Search found 59 matches
- Fri Mar 15, 2019 11:59 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Using log in Nernst Equation
- Replies: 1
- Views: 324
Using log in Nernst Equation
Why do must you include 2.303 when using log in the Nernst equation?
- Fri Mar 15, 2019 11:47 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Microscopic Reversibilty
- Replies: 1
- Views: 210
Microscopic Reversibilty
I'm still confused about what microscopic reversibility is and when this type reversibility is applied?
- Fri Mar 15, 2019 11:43 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: applying Le Chatelier's Principle
- Replies: 4
- Views: 761
applying Le Chatelier's Principle
On the first midterm, for the first question part how do you know/ prove that the shift in the reaction is forward?
- Sun Mar 10, 2019 12:18 am
- Forum: General Science Questions
- Topic: Discussion Section Test
- Replies: 3
- Views: 610
Re: Discussion Section Test
The reason why delta G>0 would be wrong is that during photosynthesis a plant uses light energy from the sun and carbon dioxide plus water to convert it into glucose and oxygen. This means that glucose is a product of the chemical reaction that is occurring, therefore, being exergonic.
- Sun Mar 10, 2019 12:05 am
- Forum: General Rate Laws
- Topic: reaction process
- Replies: 1
- Views: 231
reaction process
How can you tell difference between a reaction being slow or fast?
- Wed Mar 06, 2019 11:20 am
- Forum: Van't Hoff Equation
- Topic: Temp Units
- Replies: 11
- Views: 1316
Re: Temp Units
I believe you would K units for temperature.
- Sun Mar 03, 2019 7:36 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: n and k
- Replies: 3
- Views: 403
Re: n and k
N is needed because it gives insight into the reaction mechanism of the reactant. K is needed because the rate constant that depends on the temperature and activation energy.
- Sun Mar 03, 2019 7:30 pm
- Forum: Student Social/Study Group
- Topic: Week 8
- Replies: 2
- Views: 533
Re: Week 8
Monday- Nernst equation ( using log, the presence of H+ or pH), Concentration cell using Nernst equation Wednesday- applications of electron transfer reactions( ion-selective electrodes), electrolysis, Kinetics, Kinetic analysis, reaction rate, average rate, instantaneous rate Friday- unique rate, i...
- Sun Mar 03, 2019 7:21 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Cell diagram
- Replies: 4
- Views: 460
Re: Cell diagram
Cell diagrams are used to write the redox reaction of the physical set up of the cell. It consists of a salt bridge represents by two lines (II) and one line (I) to represent the interface between phases in contact with each other. The anodes are on the left of the salt bridge while the cathode is o...
- Sun Feb 24, 2019 8:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: equilibruim based on enthalpy
- Replies: 3
- Views: 382
equilibruim based on enthalpy
How can you determine the shift in the equilibrium of a chemical reaction when only given the change of enthalpy of the reaction?
- Sun Feb 24, 2019 8:06 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Free Energy is a state function?
- Replies: 5
- Views: 605
Re: Free Energy is a state function?
To add on, state functions are able to be added and subtracted which is how Gibbs energy is obtained between enthalpy, entropy and temperature values. State functions are also independent on the path taken to obtain that state.
- Sun Feb 24, 2019 7:54 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation and Reduction?
- Replies: 6
- Views: 803
Re: Oxidation and Reduction?
Oxidation means the loss of electron. Reduction is the gain of an electron.
- Sun Feb 17, 2019 5:21 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Enthalpy
- Replies: 4
- Views: 648
Enthalpy
Why does the magnitude in the change in entropy depend on temperature when heat is transferred?
- Sun Feb 17, 2019 5:16 pm
- Forum: Calculating Work of Expansion
- Topic: work
- Replies: 2
- Views: 309
work
Just a verification for work equations:
We would use W=-Pdelta V when pressure is constant and W=-nRTln(V2/V1) when pressure is not constant?
We would use W=-Pdelta V when pressure is constant and W=-nRTln(V2/V1) when pressure is not constant?
- Sun Feb 17, 2019 4:51 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Temperature
- Replies: 2
- Views: 255
Temperature
Based on the temperature a reaction has, how can one know if reaction being favored is forward or reverse?
- Sun Feb 10, 2019 10:42 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Degeneracy
- Replies: 3
- Views: 579
Re: Degeneracy
Degeneracy (w) is the number of ways of achieving a given energy state. The relationship shared between entropy and degeneracy is the Boltzmann's equation- S= kB ln W. The way degeneracy would be calculated is W=2^N in which N represents the particles that can be found in one of two states. When con...
