Share
Explore BrainMass

General Chemistry

Calculate the Change in Enthalpy for the Reaction

1- Calculate the change in enthalpy for the reaction. (Use 1.0g/mL as the density of the solution and 4.18J/g⋅ ∘ C as the specific heat capacity.)? Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the a

Solving various thermodynamics questions

1 - The air in an inflated balloon (defined as the system) is warmed over a toaster and absorbs 130J of heat. As it expands, it does 76kJ of work. What is the change in internal energy for the system? 2 - A piston has an external pressure of 8.00 atm. How much work has been done in joules if the cylinder goes from a volume o

Calculating the Mass of the Reaction and the Concentration

For the reaction shown, calculate how many moles of NO 2 form when each amount of reactant completely reacts. 2N 2 O 5 (g)→4NO 2 (g)+O 2 (g) 2.0mol N 2 O 5 6.4mol N 2 O 5 10.0g N 2 O 5 1.50kg N 2 O 5 For each reaction, calculate the mass (in grams) of the product formed when 10.1g of the underlined react

Calculating Delta H, S, and G

Use the data sheet to calculate Delta H, Delta S and Delta G at 25 degrees Celsius for each of the following reactions. In each case show that Delta G- Delta H-T Delta S. 1. Ni(s) + Cl2(g) --> NiCl2(s) 2. CaCO3(s, calcite) --> CaO(s) + CO2(g) 3. 2CH2OH(l) + 3O2(g) --> 2CO2(g) + 4H2O(l) Please see the attached docu

Polarity, bond dissociation energy of molecules

Detailed answers & explanations would be great. If hand written please do not write in cursive for I have trouble reading it. 1. Using Lewis (electron-dot) structures, explain why the ClF3 molecule is polar and the BF3 molecule is not polar. 2. For the following questions refer to the following diatomic species. (A) Li2

Colligative Properties-non-calibrated thermometer

Suppose your thermometer read consistently 1.0 o C lowered throughout both parts in the colligative properties lab. What effect would that have on your experimental value for the molar mass of your unknown solute? -no effect -higher molar mass -lower molar mass If the freezing point of the mixture had been incorrectly

Freezing Points colligative properties

Arrange the following in order of increasing freezing points ( from lowest to highest temperature ) : 0.20 m glucose, 0.20 m NaCl, 0.40 m BaCl2 and 0.4 0 m AlCl3 Which one of the following will have the lowest freezing point ? -0.1 m BaCl2 -0.1 m glucose -0.2 m Na 3PO4 -0.3 m NaCl

Iridium atom radius

The very dense metal iridium has a face-centered cubic unit cell and a density of 22.56 g/cm3. Use this information to calculate the radius of an atom of the element. Please provide detailed explanation. Thanks!

How to Determine the Frequency of an Interacting Photon

What is the best and easy way to determine the frequency (in hz) of the interacting photon. Here are the conditions: A photon interacts with a ground state electron in a hydrogen atom and is absorbed. The electron is ejected from the atom and exhibits a de Broglie wavelength of 4.548 x 10^10 m.

Predicting Binding Energies

Predict the order for increasing binding energies of the C(1s) electron for the following compounds giving your reasoning. CF4, CH4, CH2Br2, CH2Cl2, CHCl3, CH3Br, CH3I Some electronegativity values that you may find useful: Hydrogen: 2.1 Fluorine: 3.9 Chlorine: 3.0 Bromine: 2.8 Iodine: 2.5

Nuclear Chemistry Questions

Please provide some assistance with a few practice nuclear chemistry questions. I have attached two files, one with the questions and the other with a figure which is needed for some of the questions.

Original Sample of Nuclides, etc.

Please see the attachment for the questions, which are chemistry questions related to finding a compound's half-life, balancing equations, etc. Please show the steps involved with solving these problems.

Chemistry: Bonds and Molecules

Hi, I need some assistance answering the following questions: 1. Use the concept of resonance to explain why all six C-C bonds in benzene are equal in length. 2. Do you expect the O-O bond in H2O2 to be longer or shorter than the O-O bond in O2? 3. Consider the nitryl cation, NO2+ - Are resonance structures needed to descr

Seeing a Lightbulb and the Attraction of an Electron to a Nucleus

We can draw an analogy between the attraction of an electron to a nucleus and seeing a lightbulb-in essence, the more nuclear charge the electron "sees," the greater the attraction. 1. Within this analogy, discuss how the shielding by core electrons is analogous to putting a frosted-glass lampshade between the lightbulb and you

A Balloon as a Barometer and Thermometer

You have a balloon that is not permeable to gas molecules. The balloon is spherical and has a circumference of 3.141592654 m when it is filled with a gas at 20 EC and 1.0000 atm pressure. Explain how this could be used as a barometer and a thermometer, not necessarily using the same balloon, and then determine the circumference

Moseley and Atom Property

What property of the atom did Moseley associate with the wavelength of X-rays emitted from an element in his experiments? In what ways did Moseley's discovery affect the meaning of the periodic table? Please explain in detail.

