Search found 72 matches
- Thu Mar 14, 2019 4:27 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Mechanisms
- Replies: 2
- Views: 296
Reaction Mechanisms
If given reaction mechanisms, can you tell whether the reaction is exothermic? If so, how?
- Thu Mar 14, 2019 11:52 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pseudo Equilibrium Constant
- Replies: 1
- Views: 227
Pseudo Equilibrium Constant
What is the purpose of calculating the pseudo equilibrium constant for a reaction profile?
- Thu Mar 14, 2019 9:16 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation
- Replies: 2
- Views: 487
Nernst Equation
There are two forms of the Nernst Equation given on the constants and formulas sheet. One is E(reaction) = E(standard) - (RT/nF)*lnQ and the other is E(reaction) = E(standard) - (0.05916V/n)*logQ. Can someone please explain what the difference is between these two forms of the equation and when you ...
- Tue Mar 12, 2019 12:58 pm
- Forum: Balancing Redox Reactions
- Topic: Problem 14.119- Sixth Edition
- Replies: 1
- Views: 241
Problem 14.119- Sixth Edition
One stage in the extraction of gold from rocks involves dissolving the metal from the rock with a basic solution of sodium cyanide that has been thoroughly aerated. This stage results in the formation of soluble Au(CN)2- ions. The next stage is to reduce gold to the metal by the addition of zinc dus...
- Sun Mar 10, 2019 10:07 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Mechanisms
- Replies: 2
- Views: 259
Reaction Mechanisms
Consider the conversion of C to D via a one-step mechanism. The activation energy of this conversion is 3 kcal/mol. The energy difference between D and the transition state of the reaction is 7 kcal.mol. Calculate delta H for the reaction C --> D. Could someone please explain how to do this problem?
- Thu Mar 07, 2019 12:11 am
- Forum: General Rate Laws
- Topic: Types of Rate Laws?
- Replies: 1
- Views: 194
Re: Types of Rate Laws?
An integrated rate law gives the concentration of reactants or products at any time after the start of the reaction. The instantaneous rate of the reaction is the slope of the tangent to the curve at a single instant. The average reaction rate in a particular interval is the change in molar concentr...
- Thu Mar 07, 2019 12:03 am
- Forum: Second Order Reactions
- Topic: graph for second order
- Replies: 7
- Views: 755
Re: graph for second order
If a plot of 1/[A] against time is a straight line with a positive slope of k, the reaction is second order.
- Wed Mar 06, 2019 11:49 pm
- Forum: General Rate Laws
- Topic: 15.3
- Replies: 2
- Views: 360
Re: 15.3
The rate of reaction of NO2 can be found by the change in concentration of NO2 divided by the change in time. We are given the initial and final concentrations of NO2 in the problem (450 mmol/L to 320 mmol/L) and the change in time (20s). Therefore, the rate of reaction of NO2 is -(320 mmol/L - 450 ...
- Tue Feb 26, 2019 5:16 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Problem 14.17- Sixth Edition
- Replies: 1
- Views: 396
Problem 14.17- Sixth Edition
a) Write balanced half-reactions for the redox reaction between sodium perchlorate and copper(I) nitrate in an acidic solution.
How do you know which one of these species is being reduced or oxidized and which one is at the cathode or anode? There is no indication in the problem.
How do you know which one of these species is being reduced or oxidized and which one is at the cathode or anode? There is no indication in the problem.
- Tue Feb 26, 2019 10:33 am
- Forum: Balancing Redox Reactions
- Topic: Standard Potential
- Replies: 2
- Views: 264
Re: Standard Potential
Eo is an intensive property (the voltage difference is the same and does not depend on how many times the reaction occurs). It stays the same when the half reaction is balanced. However, when one of the half reactions must be reversed, the sign of Eo changes.
- Tue Feb 26, 2019 10:19 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Problem 14.15- Sixth Edition
- Replies: 1
- Views: 205
Problem 14.15- Sixth Edition
Write the half-reactions, the balanced equation for the cell reaction, and the cell diagram for each of the following skeletal equations: Part c) Cd(s) + 2Ni(OH)3 (s) --> Cd(OH)2 (s) + 2Ni(OH)2 (s) The cell diagram in the answer key is the following: Cd (s) | Cd(OH)2 (s) | KOH (aq) || Ni(OH)3 (s) | ...
