Chemistry FinalName and date submitted (3 pts):

Create space in the Word document below, and write or type your answers. Turn in your completed work as an email attachment. YOU MUST SHOW ALL YOUR WORK to get credit.

(25 questions, with 2 extra-credit questions; 100 points + 10 points)

Gases

Tip: Convert all temperatures to Kelvin (°K) first. Use consistent units for pressure and volume. Choose the value of ‘R’ with the correct units for the problem you are solving.

1. Write out the formula for each of these gas laws. Then explain to your spellbound colleagues at the Royal Academy of Science what each one means in plain English using one sentence each.

a. Charles’ lawb. Boyle’s lawc. Gay-Lussac’s lawd. The combined gas lawe. The ideal gas law

2. What is meant by Standard Temperature & Pressure (STP)? Be specific – what is the T and P?

3. Combined Gas LawIf a gas at a pressure of 1.0 atm and a temperature of 22.0 °C occupies 0.50 L, what volume will it occupy if the pressure and temperature are raised to 2.0 atm and 25.0 °C? (Hint: 0.10-0.40 L)

4. Ideal Gas Lawa. A 500 mL flask is filled with pure helium gas (He) at STP. How many moles of He are present?

(Hint: 0.010-0.030 mol)

b. A weather balloon contains 10,000 L of helium at STP. How many moles of He are present? (Hint: 400-475 mols)

Solids and Liquids

5. List the three groups (types) of intermolecular forces. Intermolecular forces act between molecules, and result in us having solids and liquids.

6. Explain why ice floats on liquid water. Be specific from a chemistry standpoint.

7. Give operational definitions of a) evaporation, and b) boiling, and explain the difference(s) between the two phenomena.

8. Refer to the graph below to determinea. The boiling point in °C of ethyl alcohol (ethanol) when it is at 1 atm pressure.b. The boiling point in °C of ether at 0.5 atm (i.e. 380 mm Hg).c. The pressure in mm Hg at which water boils at 60 °C.

Solutions

9. Molarity: a. You prepare 2.50 L of aqueous solution that contains 1.50 mols of CaCO3. What is the

molarity of the solution? (Hint: 0.40-0.70 M)

b. You prepare 10.0 L of aqueous solution that contains 100 grams of KNO3. What is the molarity of the solution? (Hint: 0.090-0.140 M)

Problems 11-16: You have been retained by an Aerospace manufacturing company to give your advice and recommendations on treating their wastewater coming from a large electroplating operation in the Midwestern U.S.

10. You begin by doing some testing and determine that the raw wastewater has a pH of 6.0, and the level of dissolved copper (Cu) in the untreated waste stream at that pH is 100 mg/L.

a. Is the raw, untreated wastewater acidic, neutral, or basic? b. If you need to treat an average of 1,000,000 liters of wastewater per day, how much copper

in grams is present in this amount of raw wastewater? (Hint: 92,000-162,000 g)

11. Referring to the solubility of Cu in Figure 1, what pH would result in Cu being the least soluble in the wastewater?

Fig. 1: Solubility of metal hydroxides as a function of pH (Source: EPA)

12. Your recommendation: If they raise the pH of the wastewater to an optimum level, and allow time for the resulting sludge to settle (in the form of copper hydroxide), you estimate that the level of dissolved copper remaining in the waste stream could realistically be reduced to a level of 0.01 mg/L. Stated differently, their raw untreated wastewater contains 100 mg/L of dissolved copper, and by continuously adjusting the pH upward to an optimum level, followed by mixing and settling, you can reduce the dissolved copper in the outgoing, treated wastewater to only 0.01 mg/L. The sludge on the bottom of the tank can be scraped out and dealt with separately (we’re not concerned with that, here). a. Given that you need to treat 1,000,000 liters of raw wastewater per day, how much copper

in grams would be left in one day’s worth of treated wastewater? (Hint: 0.00-50.0 g)

b. The facility in question is permitted by the Environmental Protection Agency (EPA) to discharge no more than 25 grams per day of dissolved Cu into the sanitary sewer. Based on your calculations in ‘a’ above, would the facility be in compliance?

13. It was stated above that you would need to somehow raise the pH of the incoming wastewater to drop out the Cu as ‘sludge’. Which of the following compounds would not work as an additive for the purpose of raising the pH from 6.0 to some optimum level?

i. NaOHii. Ca(OH)2

iii. HCliv. NH4OH

14. Extra credit (5 points): If they directed their untreated wastewater stream to a central treatment plant (to be designed by you for a suitable fee), and you figure it takes 2 hours to settle the sludge or ‘floc’ to the bottom of the clarifier tank (in other words you need 2-hrs retention time in the clarifier), and the treatment plant can run 24 hours per day, how large must you design the clarifier tank volume in Liters? More details: a clarifier runs continuously… raw water enters continuously, sludge settles continuously, and purified water is drawn off continuously.

Fig. 2: Cutaway of a typical industrial clarifier, with bottom scrapers to remove sludge

15. More extra credit (5 points): If the clarifier was circular, and needed a liquid depth of 2 meters, what would the inside diameter of the tank need to be in order to contain the volume in liters you just calculated in the above question, without sloshing over the sides. State all your assumptions.

Thermodynamics

16. Standard conditions: What is meant by “standard state conditions” in Thermodynamics discussions? Be specific as to temperature and pressure.

