chapter03_part1 - Chapter 3 Chemical Compounds 61...

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Chapter 3: Chemical Compounds 61 End-of-Chapter Solutions for Chapter 3 Summary Problem Part I Answer: 1. (a) NH 4 ClO 4 (b) NH 4 ClO 3 (c) NH 4 ClO 2 2. (a) NH 4 + , ClO 4 (b) Yes; it contains ions. 3. 5.8 × 10 6 mol NH 4 ClO 4 Strategy and Explanation: Given the names of three compounds, determine their chemical formulas. Determine the identity of the ions when one compound is dissolved in water and explain whether it would conduct electricity. Given the mass of the compound determine the number of moles. 1. Table 3.7 gives the names and formulas of common ions. Make neutral combinations (equal numbers of positive and negative charges) with the common ions involved. (a) Ammonium (NH 4 + ) and perchlorate (ClO 4 ) must be combined in a 1:1 ratio, to make NH 4 ClO 4 . (b) Chlorate (ClO 3 ) must be combined with ammonium in a 1:1 ratio, to make NH 4 ClO 3 . (c) Chlorite (ClO 2 ) must be combined with ammonium in a 1:1 ratio, to make NH 4 ClO 2 . 2. In aqueous solution, the cations and anions separate disperse into the solution. (a) When NH 4 ClO 4 dissolves in water, it will ionize completely to produce NH 4 + and ClO 4 . (b) Electricity is conducted in an aqueous solution by ions present in the solution. Because ions are present in this aqueous solution, it would conduct an electric current. 3. To calculate the molar mass of a compound, we perform a series of steps: First, look up the atomic mass of each element on the periodic table or in a table of atomic masses to identify the molar mass of the element. Second, determine the number of moles of atoms in one mole of the compound by examining the formula. Third, multiply the number of moles of the element by the molar mass of the element. Last, add all individual masses. (a) 1 mol of NH 4 ClO 3 contains 1 mol of N, 4 mol of H, and 1 mol of Cl, and 2 mol O. 1 mol N 1 mol NH 4 ClO 3 " 14.0067 g 1 mol N # $ % ( + 4 moles H 1 mol NH 4 ClO 3 " 1.0079 g 1mol H # $ % ( + 1 moles Cl 1 mol NH 4 ClO 3 " 35.453 g 1mol Cl # $ % ( + 3 moles O 1 mol NH 4 ClO 3 " 15.9994 g 1mol O # $ % ( = 117.489 g mol NH 4 ClO 3 Once a person gets used to what the numbers mean, this calculation is often abbreviated as follows: 1 × (14.0067 g) + 4 × (1.0079 g) + 1 × (35.453 g) + 3 × (15.9994 g) = 117.489 g/mol Convert pounds to grams, using the mass conversion provided on the inside front cover of the textbook, then use the molar mass as a conversion factor to determine the number of moles. 1.5 " 10 6 g NH 4 ClO 4 " 456.59 g 1 lb " 1 mol NH 4 ClO 4 117.489 g NH 4 ClO 4 = 5.8 " 10 6 mol NH 4 NO 3 Part II Answer: 1. C 18 H 13 O 2 2. 1.53 × 10 –3 mol ibuprophen Strategy and Explanation: 1. Given the percent mass of the elements in a compound and the molar mass, determine the empirical and molecular formulas. Choose a convenient mass sample of ibuprophen, such as 100.00 g. Using the given mass percents,
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This note was uploaded on 12/17/2009 for the course CHE 129/130 taught by Professor Hanson during the Spring '09 term at SUNY Stony Brook.

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chapter03_part1 - Chapter 3 Chemical Compounds 61...

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