- Sat Feb 23, 2019 4:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating standard cell potentials
- Replies: 1
- Views: 1515
Calculating standard cell potentials
I thought that one of the half reactions must be reversed to form a redox reaction. Why is it that for a majority of the homework problems, the standard reduction potential for the anode, does not change signs when calculating the standard reduction potential for the cell? For example, for part a fo...
- Fri Feb 22, 2019 9:08 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Question 9.63
- Replies: 2
- Views: 324
Re: Question 9.63
You can determine which of the following compounds are stable with respect to decomposition into their elements by analyzing their standard free energies of formation. Compounds with a positive free energy of formation are unstable with respect to the elements. Since PCl5 (g) and SO2 (g) have negati...
- Fri Feb 22, 2019 9:02 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Problem 11.111-Sixth Edition
- Replies: 1
- Views: 260
Problem 11.111-Sixth Edition
A certain enzyme-catalyzed reaction in a biochemical cycle has an equilibrium constant that is 10 times the equilibrium constant of the next step in the cycle. If the standard Gibbs free energy of the first reaction is -200 kJ/mole, what is the standard Gibbs free energy of the second reaction? Can ...
- Thu Feb 21, 2019 2:20 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Problem 9.89-Sixth Edition
- Replies: 1
- Views: 416
Problem 9.89-Sixth Edition
Problem 9.89: Some entries for Sm in Appendix 2A are negative. What is common about these entries and why would the entropy be negative?
From what I see, the negative entries all correspond to aqueous ions. Why is this?
From what I see, the negative entries all correspond to aqueous ions. Why is this?
- Wed Feb 13, 2019 1:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Extensive vs Intensive Properties
- Replies: 2
- Views: 291
Extensive vs Intensive Properties
Are work and heat extensive or intensive properties?
- Wed Feb 13, 2019 8:53 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Cv and Cp
- Replies: 3
- Views: 373
Cv and Cp
Can someone please explain how we know to use Cp or Cv when calculating the entropy change for something that has a change in temperature? I know the problem should indicate constant pressure or constant volume but it doesn't always say so.
- Tue Feb 12, 2019 10:41 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Statistical and residual entropy
- Replies: 3
- Views: 357
Statistical and residual entropy
Can someone please explain what the difference is between statistical and residual entropy and if it is just dependent on the number of microstates?
- Wed Feb 06, 2019 9:32 am
- Forum: Calculating Work of Expansion
- Topic: Work
- Replies: 5
- Views: 449
Work
If a problem indicates constant volume in one way or another, do we always assume w=0?
- Wed Feb 06, 2019 9:27 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Irreversible/Reversible Processes
- Replies: 2
- Views: 266
Irreversible/Reversible Processes
Can someone please explain why isothermal, reversible processes do more work than their irreversible counterpart?
- Wed Feb 06, 2019 9:27 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Irreversible/Reversible Processes
- Replies: 3
- Views: 389
Irreversible/Reversible Processes
Can someone please explain why isothermal, reversible processes do more work than their irreversible counterpart?
- Wed Feb 06, 2019 9:19 am
- Forum: Phase Changes & Related Calculations
- Topic: C (gr) ?
- Replies: 2
- Views: 2181
Re: C (gr) ?
C(gr) represents carbon as graphite. Graphite is the most stable form of carbon at normal temperatures. The standard enthalpy of formation of an element in its most stable form is zero. For instance, the standard enthalpy of formation of C(gr) is zero because C(gr) --> C(gr) is a "null formatio...
- Tue Jan 29, 2019 4:13 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: What is the difference between delta H and q?
- Replies: 3
- Views: 1628
Re: What is the difference between delta H and q?
Enthalpy change (delta h) only applies to reactions done at constant pressure and it is the state of a system while it contains a certain amount of heat. Heat (q) is just the energy that causes those changes and is the energy transferred as a result of a temperature difference.
- Tue Jan 29, 2019 4:07 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeters
- Replies: 3
- Views: 361
Re: Calorimeters
I'm not sure if we need to use calorimeters in any calculations but I think we should just know that calorimeters measure transfers of energy as heat by recording the change in temperature produced by a process taking place within it. Bomb calorimeters are used to measure heat transfers at constant ...
- Tue Jan 29, 2019 4:02 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat and work
- Replies: 4
- Views: 457
Re: Heat and work
Heat, represented by q, is the transfer of energy as a result of a temperature difference. When energy enters a system as heat, q is positive. When energy leaves a system as heat, q is negative. The measurement of heat produced or absorbed by a process is used to monitor the delta U, or internal ene...
