DOC PREVIEW
UCSB CHEM 1A - Exam 2A v2

This preview shows page 1-2 out of 6 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 6 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 6 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 6 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

1 Chem. 1A Exam 2 Nov 25, 2013 Name: Last Name First Name FORM A Perm: There are a total of six pages (20 questions) on the exam, each question is worth 5 points. Show all your work on the exam and circle the answers. You will keep the exam so you can check your answers. The answers to the exam will be posted on our course web page. SCANTRON FORM: Completely fill bubbles 1) Write your name Completely fill answers 2) Bubble in FORM A 3) Bubble in your PERM number (7 digits only, no extra numbers) INFORMATION PAGE: Remove the information page. No other notes or books are allowed. INSTRUCTIONS: No hats or hoods allowed. No sharing of calculators. Cell Phones, iPods, headsets, and any other electronic devices must be turned off and put away. Show your work. Answers are given at the end of the exam. Questions 1 – 3. Indicate true or false for each of following statements. 1. When two opposing processes are proceeding at identical rates, the system is at equilibrium. A) True B) False 2. The concentration of the products and the concentration of reactants are equal and constant at equilibrium. A) True B) False 3. An endothermic reaction shifts toward reactants when heat is added to the reaction. A) True B) False 4. Which of the following relationships is not true? A) PV = constant when temperature and moles of gas are held constant. B) V/T = constant when pressure and moles of gas are held constant. C) nT = constant when pressure and volume are held constant. D) P/n = constant when volume and temperature are held constant. E) All of these are true. 5. A sample of nitrogen gas has a volume of 150.0 mL at STP. What volume does the gas occupy if the absolute temperature is tripled and pressure is tripled? A) 450.0 mL B) 50.00 mL C) 150.0 mL D) 500.0 mL E) 67.20 L2 6. Which of the following is a conjugate acid-base pair? A) HCl / OCl– B) H3PO4 / PO43– C) NH4+ / NH3 D) H3O+ / OH– E) Ca2+ / Ca(OH)2 7. The strong acid HA is added to water. Which of the following is the strongest base in this solution? A) HA B) H2O C) H3O+ D) A– E) H2A– 8. Which reaction does not proceed far to the right? A) HCl + H2O  H3O+ + Cl– B) H3O+ + OH–  2H2O C) HSO4 + H2O  H2SO4 + OH– D) HCN + OH–  H2O + CN– E) H2SO4 + H 2O  H3O+ + HSO4 9. Consider the following endothermic reaction at equilibrium: 2CO(g) + O2(g) 2CO2(g) Under what experimental conditions can we maximize the partial pressure of CO2 at equilibrium? A) high temperature and high pressure B) high temperature and low pressure C) low temperature and low pressure D) low temperature and high pressure E) none of these3 10. Consider the following reaction: 2HF(g) H2(g) + F2(g) K = 1.00  10–2 Given 1.30 mol of HF(g), 0.083 mol of H2(g), and 0.025 mol of F2(g) are mixed in a 4.00-L flask, determine the reaction quotient, Q, and the net direction to achieve equilibrium. A) Q < K; the equilibrium shifts to the right (). B) Q < K; the equilibrium shifts to the left (←). C) Q > K; the equilibrium shifts to the left (←). D) Q > K; the equilibrium shifts to the right (). E) Q = K; the system is at equilibrium. 11. In deciding which of two acids is the stronger, one must know A) the concentration of each acid solution only. B) the pH of each acid solution only. (See iClicker question from Lecture) C) the equilibrium constant of each acid only. D) all of the above (A, B and C). E) both the concentration and the equilibrium constant of each acid. Questions 12 – 13. Consider the following reaction at equilibrium. HF F– (aq) + H+ (aq) 12. When NaF is added to the solution does Ka increase, decrease or remain the same? A) Increases B) Decreases C) Remains the same 13. When NaF is added to the solution does the pH increase, decrease or remain the same? A) Increases B) Decreases C) Remains the same 14. (5 pts) Consider the reaction between 80.0 mL of 0.100 M NaOH and 60.0 mL of 0.100 M H2SO4. The reaction goes to completion. Calculate the pH of the solution. A) 1.07 B) 12.2 C) 1.54 D) 1.84 E) 12.54 15. Nitrogen gas (N2) reacts with hydrogen gas (H2) to form ammonia (NH3). At 200°C in a closed container, 1.1 atm of nitrogen gas is mixed with 2.3 atm of hydrogen gas. At equilibrium, the total pressure is 2.2 atm. Calculate the partial pressure of hydrogen gas at equilibrium. N2 (g) + 3 H2(g) 2 NH3(g) A) 2.3 atm B) 0.60 atm C) 0.77 atm D) 0.50 atm E) 1.9 atm 16. Calculate the pH of a 0.25 M NaA solution at 25ºC. For the acid, HA, Ka = 1.8  10–5. A) 4.93 B) 2.67 C) 8.35 D) 11.33 E) 9.075 17. A 2.39 gram sample of manganese metal (molar mass = 54.94 g/mol) was reacted with excess HCl gas to produce H2 gas and the unknown compound MnClx. If 3.51 L of dry H2 is produced at a pressure of 0.977 atm and a temperature of 275 K, then what is the value of “x” in the unknown compound MnClx? Assume the reaction goes to completion. A) 5 See assigned homework: Ch. 5 #113 (6th edition Ch.5 #105) B) 3 C) 4 D) 2 E) 7 18. Consider the decomposition of hydrazine as follows. N2H4(g) 2H2(g) + N2(g) At a certain temperature, Kp = 2.5  103. When pure hydrazine is placed in an otherwise empty vessel at this temperature, equilibrium is reached after 30.0% of the hydrazine has decomposed. Calculate the partial pressure of hydrogen gas at equilibrium. A) 54 atm B) 76 atm C) 127 atm D) 5776 atm E) 33 atm More Problems6 19. Consider the reaction: HA(aq) + H2O (l) H3O+(aq) + A–(aq) If A– is a stronger base than H2O, is the value of Ka greater than, less than, or equal to one? A) Ka > 1 B) Ka < 1 (See iClicker question from Lecture) C) Ka = 1 D) Cannot be determined from the information given. 20. The pH of a 0.120 M solution of a weak base is 10.97 at 25ºC. Calculate the pH of a 0.0316 M solution of this base at 25ºC. A) 10.89 B) 11.54 C) 10.39 D) 10.68 E) 10.26 ANSWERS: 1. A 2. B 3. B 4. E 5. C 6. C 7. B 8. C 9. A 10. A 11. C 12. C 13.


View Full Document

UCSB CHEM 1A - Exam 2A v2

Download Exam 2A v2
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Exam 2A v2 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Exam 2A v2 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?