- Sun Feb 10, 2019 10:33 pm
- Forum: Calculating Work of Expansion
- Topic: Work Formula Involving Integral
- Replies: 3
- Views: 302
Re: Work Formula Involving Integral
In a way it could be considered to be a form of obtaining w=-P times delta V; however, this equation is used to during an irreversible pathway which is temperature (T) changes along a pathway decrease then increase work done against constant Pex. The integral form of obtaining work done in a system ...
- Sun Feb 10, 2019 10:13 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat as path function
- Replies: 3
- Views: 420
Re: Heat as path function
State property is not dependent on a path is taken to obtain that state. This means that the state property can either be added or subtracted. In this case, heat cannot be considered a state function because heat and work depend on a path to reach work and heat.
- Sun Feb 03, 2019 11:17 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Hess's Law depends on enthalpy as a state function
- Replies: 3
- Views: 1030
Re: Hess's Law depends on enthalpy as a state function
Remember that state properties do not depend on a path taken to obtain that state and they can also be added or subtracted. Therefore changes in enthalpy (Hess's Law) are additive like a state function. In addition, enthalpy change at each step of a multi-step reaction can be additive to give the to...
- Sun Feb 03, 2019 11:07 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: intensive vs extensive properties
- Replies: 2
- Views: 295
intensive vs extensive properties
What are the differences between intensive and extensive properties?
- Sun Feb 03, 2019 11:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: RXN constant P
- Replies: 2
- Views: 305
RXN constant P
When is the rxn constant P significant and insignificant? Why is knowing its significance important?
- Sun Jan 27, 2019 9:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Properites
- Replies: 7
- Views: 606
State Properites
Why are work and heat not considered a state property?
- Sun Jan 27, 2019 9:16 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard reaction enthalpy
- Replies: 2
- Views: 241
Standard reaction enthalpy
How can the standard reaction enthalpy be calculated if the bond enthalpies are not provided in the problem?
- Sun Jan 27, 2019 9:06 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: closed vs isolated
- Replies: 14
- Views: 1004
Re: closed vs isolated
A closed system only allows for the exchange of energy in the system. On the other hand, an isolated system does not allow the exchange of energy or matter in the system.
- Sun Jan 20, 2019 10:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: The pH of Solutions of Weak Acids and Bases 12.73
- Replies: 1
- Views: 472
Re: The pH of Solutions of Weak Acids and Bases 12.73
The pH of the solution can be found by first finding the equilibrium the conjugate acid of the weak base and finding its Ka and Kb. From there an ICE table can be created in order to find the concentrations based on the concentrations that were provided by the problem. You could then find the Ka by ...
- Sun Jan 20, 2019 10:37 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: 6th Edition 12.39
- Replies: 1
- Views: 411
Re: 6th Edition 12.39
The same values of the molecules can be used because in order to find the Ka you would be able to use the equation Ka +Kb= 1x10^-14 since the Kb value has been provided. This would also be applied if the Ka were to be provided in order to find the Kb.
- Sun Jan 20, 2019 10:10 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5% rule
- Replies: 12
- Views: 21333
5% rule
How does the 5% rule work? How do we know it should be used when calculating an equilibrium?
- Sun Jan 13, 2019 7:28 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Quotient Meaning
- Replies: 2
- Views: 211
Re: Reaction Quotient Meaning
The reaction Q comes into play when the direction in which the reaction will proceed (left or right) and is used when comparing it to the equilibrium constant, K. If Q<k, the reactant proceeds forward to the product side. If Q>k, then it is a reverse reaction and favors the reactant side of the equa...
- Sun Jan 13, 2019 7:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 7th edition 5I.3
- Replies: 2
- Views: 255
Re: 7th edition 5I.3
I believe that the reactants for this problem would be H2 and I2 and the product would be HI. In addition, you can assume H2 is a reactant that is what the problem is asking to find the concentration for and the concentration for I2 has been provided.
- Sun Jan 13, 2019 7:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Tables
- Replies: 3
- Views: 297
ICE Tables
When adding the x variable to the changing concentration is the reactant side always going to add a negative x (-x) and the products side added a positive x (+x)? Are there special cases when this is not the case?
- Mon Jun 04, 2018 9:29 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal charge
- Replies: 5
- Views: 656
Re: Formal charge
Bonds are always counted as one electron, never as two electrons. If a single bond is present there is one election. In the presence of a double bond, there are two electrons If a triple bond is present there are three electrons.
- Mon Jun 04, 2018 9:24 pm
- Forum: Ideal Gases
- Topic: Memorization
- Replies: 12
- Views: 1192
Re: Memorization
I believe you do not have to because it is provided in the constant and equation page during a test but it wouldn't hurt to know it.
- Fri Jun 01, 2018 12:13 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: regions of e- density
- Replies: 4
- Views: 480
Re: regions of e- density
I believe the different regions of electron density do correspond to different molecular shapes because it was said in class that different hybridizations describe shapes. I this would connect to your question because the regions of electron density= number of hybrid orbitals. Hope it helped.