- Tue Jan 22, 2019 10:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp
- Replies: 3
- Views: 358
Kp
When calculating Kp, do the partial pressures have to be in either bar or atm?
- Mon Jan 21, 2019 9:31 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 4
- Views: 411
Re: Le Chatelier's Principle
Le Chatelier's Principle: When a stress is applied to a system in dynamic equilibrium, the equilibrium tends to adjust to minimize the effect of the stress.
- Sat Jan 19, 2019 2:41 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: #14 chem. equilibrium part 4 post-module assessment
- Replies: 2
- Views: 329
Re: #14 chem. equilibrium part 4 post-module assessment
The correct answer should be C. If the amount of NO2 is increased, the equlibrium will shift to the products, which will result in an increase in NO. If SO3 is removed by condensation, the equilibrium will shift to the products again, which will result in an increase in NO. If the pressure is triple...
- Sat Jan 19, 2019 2:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Problem 12.33 Sixth Edition
- Replies: 2
- Views: 320
Problem 12.33 Sixth Edition
A student added solid Na20 to a 200.0 mL volumetric flask, which was then filled with water, resulting in 200.0 mL of NaOH solution. 5.00 mL of the solution was then transferred to another volumetric flask and diluted to 500.0 mL. The pH of the diluted solution is 13.25. What is the concentration of...
- Sat Jan 19, 2019 2:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Chemical Equilibrium part 4 Post-module assessment
- Replies: 1
- Views: 251
Re: Chemical Equilibrium part 4 Post-module assessment
The correct answer should be C. If you increase the amount of carbon monoxide, the equilibrium will shift towards reactants since change in concentration of a chemical reaction at equilibrium represents a fixed P/R ratio. Therefore, more reactant will form until the original P/R ratio is attained (s...
- Wed Jan 16, 2019 10:53 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 11
- Views: 1509
Le Chatelier's Principle
What is the effect of increasing or decreasing the partial pressure of a reactant or product in a chemical reaction? How will we know which direction the reaction will shift?
- Wed Jan 16, 2019 10:41 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 4
- Views: 425
Re: Le Chatelier's Principle
Le Chatelier's principle suggests a good way of ensuring that a reaction goes on generating a substance: simply remove products as they are formed. In the continuing hunt for equilibrium, the reaction generates more product.
- Tue Jan 15, 2019 5:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Adding Equations
- Replies: 3
- Views: 390
Re: Adding Equations
Here is the rule based on the textbook: If a chemical equation can be expressed as the sum of two or more chemical equations: The equilibrium constant for the overall reaction is the product of the equilibrium constants for the component reactions. When you add the two reactions, Cl2 is present as a...
- Mon Jan 14, 2019 10:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pressure [ENDORSED]
- Replies: 2
- Views: 285
Re: Pressure [ENDORSED]
If the pressure of a reaction vessel is increased by adding an inert gas, then moles of reactant, product, and volume are constant. Therefore, there is no change in the reactant and product concentration and no effect on the reaction. Remember that an inert gas does not undergo chemical reactions un...
- Mon Jan 14, 2019 10:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th Edition 11.89
- Replies: 3
- Views: 241
Re: 6th Edition 11.89
Part b asks you to calculate the equilibrium constant for the reaction. The formula to calculate the equilibrium constant is as follows: K=(PB)*(PC)^2/(PA)^2 The partial pressures in the graph they give us are in kPA. To use the K formula, I believe you need to have the partial pressures in atm or b...
- Mon Jan 14, 2019 10:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th Edition 11.39
- Replies: 2
- Views: 194
Re: 6th Edition 11.39
Here is the rule based on the textbook: If a chemical equation can be expressed as the sum of two or more chemical equations: The equilibrium constant for the overall reaction is the product of the equilibrium constants for the component reactions. When you add the two reactions, Cl2 is present as a...
- Wed Jan 09, 2019 9:37 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Compostition vs Concentration for Equilibrium
- Replies: 2
- Views: 222
Re: Compostition vs Concentration for Equilibrium
According to the textbook, chemical equilibrium is defined as the stage in a chemical reaction when there is no further tendency for the composition of the reaction mixture— the concentrations or partial pressures of the reactants and products— to change. So I believe composition does refer to conce...
