20#15

Given the following half-reactions and associated standard reduction potentials:
AuBr−4(aq)+3e−→Au(s)+4Br−(aq)
E∘red=−0.858V
Eu3+(aq)+e−→Eu2+(aq)
E∘red=−0.43V
IO−(aq)+H2O(l)+2e−→I−(aq)+2OH−(aq)
E∘red=+0.49V
Sn2+(aq)+2e−→Sn(s)
E∘red=−0.14V

a) Write the cell reaction for the combination of these half-cell reactions that leads to the largest positive cell emf.

b) Calculate the value of this emf.

E∘max = _____ V

c) Write the cell reaction for the combination of half-cell reactions that leads to the smallest positive cell emf.

d) Calculate the value of this emf.

E∘min = _____ V

What is the pH at the equivalence point 10.0 mL of 1.00 M NH₃ (K_b = 1.8 x 10^-5) is titrated against 2.00 M HCl?

At 1 atm, how much energy is required to heat 73.0 g of H2O(s) at –22.0 °C to H2O(g) at 121.0 °C?

1. What is the principal use of calcium proprionate (the calcium salt of propionic acid) based from The Merck Index?

2. What is the result of treating calcium chloride with oxalic acid?

3. Explain why oxalic acid can be a deadly poison?

How many unique 1 H NMR signals exist in the spectrum of the following compound: 1,3-dibromobenzene?

Cyanide recovered from the refining of gold ore
can be determined indirectly by EDTA titration. A known
excess of Ni2 is added to the cyanide to form tetracyanonickelate(
II):
4CN + Ni ---> Ni(CN)4
When the excess Ni2 is titrated with standard EDTA,
Ni(CN)4 does not react. In a cyanide analysis, 12.7 mL of
cyanide solution were treated with 25.0 mL of standard solution
containing excess Ni to form tetracyanonickelate. The excess
Ni required 10.1 mL of 0.013 0 M EDTA for complete
reaction. In a separate experiment, 39.3 mL of 0.013 0 M EDTA
were required to react with 30.0 mL of the standard Ni
solution. Calculate the molarity of CN in the 12.7-mL sample
of unknown.

1. Listed below are the atomic weight, density, and atomic radius for three hypothetical alloys. For each determine its crystal structure and then justify your determination.

Alloy // Atomic weight (g/mol) // Density (g/ cm^3) // Atomic Radius (nm)

A // 43.1 // 6.4 // 0.122

B   // 184.4 // 12.3 // 0.146

C // 91.6 // 9.6 // 0.137

What is the molar solubility of CaF₂ in 0.10 M NaF solution 25 degrees C?

The K_sp for CaF₂ is 3.4x10^-11.

The answer is 3.4x10^-9 M. Please explain how to get to that answer. Thank you!

Calculate the following quantities for the reaction in which ammonia is formed from its atomic components:

a) The stoichiometric coefficients of the reactants and products.

b)The stoichiometric ratio of N₂ to H₂.

c)(moles NH₃ produced)/(mole N₂ reacted)

d)(lb_m H₂ reacted)/(lbmole NH₃ produced)

e)The Kmole of N₂ and H₂ that must react to form 150 Kmoles of NH₃.

f)The lb_m of NH₃ produced and lb_m of H₂ reacted if 20 lb_m of N₂ react completely.

Saturdated water vapor (steam) is commonly used as a heat source in heat exchanger applications. Why saturated vapor? Why saturated water vapor? In a plant of any reasonable size, several varieties of saturated steam are commonly available; for example, saturated steam at 4.5,9,17, and 33 bar. But the higher the pressure the lower the useful energy content (why?), and the greater the unit cost. Why then is higher-pressure steam used?

calculate the ph of a solution made by mixing 20.0 ml of 0.200 m h2so3, 10.0 ml of 0.120m naoh, 10.0ml of 0.150 m hcl, and 10.0ml of 0.200 m na2so3. (pka1: 1.857, pka2: 7.172 for h2so3)

The fundamental vibrational transition of the 12C16O in the electronic ground state from v=0 to v=1 occurs at 2,170 cm-1. The bottom of the Morse potential for the anharmonic oscillator is well approximated by a parabola, the potential well for the harmonic oscillator, especially when the transition is measured with precision limited to 1 cm-1. a) Demonstrate that, in the harmonic oscillator approximation of the IR spectroscopy, the frequency of the fundamental transition is equal to the frequency of the oscillator in the zero energy state. b) What is the elastic force constant k of the 12C16O bond in the harmonic oscillator approximation? (Hint: you have to use the reduced mass of the diatomic oscillator. A12C = 12.000 amu, A16O = 15.995 amu, 1 amu = 1.6605 x 10-27 kg, c = 2.9979x108 m s-1) c) The first overtone of the 12C16O occurs at 4,260 cm-1. Compare this frequency against the fundamental frequency and state 2 points of departure from the harmonic oscillator results predicted by Quantum Mechanics.

1. A coupon of very pure Gold and highly clean surface is exposed to an Argon Fluoride (ArF) excimer laser beam of wavelength 193.4±0.2 nm inside an ESCA (Electron Spectroscopy for Chemical Analysis) ultrahigh vacuum spectrometer. The coupon surface faces the entrance aperture of a hemispherical electrostatic energy analyzer and detector. The coupon and the analyzer entrance aperture are electrically connected together at ground potential (zero Volts). A fraction of the photo-emitted electrons enters the analyzer and their energy distribution is measured. a) (2 points) What is the energy of a photon in the ArF laser beam expressed in electron-Volts (eV)? b) (2 points) The highest energy of the detected electrons was 1.3±0.1 eV. What was the Work Function of this Gold surface in eV?

1. Write a balanced equation for the complete combustion of each of the following:

a. 2,2-dimethylbutane

Express your answer as a chemical equation. Identify all of the phases in your answer.

b.   cyclopentane

Express your answer as a chemical equation. Identify all of the phases in your answer.

2. Consider the compound ethylcyclopentane

a. Write the equation for the complete combustion of ethylcyclopentane.

Express your answer as a chemical equation.

b. Calculate the grams O2 required for the reaction of 35.0 g ethylcyclopentane.

Express your answer with the appropriate units.

c. How many liters of CO2 would be produced at STP from the reaction in part b?

Express your answer with the appropriate units.

Draw a titration on a molecular level. Clearly indicate the titrant and substance being titrated as well as the products of the reaction.