Search found 68 matches
- Sun Mar 17, 2019 9:40 am
- Forum: Balancing Redox Reactions
- Topic: How to balance half reaction
- Replies: 5
- Views: 805
Re: How to balance half reaction
You can add H2O to the side that needs more oxygens, then add double OH- along with it and add double the H2O to the other side.
- Sun Mar 17, 2019 9:38 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: intermediate
- Replies: 26
- Views: 1941
Re: intermediate
The intermediate can't exist in the rate law because something was used to form it. So since it came from something, you gotta trace it back to the original components.
- Sun Mar 17, 2019 9:37 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: E cell
- Replies: 3
- Views: 614
Re: E cell
Voltage usually isn't negative.
- Sun Mar 10, 2019 6:02 pm
- Forum: General Rate Laws
- Topic: Rate constant k
- Replies: 5
- Views: 570
Re: Rate constant k
Think of it as the rate that the chemical reaction is going, in terms of time.
- Sun Mar 10, 2019 6:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm average
- Replies: 5
- Views: 626
Re: Midterm average
It's either 80%, which is 96 points, or 80 points, which is 73%.
- Sun Mar 10, 2019 5:58 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Chain Reaction
- Replies: 1
- Views: 225
Re: Chain Reaction
It's pretty simple. The propagation phase describes the 'chain' part of chain reactions. Once a reactive free radical is generated, it can react with stable molecules to form new free radicals. ... Propagation steps often involve hydrogen abstraction or addition of the radical to double bonds.
- Sun Mar 03, 2019 1:00 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Why do we use concentration cells?
- Replies: 2
- Views: 423
Re: Why do we use concentration cells?
I think a galvanic cell has a potential of any voltage, while the concentration cell has a voltage of 0 at stp.
- Sun Mar 03, 2019 12:56 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Why does reaction free energy depend on pressure and the equal constant?
- Replies: 3
- Views: 440
Re: Why does reaction free energy depend on pressure and the equal constant?
Could the reaction happen faster at a higher temperature?
- Sun Mar 03, 2019 12:54 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 7
- Views: 784
Re: Test 2
So the one with better oxidizing power is the most positive one?
- Mon Feb 25, 2019 1:25 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Order of redox reaction in a galvanic cell
- Replies: 1
- Views: 244
Order of redox reaction in a galvanic cell
Does reaction order matter in a galvanic cell?
- Mon Feb 25, 2019 1:19 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Equations
- Replies: 5
- Views: 658
Re: Equations
You're welcome!
- Mon Feb 25, 2019 1:18 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy for Equilibrium
- Replies: 1
- Views: 245
Gibbs Free Energy for Equilibrium
I am confused as to whether the change in Gibbs free energy for a reaction at equilibrium is 0 or -RTln(K). And if it is the latter, how can a reaction at equilibrium have a change in energy?
- Sat Feb 16, 2019 10:47 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Equilibrium Constant and Gibbs Free Energy
- Replies: 3
- Views: 396
Re: Equilibrium Constant and Gibbs Free Energy
What is the difference between the delta G with the degree sign and the total G?
- Sat Feb 16, 2019 10:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: First Law
- Replies: 3
- Views: 393
Re: First Law
Delta nRT is like a less accurate version of PV so it's not ideal to use it every time.
- Sat Feb 16, 2019 10:40 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pressure Equation
- Replies: 7
- Views: 786
Re: Pressure Equation
Use it when they give you a change in pressure that isn't from a volume change. For example they would say that a cylinder is filled with an ideal gas which increases its pressure from 1 to 10 atm.
- Sun Feb 10, 2019 11:27 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Gibbs free energy
- Replies: 2
- Views: 304
Re: Gibbs free energy
I think the main point of Gibbs free energy is to determine whether a reaction is spontaneous or not.
- Sun Feb 10, 2019 11:24 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Equations
- Replies: 5
- Views: 658
Re: Equations
https://www.youtube.com/watch?v=TnDCxw0y6YM The first 10 minutes gives a good explanation of the equations you need.
- Thu Feb 07, 2019 1:18 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work on an adiabatic process?
- Replies: 2
- Views: 303
Work on an adiabatic process?
Can positive and negative work be done on an adiabatic system?