- Fri Jun 01, 2018 12:03 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar and non polar
- Replies: 3
- Views: 335
Polar and non polar
I understand that a polar molecule must have polar bonds with dipoles that do not cancel. I also understand that a nonpolar molecule must have zero an electric dipole moment which is possible if it contains non-polar bonds. My question is how can you identify the difference and determine whether a m...
- Thu May 31, 2018 11:46 pm
- Forum: Hybridization
- Topic: hybridization
- Replies: 2
- Views: 580
hybridization
Can someone explain how hybridization works? How can a hybridized molecule be determined and the orbitals assigned to it as well? For example, NH3( ammonia).
- Wed May 23, 2018 1:15 am
- Forum: Lewis Structures
- Topic: H Formal Charge
- Replies: 4
- Views: 480
Re: H Formal Charge
Hydrogen does not have a formal charge because it is a stable atom. It only has one electron in its shell. When taking the formal charge it would be:
V-(L+1/2B)
1-(0+1/2*2)=1-1=0
The zero indicates a neutral charge.
V-(L+1/2B)
1-(0+1/2*2)=1-1=0
The zero indicates a neutral charge.
- Mon May 21, 2018 11:20 pm
- Forum: Lewis Structures
- Topic: 3.41 part c
- Replies: 4
- Views: 565
Re: 3.41 part c
You would start the structure with NH2 followed by H2C and COOH. The central atoms in the Lewis structure would be Nitrogen, Carbon, and Oxygen.
- Mon May 21, 2018 11:12 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Order
- Replies: 4
- Views: 610
Re: Bond Order
In class, it was mentioned the strength of a bond is measured by its dissociation energy which is the energy required to break the bonds. It ranges between a single, double or triple bond. The single bond is the longest and weakest while the triple bond is the shortest and strongest. For example, N2...
- Thu May 17, 2018 11:26 pm
- Forum: Lewis Structures
- Topic: Identifying radicals [ENDORSED]
- Replies: 4
- Views: 2473
Identifying radicals [ENDORSED]
I know that radical is an atom, molecule, or ion that has unpaired electron but I still have difficulty identifying the radical. Can someone explain how to identify a radical? For example, problem 3.55 part (B)-CH3
- Thu May 17, 2018 11:13 pm
- Forum: Ionic & Covalent Bonds
- Topic: Help on 3.21
- Replies: 2
- Views: 270
Re: Help on 3.21
For part C the ground state configuration for Te2- is [Xe] with no unpair electron. For part D the ground state configuration for Ag+ is [Kr]4d10 with no unpaired electrons are well.
- Thu May 17, 2018 11:07 pm
- Forum: Electronegativity
- Topic: Connection
- Replies: 3
- Views: 532
Re: Connection
Electronegativity and polarity are connected through the bonds made between atoms. The greater difference in electronegativity between the atoms the more polar the bond is going to be.
- Thu May 17, 2018 10:57 pm
- Forum: Lewis Structures
- Topic: Test #3
- Replies: 11
- Views: 1318
Re: Test #3
I think it will cover everything we have learned after to test #2 up to what we are currently learning. So I would assume it is all of chapter 3.
- Mon May 07, 2018 11:18 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Module Question #17
- Replies: 4
- Views: 538
Re: Module Question #17
You are starting the problem correctly by multiplying the speed of light to the mass of an electron to 1/100; however, your uncertainty in momentum is not 3x10^6. The uncertainty in momentum is actually 2.731 x 10^-24 which is the mistake is made. From there like you mentioned, you would divide the ...
- Mon May 07, 2018 10:44 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: homework week 6
- Replies: 3
- Views: 507
Re: homework week 6
I would assume from chapter 3 because that is what we learned started last Wednesday and what we learned today is from that chapter but I think we could also include chapter 2 because it helps review for the midterm.
- Mon May 07, 2018 12:06 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Homework problem 2.93
- Replies: 2
- Views: 384
Re: Homework problem 2.93
You are correct in the concept that cations are smaller than there parent element and anions are bigger than their parent element. You may have read the solution incorrectly as the correct answer mentioned in the textbook is A= Cl, B= Na, C= Cl- and D=Na+.
- Thu May 03, 2018 11:13 pm
- Forum: Ionic & Covalent Bonds
- Topic: Help on 2.43
- Replies: 3
- Views: 404
Re: Help on 2.43
The ground-state configuration of the elements is the last noble gas of the row above it with the electron configuration. So the elements configuration for a,b, and d would be
silver- [Kr]4d^10 5s
beryllium-[He]2s^2
gallium-[Ar]3d^10 4s^2 4p
silver- [Kr]4d^10 5s
beryllium-[He]2s^2
gallium-[Ar]3d^10 4s^2 4p
- Tue May 01, 2018 5:15 pm
- Forum: Balancing Chemical Reactions
- Topic: Why didn't we take into account charges
- Replies: 4
- Views: 435
Re: Why didn't we take into account charges
We don't take into consideration the electron charge of the elements because when they put with another element they balance each other. For example, water uses hydrogen and oxygen. hydrogen has a +1 charge while oxygen has a -2 charge with is why it water requires two hydrogens to satisfy oxygens o...
