Consider the reaction:

2 NO₂ (g) ⇌ N₂O₄ (g)

The ΔGf° for NO₂ (g) = 52 kJ/mol and for N₂O₄ (g) = 98 kJ/mol at 298 K.

Calculate the ΔG at the following values.

0.8 M NO₂ (g) & 3.0 M N₂O₄ (g)

4.0 M NO₂ (g) & 0.9 M N₂O₄ (g)

2.2 M NO₂ (g) & 2.4 M N₂O₄ (g)

2.4 M NO₂ (g) & 2.2 M N₂O₄ (g)

A 26.1 mL sample of 0.316 M ethylamine, C₂H₅NH₂, is titrated with 0.249 M hydroiodic acid.
After adding 12.4 mL of hydroiodic acid, the pH is______ .

B.A 21.5 mL sample of 0.261 M ethylamine, C₂H₅NH₂, is titrated with 0.210 M hydrobromic acid.
After adding 39.0 mL of hydrobromic acid, the pH is ______

Calculate the concentration in osmolarity of a solution prepared by adding 5.00 g NaCl (molar mass = 58.44) to a 100 mL volumetric flask, filling the flask to the mark with distilled water, and mixing.

In The first order reaction A -> products, [A] = .400 M initally and .250 M after 15 min, what will [A] be after 175 min?

Find the Percentage yield of [1,3,5-C6H3(CH3)3]Mo(CO)3 and discussion of factors responsible for the low yield?

Procedure: 0.5 g (~ 1.9 mmol) of Mo(CO)6 was added with 5mL (~36mmol) of mesitylene.  The apparatus is assembled in the hood using a straight reflux condenser. The Mo(CO)6 is volatile when heated and will sublime into the condenser during the reaction. Pass nitrogen over the reaction mixture continuously during the reaction. After 25 min, stop reflux When the solution has cooled to room temperature, add 8 mL of hexane to complete the precipitation. Suction filter the solution and rinse the yellow product (that is contaminated with black metallic molybdenum), with 5 mL of hexane. Purify the crude product by dissolving it in a minimum of CH2Cl2(no more than ~ 5 mL). Filter your solution and then add ~15 mL of hexane to the filtrate liquid to precipitate the product. Suction filter off the yellow [1,3,5-C6H3(CH3)3]Mo(CO)3 precipitate, wash twice with 4 mL of hexane, and allow the product to dry.

Initial mass 0.5 g of Mo(CO)6, product at the end 0.05g

Assume that the co-polymer is a 1:1 mixture of styrene and maleic anhyride and draw the structure of the repeating monomer unit. Calculate the percent yield based upon the amount of maleic anhydride used. Use the molecular weight of one repeating monomer unit for the weight of the product.

- 2.5 mL of styrene used

- 1.581 g of maleic anhydride used

- actual yield for nylon= 0.805 g

- molecular weight of one repeating monomer unit= 226.32 g/mol

calculate the pH of a 4.20x10^-8 M solution of HBr with water

I remember from class that a –OH group is a bad leaving group. How is it that this reaction will progress when bad leaving groups do not favor substitution reactions? (A partial discussion of the mechanism might help you here)

I think I added phosphoric acid instead of hydrochloric acid. So I went ahead and added the HCl. Would this lead to a different product? Explain why. Otherwise, explain what would happen and give the identity of the possible side product.)

1. Which, if any, of the molecules in Exercise 1 had resonance structures? How many resonance structures did each molecule have? 2. Both chlorine and fluorine are represented by a green modeling piece that has 4 holes. Is using the same piece for two different atoms acceptable? Why or why not? 3. List all of the possible geometric structures of a molecule that contains two atoms. 4. Explain why only the lone pairs on the central atom are taken into consideration when predicting molecular shape. What molecules from the lab activity are exceptions to this? Molecule 1: CCl4 Molecule 2: H2 Molecule 3: H2O Molecule 4: CO2 Molecule 5: O2 Molecule 6: H2O2 Molecule 7: CH4 Molecule 8: C2H4 Molecule 9: CH2O Molecule 10: CH3OH Molecule 11: CH3NH2 Molecule 12: NF3 Molecule 13: NH3 Molecule 14: [NH4]+ Molecule 15: [NO2]- Molecule 16: SO2 Molecule 17: OF2 Molecule 18: H2S Molecule 19: SF6 Molecule 20: ICl5

1)You are instructed to reflux the reaction for 1 hour. If the instructions simply told you to reflux until the reaction was complete, how would you know when this was?Questions regarding Organic Chemistry Lab: Fischer Esterification

2)Why do we wash the organic with aqueous base? Is acetic acid water soluble (how do you know)? If it is water soluble, why don’t we just wash with water instead of aqueous base?

3)In most cases of Fischer esterification, the carboxylic acid is the more “valuable” piece and the alcohol is used in excess. Let’s say you are making the ethyl ester of an acid and use the ethanol in excess. What technique would be used to remove the excess ethanol?

Thanks in advance!

Show by calculations whether MnS (K_sp = 5.6 ✕ 10^-16) will precipitate when a 0.01 M solution of Mn⁺² containing 0.02 M H⁺¹ is saturated with H₂S (0.1 M). For H₂S, K₁xK₂ = 6.3 ✕ 10^-22

a) [Mn⁺²][S^-2] K_sp; no, a precipitate will not form

b) [Mn⁺²][S^-2] > K_sp; yes, a precipitate will form     

c) [Mn⁺²][S^-2] < K_sp; yes, a precipitate will form

d) [Mn⁺²][S^-2] > K_sp; no, a precipitate will not form

Why is AX4 tedreahedral rather than square planar? Use pictures and bond angeles in explanation

Explain why the fire service uses an acronym to assist in the development of the strategies and tactics

Consider phosgene, COCl2(g). It is an important intermediate in the manufacture of some plastics. It can decompose into carbon monoxide and chlorine gases. Its ΔHf° is -220.1 kJ/mole. a) Write the balanced chemical equation for the decomposition of phosgene including an equilibrium arrow and the states in ( ). b) Write the equilibrium constant expression for this decomposition. c) At 500°C, after the reaction has reached equilibrium, Pcarbon monoxide = 0.413 atm, Pchlorine = 0.237 atm, and Pphosgene = 0.217. Calculate Kp at 500°C. d) Initially, a flask is charged with 0.689 atm phosgene, 0.250 atm chlorine, and 0.333 atm carbon monoxide. After equilibrium is established at 500°C, the new pressure on phosgene is 0.501 atm. Calculate the pressures of chlorine and carbon monoxide at equilibrium. e) [For the first part, you cannot use the equilibrium shortcut; both Kp and the concentrations are too large to be considered negligible…quadratic equation ahead…] i) Initially a second flask contains 0.750 atm of chlorine, 0.750 atm carbon monoxide, and 0.500 atm phosgene. What is the pressure of each gas when equilibrium is established? ii) Suppose enough phosgene is added to the flask to raise the pressure temporarily to 2.00 atm. According to Le Chatelier’s Principle, in which direction will the reaction shift to get back to equilibrium? f) According to Le Chatelier’s Principle, explain which direction the reaction will shift to get back to equilibrium if: i) the reaction is transferred into a flask that is larger in volume? ii) helium gas is added? iii) the temperature is increased? iv) a platinum-iridium-magnesium-palladium (PIMP) catalyst is added?

Consider formic acid, HCHO2 (Ka = 1.9x10-4) and its conjugate base, CHO2-.

a) A buffer is prepared by dissolving 25.0 grams of sodium formate in 1.30 L of a solution of 0.660 M formic acid. Assume the volume remains constant after dissolving the sodium formate.

   i) Calculate the pH of this buffer.

   ii) Calculate the pH after 0.100 mole of nitric acid is added to this buffer.

   iii) Calculate the pH after 10.0 grams of potassium hydroxide is added to this buffer.

   iv) What is the buffer capacity of this buffer?

b) 35.0 mL of 0.739 M formic acid is titrated with 0.431 M potassium hydroxide.

   i) What is the pH of the formic acid solution before titration begins?

   ii) How many milliliters of KOH is required for this titration to reach its equivalence point?

   iii) What is the pH of the solution after 10.0 mL of KOH has been added?

   iv) What is the pH of the solution halfway to equivalence?

   v) What is the pH of the solution at the equivalence point?