Chemistry Exam 1 - October 23, 2006, Exams of Political Science

Download Chemistry Exam 1 - October 23, 2006 and more Exams Political Science in PDF only on Docsity! Chem. 1A Exam 1 Yellow Version October 23, 2006 1 1. (4 pts) Write the appropriate symbol for the species containing 30 neutrons, 26 protons, and 24 electrons. 2. (6 pts) Write the molecular formula for the following compounds: lead (II) sulfate magnesium hydroxide 3. (6 pts) The mass of the compound X3(PO4)2 is 310.18 g/mol. Identify X in this compound. 4. (12 pts) Circle true or false for each of the following statements about atomic structure. a) A cation is formed when an atom gains electrons. True False b) The number of protons is the same for all neutral atoms of an element. True False c) The electrons occupy a very large volume compared to the nucleus. True False d) The number of protons and neutrons is always the same in a neutral atom. True False e) The protons and neutrons in the nucleus are very tightly packed. True False f) Almost all of the mass of the atom is concentrated in the nucleus. True False 5. (6 pts) Balance the following equation using integer coefficients. FeS2 + O2 Fe2O3 + SO2 Chem. 1A Exam 1 Yellow Version October 23, 2006 2 6. (10 pts) Magnesium metal reacts with hydrochloric acid to form aqueous magnesium chloride and hydrogen gas. When 4.85 g of magnesium is added to 60.0 mL of 3.00 M hydrochloric acid, what mass of hydrogen gas is produced? Assume that the reaction goes to completion. 7. (10 pts) Consider the following reaction which occurs in the electrolysis of a brine solution: 2 NaCl (aq) + 2 H2O Cl2 (g) + H2 (g) + 2 NaOH (aq) A 20.0 gram sample of sodium chloride was placed in 20.0 grams of water. If 9.85 grams of Cl2 was obtained, what was the percent yield of Cl2?