Chemistry Joke of the Day

Announcements Exam #1: Tonight!, 7:00-8:30pm, locations posted on website, bring ID Conflict Exam: 5:00-6:30pm, 161 Noyes, bring ID No Lab this week! No book homework due Friday! Lecture on Thursday! (New Material) Exam scores posted late Wednesday evening. Get graded exams back on Friday. Liquid nitrogen ice cream winner = highest section average!!!

Exam Format – 90 minutes total 15 Multiple Choice Questions 2 Free Response Questions 5 possible choices 50% of test grade ~3 minutes to answer each (~45 min on this half of exam) Write in answers – both qualitative and quantitative 50% of test grade ~45 minutes on this half of exam ***A periodic table & cover sheet with equations will be attached.***

Clicker #1 You have a 16.0 oz (473 mL) glass of lemonade with a concentration of 2.00 M. The lemonade sits out on your counter for a couple of days and 150. mL of water evaporates from the glass. What is the new concentration of the lemonade?   a) 1.52 M b) 2.00 M c) 2.93 M d) 6.31 M e)none of these

Clicker #2 Use unbalanced equation to answer the question below. If 2.50 moles of Si were produced, how many moles of NaF were also created? a) 0.417 mol b) 2.50 mol c) 6.00 mol d) 15.0 mol e) Impossible to determine without the moles of reactants.

Clicker #3 10.0 mL of 0.30 M sodium phosphate solution reacts with 20.0 mL of 0.20 M lead(II) nitrate solution.   What is the concentration of nitrate ions left in solution after the reaction is complete? 0.0 M 0.20 M 0.27 M 0.40 M 0.80M

Clicker #4 10.0 mL of 0.30 M sodium phosphate solution reacts with 20.0 mL of 0.20 M lead(II) nitrate solution.   What is the concentration of phosphate ions left in solution after the reaction is complete? 0.0 M 0.011 M 0.033 M 0.10 M e) 0.30 M

Clicker #5 Consider the following reaction where X represents an unknown element: 6 X(s) + 2 B2O3(s)  B4X3(s) + 3 XO2(g) If 175 g of X reacts with diboron trioxide to produce 2.43 moles of B4X3, what is the identity of X? a) Ge b) Mg c) Si d) N e) C

Clicker #6 Consider the equation: A + 3B  4C. If 3.0 moles of A is reacted with 6.0 moles of B, which of the following is true after the reaction is complete?   A is the leftover reactant because you only need 2 moles of A and have 3. A is the leftover reactant because for every 1 mole of A, 4 moles of C are produced. B is the leftover reactant because you have more moles of B than A. B is the leftover reactant because 3 moles of B react with every 1 mole of A. Neither reactant is leftover.

Clicker #7 You pour Solution #1 and Solution #4 together in a large, empty beaker. What is the concentration of the new HCl mixture?   3.00 M 3.25 M 3.40 M 4.25 M 6.50 M

Clicker #8 Consider separate solutions of NaCl, CaCl2, and AuCl3 made by dissolving equal masses of each solute in equal volumes of solution. Which solution has the greatest concentration of chloride ions?   a) NaCl b) CaCl2 c) AuCl3 At least two of the above solutions have the same greatest concentration of chloride ions. e) Not enough information is given to solve this problem.

Clicker #9 Consider the following reaction at 1.10 atm and 19oC: 0.257 mol of sodium chloride, 3.00 L of ammonia, 2.00 L of carbon dioxide, and an unlimited amount of water react to form aqueous ammonium chloride and solid sodium bicarbonate. How many moles of ammonium chloride are formed in this reaction? 0.138 mol 0.184 mol 0.257 mol 0.0643 mol 0.0918 mol

Clicker #10 An air bag is deployed by utilizing the following balanced reaction: What mass of NaN3 must be used to inflate an air bag to 85.0 L at 1.00 atm and 25°C? 3.48 g 27.6 g 151 g 226 g 339 g

Clicker #11 ) Which of the following is the correct net ionic equation for the reaction between barium hydroxide and sulfuric acid? a) b) c) d) e) There is no net ionic equation for this reaction.