Answer Sheet Chem Lab Division C Team Name: ______

Chemistry Lab

Science Olympiad Invitational Boyceville, WI

Team Name: ______Team Number: _____

AAppley (MVHS, IA) JFariss (Wayzata, MN) Division C Answer Sheet Chem Lab Division C Team Name: ______SciOly Invitational Boyceville, WI Team Members: ______

Only this sheet will be graded. Work shown on Lab Sheet and Test will be used for tie-breakers.

LAB 1. ______13. ______, ______2. ______3. ______4. ______14. ______5. ______15. ______6. ______16. ___ 7. ______17. 8. ______9. ______10. ______11. ______12. ______18. ___ 19. ___ WRITTEN 20. ___ 1. ___ 21. ___ 2. ___ 22. ___ 3. ___ 23. ___ 4. ___ 24. ___ 5. ___ 25. ___ 6. ___ 7. ___ 26. ___ 27. ___ 8. ___ 28. ___ 9. ___ 29. ___ 10. ___ 30. ___ 11. ___ 12. ___ 31. ______32. ______33. ______35. ______34. ______36. ______

Please answer all questions on the scoring sheet provided, blank answers will be counted as zero points. You have 50 minutes to complete this exam and the lab. Spend the full time, checking answers between partners. You may separate the test and write on it, but please place the pages back in the correct order before submitting. Only answers on the score sheet will be graded.

Lab Portion

General Lab Guidelines:

● Goggles MUST be on properly!! ● You must follow the proper rules of Sig Figs. ● Show all work and label all units for each problem. ● Copy your answers onto the answer sheet with correct units. ● The instructors will show you where mass balances are located. ● Materials: Goggles, baking soda, vinegar, mass balance, weigh boat, 250 mL beaker, periodic table, white tray and a calculator.

1.) Mass out between 19.50g and 20.50g of Baking Soda (NaHCO3). What was the mass of the Baking Soda?

2.) How many moles of NaHCO3 are in the weigh boat?

3.) Assume there are 175.00 mL of Vinegar in the beaker. The density of vinegar is 1.05g/mL. How many grams of Vinegar are in the graduated cylinder, record to the hundredths place?

4.) Remember, Vinegar is 5.00% Acetic Acid (HC2H3O2) by mass. What is the mass of Acetic Acid in the Vinegar?

5.) How many moles of Acetic Acid (HC2H3O2) are in the graduated cylinder? Directions: The reaction between Baking Soda (NaHCO3) and Vinegar (HC2H3O2) is:

NaHCO3(s) + HC2H3O2(aq) -> NaC2H3O2(aq) + CO2(g) + H2O(l)

6.) Knowing this reaction, which of the reactants is your limiting reactant?

7.) Calculate the theoretical yield of CO2 in grams.

8.) For this question: Assume the temperature in this room is 25oC and 1 atm of pressure. Based off of the limiting reactant, what is the theoretical yield for Volume (L) of CO2?

9.) Squeeze as much air out of the baggie as possible. What is the mass of the baggie at the lab station? You may want to use the white tray to help keep all of the mass of the baggie on the balance.

Directions:

1.) Mix the Vinegar and Baking Soda in the baggie and seal it most of the way. 2.) Shake the baggie to ensure a complete reaction and wait 30 seconds. Careful not to spill any! 3.) Squeeze as much of the gases out of the bag as possible, without spilling the remaining reactants/products.

.10.) What is the mass of the baggie with the remaining reactants/products still in it?

11.) Using data collected earlier in this lab, how much CO2 was actually produced/released in this experiment?

12.) What was the percent error for the amount of CO2 produced? (You may end with a large percent error)

Directions: After you have completed this section of the exam, please clean your station and return materials as instructed. Written Portion

1) Which of the following is NOT required for a reaction to occur? a) collide b) be spontaneous and exothermic c) collide with the correct orientation d) collide with enough energy to overcome the activation energy

2) Which letter (a-e) would decrease in the presence of a catalyst?

3) Which of the following describes this reaction? a) exothermic b) endothermic

4) How would the magnitude of the values of a) and b) on this graph compare for the reverse reaction? a) a) would decrease, b) wouldn’t change magnitude. b) b) would increase, a) wouldn’t change magnitude c) Both a) and b) would inverse, but not change magnitude d) Magnitudes of both a) and b) would decrease.