- Tue Jan 08, 2019 9:10 pm
- Forum: Ideal Gases
- Topic: Solid/Liquid in Reactions
- Replies: 4
- Views: 205
Re: Solid/Liquid in Reactions
Some reactions in solution involve the solvent as a reactant or product. When the solution is very dilute, the change in solvent concentration due to the reaction is insignificant so the solvent can be treated as a pure substance just like a solid. Also, the activity of a pure solid or liquid is 1 s...
- Tue Jan 08, 2019 9:04 pm
- Forum: Ideal Gases
- Topic: units in av focus topics
- Replies: 1
- Views: 221
Re: units in av focus topics
When calculating concentration in units of mol/m^3 and you are given a pressure in atm, a temperature in Kelvin, and an R value with units of m^3*atm/K*mol, you do not need to do any conversions because the units atm and K should cancel leaving you with a concentration in mol/m^3. Just plug in the R...
- Mon Jan 07, 2019 5:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th edition hw problem 11.7
- Replies: 3
- Views: 221
Re: 6th edition hw problem 11.7
You must count the number of diatomic molecules in each of the flasks. It goes from 11 to 8 to 5 to 5 from left to right. Since there was no change after the third flask, equilibrium is reached there.
- Wed Dec 05, 2018 9:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Structures
- Replies: 12
- Views: 1235
Bent Structures
Would it be appropriate to say that all bent or angular moleculars are polar? Because even if the atoms are the same (such as in ozone, O3), the molecule is still polar, or is ozone just a special case?
- Tue Nov 27, 2018 11:55 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing Power/Polarizability
- Replies: 2
- Views: 344
Polarizing Power/Polarizability
According to the textbook, ionic bonds acquire more covalent character as the distortion of the electron cloud on the anion increases. What exactly does this mean?
- Tue Nov 27, 2018 9:46 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Drawing a Dipole
- Replies: 6
- Views: 624
Re: Drawing a Dipole
Yes when drawinga dipole moment, arrows are used to show the polarity points from the positive areas to the negative areas. For example, in water, there is a higher electron density around the oxygen atom, giving it an overall negative charge and the hydrogen atoms overall positive charges. The arro...
- Mon Nov 26, 2018 3:59 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand
- Replies: 4
- Views: 409
Re: Ligand
Ligands are basically just the Lewis bases attached to the central metal atom or ion in a d-metal complex.
- Mon Nov 26, 2018 3:58 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordinate covalent bond
- Replies: 2
- Views: 218
Re: Coordinate covalent bond
Taken from the textbook, a coordination compound is an electrically neutral compound in which at least one of the ions present is a complex. A complex is a species consisting of a central metal atom or ion to which a number of molecules or ions are attached by coordinate covalent bonds.
- Mon Nov 26, 2018 1:47 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Polar Bonds
- Replies: 3
- Views: 1631
Re: Polar Bonds
A good example of a nonpolar molecule with polar bonds is CO2. The central carbon will have a net positive charge and the two outer electrons will have a net negative charge. Since the shape of the molecule is linear, these two bond dipoles will cancel each other and the overall molecule will have z...
- Mon Nov 26, 2018 1:39 pm
- Forum: Dipole Moments
- Topic: Dipole Moments
- Replies: 4
- Views: 342
Re: Dipole Moments
If dipole moments are equal and opposite of each other, they will cancel each other, which gives rise to a nonpolar molecule. Some completely non polar molecules can have polar individual bonds. If the dipole moments in a particular molecule do not cancel out, then you will have a polar molecule.
- Mon Nov 26, 2018 1:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole Moment
- Replies: 1
- Views: 210
Re: Dipole Moment
Bond dipole moment is used to measure the polarity of a chemical bond within a molecule. There is a dipole moment whenever there is a separation of positive and negative charges due to the unequal attraction that the two atoms have for the bonded electrons. The larger the difference in electronegati...
- Mon Nov 26, 2018 12:53 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 4
- Views: 734
Re: Polarizability
In general, an atom is more polarizable the larger it is and an atom has more polarizing power the smaller it is. Therefore, polarizability increases down a group because atomic size increases and larger electron clouds distort more easily. Polarizability would decrease across a period because of in...
