Practice Problems Exam 1

# Practice Problems Exam 1 - CHM 115 Multiple choice sample...

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CHM 115 Multiple choice sample questions 1. How many mL of O 2 measured at 752 mm Hg and 23.0 o C are expected if 3.00 g of H 2 O 2 are completely decomposed? 2 H 2 O 2 (ℓ) 2 H 2 O(ℓ) + O 2 (g) (a) 1.08 mL (b) 1.42 mL (c) 84.1 mL (d) 1080 mL (e) 2.08 x 10 3 mL 2. Ethanol, C 2 H 5 OH, can be used as a gasoline additive. How many moles of O 2 are required to burn 1 mole of ethanol? (a) 0.065 mol (b) 2.1 mol (c) 3.0 mol (d) 3.5 mol (e) 6.0 mol 3. A pair of students completing the laboratory during Week 4 found that an average of 0.3541 g of sodium carbonate (105.9888 g/mol) was required to react with 25.00 mL of HCl. Given the balanced chemical equation below, calculate the concentration of the HCl solution. Na 2 CO 3 (s) + 2 HCl (aq)  2 NaCl(aq) + CO 2 ( g ) + H 2 O(ℓ) (a) 0.07068 M (b) 0.08352 M (c) 0.1336 M (d) 0.2673 M (e) 0.5346 M 4. Elemental phosphorus is made by heating calcium phosphate [Ca 3 (PO 4 ) 2 ] with carbon and sand in an electric furnace. What is the weight percent of phosphorus in calcium phosphate? (a) 9.98 % (b) 14.4 % (c) 20.0 % (d) 25.4 % (e) 32.5 % 5. You are asked to design a reactor in which benzene and water react as shown below. If 10.0 g of benzene reacts with an excess of water in a 5.0 L vessel at a temperature of 500 K, then what will be the increase in pressure due to the formation of H 2 ? Assume that the volume of the liquid reactants is negligible. C 6 H 6(ℓ) + H 2 O (ℓ) C 6 H 6 O (s) + H 2(g)

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(a) The pressure will increase by less than 0.5 atm (b) The pressure will increase by 0.5 – 1.5 atm (c) The pressure will increase by 1.5 – 2.5 atm (d) The pressure will increase by 2.5 – 5.0 atm (e) The pressure will increase by more than 5.0 atm 6. 100.0 mL of a 0.0250 M NaOH solution is diluted to 200.0 mL. Which of the following statements is true? (a) The concentration is 0.0125 M (b) The number of moles of NaOH decreases by half. (c) The concentration is 0.0250 M. (d) The number of moles of NaOH remains the same. (e) Both A and D are true. 7.
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Practice Problems Exam 1 - CHM 115 Multiple choice sample...

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