5) If the forward reaction of a system in equilibrium is exothermic, for example A + B ↔ C + D + heat, increasing the temperature of the system will a) shift the equilibrium to the right b) shift the equilibrium to the left c) decrease the rate of the forward reaction d) increase the rate of the reverse reaction

6) In a certain process, 600 J of work is done on the system which gives off 250 J of heat. What is the change in internal energy for the process? a) 850 J b) -350 J c) 350 J d) -850 J

7) The specific heat of ethanol is 2.44 J/g℃ . How many kilojoules of energy are required to heat 50.0 g of ethanol from - 20.0℃ to 68.0 ℃ ? a) 10.7 kJ b) 8.30 kJ c) 2.44 kJ d) 1.22 kJ

8) Consider the thermal energy transfer during a chemical process. When heat is transferred to the system, the process is said to be ______and the sign of ΔH is ______. a) exothermic, positive b) endothermic, negative c) exothermic, negative d) endothermic, positive

9) Determine the situations that have a + sign for ΔS a) file folders are organized b) substance freezes c) salt dissolving in water.

d) BaO (s) + H2O (g) → Ba(OH)2 (s)

10) Which one of the following would have an enthalpy of formation value (ΔHf) of zero?

a) H2O(g) b) S (l) c) O(g)

d) O2(g)

11) ΔH for the reaction,

IF5 (g) ↔ IF3 (g) + F2 (g) is ___ kJ, give the data below.

IF (g) + F2 (g) ↔IF3 (g) ΔH = -390 kJ

IF (g) + 2 F2 (g) ↔ IF5 (g) ΔH = -745 kJ

a) +355 b) -1135 c) +35 d) +1135

12) In the Haber process for the manufacture of ammonia, using the data below determine if the reaction would be spontaneous at 298K?

Equation N2 + 3H2 → 2NH3 Enthalpy change ΔH = -93kJ / mol Entropy change ΔS = -198 J/ mol K a) yes b) no 13) Consider the freezing of water. a) Is this process exo- or endothermic?

b) In what temperature range is it spontaneous?

14) What is the ΔE for a system which has the following two steps:

Step 1: The system absorbs 20 J of heat while 60 J of work are performed on it.

Step 2: The system releases 10 J of heat while doing 40 J of work.

15) If 25 J of heat are required to change the temperature of 5.0 g of substance A by 2.0°C, what is the specific heat of substance A?

16) For a certain chemical rxn, ΔH = 34.5 kJ and ΔS = -45. 6 J/K. Predict if this reaction is spontaneous at 298 K. Yes or No

17) Write a thermochemical equation for the reaction between sodium metal and water in kJ/mol. DATA: mass of Na 0.56 g mass of water 15.6 g initial temperature of water 19.2 °C final temperature of mixture 29.8 °C

18) Which change in state requires that energy be added to the substance? a) vaporizing c) freezing b) deposition d) condensing

19) Approximately what volume does 3.0 moles of Kr gas occupy at STP? a) 22.4 L b) 44.8 L c) 67.2 L d) 89.5 L

20) According to Kinetic-Molecular Theory, which of the following is NOT true about all matter? a) matter is made up of very small particles b) matter is always in motion and solids are the slowest relative c) all matter is separated by large areas of empty space

21) The pressure a gas exerts on its container depends upon a) the type or identity of the gas b) the amount of gas c) the temperature of the gas particles d) both the amount and temperature

22) What is the phase change called that is a gas changing directly to a solid? a) sublimation b) condensation c) deposition d) vaporization

23) What is the point on a phase diagram where the pressure and temperature are so large that the liquid and gas phase are indistinguishable. a) triple point b) critical point c) vaporization point d) boiling point

24) If a solid has heat or energy added to it and it increases in temperature, what can you say about the energy. a) the kinetic energy is increasing b) the potential energy is increasing c) there is no change in energy d) the kinetic energy decreases e) the potential energy decreases 25) Which two variables are inversely related according to the gas laws? a) pressure and temperature b) temperature and volume c) pressure and volume d) volume and amount

26) Which value of R would you use with the following data: V= 2 L, P = 7 atm, T= 350 K, and n= 1 mol? a) 0.0821 b) 8.314 c) 62.4 d) You could use any value with this set of data

27) A sample of gas at 0.988 atm occupies a volume of 25.0 cm3. What volume will it occupy at 0.790 atm? (Assume temperature is constant.) Whose law would you use to solve this problem? a) Gay-lussac’s b) Boyle's c) Charles's d) Combined

28) Which of these values for pressure is not the same? a) 220 kPa b) 8.5 atm c) 1672 torr

29) At 98.7 kPa and 22.0℃ , a gas occupies 25.0 mL. At what temperature will the gas occupy 35.0 mL if the pressure is changed to 100. kPa? a) 239 K b) 418 K c) 312 K d) too many variables to answer

30) How many moles of gas are present in 0.0250 L at 2.50 atm and 35.0℃ ? a) 2.47 x 10-3 mol b) 3.45 mol c) 24.5 mol d) 0.554 mol Use the graphs to the left to answer the following:

31) At what temperature does the substance melt?

32) How much energy in kJ are required to boil the substance K?

33) What phase is present at 310 K?

34) A sample of gas at 89 oC and 0.870 atm occupies a volume of 3.0L. What volume would this gas occupy at 65oC and 15 kPa?

35) Butane (C4H10) combusts with oxygen to form carbon dioxide and water. If 0.85 grams of butane reacts, how many liters of carbon dioxide will form at STP?

36) Calculate the moles of ammonium sulfate produced from 0.75 L of ammonia at 350 K and 255 kPa.