Recitation Worksheet 8 Key v2

1 Recitation Worksheet ± : Chemical Equilibrium , (13.1 – 13.5) Name: MyID: Instructions: 1. Use the equation below to answer the following questions: Fe(OH) 3 (s) + 3 H + (aq) ⇌ Fe 3+ (aq) + 3 H 2 O(l) K = 9.1 x 10 3 A. The correct equilibrium constant expression for this reaction is i. [ FeOH 3 ] [H + ] య [Fe 3+ ][H 2 O ] య ii. [Fe 3+ ][H 2 O ] య [ FeOH 3 ] [H + ] య iii. [Fe 3+ ][H 2 O ] [ FeOH 3 ] [H + ] iv. [Fe 3+ ] [H + ] య v. [ FeOH 3 ] [H + ] [Fe 3+ ][H 2 O ] ±² Please enter your first and last name as it appears on the eLC classlist (do not use a nickname). ³² Your UGA myID is a combination of letters and numbers (example: Dr. Abdelrahman MyID is ema88805). Do not use your 81x number. D² If you do not have access to a printer, type your answers in the worksheet PDF and then upload it to Gradescope by 6DWXUGD\ , 0DUFK ± ´ WK at 1 ³ : µµ pm ¶QRRQ· . Write your work on separate sheets of paper, convert to a PDF and upload to the "Recitation Worksheet ¸ Dropbox" on eLC. E² If you are using an app to annotate the worksheet, make sure the pages are in the correct order and have the same layout as the original or Gradescope will not be able to read it. F² If you have access to a printer, print out the worksheet, write your answer in the answer boxes, and show your work on it when appropriate. Then convert it to a PDF and upload to Gradescope by 6DWXU day, 0DUFK ± ´ WK at 1 ³¹µµ pm. You do not need to upload anything to eLC. The pages must be in the correct order and have the same layout as the original, or Gradescope will not be able to read it. G² There is a Gradescope App available for both iOS and Android devices that allows you to scan and submit your printed work or you can submit your fillable PDF directly. Detailed instructions on how to access and use the app can be found on your CHEM 1212 class eLC page under content ⟶ Welcome module ⟶ Gradescope ⟶ Gradescope new mobile app. º² Answers must be written in the corresponding answer box, or no credit will be awarded. »² The instructions for uploading worksheets to Gradescope can be found in the Content area of eLC in the Welcome Module. ¼² $ SHULRGLF WDEOH DQG IRUPXOD VKHHW DUH LQFOXGHG DW WKH HQG RI WKLV ZRUNVKHHW² 3OHDVH NHHS WKHVH SDJHV DWWDFKHG WR WKH ZRUNVKHHW LQ WKH FRUUHFW ZKHQ VXEPLWWLQJ LW WR *UDGHVFRSH²

2 B. What is the equilibrium concentration for [Fe 3+ ] if the equilibrium concentration for [H + ] = 2.5 x 10 -8 ? 8 se scientific notation to report your answer. M 2. Use the reaction below to answer the following questions N 2 (g) + O 2 (g) + Cl 2 (g) ⇌ 2 NOCl(g) K p = ? A. Calculate K p at 25 °C using the set of equations provided. 8 VH VFLHQWLILF QRWDWLRQ WR UHSRUW \RXU DQVZHU² ଵ ଶ N 2 (g) + O 2 (g) ⇌ NO 2 (g) K p = 1.0 x 10 -9 NOCl(g) + ଵ ଶ O 2 (g) ⇌ NO 2 Cl(g) K p = 1.1 x 10 2 NO 2 (g) + ଵ ଶ Cl 2 (g) ⇌ NO 2 Cl(g) K p = 3.0 x 10 -1 ; ; ±³ ±³

4 5. You are given two elementary reactions below which are the reverse of one another and the reaction rates for elementary reaction are provided as well. Which of the following statements about an equilibrium mixture of X, Y, and Z is false ? X + Y ⟶ Z + Z Rate = k 1 [X][Y] Z + Z ⟶ X + Y Rate = k 2 [Z] 2 A. At equilibrium, k 1 and k 2 can have different values B. At equilibrium, k 1 [X][Y] = k 2 [Z] 2 C. At equilibrium, X and Y still react to form Z D. At equilibrium, the concentrations of X and Y must be the same E. At equilibrium, [ X ] [Y] [Z] 2 is a constant 6. A graph for the reaction A(g) ⇋ 2B(g) shows the change in concentration over time. What is the equilibrium constant for this reaction? A. 1.8 B. 1.2 C. 4.4 D. 0.82 E. 0.57 A B

5 7. For the reaction A(g) + B(g) ⇌ C(g), K p < 1. Which of the following charts below describes the approach to equilibrium of a mixture of B(g) and C(g)? A. B. C. D.

