Physical Chemistry Thermodynamics:

The enthalpy of combustion of benzoic acid (C6H5COOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters; its value has been accurately determined to be —3226.7 kJ mol-1, (a) When 0.9862 g of benzoic acid was oxidized, the temperature rose from 21.84°C to 25.67°C. What is the heat capacity of the calorimeter? (b) In a separate experiment, 0.4654 g of glucose (C6H1206) was oxidized in the same calorimeter, and the temperature rose from 21.22°C to 22.28°C. Calculate the enthalpy of combustion of glucose, the value of delta r U for the combustion, and the molar enthalpy of formation of glucose.

Conformational analysis of a molecule was performed using a global-optimisation method where the energy was evaluated using Hartree-Fock (HF) theory. The binding energy of the low-energy conformers with a host complex was then calculated using the same level of theory.

It was found that the lowest-energy conformer matched well with a known X-ray crystal structure but the binding energy with the host molecule was far too small.

(i) Define the term conformer. (ii) Explain the general principles of global optimisation of a molecule and why global optimisation is challenging to perform. (iii) Summarise the main contributions and terms that Hartree-Fock theory captures. (iv) Explain why the low-energy conformers might be reasonably modelled by HF theory. (v) Explain why HF theory fails to model the binding energy. Suggest a plausible alternative for obtaining more accurate binding energies, with comparable computational cost.

Enough detail required in answer please

The inside of a cell is extremely crowded. We will try to gain some insight for exactly how crowded by considering some numbers that are estimates of the situation in the common bacterium E. coli. One can estimate the total number of proteins present in a cell in several ways. For example, one can measure the dry mass of a cell (the amount of material left once the cell is dried out), analyze the composition to determine what fraction is amino acids, estimate the average molecular weight of a protein, and use all these numbers to calculate the total number of protein molecules present. Alternatively, one can use experimental analysis to determine the approximate amount of proteins present in a sample consisting of a known number of cells. All of these methods agree that a typical E. coli bacterial cell contains about 3 x 10⁶ proteins.

a) We can estimate the volume of an E. coli cell to be about 1 µm³, that is, equivalent to a cube of 1 µm on each side. Convert that volume to liters, and assuming there are 3 x 10⁶ total proteins present, calculate the total molar concentration of proteins contained in a bacterial cell.

b) Take the reciprocal of the molar concentration obtained in part a, and convert units to find the number of cubic nanometers per protein molecule.

c) One way to think about the volume per protein molecule found in part b is that if you divided up the total volume of the cell into tiny cubes, with each cube having the volume found in part b, then on averge, each cube would contain one protein. The length of each side of one of these cubes would just be the cube root of the volume per protein molecule. Further, the length of each side of the cube is an estimate of the center-to-center separation distance of each protein molecule. From the volume per protein obtained in part b, use this approach to estimate the center-to-center distance between protein molecules (on average) in an E. coli cell.

d) Averaged across a cell's inventory of proteins, the average protein molecular weight is about 30000 grams per mole (i.e., 30 kiloDaltons). For proteins, an average mass density is found of about 1.4 g/cm³. Use these numbers, after appropriate unit conversions, to calculate the average volume of a protein molecule in cubic nanometers. Compare this number to the value obtained in part b, and estimate what fraction of the total volume of a cell is filled with proteins.

Question #1.) An unknown liquid requires 7.72 kJ of energy to change 12.4 grams 10.00 degrees C. Calculate the specific heat of the material.

Question #2.) Use the standard heats of formation from the textbook to calculate delta H for the following reaction:

C6H12O6 + O2 (g) --> CO2 (g) + H2O (g)

Question #3.) Calculate the standard enthalpy of formation of solid Ca(OH)2, given the following data:

Ca(s) + O2(g) + H2(g) --> Ca(OH)2

2Ca(s) + O2(g) --> 2CaO (s)                    H= -848.6 kJ

2 Ca(OH)2 (s) --> 2 CaO (s) + H2O (l)    H = +92.2 kJ

H2 + 1/2 O2 --> H2O (l)                          H = -236 kJ

What is the solubility ( in g/L) of lead(II) chromate, PbCrO4 in 0.13M potassium chromate, K2CrO4.

A certain weak base has a Kb of 7.40 × 10-7. What concentration of this base will produce a pH of 10.07?

Determine the pH of an HNO2 solution of each of the following concentrations.

0.540 M

0.100 M

1.30×10⁻² M

In which cases can you not make the simplifying assumption that x is small?

Qualitative scheme for seperation of ions Ag, Pb2+, Fe3+, Cu2+, Al3+, Mn2+, Ni2+, Ba

How many N2 molecules in your next breath were present in Julius Caesar’s last breath (died in 44 BC, March 15 in Rome)?

a) First find the probability of the N2 in Caesar’s last breath still being present in the atmosphere.

b) For simplicity, assume 1 breath = 1 Liter . How many N2 molecules in your next breath were present in Julius

Caesar’s last breath?

Describe the response mechanism of the fluoride-ion-selective electrode. Explain why the OH- is the major interfering ion in F- ISE measrements.

Radiolytic decomposition of water on the coolant side of zirconium cladding is generating a pressure of H2 of 10-4 bar with thus a similar surface concentration of H2. Hydrogen, H2, is thus diffusing into the zirconium, which can in fact contain a considerable amount of dissolved hydrogen. Using the data and assumptions below, and other information you may need to gather from other sources, and assuming
 The cladding is uniformly at 400 degrees C
 PWR reactor pressure is 1800 psi
 The cladding is pure Zr
 The cladding is 1 mm in thickness
 There is a sink for hydrogen at the inner clad thus the H2 pressure is negligible
 The diffusion coefficient is described by
ln D = ln A – Ea/RT
where
D = diffusion coefficient
A = pre-exponential factor (7.9 x 10-3 cm2/s)
Ea = activation energy for diffusion (44900 J/mol)
R = ideal gas law constant
T = absolute temperature
a. Compute the flux of hydrogen into the cladding at steady state
b. Sketch the concentration profile across the cladding
c. More realistically, zirconium can react with hydrogen to form zirconium hydride, ZrH2. Determine whether we will see hydride formation in the cladding.

For each of the following, determine the FOS and dn configuration for the transition metals. Be sure to clearly show the FOS and/ or charges for all relevant ligands and species.

A. Cr(OH2)3(OH)3

B. [Cr(NH3)6][Cr(CN)6]

C. TiCl3

D. Cp2Hf(CO)2

E. Fe(CO)5

2a)   Consider the following reaction:
3NaHCO3(aq) + H3C6H5O7(aq)  3CO2(g) + 3H2O(l) + Na3C6H5O7(aq)
If 1.00 grams of NaHCO3 reacts with 1.00 grams of H3C6H5O7, what is the limiting reagent?
2b What mass of water will be formed?
2c After the reaction has gone to completion, what mass of the excess reagent remains?

Compare the number of moles of nitrogen-oxygen species in air containing 300 ppbv nitric oxide, with fog consisting of 10,000 droplets per cm^3, having an average diameter of 2 um, and containing nitrate ion at a concentration of 3 * 10^5 moles L-1

If 100 mL of 1.0 M sulfuric acid, H2SO4, is neutralized with 1.0 M calcium hydroxide, Ca(OH)2, how many mL of base must be added?