Explore BrainMass

Physical Chemistry

Physical Chemistry is the examination of physical laws and concepts as they apply to predominantly the macroscopic and supra-molecular levels of chemical systems. Although it focuses on the macroscopic level, as most physical laws describe properties related to the bulk, Physical Chemistry also delves into atomic and subatomic properties. Physical Chemistry applies principles of physics, such as energy, thermodynamics and motion to chemical systems, in order to study and understand chemical substances. For example, Gas Laws have been developed to describe the behavior of different gases under different conditions of pressure, volume and temperature. Such relationships have been examined under independent physical laws, such as Boyle’s Law, Charles’ Law, Avogadro’s law; and they have also been combined to form the ideal gas law, which uses multi-variable analysis to predict the behavior of a particular gas. Principles such as energy and motion can also be applied at the atomic and sub-atomic levels. For example, the holistic behavior of radioactive substances may be considered, along with its atomic and sub-atomic behavior. Thus, although many of the topics in Physical Chemistry overlap with topics in the other branches of Chemistry, it focuses more on the physical properties of chemical substances, describing and examining how specific substances behave under different physical contexts.

Categories within Physical Chemistry

Chemical Kinetics

Postings: 191

Chemical kinetics is the study of the rates of chemical reactions.

Work and Energy for a Heat System

Please work the following practice problem. Being very thorough. Explain how you intend to approach the problem, important information and or equations that are relevant to solve/understand the thought process. Consider a situation in which the surroundings heat a system and the system contains a gas which expands against a

Mathematical Relations for Coefficient of Performance

This page shows efficiency of a carnot engine. The refrigerator uses the same process only it run backwards. By using the same recipe as in the link above I want a mathematical derivation of the coefficient of performance of a refrigerator. A little additional informati

Physical Science: Temperature, Climate, and Renewable Resources

1. Explain how the temperature difference between the poles and the equator drives the motion of the oceans and atmosphere. 2. What are the differences between ice caps and glaciers? 3. How do ocean currents affect local climate? 4. Why do we call groundwater in most areas a "nonrenewable resource"? 5. What is the Gulf Strea

1.0 M solution of a strong acid, HA

Are the following statements about a 1.0 M solution of a strong acid, HA, true or false? [A-] › [H+]: True/False The pH is 0.00: True/False [H+] = 1.0 M: True/False [HA] = 1.0 M: True/False From the given solubility data given, calculate the value of Ksp for the following compounds. SrF2; 7.3 x 10-2 g/L Ag3PO4; 6.7 x

Calculating Pressures using different laws

Converting between Units of Pressure Part A: Convert 0.700atm of pressure to its equivalent in millimeters of mercury. Express the pressure numerically in millimeters of mercury Part B The Pressure in car tires is often measured in pounds per square inch (lb/in2) with the recommended pressure being in the range of 25 to

Order of a reaction

Consider a kinetic study of oxidation of a new plastic stabiliser being proposed for the automobile industry. Stabiliser + H+ + O2 ----> Byproduct Trial [ Stabiliser] [H+] [O2] Rate (M min^-1) 1 0.40 0.30 0.560 7.14 x 10^ -4 2 1.20 0.30

Calculating Delta H

Use some or all of the following reaction enthalpies to calculate delta H for the reaction: 3NH3(aq) + ClO- (aq) --> N2H4(g) + NH4+ (aq) + Cl- (aq) + OH- (aq) Cl- (aq) + H2O2(l) --> H2O(l) + ClO- (aq) delta H = - 6.5kJ/mol N2(g) + 3H2(g)--> 2NH3(g) delta H = -160.6kJ/mol H2O(l) + 1/2 N

Nernst Equation

You are titrating 100.0 mL of 0.0400 M Fe^2+ in 1 M HClO_4 to give Fe^3+ and Ce^3+ using Pt and calomel electrodes to find the endpoint. a) Write the balanced titration reaction. Ce^4++Fe^2+ Ce^3++Fe^3+ Complete the two half reactions for the Pt electrode. Ce^4+ + e^- Ce^3+ + e^-

Standard potentials measured against the standard hydrogen electrode

Standard potentials are measured against the standard hydrogen electrode (S.H.E.). Because it is not always convenient to use a S.H.E., often other reference electrodes are used. The saturated calomel electrode (S.C.E.) is one commonly used reference electrode, with a potential of 0.242 V versus the S.H.E. Using a table of stand

Ionic strength

Question 1 Determine the ionic strength, μ, for each of the following solutions. Assume complete dissociation of each salt and ignore any hydrolysis reactions. a) A solution of 0.00556 M FeSO3 b) A solution of 0.00282 M CuCl2 c) A solution of 0.000853 M CaBr2 and 0.000509 M La(NO3)3 Question 2 Part 1 What happens t

Thermochemistry and Periodic Properties of Elements

1. State which atom is larger according to periodic trends. Explain the difference for each of the pairs. a) Br, F b) Ca, Mg c) C, Si d) He, Ar 2. State which atom has a smaller first ionization energy according to periodic trends. Explain the difference in ionization energy for the pairs. a) O, S b) K, Na c) Cd, Zn d

