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# Physical Chemistry

### Aqueous Solutions, Buffer Solutions Sample Question

Calculate the OH- each aqueous solution with the following H3O+ 1.0Ã?10^â?'3 M 4.9Ã?10^â?'6 M 1.9Ã?10^â?'12 M 4.2Ã?10^â?'13 M What substance would you add to KF(aq) in order to form a buffer solution?

### PH Problems for a Solution

Calculate the PH of each solution given the following H3O or OH- values. H3O+ = 1*10^-3 Express your answer using one decimal place. H30= 1*10^-8 OH- = 1Ã?10^â?'5 OH-= 4.0Ã?10^â?'11 H3O = 5.5Ã?10^â?'8 OH- = 8.0Ã?10^â?'4

### Moles of Aluminum, Sulfur and Oxygen Atoms

Calculate the number of moles of aluminum, sulfur, and oxygen atoms in 8.00 of aluminum sulfate, . Express the number of moles of Al, S, O, and atoms numerically, separated by commas. Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 8.40 of magnesium perchlorate, . Express the number of moles o

### Electrode Potentials: Example Questions

Hello, I am working on a lab and trying to verify my results with what the "expected" value should be. Please help me by answering the following question: Use standard electrode potentials to calculate the voltage of a cell using: a) Zn/Zn 2+ and Pb/Pb 2+ half cells. b) Zn/Zn 2+ and Cu/Cu 2+ half cells c) Cu/Cu 2+ a

### Calculate the standard emf for each of the following reactions

1. Calculate the standard emf for each of the following reactions: a)H2(g) + F2(g)---> 2H+(aq) + 2F-(aq) b)Cu(s) + Ba 2+(aq)---> Cu 2+(aq) + Ba(s) c)3Fe 2+(aq)---> Fe(s) + 2Fe 3+(aq) d)Hg2 2+(aq) + 2Cu+(aq)----> 2Hg(l) + 2Cu 2+(aq) 2. The standard reduction potential for the reduction of RuO4-(aq) to RuO4 2-(aq) is +0

### Determining Half-Life: Wait Time Before Performing Experiment

We are performing an experiment using half-life =4.5 x 10^3 days labeled phenylalanine in which the five atomic hydrogens are labeled.To perform the experiment, the initial activity cannot be lower than 10% of the initial activity when the sample was received. Calculate how long after receiving the sample can you wait before per

### Evaluating Receptor/Ligand Binding

3. Evaluating Receptor/Ligand Binding as a Reversible Mixed Second-Order Reaction The solutions for reversible binding between receptors and ligands to form complexes, R + L C, when ligand is in excess are: where the equilibrium dissociation constant and relaxation time are defined as and , respectively. a.

### Solubility of Ni(OH)2

Here is the question: Calculate the solubility of Ni(OH)2 in a) distilled water and b) at pH of 4.0. Justify your answer. I know I need to use a mass balance ans the reaction for disolution is Ni(OH)2 <------> Ni2+ + 2OH- The ksp for Ni(OH)2 is 6 x 10^-16

### pH and pOH

Here is the pH of each of the following: ? pH = log[H3O+] , pH + pOH = 14, [H3O+] * [OH-] = 1.0 X 10^-14 ? pH = -log(0.001) = 3 then... ? pOH = -log[OH-] = -log(0.001) = 3 ? pH = 14- pOH = 14 - 3 = 1 Could you show me a few of the steps between line one and two in both of these conclusions? thanks.

### Balancing equation to calculate correct number of moles

If CaC2 + 2 H2O --> C2H2 + Ca(OH)2 then, there are 65 grams of calcium carbide and 1.3 moles of calcium carbide and 1.3 moles of acetylene and 33.8 grams of acetylene. just want to make sure?

### Solubility of a Salt & "Salting In"

Solubility of a Salt & "Salting In" The solubility product of the sparingly-soluble salt Ag2S in water, at 25 C, represents the reaction: 2 Ag(s) + S(rh)  Ag2S(aq) where silver sulfide dissociates completely into silver and sulfide ions upon dissolution in water. Here S(rh) stands for rhombic crystalline solid su

### Water as a base

Is H2O always the base, for example in the following: SO4^2- + H2O --> HSO4^- + OH^- I said SO4^2- is the acid and H2O is the base for CH3COOH + H2O --> CH3COO^- + H3O^+ I said...CH3COOH is acid and again H2O is the base ?

### Partition coefficient in solvent extraction

Problem: Given that the partition coefficient for a solute is K in a water-ether solvent extraction system, is it more effective to do one extraction with V mL of ether or three extractions with V/3 mL of ether. Assume that the volume of water in the system to be V0 mL

### Determining Gas Pressure, Vapor Pressure, and Evaporation Rate

1. 75-100 words, explain in molecular terms, why the pressure of gas increases when the temperature increases. 2. 75-100 words, explain in molecular terms, whether the vapor pressure of gas varies with temperature. 3. 75-100 words, explain in molecular terms, whether evaporation rate of a liquid is constant or varied in th

### Bomb Calorimeter, gross heat of combustion

In the following experiment 1.1651g of benzoic acid (6318 cal/gm) produced a net corrected temperature rise of 3.047C, also 8 cm (2.3 cal/cm) of fuse wire were consumed in the firing. How does one go about to compute the gross heat of combustion, in cal/gram. Then using this standardization how does one find the gross heat of