- Sun Apr 29, 2018 5:21 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s orbital lower in energy than 3d
- Replies: 3
- Views: 1435
Re: 4s orbital lower in energy than 3d
The 3d state is higher in energy than the 4s state for potassium and calcium because Z(atomic number) is equal to 20. In addition, the d-electron are higher in energy than the p-electron on the same shell which results in higher energy than s-electron of the same shell too.
- Sun Apr 29, 2018 5:05 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: HW 2.31 [ENDORSED]
- Replies: 5
- Views: 696
Re: HW 2.31 [ENDORSED]
the subshells 2d and 4g do not exist because there is not an element to be assigned to in that subshell. The d-block of subshells is for transition metals and begin at 3d. The 4g could simply not be possible because the subshells on the periodic table go up to the f-block. The 4d and 6f subshells ca...
- Tue Apr 24, 2018 3:59 pm
- Forum: Einstein Equation
- Topic: converting from keV to joules
- Replies: 7
- Views: 838
Re: converting from keV to joules
I think we don't because it was one of the conversions located in the front of test one.
- Tue Apr 24, 2018 3:34 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Homework Question 1.11
- Replies: 1
- Views: 193
Re: Homework Question 1.11
The textbook mentions that the series consists of the lines of the spectrum that show its lowest energy level. For the Balmer series its lowest energy level is n=2 as the Lyman series the lowest energy level would be n=1. For the Paschen series the lowest energy level would be n=3 and for the Bracke...
- Sun Apr 22, 2018 10:19 pm
- Forum: Balancing Chemical Reactions
- Topic: Q4
- Replies: 3
- Views: 553
Re: Q4
when you are writing a combustion equation you will always add O2 to the reactant part of the equation because the product will be CO2 and H2O.
So in writing the combustion equation of fluorene, it would be: C13H10+O2----> CO2+H2O. You then have to balance the equation to make it side equal.
So in writing the combustion equation of fluorene, it would be: C13H10+O2----> CO2+H2O. You then have to balance the equation to make it side equal.
- Fri Apr 20, 2018 12:46 am
- Forum: General Science Questions
- Topic: Test #2 [ENDORSED]
- Replies: 6
- Views: 881
Re: Test #2 [ENDORSED]
The problems are from chapter one: 3,5,7,9,11,13,15,21,23,25,27,33,37,39,41.
- Sat Apr 14, 2018 9:30 pm
- Forum: Properties of Light
- Topic: wavelength description [ENDORSED]
- Replies: 11
- Views: 1183
Re: wavelength description [ENDORSED]
From what I understood during the lecture the amplitude of a wavelength represents its height.
- Thu Apr 12, 2018 1:42 am
- Forum: Limiting Reactant Calculations
- Topic: M1 hw
- Replies: 3
- Views: 365
Re: M1 hw
The molar mass 31.038 of 2NH3 would not be used because the 2 in 2NH3 serves as stoichiometric coefficient being used to balanced the equation as a whole. The molar mass 17.031 would be the one being used because it is the molar mass if ammonia (NH3) and would be used to find the moles of NH3 to the...
- Mon Apr 09, 2018 12:38 pm
- Forum: Significant Figures
- Topic: Sig fig simple question [ENDORSED]
- Replies: 5
- Views: 618
Re: Sig fig simple question [ENDORSED]
yes this is correct
- Sat Apr 07, 2018 9:38 pm
- Forum: Empirical & Molecular Formulas
- Topic: Finding the molecular formula [ENDORSED]
- Replies: 5
- Views: 658
Finding the molecular formula [ENDORSED]
After finding the empirical formula of a molecule, would you use the molar mass of the empirical formula to find the molecular formula of a molecule?
- Sat Apr 07, 2018 8:22 pm
- Forum: SI Units, Unit Conversions
- Topic: writing out conversions in one long line vs. steps
- Replies: 16
- Views: 1394
Re: writing out conversions in one long line vs. steps
I find more convenient to write the conversion in one long line because it is easier for me to see the conversion between the units. It's also easier for me to see the units that needed to be canceled.
- Sat Apr 07, 2018 8:02 pm
- Forum: SI Units, Unit Conversions
- Topic: Units + their meanings
- Replies: 3
- Views: 433
Re: Units + their meanings
The unit for moles is "mol". In addition, the unit g/mol signifies mass per mole of a particle which is what defines molar mass.