- Mon Nov 26, 2018 12:40 pm
- Forum: Hybridization
- Topic: How to find hybridization orbitals 4.35
- Replies: 3
- Views: 351
Re: How to find hybridization orbitals 4.35
If this is for the 6th Edition, heres an example. For part a for Problem 4.35, you should have drawn a trigonal planar arrangement for the molecule BF3 with three lone pairs on each of the fluorines and three regions of electron density around the boron atom. This would give you a hybridization of s...
- Mon Nov 26, 2018 12:35 pm
- Forum: Hybridization
- Topic: Hybridization and Reactivity
- Replies: 2
- Views: 608
Re: Hybridization and Reactivity
Benzyne would be highly reactive because the two carbon atoms that are sp hybridized are constrained to have a very strained structure compared to what their hybridization would like to adopt (linear arrangment) with 180 degree angles at these C atoms. The formation of a diradical would allow the C ...
- Mon Nov 26, 2018 12:26 pm
- Forum: Hybridization
- Topic: Bonds
- Replies: 5
- Views: 431
Re: Bonds
There can only be one sigma bond between two atoms while there can be zero, one, or two pi bonds between two atoms. In general, sigma bonds determine the shape of a molecule whereas pi bonds make atoms move closer together.
- Sat Nov 10, 2018 12:02 pm
- Forum: Lewis Structures
- Topic: Lewis Structure
- Replies: 10
- Views: 809
Re: Lewis Structure
Remember exceptions to the octet rule. For example, Boron and Aluminum commonly fail to complete an octet and often form compounds in which they have 6 valence electrons. Remember which elements can have an expanded octet. The octet rule can be expanded by some elements by using the d orbitals found...
- Sat Nov 10, 2018 11:49 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability Vs. Polarizing Power
- Replies: 3
- Views: 665
Re: Polarizability Vs. Polarizing Power
A cation's polarizing power refers to its ability to attract valence electrons from a nearby anion and polarizability refers to the anion's tendency to become polarized by the cation. Small cations with high positive charges are said to have more polarizing power because the positive charge is distr...
- Sat Nov 10, 2018 11:25 am
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation
- Replies: 4
- Views: 785
Re: Shrodinger Equation
Schrodinger's wave function equation basically just uses a wave function to describe an electron in an atom. It uses the concept that an electron, with wavelike properties and indeterminacy in momentum and position, can be described by a mathematical wave function.
- Tue Oct 30, 2018 11:38 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity???
- Replies: 3
- Views: 422
Re: Electron Affinity???
Oxygen has a smaller atomic radius than sulfur so oxygen electrons experience more repulsions between each other since the valence shell is held closer to the nucleus. When an external electron is introduced, energy is released (electron affinity) but at the same time energy is consumed due to insta...
- Tue Oct 30, 2018 11:24 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Cu+ electron configuration
- Replies: 2
- Views: 2024
Re: Cu+ electron configuration
Cu+ would have a total of 28 electrons since you are losing one electron and Cu normally has 29 electrons. Argon is the nearest noble gas to Cu for the shorthand notation. Half filled and fully-filled orbitals are more symmetrical than any other configuration and symmetry leads to greater stability....
- Tue Oct 30, 2018 10:15 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electron Spin
- Replies: 3
- Views: 1096
Re: Electron Spin
The up arrow electron is positive 1/2 which indicates a counterclockwise spin and the down arrow electron is negative 1/2 which indicates a clockwise spin.
- Tue Oct 30, 2018 9:04 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electron Spin
- Replies: 3
- Views: 1096
Electron Spin
In regards to electron spin for unpaired electrons, how do we know if the electron is spinning clockwise or counterclockwise? Based on what I've seen in class, an unpaired electron has a counterclockwise spin with a magnetic spin quantum number of +1/2. Why is this so?
- Wed Oct 24, 2018 9:42 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Quantum World Worksheet #7
- Replies: 2
- Views: 367
Re: Quantum World Worksheet #7
The Rydberg equation is as follows: frequency = -R((1/n(initial)^2)-(1/n(final)^2)). If you have a negative sign in front of the Rydberg equation, the first n in the equation has to be the starting level. If there is no negative sign in front of the Rydberg equation, the second n will be the startin...
- Mon Oct 22, 2018 8:24 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Quantum World Worksheet #7
- Replies: 2
- Views: 367
Re: Quantum World Worksheet #7
I had the same issue. I ended up with n2 being approximately 3.2. Someone please advise thanks.