### Proteins and enzymes

1- Write a brief paragraph that explains the buildup of proteins from amino acids to the final quaternary structure of the protein. 2-Describe how the structure of an enzyme is essential to its functioning. 3-What is the fundamental relationship between nucleic acids and protein synthesis? 4-ATP is the most common stor

### Precipitation Titration of Cobalt Chloride

LEASE NOTE: Titration requires several steps in order to obtain exact results. The procedures described in this lab assume that you have already done the TITRATION TUTORIAL and are familiar with the technique. 1. Take a 150 mL Erlenmeyer flask from the Glassware shelf and place it on the workbench. 2. Add 10 mL of cobalt c

### Lindemann-Hinshelwood Mechanism Sample Question

The reaction of CO and Cl2 consists of a series of steps as outlined below: Write an expression for d[COCl]/dt and write the overall reaction. Step rate constant Cl2 + M -> 2 Cl + M k1 2 Cl + M -> Cl2 + M k-1 Cl + CO + M -> COCl + M k2 COCl + M -> Cl

### Rate of Reaction for NO and Br2

The gas phase reaction 2 NO(g) + Br2(g) 2 NOBr(g) is second order in NO and first order in Br2. In a volume of 1.50 liters, 0.200 mol of NO and 0.0800 mol of Br2 were brought together, and the initial rate was found to be 5.67 x 10-4 mol. l-1 .s-1. a. Calculate the rate constant (including u

### Rate Law mechanism observed

The rate law for the Br—- catalyzed reaction Br- C6H5NH2 + HNO2 + H+ C6H5N2+ + 2H2O is observed to be rate = = k [H+][HNO2][Br -]. A proposed mechanism is k1 (1) H+ + HNO2 H2NO2+ (rapid equilibrium) k-1 k2 (2) H2NO2+ + Br-

### Debye Temperature for Crystalline Solids

Many crystalline solids have constant pressure molar heat capacities at low temperature that obey the Debye T3-Law, which is where R is the ideal gas constant and TD is a constant characteristic of the material known as the Debye temperature. This equatio

### Quant problems

1.In the laboratory you have prepared various reagents for your experiments. briefly describe the preparation of 3.00 L of 0.150 M H3PO4 from concentrated commercial reagent. This reagent if 86.0% H3PO4 and has a density of 1.84g/mL. The molar mass of H3PO4 is 97.995 g/mol 2. The following data were obtained for the determina

### Wet and dry basis sample questions

3. 10 kg of food at a moisture content of 320% dry basis is dried to 50% web basis. Calculate the amount of water removed. 4. A batch of 5 kg of food product has a moisture content of 150% dry basis. Calculate how much water must be removed from this product to reduce its moisture content to 20% wet basis. 5. A liquid prod

I am doing an experiment of absorption spectrophotometry for the analysis of zinc in commercial mouthwash. This experiment differs from others because I have to use the standard addition approach instead of calibration curves to take into account of the matrix effect. I have difficulty constructing a standard addition plot becau

### Isotopes decay

Isotopes decay according to first order kinetics with a predictable half life. Given 234Th → 234Pa with t1/2 = 24.10d and 234Pa → 234U with t1/2 = 6.69h. Graph the relative amounts of 234Th , 234Pa and 234U over time. (You may have to enhance the concentration of one of the components to see it on the graph.)

### Second order reaction

The reaction of CH3CH2NO2 + OH- --> H2O + CH3CHNO2 - is a second order and k at 273 K is 39.1 min-1mol-1 An aqueous solution is 0.004 molar in nitroethane and 0.005 molar in NaOH. How long will it take for 90% of the nitroethane to react?

### Determine the form of the rate law

The reaction between selenious acid and iodide ion in acidic solution is: H2SeO3 + 6I-+ 4 H+ --> Se(s) + 2I3- + 3H2O The initial reaction rates were measured at 273 K at a variety of concentrations, as indicated in the following table, in mol/L. These initial rates were evaluated from plots of H2SeO3 vs time. Determine the fo

### Calculating Molar Concentration and pH: Example Problem

Hey there. I am having trouble with this question. Calculate the molar concentration of OH- ions in a 0.550 M solution of hypobromite ion (BrO-; Kb=4.0 x 10^-6). What is the pH of this solution? Could you please show the work. And no power points please. Thanks in advance!

### Acid-Base Equilibria

Hey there. I am having trouble with this question. Calculate the percent ionization of propionic acid (C2H5COOH) in solutions of each of the following concentrations: a) 0.250 M b) 0.0800 M c) 0.0200 M ** Ka = 1.3 x 10 ^ -5 Could you please show the work. And no power points please. Thanks in advance!

### Calculating Ka Value for Acid: Example Question

Hey there. I am having trouble with this question. Phenylacetic acid (C6H5CH2COOH) is one of the substances that accumulates in the blood of people with phenylketonuria, and inherited disorder that can cause mental retardation or even death. A 0.085 M (mol/L) solution of C6H5CH2COOH has a pH of 2.68. Calculate the Ka value