Moles and Molecules

Sulfur trioxide is made industrially in large quantities by combining oxygen and sulfur dioxide, SO2. What amount in moles is represented by 1.00 kg of sulfur trioxide? How many molecules of sulfur trioxide in 1.00 kg sulfur trioxide? Please explain in detail. Thanks!

Atomic Mass and Ionic & Covalent Bonding

1) Explain why the atomic mass of an atom is a decimal number and how that value was determined before being placed on the periodic table. 2) How are ionic and covalent bonding similar? How are they different? You should discuss how they bond and what the major differences are in their nomenclature (the way they are named).

Chemistry Study Questions

1. What scientific principle or law is used in the process of balancing chemical equations? 2. In balancing equations, why should you not change subscripts in chemical formulas? 3. Define the terms limiting reactant and excess reactant. 4. Why are the amounts of products formed in a reaction determined only by the amount of

Chemistry: Assessing a Planet.

2. You are the Science Officer on the Starship Enterprise© and you come across a new planet. You find that no light with wavelength less than about 650 nm reaches the surface of the planet. Assuming that the biochemistry of the plants on this planet is essentially identical to that on the planet Earth, what color will the pla

Softened and Hard Water

Many people have what has been called hard water. Water is classified as being hard because of the amounts of ions, mainly of calcium, magnesium, and iron, that it contains. Hard water will not allow for soap suds to form easily and usually will leave deposits on surfaces such as bathtubs. To make the water "soft" (that is remov

Sorting into Isoelectronic Groups

Question: Sort these species into isoelectronic groups. It doesn't matter which group goes in which box, so long as the correct species are grouped. He, Li+, O^2-, Rb+, Se^2-, F-, Be^2+, Y^3, Mg^2+ HINT: Use a periodic table to determine the atomic number of the atom. For example, xenon's atomic number is 54. A neut

Neutral Atoms Electron Configurations

1. Which of the following electron configurations of neutral atoms represent excited stats? __ (Ar)4s^2 3d^3 __ 2s^2 __ (Kr)5s^14d^5 __ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^2 __ (Xe)6s^2 4f 2. Which neutral atoms have the following electron configurations. Name the symbol. ___________________ (Ar)4s^2 3d

Electron Configuration Pictorial Representation

Write the corresponding electron configuration for the following pictorial representation. Give the full electron configuration. Name the element, assuming that the configuration describes a neutral atom. HINT: Checklist: •Be sure to format your answer correctly, using lowercase letters and superscripted numbers whe

Measuring Electrostatic Potential Energy

Two particles with charges q1 and q2 are separated by distance d. Rank these scenarios according to the magnitude of the electrostatic (coulombic) potential energy. Ignore sign. Scenario 1: q1 = +4 q2 = -4 d = 4 A Scenario 2: q1 = +1 q2 = -1 d = 1 A Scenario 3: q1 = +1 q2 = -1 d = 3 A

Calculate the atomic weight of rubidium

Rubidium has two naturally occurring isotopes with the following masses and natural abundances: Isotope Mass Abundance Rb-86 85.9118 72.15 Rb-87 86.9092 27.85 Calculate the atomic weight of rubidium. Please explain in details.

Sodium Atoms and Configurations

See the attached file. Consider the Na atom. Although the ground state of Na atom has one and only one corresponding electron configuration, other electron configurations are certainly possible for Na atom; they correspond to higher-lying excited electronic states. The table below gives some of the possible electron configura

Hamiltonian and electron configuration

What is the Born-Oppenheimer electronic Hamiltonian for the H_2^+ cation (atomic units only)? Write down the electron configurations for C2 and F2. What is the bond order for each? Which one is likely to have larger bond dissociation energy? Which one is likely to have a longer bond length?

Spatial Orbitals and Electron States

In terms of one-electron integrals h and two-electron integrals J and K over spatial orbitals, what is the Hartree-Fock energy of the Be atom? For the purposes of this problem, label your one- and two-electron integrals using subscripts corresponding to the relevant orbitals (i.e., write your answer in terms h_1s,? h?_2s,J_(1s