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Homework 9 - Preparatory Chemistry - Fall 2008 | CHEM 1301, Assignments of Chemistry

Material Type: Assignment; Professor: Li; Class: Preparatory Chemistry; Subject: CHEMISTRY; University: Texas Tech University; Term: Spring 2008;

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Uploaded on 03/11/2009

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Homework 12 (Chapters 8 & 12)
Name ________________________ Section: CHEM 1301 – 001
(print your name) Due: Thursday, April 24, 2008
1. A compound that contains carbon, hydrogen and oxygen is found to have an
empirical formula of C3H4O. If the molar mass of this compound is 224 g/mol, what
is its molecular formula?
(a) C3H4O
(b) C15H20O5
(c) C12H16O4
(d) C6H8O2
(e) C9H12O3
2. Determine the simplest formula of the compound with the following mass percents of
the elements present: 17.9% Fe, 51.3% bromine and 30.8% oxygen.
(a) Fe(BrO3)2
(b) Fe(BrO)2
(c) Fe(BrO2)3
(d) Fe(BrO3)3
(e) Fe(BrO2)2
3. Strontium periodate has the formula Sr(IO4)2. Calculate the mass percent of oxygen in
this compound.
(a) 5.73% oxygen
(b) 3.67% oxygen
(c) 23.0% oxygen
(d) 3.40% oxygen
(e) 27.2% oxygen
4. Which of the following compounds has the most mass percent of oxygen?
(a) H2O
(b) H2O2
(c) Li2O
(d) NaO2
(e) N2O5
5. Choose the pair of compounds with the same empirical formula.
(a) C2H2 and C6H6
(b) H2O and H2O2
(c) K2CrO4 and K2Cr2O7
(d) K2SO4 and K4S2O7
(e) N2O3 and N2O4
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Homework 12 (Chapters 8 & 12)

Name ________________________ Section: CHEM 1301 – 001 (print your name) Due: Thursday, April 24, 2008

  1. A compound that contains carbon, hydrogen and oxygen is found to have an empirical formula of C 3 H 4 O. If the molar mass of this compound is 224 g/mol, what is its molecular formula? (a) C 3 H 4 O (b) C 15 H 20 O 5 (c) C 12 H 16 O 4 (d) C 6 H 8 O 2 (e) C 9 H 12 O 3
  2. Determine the simplest formula of the compound with the following mass percents of the elements present: 17.9% Fe, 51.3% bromine and 30.8% oxygen. (a) Fe(BrO 3 ) 2 (b) Fe(BrO) 2 (c) Fe(BrO 2 ) 3 (d) Fe(BrO 3 ) 3 (e) Fe(BrO 2 ) 2
  3. Strontium periodate has the formula Sr(IO 4 ) 2. Calculate the mass percent of oxygen in this compound. (a) 5.73% oxygen (b) 3.67% oxygen (c) 23.0% oxygen (d) 3.40% oxygen (e) 27.2% oxygen
  4. Which of the following compounds has the most mass percent of oxygen? (a) H 2 O (b) H 2 O 2 (c) Li 2 O (d) NaO 2 (e) N 2 O 5
  5. Choose the pair of compounds with the same empirical formula. (a) C 2 H 2 and C 6 H 6 (b) H 2 O and H 2 O 2 (c) K 2 CrO 4 and K 2 Cr 2 O 7 (d) K 2 SO 4 and K 4 S 2 O 7 (e) N 2 O 3 and N 2 O 4
  1. A 4.00 g of sample that might contain oxygen is analyzed and produces 7.64 g CO 2 and 4.69 g H 2 O. What is the empirical formula of such sample? (a) C 2 H 4 O (b) CH 2 O (c) CH 3 O 2 (d) C 2 H 6 O (e) CH 4 O
  2. 0.500 g of a compound with molar mass of 180.15 g/mol is used for combustions analysis, and produces 0.733 g CO 2 and 0.300 g H 2 O, calculate the molecular formula. (a) C 5 H 8 O 7 (b) C 6 H 12 O 6 (c) C 7 H 16 O 5 (d) C 9 H 8 O 4
  3. What is the mass percent of hydrogen in water? (a) 5. (b) 33. (c) 11. (d) 88.
  4. What would the empirical formula be for the molecular compound C6H9O4? (a) C3H9O (b) C2H3O (c) C3H6O (d) C6H9O
  5. What is the molecular formula of a compound given the molar mass of the compound as 186.5 g/mol and empirical formula as C H? 2 7 (a) C 4 H 14 (b) C 8 H 28 (c) C 10 H 25 (d) C 12 H 42
  6. The compound cupferron is used to separate copper and iron from other metals in solution. An analysis of cupferron shows that it is made up of carbon, hydrogen, nitrogen, and oxygen in the following percents by weight: % C = 46.44; % H = 5.85; % N = 27.08; % O = 20. What is the empirical formula of the compound? (a) C1.5HN3O4. (b) C3H4.5N1.5O (c) C6H9N3O (d) C12H9N6O
  1. How many grams of KBr are there in 52.8 mL of a 1.40 M KBr solution? (a) 0.0739 g KBr (b) 0.621 g KBr (c) 167 g KBr (d) 3.16 g KBr (e) 8.80 g KBr
  2. What volume of 2.20 M HCl must be added to enough water to prepare 4.70 liters of 1.06 M HCl? (a) 2.26 L (b) 0.496 L (c) 9.75 L (d) 2.02 L (e) 0.442 L
  3. How many moles of NH 4 NO 3 are there in 75.0 mL of 0.230 M NH 4 NO 3? (a) 3.07 mole NH 4 NO 3 (b) 0.0173 mole NH 4 NO 3 (c) 1.725 mole NH 4 NO 3 (d) 0.0326 mole NH 4 NO 3 (e) 0.0307 mole NH 4 NO 3
  4. A 100.-mL sample of aqueous sulfuric acid, H 2 SO 4 , is reacted with 0.230 M KOH. When reaction is finished, 32.50 mL of KOH has been used. What is the molar concentration of the sulfuric acid? (a) 0.0374 M H 2 SO 4 (b) 0.130 M H 2 SO 4 (c) 32.5 M H 2 SO 4 (d) 0.813 M H 2 SO 4 (e) 0.0650 M H 2 SO 4
  5. What is the molarity of 3.68 mL of a solution containing 0.0025 moles of calcium chloride? (a) 1.5 M (b) 6.8 x 10-4^ M (c) 6.8 x 10-3^ M (d) 0.68 M (e) 0.068 M
  6. Which of the following compounds would you expect to be insoluble in water (a) NaCl (b) NH 3 (c) HCl (d) CCl 4 (e) C 2 H 5 OH (alcohol)
  1. In soda pop, CO 2 (g) is a _____________, and syrup is the ____________ (a) solute, solute (b) solute, solution (c) solvent, solvent (d) solvent, solute (e) solvent, solution
  2. 500 mL 0.4M calcium chloride contain _____ moles of calcium ions and _____ moles of chloride ions. (a) 0.4, 0. (b) 0.4, 0. (c) 0.2, 0. (d) 0.2, 0. (e) 0.4, 0.
  3. To prepare 100mL 0.4M HCl from a stock solution of 2M HCl one needs to __________. (a) dilute 20 mL 2M HCl with 100 mL HCl (b) dilute 80 mL 2M HCl to a total volume of 100 mL solution (c) dilute 20 mL 2 MHCl with enough water to make a total volume of 100 mL solution (d) use 500 mL 2M HCl and boil it down to a final volume of 100 mL solution (e) none of above