- Sat Feb 02, 2019 7:02 pm
- Forum: Phase Changes & Related Calculations
- Topic: Negative work
- Replies: 11
- Views: 1014
Negative work
Can negative work be done on a system? Does increasing the volume count as negative work?
- Sat Feb 02, 2019 6:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Drawing a heating curve
- Replies: 6
- Views: 1083
Drawing a heating curve
How do you know how steep to make the slopes in a heating curve and how long/short to make the lines??
- Sat Feb 02, 2019 6:50 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: calorimeters
- Replies: 7
- Views: 605
Re: calorimeters
The energy of the reaction should be contained inside the bomb calorimeter.
- Sun Jan 27, 2019 5:54 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE
- Replies: 19
- Views: 1424
Re: ICE
Concentration at equilibrium, so you basically add I and C to get the expected concentration at eq
- Sun Jan 27, 2019 5:52 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Catalysts in Kc
- Replies: 6
- Views: 675
Catalysts in Kc
Why doesn't a catalyst affect the equilibrium constant?
- Sun Jan 27, 2019 5:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lecture Slides
- Replies: 5
- Views: 462
- Wed Jan 23, 2019 5:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th edition, 12.69
- Replies: 3
- Views: 363
Re: 6th edition, 12.69
So the first step is to take off a Cl from the compound, because it's an ionic compound and ionic compounds fully dissociate. So for NH 4 Cl, it would turn into NH 4 + . Then do the chemical equation if you added H 2 O to the ion. The products should be NH 3 and H 3 O + . From there you can do an IC...
- Sun Jan 20, 2019 1:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion Section Test
- Replies: 4
- Views: 469
Re: Discussion Section Test
All of them should be short answer. They want to see you do the calculations.
- Sun Jan 20, 2019 1:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Water in K
- Replies: 3
- Views: 335
Re: Water in K
Can water be in the form (aq) or does it only usually occur as a liquid or gas?
- Sun Jan 20, 2019 1:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentrations Effect on K
- Replies: 8
- Views: 516
Re: Concentrations Effect on K
What if there are two products from one reactant? Wouldn't the products then be doubled if you added .100 mol of substance of each?
- Tue Jan 15, 2019 1:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp
- Replies: 7
- Views: 675
Re: Kp
you wouldn't need to convert, but make sure to keep all the units the same because Kp is a ratio.
- Tue Jan 15, 2019 1:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Temperature Relation
- Replies: 3
- Views: 309
Re: Temperature Relation
Basically when temperature is manipulated, you can add or remove heat from the system. Usually a reaction takes energy to occur, so increasing the energy makes it easier for the forward reaction to happen.
- Tue Jan 15, 2019 1:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw
- Replies: 2
- Views: 220
Re: Kw
Kw is like [H3O+] and [-OH] combined, which equals 1.0 x 10-14
- Tue Jan 15, 2019 1:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw
- Replies: 2
- Views: 218
Re: Kw
Could the pH be higher at a different temperature?
- Tue Jan 15, 2019 1:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q vs. K
- Replies: 5
- Views: 476
Re: Q vs. K
Can Q fluctuate around K so that it could be higher at one point and lower at another point?
- Tue Jan 15, 2019 1:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ksp
- Replies: 2
- Views: 177
Re: Ksp
Ksp is the degree at which a solid will dissolve in solution. We haven't talked about it in class yet.
- Sun Dec 09, 2018 9:50 am
- Forum: Administrative Questions and Class Announcements
- Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
- Replies: 118
- Views: 20799
Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Finally it makes sense thank you!
- Sun Dec 09, 2018 9:22 am
- Forum: Naming
- Topic: -ate in naming
- Replies: 7
- Views: 1632
Re: -ate in naming
If it's a coordination compound that overall is neutral, but the complex is negative you add -ate to the end. More specifically, you replace the ending of the metal name with -ate.
- Sun Dec 09, 2018 12:02 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: sig figs
- Replies: 4
- Views: 502
Re: sig figs
Based on my understanding it's roughly the same as what the problem gives. So if the concentration was 4.20 x 10^-6 mol then the pH would be 5.38.
- Sun Dec 02, 2018 10:18 am
- Forum: Bronsted Acids & Bases
- Topic: Are Bronsted and Lewis acids the same thing?