7 C. What is the value of K p ? 10. You are a given a solution of silver sulfate and the ionization of silver sulfate in water can be represented by the equation below Ag 2 SO 4 (s) ⇌ 2 Ag + (aq) + SO 4 2- (aq) K= 1.1 x 10 -5 at 298 K If the solution a 1.5 L solution contains 6.55 g Ag 2 SO 4 , and you attempt to dissolve additional solid silver sulfate in the solution will it dissolve? A. Yes B. No

8 11. The diagram below represents the reaction between A 2 (g) + B 2 (g) ⇌ 2 AB(g), A 2 molecules are represented by red spheres, B 2 molecules are represented by blue spheres and the reaction has an equilibrium constant, K c = 1.5. Which of the following diagrams a – c represents: A. The reaction at equilibrium ² B. Q c < K c C. Q c > K c a b c

Formula Sheet Length 1 kilometer = 0.62137 mile 1 inch = 2.54 centimeters (exactly) 1 Å ngstrom = 1 × 10 −10 meter Energy 1 joule = 1 kg·m 2 /s 2 1 calorie = 4.184 joules 1 Calorie = 1 kilocalorie = 1000 calories 1 L·atm = 101.325 joules Pressure 1 pascal = 1 N/m 3 = 1 kg/m·s 2 1 atmosphere = 101.325 kilopascals = 760 mm Hg = 760 torr = 14.70 lb/in 2 1 bar = 1 × 10 5 Pa (exactly) Temperature 0 K = −273.15°C K = °C + 273.15 °C = (5/9)(°F − 32) Mass 1 kg = 2.205 lbs Volume 1 mL = 1 cm 3 = 1 cc Constants c = 2.998 × 10 8 m/sec h = 6.626 × 10 −34 J·sec −1 R = 0.08206 L·atm/mol·K = 8.314 J/mol·K Specific heat of water = 4.184 J/g·K Mass of an electron: 9.109 x 10 −31 kg Mass of a proton: 1.673 x 10 -27 kg RH = 2.18 x 10 −18 J Specific heat of water = 4.184 J/g·K STP = 273.15 K and 1 atm Avogadro's number: 6.022 × 10 23 Equations d (density) = m/V P 1 V 1 =P 2 V 2 V 1 /T 1 =V 2 /T 2 P 1 V 1 /n 1 T 1 =P 2 V 2 /n 2 T 2 PV=nRT (P + a(n 2 /V 2 ))·(V − nb) = nRT molar mass (M) = mRT/PV density (d) = MP/RT x A = n A /n tot = P A /P tot = V A /V tot P tot = P A + P B + … n tot = n A + n B + … ࠵? ௥௠௦ = ඨ 3࠵?࠵? ࠵?

࠵?࠵?࠵?࠵? ࠵?࠵? ࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵? ࠵? ࠵?࠵?࠵?࠵? ࠵?࠵? ࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵? ࠵? = ඨ ࠵?࠵? ஻ ࠵?࠵? ஺ Q = C × ΔT = c specific × m × ΔT Q = n × ΔH (kJ/mol) = m × ΔH (kJ/g) w = −PΔV ΔE = q + w ΔH° = ΣnΔHf°(products) − ΣnΔHf°(reactants) ΔH° = ΣnΔH°(bonds broken) − ΣnΔH°(bonds formed) E=hν c=λν λ = h/mv ∆࠵? = −2.18 × 10 ିଵ଼ ࠵?( 1 ࠵? ௙ ଶ − 1 ࠵? ௜ ଶ ) C g = kP g P solution =P solvent X solvent P solution =∑P j =∑P j X j ΔT b = K b m i ΔT f = K f m i π = MRT i Thermodynamic and Electrochemistry S = k b × ln( W ) k b = 1.381 × 10 −23 J/K ΔS = q rev /T ΔS surr = q surr /T = −q rev /T ΔS univ = ΔS sys + ΔS surr ΔS° rxn = Σ ν S° products − Σ ν S° reactants ΔH° rxn = Σ ν H° products − Σ ν H° reactants ΔG° rxn = Σ ν G° products − Σ ν G° reactants ΔG = ΔH – TΔS ∆ G = ∆ G° + RT·lnQ R=8.314 J/mol.K ∆ G° = −RT·lnK ∆ G= −nFE cell F = 96485 J/(V·mol e − ) E° cell = RT/nF lnK E° cell = (0.0257/n) lnK = (0.0592/n) logK E cell = E° cell − (RT/nF) lnQ E cell =E° cell − (0.0257/n) lnQ Electrolysis: Q (total charge) = I × t = n × F Integrated Rate Laws & half-life