Net Ionic Equations and Balancing

I'm not sure what it is about this stuff that confuses me but I can't seem to get this stuff to stick. Detailed work would be kindly appreciated. Write balanced molecular, ionic and net ionic equations for the following: 1. Mg(OH)2 (aq) + HCL (aq) --> MgCl2 (aq) + H20 (l) 2. K2(C2O4) (aq) + CaCl2 (aq) --> KCL (aq) CA(C2O4)

Standard Temperature and Pressure of Chlorine

Chlorine is widely used to purify municipal water supplies and to treat swimming pool waters. Suppose that the volume of a particular sample of Cl2 gas is 8.70 L at 895 torr and 240C. 1) How many grams of chlorine are in the sample? 2) What volume will the chlorine occupy at Standard Temperature and Pressure (STP)? 3) At wh

Combustion Analysis of Toluene

Combustion analysis of toluene, a compound containing carbon and hydrogen only, gives 5.86 mg carbon dioxide and 1.37 mg of water. What is its empirical formula? Menthol is composed of carbon, hydrogen and oxygen. A 1.005 g sample is combusted, producing 0.2829 g carbon dioxide and 0.1159 g of water. If the molar mass of ment

Chemistry: Change in Temperature in the Production of Silver Chloride

When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl-(aq) ?AgCl(s) deltaH = -65.5 kJ Calculate deltaH for the production of 0.200 mol of AgCl by this reaction. Calculate deltaH for the production of 2.50 g of AgCl. Calculate deltaH when 1.500 mmol of AgCl dissolves

Stoichiometry Help Needed

I once again am stuck on some problems in this chapter. While there is many more I don't get these six I think would help me with the others I'm stuck on. Would highly appreciate very detailed work shown so I can understand the process and apply to other questions of like nature. 1. Using the the following equation: 2 NAOH +

Chemical Reactions and Stoichiometry Problems

Please assist with answering the following questions. I'd love to be able to see a step to step process for solving these, that way when I come across problems similar to this in the future and then, I don't get lost again. 1. 2Mn02 + 4KOH + O2 + CL2 ---> 2KMnO4 + 2KCL + 2H2O For the reaction above, there is 100.0 g of each

Solid State Chemistry - Density, Absorption, Charge

1.) FREE CARRIER DENSITY Chemical analysis of a germanium crystal reveals indium at a level of 0.0003091 atomic percent. Assuming that the concentration of thermally excited charge carriers from the Ge matrix is negligible, what is the density of free charge carriers (free carriers/cm3) in this Ge crystal? 2.) BORON DOPING D

Calculating Rate Constant using Hard-Sphere Theory

I have a problem I am unable to figure out, I keep using the hard-theory formula for "A" to get the rate constant, however the value I get seems way to small every time I try to do it. Can someone please help me with this problem? I posting the homework set its problem number 5, I keep getting (4.28x10^-29dm3/mol s) as "k" pleas

Solid State Chemistry Questions

Hello. I need some help with the following. Can you please help? Please check the file attached. 1.) Of the molecules below, select those that are paramagnetic. It may be useful to draw a molecular orbital energy diagram and to fill in the electrons for each molecule. Li2 B2 N2 CN− O−2 O2−2 2.) Give the bond ord

Containers of Water Diluted

Please see the attachment for a visual depiction of the containers. Please calculate the dilution factors for all five containers and show all the work. Thanks! Five containers of water, numbered 1 to 5, are placed in a line: Container #1 contains 5 ml of water. Container #2 contains 1 ml of water. Container #3 contains

Rate limiting steps in metal oxide epitaxy

On the bottom right-hand side of the third page of the pdf attached (page 2 of the article), the author states: "Metal deposition rates are easily converted into the oxide growth rate under the assumption that the metal arrival rates are the rate limiting steps, which is true for growth under oxygen- rich conditions." I am

Dilution Factors & Serial Dilution

Seven test ubes each containing 4.5 ml of water are lined up. 0.5 ml of yeast culture is pipetted in to test tube #1 . Then 0.5 ml of the solution form test tube #1 is pipetted into test tube #2. Then 0.5 ml of the solution for test tube #2 is pipetted into test tube # 3 and so on until 0.5 ml of the solution from test tube #

Thermodynamic Calculations for Ideal Gases

One mole of an ideal gas a 273.15 K is allowed to expand isothermally from 10.0 MPa to 1.00 MPa. Make a table to show your answers for the following questions. (Show your work - the subscript m indicates the value per mole.) - View attached document to see questions a)-d).

Working with Temperature and Gas

1. What is the final temperature if 25 mL of milk 3.0 degrees Celsius is mixed with 150 mL of coffee at 95 degrees Celsius? Start by writing the equation that shows conservation of energy. State any assumptions you make. 2. If the temperature is raised sufficiently high, proteins, DNA, and RNA will actually begin to unfo

Dilution and Colony-Forming Units

Ten grams of hamburger were added to 90 mL of sterile buffer. This was mixed well in a blender. One-tenth of a mL of this slurry was added to 9.9 mL of sterile buffer. After thorough mixing, this suspension was further diluted by successive 1/100 and 1/10 dilutions. One-tenth of a mL of this final dilution was plated onto Plate

Change in volume: scuba diving

When scuba diving, it is important to come back to the surface of the water from deep dives slowly. If this does not happen, then the diver can get the ?bends?. Determine the amounts of N2 and O2 dissolved in 7.5 L of blood at 298 K at a depth of 100.0 feet below the surface of the water. What is the total volume of dissolved ai