- Replies: 2
- Views: 584
Are Bronsted and Lewis acids the same thing?
Are Bronsted and Lewis acids the same thing just with different names? Would H2SO4 be considered a Bronsted acid and a Lewis acid?
- Sun Dec 02, 2018 10:16 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sig Figs for pH and pOH calculations
- Replies: 1
- Views: 205
Re: Sig Figs for pH and pOH calculations
Yeah I think you should use the sig figs for whatever you get as the concentration before you log it.
- Sun Dec 02, 2018 10:14 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Final pH
- Replies: 3
- Views: 334
Re: Final pH
pH and pOH are inversely related. The molal ratio of H30+ and -OH in solution is equal to 10^-14.
- Thu Nov 22, 2018 11:44 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: I3- molecular shape
- Replies: 2
- Views: 362
Re: I3- molecular shape
Is it three iodine atoms or an iodine ion with -3 charge?
I think the molecule would be bent because there are lone pairs on the middle iodine atom.
I think the molecule would be bent because there are lone pairs on the middle iodine atom.
- Thu Nov 22, 2018 11:39 am
- Forum: Dipole Moments
- Topic: Repulsion
- Replies: 2
- Views: 291
Re: Repulsion
I think it depends on valence electrons and bonding, but if you're talking about molecular structures then it is because electron clouds carry a negative charge, so they want to be as far away from each other as possible, like two magnets repelling each other.
- Thu Nov 22, 2018 11:35 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw vs Tetrahedral Bipyramidal
- Replies: 2
- Views: 843
Re: Seesaw vs Tetrahedral Bipyramidal
Basically one lone pair takes the place of the atom in the middle trigonal planar arrangement. The name is determined by the atoms, so the electrons do the same thing but aren't considered when naming the molecule.
- Sun Nov 18, 2018 8:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polar molecules
- Replies: 2
- Views: 291
Re: polar molecules
The molecule can't be nonpolar because the one lone pair exhibits a different pull on the structure, so the three other atoms in the trigonal pyramidal structure pull away in the other direction.
- Sat Nov 17, 2018 10:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: polar/nonpolar
- Replies: 3
- Views: 355
Re: polar/nonpolar
Isomers are polar when the vectors of charge are stronger on one side. The molecules with the largest dipole moment are the ones that have the greatest difference in electronegativity.
- Sat Nov 17, 2018 10:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: polar/nonpolar
- Replies: 3
- Views: 355
Re: polar/nonpolar
Isomers are polar when the vectors of charge are stronger on one side. The molecules with the largest dipole moment are the ones that have the greatest difference in electronegativity.
- Sat Nov 17, 2018 10:28 pm
- Forum: Hybridization
- Topic: Electron promotion
- Replies: 2
- Views: 341
Re: Electron promotion
Do we need to know electron promotion for the test?
- Sat Nov 10, 2018 9:42 pm
- Forum: Bond Lengths & Energies
- Topic: Energy of Intermolecular forces
- Replies: 2
- Views: 319
Re: Energy of Intermolecular forces
I think the energy is relative to the molecule. It doesn't have a sign in the book because it takes 250 kJ/mol of outside energy to break a bond.
- Sat Nov 10, 2018 9:35 pm
- Forum: Student Social/Study Group
- Topic: Last Friday's Lecture
- Replies: 4
- Views: 419
Re: Last Friday's Lecture
Is there any way to access it without the textbook?
- Fri Nov 09, 2018 2:57 pm
- Forum: Bond Lengths & Energies
- Topic: bond angles
- Replies: 3
- Views: 410
Re: bond angles
I think the bond angles just depend on the covalent bonds and lone pairs.
- Sun Nov 04, 2018 1:30 am
- Forum: Ionic & Covalent Bonds
- Topic: determining bond strength
- Replies: 3
- Views: 399
Re: determining bond strength
You have to compare the electromagnetivity between the two atoms. The difference tells you what kind of bond it is, and a higher difference means a stronger bond. Ionic bonds would have the strongest bonds, and hydrogen bonds would be the weakest.
- Sun Nov 04, 2018 1:27 am
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 4
- Views: 345
Re: Drawing Lewis Structures
I think you should draw the possible resonance structures and put the double sided arrow in between them.
