A sample of a chromium-containing alloy weighing 3.450 g was dissolved in acid, and all the chromium in the sample was oxidized to 2CrO42–. It was then found that 3.18 g of Na2SO3 was required to reduce the 2CrO42– to CrO2– in a basic solution, with the SO32– being oxidized to SO42–. Write a balanced equation for the reaction of 2CrO42– with SO32- in a basic solution. How many grams of chromium were in the alloy sample? What was the percentage by mass of chromium in the alloy? Review Problem 5.097a Incorrect. Did you have the chromium being reduced? Did you balance out the electrons properly so none remained in the final balanced equation? Enter a balanced net ionic equation for the reaction between 2CrO42- and SO32- in a basic solution.

For Tc-98, Tc-97, and Tc-96 what are the following for each?

1. A 33.6 mL sample of a 0.494 M aqueous acetic acid solution is titrated with a 0.379 M aqueous sodium hydroxide solution. What is the pH after 14.8 mL of base have been added?

pH =

2.How many grams of solid ammonium bromide should be added to 0.500 L of a 0.234 M ammonia solution to prepare a buffer with a pH of 10.120 ?

grams ammonium bromide =

3. How many grams of solid sodium nitrite should be added to 2.00 L of a 0.151 M nitrous acid solution to prepare a buffer with a pH of 2.593 ?

4. Give the general arrangement of the subatomic particles in an atom.

The 1H NMR of ethanol in CDCl3 will consist of three signals in the spectra: a triplet at 1.25 ppm, a quartet at 3.72 ppm, and a broad singlet at 1.32 ppm. In DMSO-d6(deuterated DMSO) the broad singlet is found at 4.63 ppm. Why is there such a dramatic change in the singlet’s position (clearly describe what is happening with structure)?

Calculate the change in pH when 7.00 mL of 0.100 M HCl(aq) is added to 100.0 mL of a buffer solution that is 0.100 M in NH3(aq) and 0.100 M in NH4Cl(aq).

Calculate the change in pH when 7.00 mL of 0.100 M NaOH(aq) is added to the original buffer solution.

Question #1.) A fixed volume of gas at constant temperature has a volume of 45.6 L at 1.24 atm. Use Boyle's Law to calculate:

a. the volume of the gas when compressed to 3.53 atm.

b. the pressure of the gas when it is compressed to 12.55 L.

Question #2.) An aerosol can with a volume od 445 mL contains 0.355 grams of propane (C₃H₈) as a propellant. What is the pressure inside the can at 27 degrees celsius?

Question #3.) At 46 degree celsius and 1.235 atm a gas occupies a volume of 0.735 L. How many moles of gas are present? What would be the pressure of the gas at 105 degrees celsius and a volume of 1.00L? How many liters would the gas occupy at STP?

NaBr heated in Na vapor produced nonstoichiometric compounds; i.e., the atomic ratios are not whole numbers. The additional uptake of Na atoms occurs by the reaction: Na -> Na⁺ + e^-, where the Na⁺ ions sit on vacant Na⁺ sites and the e^- sits on vacant Br^- sites. If a maximum amount of Na is taken up by the material in question 1 (NaBr with a= 5.94Å and observed density= 3.203g/cc), what would be the formula of the material that is formed?  

You have 225 mL of an 0.43 M acetic acid solution. What volume (V) of 1.10 M NaOH solution must you add in order to prepare an acetate buffer of pH = 4.23? (The pKa of acetic acid is 4.76.)

Suppose that you are given the task of determining the SCN^- content of a blood sample by forming the Fe(SCN)²⁺ complex and measuring the absorbance. You begin by taking a 10.00-mL volume of the blood sample, centrifuging it, transferring 0.50 mL of the clear serum to a flask, and then adding 15.00 mL of 0.20M Fe³⁺. The %T of this solution, measured at 460 nm in a 1.0-cm diameter cuvet, is 75%. A calibration curve, prepared from Fe(SCN)²⁺ standards, indicates that the Fe(SCN)²⁺ concentration of the diluted sample solution is 0.033 mM. Calculate the SCN^- content (in mM) of the original blood sample.

(Atomic weight of Fe = 55.85 g/m; formula weight of SCN^- = 58.08 g/m)

A) 0.033 mM                                                                              

B) 0.33 mM                                             

C)0.40 mM

D) 0.82 mM         

E) 1.02 mM

3. (a) Using x, y, z vectors of each atom in a SO₂molecule to derive the reducible representation (assuming that the principle axis is collinear with the z axis and the molecule is lying on the xz plane).

(b) Classify the irreducible representations into translational, rotational, and vibrational modes.

(c) Which vibrational modes are infrared active.

(d) Sketch the three vibrational modes including the symmetric stretch, antisymmetric stretch, and symmetric bend.

(e) The calculated IR spectrum of SO₂show three peaks at 1362 cm^-1, 1151 cm^-1, and 518 cm^-1. Provide a symmetric label for each of these three peaks, provided that the two stretch modes occur at much higher wavenumbers than the bend mode andthat the antisymmetric stretch occurs at higher wavenumber than the symmetric stretch.

A beaker with 145 mLmL of an acetic acid buffer with a pHpH of 5.000 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.100 mol L−1mol L−1. A student adds 6.70 mLmL of a 0.360 mol L−1mol L−1 HClHCl solution to the beaker. How much will the pHpH change? The pKapKa of acetic acid is 4.760.

Express your answer numerically to two decimal places. Use a minus ( −− ) sign if the pHpH has decreased.

A gas has a volume of 4.00 L at 0 degree Celsius. what final temperature, in degrees Celsius, is needed to change the volume of the gas to each of the following, if n and P do not change?
(a) 1.50 L
(b) 1200 ml