Practice exam 1

# Practice exam 1 - Practice Exam I Name print last print...

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Practice Exam I Name: _________________,________________ print last print first unity ID _____________ (ex jlsmith2) 1. How many moles of atoms are present in a 2.75 gram sample of N 2 O? 2.75 g N 2 O * (1 mol N 2 O/44.02 g N 2 O) * (3 mol atom/1 mol N 2 O) = 0.187 _____ 0.187 ______ mol atoms (4 pts) ------------------------------------------------------------------------------------------------------------------------------- 2. Balance the reaction below using the lowest set of integers. Please indicate any coefficients of 1. _ 1 __ P 4 + _ 16 __ H 2 O --> _ 4 ___ H 3 PO 4 + _ 10 ___ H 2 (2 pts each blank) ------------------------------------------------------------------------------------------------------------------------------- 3. What is the mass of 2.0 x 10 23 molecules of H 2 Te? 2.0 x 10 23 H 2 Te * (129.616 g H 2 Te / 6.022 x 10 23 H 2 Te) = 43.05 g ______ 43.05 _____ g (4 pts) ------------------------------------------------------------------------------------------------------------------------------- 4. A sample of CS 2 contains 5.03 grams of carbon. How many moles of S does the sample contain? 5.03 g C * (1 mol C / 12.01 g C) * (2 mol S / 1 mol C) = 0.838 mol S ______ 0.838 _____ moles S (4 pts) ------------------------------------------------------------------------------------------------------------------------------- 5. How many moles of AlCl 3 can be produced when 0.50 moles of Al reacts with 0.60 moles of Cl 2 ? 2 Al + 3 Cl 2 --> 2 AlCl 3 0.60 mol Cl 2 * (1 mol rxn /3 mol Cl 2 ) = 0.20 mol rxn <-- Limiting i 0.50 0.60 0 0.50 mol Al * (1 mol rxn /2 mol Al) = 0.25 mol rxn -0.40 -0.60 + 0.40 f 0.10 0 0.40 _____ 0.40 ______ moles AlCl 3 (4 pts) ------------------------------------------------------------------------------------------------------------------------------- 6. Circle all the choices below that correctly describe CH 4 . There may be more than one correct answer. 2 pts each correct, -1 each incorrect atom molecule element compound (4 pts) ------------------------------------------------------------------------------------------------------------------------------- 7. Give the chemical symbol for: a) the alkaline earth metal in the same period as Br. _____ Ca ______ (2 pts) b) the lightest noble gas. ______ He _____ (2 pts) c) the element in period 4 in the same group with silicon. _____ Ge ______ (2 pts)

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------------------------------------------------------------------------------------------------------------------------------- 8. For some system, the initial energy is 14 J and the final energy is -2 J. Circle the correct answer for value and type of energy change that occurs. (4 pts) E = -16 J, non-spontaneous E = -12 J, spontaneous E = +12 J, spontaneous E = +12 J, non-spontaneous E = -16 J, spontaneous E = +16 J, spontaneous ------------------------------------------------------------------------------------------------------------------------------- 9. Please complete all of the blanks in the following table. (8 pts)
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Practice exam 1 - Practice Exam I Name print last print...

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