- Sun Nov 04, 2018 1:26 am
- Forum: Lewis Structures
- Topic: Triangle Bond?
- Replies: 2
- Views: 413
Triangle Bond?
Can the oxygen atoms in O3 bind to each other in a triangle? Is this possible?
- Sun Oct 28, 2018 8:57 am
- Forum: *Shrodinger Equation
- Topic: Threshold Energy
- Replies: 4
- Views: 729
Re: Threshold Energy
Schrodinger's equation doesn't have anything to do with the photoelectric effect. Therefore, threshold energy would not be used.
- Sun Oct 28, 2018 8:54 am
- Forum: Properties of Electrons
- Topic: Degeneracy
- Replies: 11
- Views: 1213
Re: Degeneracy
Would the degeneracy be the same as the quantum number l then?
- Sun Oct 28, 2018 8:52 am
- Forum: Lewis Structures
- Topic: Periodic Table Trends
- Replies: 5
- Views: 436
Re: Periodic Table Trends
They're not the same. Electronegativity is how strongly an atom will pull electrons. Electron affinity is the energy released when an atom gains an electron.
- Sun Oct 21, 2018 8:02 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: H-Atom Equation
- Replies: 2
- Views: 314
Re: H-Atom Equation
The jump in energy is negative, so the negative sign cancels it out.
- Sun Oct 21, 2018 7:48 pm
- Forum: Einstein Equation
- Topic: Energy of photon [ENDORSED]
- Replies: 12
- Views: 1778
Re: Energy of photon [ENDORSED]
Chem_Mod wrote:Yes, E = hv or E = hc/.
How did you get that second equation?
- Tue Oct 16, 2018 11:15 pm
- Forum: Properties of Light
- Topic: Expected to know?
- Replies: 6
- Views: 653
Re: Expected to know?
Yes, but generally you should know that the visible light spectrum is 300 to 700 nm.
- Sun Oct 14, 2018 8:49 pm
- Forum: Photoelectric Effect
- Topic: SI Unit for Work Function
- Replies: 4
- Views: 1757
SI Unit for Work Function
In the Photoelectric Effect Module, the work function is given as kJ/mol. Can I use that or is that the wrong units?
- Sat Oct 13, 2018 3:00 pm
- Forum: Properties of Light
- Topic: Frequency Equations
- Replies: 2
- Views: 139
Re: Frequency Equations
You might be talking about the equation that combines E=hv with c=λv. Substitute v to get E=hc/λ.
- Sat Oct 13, 2018 2:58 pm
- Forum: Photoelectric Effect
- Topic: Properties of Light
- Replies: 5
- Views: 328
Re: Properties of Light
Energy is higher when the wavelength is smaller or the frequency is higher.
- Sat Oct 13, 2018 2:56 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1
- Replies: 5
- Views: 747
Re: Test 1
Do we get our homework back too? I'd like it back so I can review.
- Sat Oct 13, 2018 2:54 pm
- Forum: Properties of Light
- Topic: light frequency
- Replies: 3
- Views: 151
Re: light frequency
It takes more energy to move remove an electron from a lower energy level, since physically the electrons are closer to the nucleus.
- Fri Oct 05, 2018 4:09 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 33534
Re: All students read this sig fig post [ENDORSED]
How many sig figs do we need to use from a periodic table? Is the tenths place ok?
- Fri Oct 05, 2018 4:02 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: MOLARITY
- Replies: 17
- Views: 2051
Re: MOLARITY
Molarity is moles of solute in liters of solution. The unit for molarity is mol/L.
- Fri Oct 05, 2018 4:01 pm
- Forum: Empirical & Molecular Formulas
- Topic: When finding empirical formula
- Replies: 4
- Views: 471
Re: When finding empirical formula
Find the percent composition and then convert to moles.
- Wed Oct 03, 2018 2:55 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Moles and Atomic Masses/Weights
- Replies: 4
- Views: 420
Re: Moles and Atomic Masses/Weights
The problem with the whole thing is that scientists used 12.000 grams of carbon (diamond) to figure out how many atoms were in a mole. Grams are the best standard that we have, so scientists used that as a baseline measurement. Professor Caram said that scientists are currently trying to use a spher...