Demonstrate by a “microstate analysis” that four electrons in a degenerate set of three p‐orbitals gives rise to the same electronic state

113 “terms” as two electrons do (i.e. ¹D, ¹S and ³P)

2.5 grams of a metallic sample containing an unknown amount of zinc is dissolved in 500 ml of acidic water, releasing the zinc into the water as Zn²⁺ ions. A 10.00 ml aliquot of this solution is extracted with 10 ml of CCl₄ containing an excess of 8-hydroxy quinoline. The CCl₄ and aqueous phases separate and 8-hydroxy quinoline forms a fluorescent complex with Zn²⁺ ions that partitions entirely into the CCl₄ phase. The CCl₄ phase is separated and then diluted to 25 ml. This solution gives a fluorescence intensity of 155 (arbitrary units). A similar procedure is done with 10.00 ml of the unknown zinc solution plus 8.00 ml of an aqueous 2.50 ppm Zn²⁺ solution, and the final fluorescence intensity is 247. Calculate the Zn²⁺ concentration in the original 500 ml solution and the amount of zinc in the original solid.

A sample of an unknown gas with a mass of 4.67 goccupies a volume of 1.88 L at a pressure of 785 mmHg and a temperature of 20.0 ∘C. Molar mass=57.9 g/mol. If the unknown gas is composed of 3.86 g of carbon and the rest is hydrogen, what is its molecular formula?

Choose the answer which lists ionic compounds RbBr, SrCl2, SrBr2, and RbCl in order of increasing lattice energy (smallest lattice energy listed first). Be sure to show how you found the lattice energy for each element

A reaction is found to ahve a forward activation energy of 150 kj and an exothermic enthalpy of reacton (delta H = -250kJ). FInd teh activaiton energy for the reverse reaction.

What am I doing wrong in this titration problem?

Calculate the ph at the equivalence point for the following titration 0.20M HCl versus 0.20M methylamine (CH3NH2). The Ka of methylammonium is 2.3x10^-11.

First I have to divide .20M methylamine by 2 (Why?) to get .10M

Then, I set up the equilibrium:

(2.3 x 10^-11) = x^2 / .10M

Since the ka is SO small, I just multiplied .10 with (2.3 x 10^-11) to get 2.3x10^-12, which is wrong.

Why is this wrong? Since the Ka is small, the approxiamation method should work and I won't need to do the quadratic. Instead, I am told that the x value is 1.5x10^-6 from the quadratic.

Find the pH of a solution prepared from 1.0 L of a 0.20 M solution of Ba(OH)₂ and excess Zn(OH)₂(s). The Ksp of Zn(OH)₂ is 3×10⁻¹⁵ and the Kf of Zn(OH)₄²⁻ is 2×10¹⁵.

1. An aqueous solution of sodium hydroxide is standardized by titration with a 0.108 M solution of perchloric acid.

If 17.0 mL of base are required to neutralize 29.4 mL of the acid, what is the molarity of the sodium hydroxide solution?

______ M sodium hydroxide

2. An aqueous solution of potassium hydroxide is standardized by titration with a 0.130 M solution of nitric acid.

If 23.3 mL of base are required to neutralize 15.8 mL of the acid, what is the molarity of the potassium hydroxide solution?

________M potassium hydroxide

3. An aqueous solution of hydrobromic acid is standardized by titration with a 0.140 M solution of barium hydroxide.

If 27.7 mL of base are required to neutralize 26.9 mL of the acid, what is the molarity of the hydrobromic acid solution?

_______M hydrobromic acid

Refer to the reaction 2Mg + O2---> 2MgO

starting amounts 1.25mg 2Mg, and 25g of O2. What are the changes that occur in this reaction as its happening? Complete an ice table using the starting amounts and referring to the reaction above.

*I have no idea how to do these, in the words of Micheal Scott, "Why don't you explain this to me like I'm 5 years old."*

In the laboratory, a general chemistry student measured the pH of a 0.530 M aqueous solution of codeine, C18H21O3N to be 10.820. Use the information she obtained to determine the Kb for this base.

Which choice is expected to form (a) the strongest and (b) the weakest ionic bond (choices listed as strongest/weakest)?

Options:

Na+ & Cl-, Cs+ & Cl-, Cs+ & Br-, Ca2+ & Cl-,

Ca2+ & O2-, Sr2+ & O2-, Sr2+ & Cl-, Sr2+ & Br-

Electric generating plants transport large amounts of hot water through metal pipes, and oxygen dissolved in the water can cause a major corrosion problem. Hydrazine (N₂H₄) added to the water avoids the problem by reacting with the oxygen: N₂H₄(aq) + O₂(g) → N₂(g) + 2 H₂O(l)

About 4 x10⁷ kg of hydrazine is produced every year by reacting ammonia with sodium hypochlorite in the Raschig process:

2 NH₃(aq) + NaOCl(aq) → N₂H₄(aq) + NaCl(aq) + H₂O(l) Δ_rH° = −151 kJ

(a) If Δ_fH°  of NaOCl(aq) = −346 kJ/mol, find Δ_fH°  of N₂H₄(aq) given that Δ_fH° [NH₃(aq)] = −80.83 kJ/mol, Δ_fH° [NaOCl(aq)] = −346 kJ/mol, Δ_fH° [Na⁺(aq)] = −239.66 kJ/mol, Δ_fH° [Cl⁻(aq)] = −167.46 kJ/mol and Δ_fH° [H₂O(l)] = −285.840 kJ/mol.

______ kJ/mol

b) What is the heat released when aqueous N₂H₄ is added to 6.00 × 10³ L of plant water that is 2.50 × 10⁻⁴ mol/L O₂? Enter your answer in scientific notation.

____× 10___ kJ

1.True or false

      A. All compounds that contain hydrogen are acids..

      B. A solution with a pH of 5 has 10 times higher [H⁺] than a

      Solution with a pH of 6.

      C. SO₃ in the atmosphere is one cause of acid rain.                  

      D. Agricultural chemicals are the only cause of water pollution.

      E. One function of an auto catalytic converter is to convert CO₂ to CO

      F. The major elements in air are nitrogen and oxygen

      G As a radioactive isotope decays its half life changes.

      H. In the same size container at the same temperature, 25g of N₂ gas

                       has the same pressure as 25g of NH₃ gas..

     I    Chloroflurocarbon compounds are considered to be a prime cause of

                      ozone depletion in the stratosphere.

       J.   Beta radiation from an atom is the emission of a valence electron.

Fe(NO3)3+KSCN ---- FeSCN^2+KNO3

the assumption was made that all of the SCN^- which had been added to the standard solutions had been converted to FeSCN^2+.

Is this assumption reasonable. Explain considering the initial concentration of SCN- relative to that of Fe3+ in each sample