Homework-6(Ch7)_2016_answer - The Hong Kong University of Science and Technology Department of Chemistry CHEM 1020 General Chemistry IB Fall 2016-2017

Homework-6(Ch7)_2016_answer - The Hong Kong University of...

This preview shows page 1 - 4 out of 12 pages.

1 The Hong Kong University of Science and Technology Department of Chemistry CHEM 1020 General Chemistry IB Fall 2016-2017 Homework (Ch7) Answer Key Some questions are extracted from “ Chemistry: An Atoms First Approach (2 nd Edition)” 1.For each multiple choice questions, select the most appropriate answer. i)Which of the following statements is NOT correct? a)Acetic acid is a good electrolyte because it can be dissolved in water. b)Molarity is defined as moles of solute per volume of solution in liters. c)In an aqueous solution, ions are surrounded and hydrated by water molecules. d)Mole fraction is the ratio of the number of moles of a given component to the total number of moles of the solution. ii) Which of the followings is NOT an expression of concentration? iii) Which of the following solutions of strong electrolytes contains the largest number of moles of ions? iv) Consider a mixture prepared by mixing a 20. mL of 0.10 M HCl and 0.50 g of AgNO3. Which of the following species is present in the lowest concentration?
Image of page 1
2 v) Which of the following ionic compounds is soluble in water? a)Pb(OH)2b)CaSO4c)Pb(NO3)2d)CuCO3Answer: v) c vi) d vii) a Consider the reaction in zinc carbon battery below, answer questions vi) and vii). Zn(s) + 2 MnO 2 (s) + ZnCl 2 (aq) + 2 H 2 O(l) 2 MnO(OH)(s) + 2 Zn(OH)Cl(aq) vi) The oxygen atoms in water is a) oxidized. b) reduced. c) protonated. d) remaining its oxidation state. vii) One manganese cation in MnO 2 a) gains one electron. b) gains two electrons. c) losses one electron. d) losses two electrons. 2. A solution of ethanol (C 2 H 5 OH) in water is prepared by dissolving 75.0 mL of ethanol (density = 0.79 g/cm 3 ) in enough water to make a 250.0 mL solution. What is the molarity of ethanol in this solution? (Molar mass of C = 12.01 g/mol, H = 1.008 g/mol, O = 16.00 g/mol Answer: (Book Ch6, Q30) 75.0 mL × 0.79 g 1 mL × 1 mol 46.07 g = 1.3 mol C 2 H 5 OH molarity = 1.3 mol 0.250 L = 5.1 M C 2 H 5 OH (Continue on Next Page)
Image of page 2
3 3. Calculate the concentration (in M) of all ions present in each of the following solutions of strong electrolytes. i) 0.0200 mole of sodium phosphate in a 10.0 mL solution ii) 0.300 mole of barium nitrate in a 600.0 mL solution iii) 1.00 g of potassium chloride in a 0.500 L solution iv) 132 g of ammonium sulfate in a 1.50 L solution (Molar mass of K = 39.10 g/mol, Cl = 35.45 g/mol, N = 14.01 g/mol, H = 1.008 g/mol, S = 32.07 g/mol, O = 16.00 g/mol) Answer: (Book Ch6, Q32) i) M Na 3 PO 4 = 0.0200 mol 0.0100 L = 2.00 M Na 3 PO 4 (s) 3 Na + (aq) + PO 4 3 (aq) M Na + = 3(2.00) = 6.00 M M PO 4 3− = 2.00 M ii) M Ba(NO 3 ) 2 = 0.300 mol 0.6000 L = 0.500 M Ba(NO 3 ) 2 (s) Ba 2+ (aq) + 2 NO 3 (aq) M Ba 2+ = 0.500 M M NO 3 = 2(0.500) = 1.00 M iii) M KCl = 1 g KCl × 1 ?𝑜? 𝐾𝐶? 74.55 𝑔 𝐾𝐶? 0.5000 L = 0.0268 M KCl(s) K + (aq) + Cl (aq) M K + = M Cl = 0.0268 M iv) M NH 4 𝑆𝑂 4 = 132 g KCl × 1 ?𝑜? (NH 4 + ) 2 𝑆𝑂 4 132.15 𝑔 1.5 L = 0.666 M (NH 4 ) 2 SO 4 (s) 2 NH 4 + (aq) + SO 4 2 (aq) M NH 4 + = 2(0.666) = 1.33 M M SO 4 2− = 0.666 M 4. If 10. g of AgNO 3 is available, what volume of 0.25 M AgNO 3 solution can be prepared?
Image of page 3
Image of page 4

You've reached the end of your free preview.

Want to read all 12 pages?

  • Spring '14
  • Chemistry, Sodium chloride, mol HCl, mol, Sodium hydroxide, mol KOH

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes