A gas mixture with a total pressure of 770 mmHg contains each of the following gases at the indicated partial pressures: 133 mmHg CO2, 233 mmHg Ar, and 183 mmHg O2. The mixture also contains helium gas.What is the partial pressure of the helium gas?

A coffee cup calorimeter contains 480.0 g of water at 25.0 ^oC. To it are added:
380.0 g of water at 53.5 ^oC
525.0 g of water at 65.5 ^oC

Assuming the heat absorbed by the styrofoam is negligible, calculate the expected final temperature. The specific heat of water is 4.184 J g^–1 K^–1.

Select one:

a. 38.2 ^oC

b. 48.2 ^oC

c. 67.6 ^oC

d. 88.7 ^oC

Consider the tripodal molecule, NH3, under C3v point group constraints. Derive a 12 x 12 matrix for the transformational matrix of the C3 rotation axis

One of the most popular methods for determine trace amounts of water is a coulometric titration, called the Karl Fischer. Measuring trace amounts of water is one of the most challenging analytical methods.

a) What would be another method that would measure larger amounts of water contained in a sample, and how would you do it?

b) The Karl Fischer method is a secondary coulometric analysis that utilizies the generation of I2/I3 with starch, just like you did in lab, generated from the Iodide ion. This iodine molecular species then reacts with water in a complicated Redox, involving stinky pyridine....hense, the advantage of doing this by remote control under a hood. The actual limiting reagent is WATER: One mole of water reacts with one mole of generated I3.

The goal of your problem is to find the ppm of water in a 250 mL sample of pure ethanol, that has a density of 0.7893 g/mL. A current of 55.5 milliamps was run for 4 minutes 23 seconds, until the blue/black color of the starch was observed. However, the current generator box was only 89.3 % current efficient, losing some current. The electrochemical production of the tri-iodide ion reagent was the same oxidation reaction as in lab. What is the ppm of WATER contamination the 250 mL of pure ethanol?

Questions asked after completing quantitative volumetric analysis of pickling vinegar & NaOH (regular vinegar consists 5% acetic acid, CH3COOH. Piclking vinegar consists 7% of the acid).

1. Is there a trend in the values obtained in class? (there was a trend) Explain.

2. If regular vinegar costs $1.00/L & pickling vinegar costs $1.25/L, which is the best by? (i.e use a logical argument to determine which gives you the most acetic acid for your dollar)

3. Why do we only include the trials that agree withing 1% of each other? What is the difference between accuracy & precision for a series of measurements?

4. Identify 4 important sources of systematic (not human) error. Discuss why they are important.

5. If 0.25M potassium hydroxide solution was used as the titrant, instead of 0.1 M NaOH (aq), would your titration have use dmore or less itrant to reach the end point? Use a logical argument to determine how much more or less titrant would be required.

Given the following reactions of nitrosyl chloride (NOCl), calculate the ∆H°rxn, in kilojoules per mole, for the third reaction. Enter your answer to the tenths place. Don’t forget the sign! 2NOCl(g) ⟶ 2NO(g) + Cl2 (g) ΔHrxn ° = +79.2 kJ mol ⁄

NOCl(g) + 1 2 O2 (g) ⟶ NO2Cl(g) ΔHrxn ° = -39.1 kJ mol ⁄

2NO(g) + Cl2 (g) + O2 (g) ⟶ 2NO2Cl(g)

1. Your stoichiometry reaction is C → 1/3 D

A. You know the reaction order is second order in C. What is the rate law for this reaction? (Remember it has three parts)

B. If the reaction rate is 0.150 M/s when the concentration of C is 0.800, what rate would you expect if the concentration of C is 0.400M?

C. What rate of formation of D would you expect for your answer in part B (using the rate for 0.400 M C)?

2. We now have three equations we can use to predict concentration of reactants if we know the reaction order. Define the following:

A) What is k?

B) What is [A]t?

C) What is [A]o

D) What is t?

E.) How would you calculate the amount of reactant used in the reaction (using variables above)?

F.) How would you calculate the amount of product made in a reaction (using variables above)?

A) The substance sulfur dioxide has the following properties:

A sample of sulfur dioxide at a pressure of 1.00 atm and a temperature of 253.5 K is cooled at constant pressure to a temperature of 192.3 K. Which of the following are true?

Choose all that apply

The solid initially present will vaporize.

The sample is initially a liquid.

The final state of the substance is a solid.

One or more phase changes will occur.

The final state of the substance is a liquid.

B) The substance xenon has the following properties:

A sample of xenon is initially at a pressure of 63.9 atm and a temperature of 178.0 K. The pressure on the sample is reduced to 0.370 atm at a constant temperature of 178.0 K. Which of the following are true?

Choose all that apply

The sample is initially a liquid.

The liquid initially present will solidify.

One or more phase changes will occur.

The final state of the substance is a solid.

The final state of the substance is a gas.

What volume of 0.0100 M KMnO₄ solution is required to oxidize 42.5 mL of 0.0190 M FeSO₄ in sulfuric acid solution?

What is the pH of a solution containing 0.12 mol/L of NH4Cl and 0.03 mol/L of NaOH (pka of NH4+/NH3 is 9.25)?

Predict the bond angles in the following molecules.

1. What is the fraction 3/260 in scientific notation to 3 significant figures?

2. Which statement is correct about element? A) sulfur is a good conductor of heat B) iron is a transition metal C) boron is metal D) copper is a poor conductor

3. If an element has a mass number of 14, and contains 8 neurons, what is it's atomic number? A)22 B)6 C)14 D)8

4. What term describes urine sample with a ph value of 5.5? A)balanced  B)alkaline C)neutral D) acidic

5. Which term means the substance in which the solute is dissolving into? A)Solution B)Solvent C)Suspension

6. What is the oxidation number of magnesium (ma) with any compound? A) +3 B )+1 C) +2 D) 0

7. What term best describe NaoH in this reaction? HCl+NaoH=NaCl+H20 . A) Gas B) Product C) Acid D) Reactant

1. Consider this reaction:

H₂(g) +    O₂ (g)     à       H₂O (g)                                          dHo = __________

1. Balance the equation and put the correct number of moles in the equation above. (1 point)

2. Classify the forward reaction as (1) Combustion, (2) Decomposition, (3) Single replacement, (4) Double replacement, (5) Neutralization, (6) Synthesis. Circle the correct answer. (1 point)

3. In this reaction did Hydrogen get oxidized or reduced? Circle the correct answer. (1 point)

4. Based on your answer above is Hydrogen an oxidizing or reducing reactant? Circle the correct answer. (1 point)

5. In this reaction did Oxygen get oxidized or reduced? Circle the correct answer. (1 point)

6. Based on the answer above, is Oxygen an oxidizing or reducing agent? Circle the correct (1 point)
   
7. Calculate the dHo of the Synthesis reaction using the values from the table in Appendix 2. Show your work. (2 points)

8. If 4 moles of H2 is used in a balanced equation for the synthesis reaction, how many moles of water will be produced (without using the tables). Show your work. (1 point)

9. If 4 moles of H2 is used for the Synthesis reaction, calculate the enthalpy of the reaction without using the tables. Show your work. (1 point)

10. If 4 moles of H₂O is required to be produced, how many moles of H₂ and how many moles of O₂ will be required (without using tables). Show your work. (1 point).

11. If 1 mole of water is required to be produced, how many moles of H₂ and O₂ will be required (without using tables)? Show your work. (1 point)

12. If 6 moles of water is decomposed, how many moles of H₂ and O₂ will be formed? (1 point)

13. If 6 moles of water is decomposed, calculate the enthalpy of the reaction without using the values from the table available in Appendix 2 of your textbook. (2 points)

Michael Farday weighs out 3.12 g. of salicylic acid in a 100 mL flask and adds 1.89 mL of acetic anhydride (density = 1.080 g/mL). Determine the maximum (theoretical) number of grams of acetylsalicylic acid he can prepare. If Mr. Faraday obtained 3.38 g. of Aspirin, calculate the % yield. Briefly, explain why he might have obtained this amount of product.

Determine the oxidation number of iodine in each of the following compounds. Be sure to enter your answer as X+ or X-

(a)NaI

(b)I2

(c)IO2

(d)I2O7

(e)KIO4

(f)Ca(IO)2