2 SO 4 (e) boric acid, B(OH) Calculate the molar mass (g) of each of the following minerals: (a) limestone, CaCO 3 (b) halite, NaCl (c) beryl, Be 3 Al 2 Si 6 O 18 (d) malachite, Cu 2 (OH) 2 CO 3 2

3 (e) turquoise, CuAl 6 (PO 4 ) 4 (OH) 8 4H 2 O 16. Determine the number of moles of compound and the number of moles of each element in the following: (a) 25.0 g of propylene, C 3 H 6 (b) g of the amino acid glycine, C 2 H 5 NO 2 (c) 25 lb of the herbicide Treflan, C 13 H 16 N 2 O 4 F (1 lb = 454 g) (d) kg of the insecticide Paris Green, Cu 4 (AsO 3 ) 2 (CH 3 CO 2 ) 2 (e) 325 mg of aspirin, C 6 H 4 (CO 2 H)(CO 2 CH 3 ) 3

4 22. A 55-kg woman has mol of hemoglobin (molar mass = 64,456 g/mol) in her blood. How many hemoglobin molecules is this? What is this quantity in grams? 24. Determine which of the following contains the greatest mass of hydrogen: 1 mol of CH 4, 0.6 mol of C 6 H 6, or 0.4 mol of C 3 H Diamond is one form of elemental carbon. An engagement ring contains a diamond weighing 1.25 carats (1 carat = 200 mg). How many atoms are present in the diamond? 34. Determine the following to four significant figures: (a) the percent composition of hydrazoic acid, HN 3 (b) the percent composition of TNT, C 6 H 2 (CH 3 )(NO 2 ) 3 (c) the percent of 2 SO 4 in Al 2 (SO 4 ) 3 4

5 36. Determine the percent water in CuSO 4 5H 2 O to three significant figures. 38. Determine the empirical formulas for compounds with the following percent compositions: (a) 43.6% phosphorus and 56.4% oxygen (b) 28.7% K, 1.5% H, 22.8% P, and 47.0% O 40. Dichloroethane, a compound that is often used for dry cleaning, contains carbon, hydrogen, and chlorine. It has a molar mass of 99 g/mol. Analysis of a sample shows that it contains 24.3% carbon and 4.1% hydrogen. What is its molecular formula? 5

6 43. A major textile dye manufacturer developed a new yellow dye. The dye has a percent composition of 75.95% C, 17.72% N, and 6.33% H by mass with a molar mass of about 240 g/mol. Determine the empirical and molecular formulas of the dye. A g sample of a carbon-hydrogen compound produces g CO 2 and g H 2 O in combustion analysis. Its molar mass is about 106 g. Determine the compound s empirical and molecular formulas. (answers: C 4 H 5 and C 8 H 10 ) A g sample of p-cresol, a carbon-hydrogen-oxygen compound, yields g CO 2 and g H 2 O in combustion analysis. Its molar mass is g. Determine the empirical and molecular formula of p-cresol. 6

7 48. Determine the molarity of each of the following solutions: (a) mol KCl in L of solution (b) g of H 2 SO 4 in 1.00 L of solution (c) g of Al(NO 3 ) 3 in 1575 ml of solution (d) 2.76 kg of CuSO 4 5H 2 O in 1.45 L of solution (e) mol of Br 2 in ml of solution (f) g of glycine, C 2 H 5 NO 2, in 1.05 ml of solution 50. Consider this question: What is the mass of solute in L of a M solution of KBr? 52. Calculate the number of moles and the mass of the solute in the following solution: 325 ml of M KI, a source of iodine in the diet. 7

8 56. Calculate the molarity of each of the following solutions: (a) 293 g HCl in 666 ml of solution, a concentrated HCl solution (b) g FeCl 3 in L of a solution used as an unknown in general chemistry laboratories (c) mg Cd 2+ in L, the maximum permissible concentration of cadmium in drinking water (d) g C 7 H 5 SNO 3 in one ounce (29.6 ml), the concentration of saccharin in a diet soft drink. 60. If 4.12 L of a M-H 3 PO 4 solution is be diluted to a volume of L, what is the concentration the resulting solution? 62. What is the concentration of the NaCl solution that results when L of a M solution is allowed to evaporate until the volume is reduced to L? 8

9 66. An experiment in a general chemistry laboratory calls for a 2.00-M solution of HCl. How many ml of 11.9 M HCl would be required to make 250 ml of 2.00 M HCl? 67. What volume of a 0.20-M K 2 SO 4 solution contains 57 g of K 2 SO 4? 70. What mass of a 4.00% NaOH solution by mass contains 15.0 g of NaOH? 72. What mass of HCl is contained in 45.0 ml of an aqueous HCl solution that has a density of 1.19 g cm 3 and contains 37.21% HCl by mass? 76. A throat spray is 1.40% by mass phenol, C 6 H 5 OH, in water. If the solution has a density of g/ml, calculate the molarity of the solution. 9

Chapter 2 Atoms, Molecules, and Ions 103. negatively charged atom or molecule (contains more electrons than protons)

Chapter 2 Atoms, Molecules, and Ions 103 Key Terms alpha particle (α particle) positively charged particle consisting of two protons and two neutrons anion negatively charged atom or molecule (contains