- Mon Oct 22, 2018 8:19 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Pauli Exclusion Principle
- Replies: 3
- Views: 429
Re: Pauli Exclusion Principle
In short, the Pauli Exclusion Principle states that in an atom or molecule, no two electrons can have the same four quantum numbers. Because an orbital can only contain a maximum of two electrons, the two electrons must have opposing spins. The two spin states of an electron can be represented as cl...
- Thu Oct 18, 2018 4:48 pm
- Forum: *Shrodinger Equation
- Topic: Schrodingers Equation and Probability Density
- Replies: 2
- Views: 349
Schrodingers Equation and Probability Density
Based on the textbook, psi squared is the probability density, which means that wherever psi squared is large, the particle has a high probability density and wherever psi squared is small, the particle has a low probability density. What do these statements mean qualitatively in relation to the wav...
- Tue Oct 16, 2018 10:36 pm
- Forum: *Black Body Radiation
- Topic: Stefan-Boltzmann law and Wien's law
- Replies: 2
- Views: 612
Re: Stefan-Boltzmann law and Wien's law
I don't think those two were covered on the Quantum World Outline, so we probably don't need to know those for Test Two next week.
- Tue Oct 16, 2018 10:32 pm
- Forum: *Black Body Radiation
- Topic: Question 1.21
- Replies: 5
- Views: 2314
Re: Question 1.21
For question 1.21, the correct answer should be (d) the photoelectric effect. The photoelectric effect best supports the idea that electromagnetic radiation has the properties of particles because electromagnetic radiation consists of particles (or packets) of energy called photons, each photon havi...
- Tue Oct 16, 2018 10:20 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: 1.11 Problem
- Replies: 3
- Views: 199
Re: 1.11 Problem
In each of these series, the principal quantum number for the lower energy level involved is the same for each absorption line. Thus, for the Lyman Series, the lower energy level is n=1; for the Balmer series, n=2; for the Paschen Series, n=3; and for the Brackett series, n=4.
- Tue Oct 09, 2018 1:41 pm
- Forum: Properties of Electrons
- Topic: Behavior of Electrons and Energy Levels
- Replies: 3
- Views: 194
Behavior of Electrons and Energy Levels
If electrons revolve around the nucleus of an atom due to electricity and magnetism, what type of path does an electron take when it absorbs energy and jumps from a ground state to an excited state? Does it jump in a straight line or more of a curved line from one lower energy level to one higher en...
- Mon Oct 08, 2018 9:39 pm
- Forum: Empirical & Molecular Formulas
- Topic: Determining Empirical and Molecular Formulas
- Replies: 2
- Views: 386
Determining Empirical and Molecular Formulas
We are asked to solve for the empirical or molecular formula of a more complex compound such as caffeine and given the molar mass and the amounts of each of its atoms in grams. After we finally solve for the molar ratios of each of the atoms for caffeine, how do we know what order in which the atoms...
- Mon Oct 08, 2018 9:34 pm
- Forum: Limiting Reactant Calculations
- Topic: Fundamentals Problem M.11
- Replies: 2
- Views: 346
Fundamentals Problem M.11
A reaction vessel contains 5.77g of white phosphorus and 5.77g of oxygen. The first reaction to take place is the formation of phosphorus (III) oxide, P4O6: P4 (s) + 3O2 (g) --> P4O6 (s). If enough oxygen is present, the oxygen can react further with this oxide to produce phosphorus (V) oxide, P4O10...
- Thu Oct 04, 2018 5:05 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity
- Replies: 3
- Views: 310
Re: Molarity
The molar concentration is called the "molarity" and its formally known as the "amount of substance concentration." We use moles of solute and the volume of the solution to find the concentration, or molarity of a solution. Moles of solute are used to find the molarity of a solut...
- Thu Oct 04, 2018 4:42 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Periodic Table and Molar Mass?
- Replies: 2
- Views: 194
Re: Periodic Table and Molar Mass?
I had a chem discussion this morning and my TA said the periodic table will be given on the tests given in discussion.
- Thu Oct 04, 2018 4:40 pm
- Forum: Empirical & Molecular Formulas
- Topic: Molecular Formulas
- Replies: 5
- Views: 964
Re: Molecular Formulas
For problem F9, they are specifically asking you "in what atom ratios are the atoms present in vanillin." They are simply asking for the empirical formula of vanillin. Since the molecular weight was not given, you cannot determine what the molecular formula is. Using the mass percentage co...