This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: padilla (tp5647) Homework 8 Sutcliffe (53770) 1 This printout should have 24 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points How many grams of CaBr 2 are needed to prepare 4.65 L of a 7.65 M solution? 1. 0.178 g 2. 4270 g 3. 122 g 4. 7110 g correct 5. 5.26 g 6. 0.00303 g Explanation: M = 7 . 65 M V = 4 . 65 L ? g CaBr 2 = 4 . 65 L 7 . 65 mol CaBr 2 L soln 200 g CaBr 2 1 mol = 7110 g 002 10.0 points Which of the following is false? 1. 0.3 moles of HCl in 3.0 L of solution = 0.3 molar HCl. correct 2. 42.0 g of NaHCO 3 in 250 mL of solution = 2.0 molar NaHCO 3 . 3. 5 10 2 moles of Ba(OH) 2 in 1.0 L of solution = 0.05 molar Ba(OH) 2 . 4. 11.7 g of NaCl in 0.2 L of solution = 1.0 molar NaCl. Explanation: Molarity is the moles per liter of solution. We calculate the molarity of each solution: ? M HCl = . 3 mol HCl 3 L solution = 0 . 1 M HCl (The above answer choice is the correct one. The molarity of this HCl solution is not 0.3 M as described in the answer choice and the choice is therefore false.) ? M HCl = 11 . 7 g NaCL . 2 L 1 mol NaCl 58 . 44 g NaCl = 1 . 0 M HCl ? M Ba(OH) 2 = . 05 mol Ba(OH) 2 1 L = 0 . 05 M Ba(OH) 2 ? M NaHCO 3 = 42 g NaHCO 3 . 250 L 1 mol NaHCO 3 84 g NaHCO 3 = 2 . 0 M NaHCO 3 003 10.0 points We wish to dilute some 18 . 4 M H 2 SO 4 solution to make 600 mL of a 0 . 1 M H 2 SO 4 solution. How much of the 18 . 4 M solution should we start with? 1. 2.70 mL 2. 1.80 mL 3. 4.60 mL 4. 4.00 mL 5. 3.26 mL correct Explanation: M 1 V 1 = M 2 V 2 V 2 = M 2 V 2 M 1 = (0 . 1 M) (600 mL) 18 . 4 M = 3 . 26087 mL 004 10.0 points Which of the following aqueous solutions padilla (tp5647) Homework 8 Sutcliffe (53770) 2 should NOT form a precipitate with aque ous Ba(NO 3 ) 2 ? 1. K 2 CO 3 2. KOH correct 3. K 2 SO 4 4. K 3 PO 4 Explanation: All of the answer choices are soluble com pounds and would dissociate to form ions in solution. These ions could react with the Ba 2+ and NO 3 ions from Ba(NO 3 ) 2 . All an swer choices contain the cation K + that could combine with NO 3 to form KNO 3 , a soluble compound. Next we look at the possible prod ucts of the combination of Ba 2+ with anions from the answer choices. BaCO 3 , Ba 3 (PO 4 ) 2 , and BaSO 4 are all insoluble compounds and would form precipitates. Ba(OH) 2 is soluble. A mixture of Ba(NO 3 ) 2 and KOH would not form a precipitate. 005 10.0 points What volume of 0.30 M NaOH is required to react completely with 70.0 mL of 0.24 M H 2 SO 4 ? 1. 124.0 mL 2. 49.6 mL 3. 99.1 mL 4. 56.0 mL 5. 112.0 mL correct Explanation: [NaOH] = 0.30 M V H 2 SO 4 = 70 mL [H 2 SO 4 ] = 0.24 M The balanced equation for this neutraliza tion reaction is H 2 SO 4 + 2 NaOH Na 2 SO 4 + 2 H 2 O We determine the moles of H 2 SO 4 present: ? mol H 2 SO 4 = 0 . 07 L soln . 24 mol H 2 SO 4 1 L soln = 0 . 0168 mol H 2 SO 4 Using the mole ratio from the balanced chemical equation we calculate the moles of...
View
Full
Document
 Spring '08
 SUTCLIFFE

Click to edit the document details