17. Heat of fusiona. What is the heat of fusion (enthalpy of fusion) of H2O in KJ/mol? (Hint: look it up)b. How many moles of H2O are in 1000 grams of H2O? c. How much energy in KJ would it take to melt 1000 grams of H2O-ice at 0°C? (i.e. you begin

with ice at 0°C and end with liquid water at 0°C) (Hint: 300-400 KJ)

18. Specific heata. What is the specific heat of H2O in J/g·°C? (Hint: look it up)b. Now convert that number into units of KJ/g·°C. c. How much energy in KJ would it take to raise the temperature of 1000 grams of H2O from 0°

to 100°C? (i.e. you begin and end with liquid water, not steam yet) (Hint: 400-500 KJ)

19. Heat of vaporizationa. What is the heat of vaporization (enthalpy of vaporization) of H2O in KJ/mol? (Hint: look it

up)b. How much energy in KJ would it take to boil (vaporize) 1000 grams of H2O at 100°C? (i.e. you

begin with liquid at 100°C and end with steam at 100°C) (Hint: 2000-2500 KJ)

20. Putting it all together (combining the previous 3 questions)a. How much energy in KJ would it take to bring ice at 0°C up to steam at 100°C? (Hint: add up

the 3 steps)b. What step in the process requires the most energy input, 1) the melting?... 2) the heating up

to 100°C?... or, 3) the boiling?

Chemical Kinetics

21. The hypothetical reaction, A + B + C → D + E, has the rate law, Rate = k[A]2[B].

Which of the following changes would have the least effect on increasing the rate of this reaction? a. Doubling [A]0 while keeping [B]0 and [C]0 constantb. Doubling [B]0 while keeping [A]0 and [C]0 constantc. Doubling [C]0 while keeping [A]0 and [B]0 constantd. Increasing the rate constant by running the reaction at a higher temperaturee. Adding a catalyst to the reaction mixture

22. Working in your spare time in your home laboratory, you discover a new method of producing a substance we shall call ‘C’, which is a polymer material having the strength and weight characteristics of titanium! What makes this discovery especially interesting is that ‘C’ has a market value of $50/pound, whereas ‘A’ and ‘B’ only cost a few pennies/pound.

The reaction can be written as follows: 2A + B → 2C

Barely able to contain your excitement, you set out obtaining the following data concerning the rate of the reaction:

Initial concentration (mols/L) Initial rate of reaction (mols/L·s) ‘A’ ‘B’

Run 1 0.0125 0.0250 0.030Run 2 0.0250 0.0250 0.120Run 3 0.0125 0.0500 0.060

The general rate law is in the form Rate = k[A]x[B]y. You don’t know the values of ‘k’, ‘x’, or ‘y’, which is why you’re doing the study.

a. Using the results of the kinetic study, what is the ‘reaction order’ for each reactant, A and B? In other words, what is the value of ‘x’ and ‘y’?

b. What is the value of ‘k’, the rate constant? (Hint: 7,000-8,000)c. Now write out the entire rate law, showing the values of ‘k’, ‘x’, and ‘y’.

Chemical Equilibrium

23. For the reaction aA + bB ↔ cC + dD, write out the equilibrium constant expression.

Keq = ?

24. Le Chatelier’s Principle: In which of the following reactions involving gases would the forward reaction be favored by an increase in pressure?a. 2A + B ↔ ABb. A + B ↔ C + Dc. 2A + B ↔ C + 2Dd. AC ↔ A + C

25. The formation of glucose from water and carbon dioxide is one of the most important chemical reactions in the world. Plants and algae perform this reaction through the process of photosynthesis, creating the base of the food chain – glucose:

6H2O(g) + 6CO2(g) ↔ C6H12O6(s) + 6O2(g)

The following equilibrium concentrations were found: [H2O] = 7 x 10-2 M, [CO2] = 9 x 10-1 M, and [O2] = 2 x10-3 M. Calculate the value of Keq for the reaction at this temperature. (Hint: 1.5 x 10-10 to 1.1 x 10-8)

26. Le Chatelier’s Principle: After patiently experimenting in your home laboratory for 6 months, you have discovered that you can economically produce substance ‘C’, a much sought-after compound used in the pharmaceutical industry

4A(g) + catalyst ↔ 2B(g) + C(l) + heat

As part of the commercialization of the process, you are trying to figure out how to shift the equilibrium further to the right in order to produce more product.

Would the effect of each of the following actions help, or hurt, the process in terms of equilibrium?

a. Grind-up the catalyst into a fine powderb. Increase the pressure of the reactor vesselc. Increase the temperature of the reactor vesseld. Somehow continuously draw-off ‘B’ during the reaction process

Acids, Bases, and Salts

27. Calculate the hydronium ion concentration [H3O+] in moles/L, and the pH of each solution. To receive credit you must show your work. (Hints: notice that HCl is monoprotic, while H2SO4 is diprotic. Also remember the formulas, pH = -log10[H30+] which is the same as saying 10-pH = [H30+]. Also, all the pH’s you calculate will be less than 7.0 since these are all acids) a. 1 x 10-5 M HCl b. 5 x 10-3 M HClc. 1 X 10-1 M H2SO4

d. 1 x 10-5 M H2SO4

Organic Chemistry

Note: since your Organic Chemistry homework is due the same week as this exam, no further questions on this topic are necessary