Search found 68 matches

by Henry_Phan_4L
Sun Mar 17, 2019 9:40 am
Forum: Balancing Redox Reactions
Topic: How to balance half reaction
Replies: 5
Views: 104

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.
by Henry_Phan_4L
Sun Mar 17, 2019 9:38 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: intermediate
Replies: 4
Views: 133

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.
by Henry_Phan_4L
Sun Mar 17, 2019 9:37 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E cell
Replies: 3
Views: 97

Re: E cell

Voltage usually isn't negative.
by Henry_Phan_4L
Sun Mar 10, 2019 6:02 pm
Forum: General Rate Laws
Topic: Rate constant k
Replies: 5
Views: 69

Re: Rate constant k

Think of it as the rate that the chemical reaction is going, in terms of time.
by Henry_Phan_4L
Sun Mar 10, 2019 6:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm average
Replies: 5
Views: 111

Re: Midterm average

It's either 80%, which is 96 points, or 80 points, which is 73%.
by Henry_Phan_4L
Sun Mar 10, 2019 5:58 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Chain Reaction
Replies: 1
Views: 30

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.
by Henry_Phan_4L
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: 55

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.
by Henry_Phan_4L
Sun Mar 03, 2019 12:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 7
Views: 135

Re: Test 2

So the one with better oxidizing power is the most positive one?
by Henry_Phan_4L
Mon Feb 25, 2019 1:19 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equations
Replies: 5
Views: 107

Re: Equations

You're welcome!
by Henry_Phan_4L
Mon Feb 25, 2019 1:18 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy for Equilibrium
Replies: 1
Views: 38

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?
by Henry_Phan_4L
Sat Feb 16, 2019 10:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium Constant and Gibbs Free Energy
Replies: 3
Views: 55

Re: Equilibrium Constant and Gibbs Free Energy

What is the difference between the delta G with the degree sign and the total G?
by Henry_Phan_4L
Sat Feb 16, 2019 10:45 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: First Law
Replies: 3
Views: 63

Re: First Law

Delta nRT is like a less accurate version of PV so it's not ideal to use it every time.
by Henry_Phan_4L
Sat Feb 16, 2019 10:40 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Pressure Equation
Replies: 7
Views: 179

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.
by Henry_Phan_4L
Sun Feb 10, 2019 11:27 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Gibbs free energy
Replies: 2
Views: 45

Re: Gibbs free energy

I think the main point of Gibbs free energy is to determine whether a reaction is spontaneous or not.
by Henry_Phan_4L
Sun Feb 10, 2019 11:24 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equations
Replies: 5
Views: 107

Re: Equations

https://www.youtube.com/watch?v=TnDCxw0y6YM The first 10 minutes gives a good explanation of the equations you need.
by Henry_Phan_4L
Thu Feb 07, 2019 1:18 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work on an adiabatic process?
Replies: 2
Views: 49

Work on an adiabatic process?

Can positive and negative work be done on an adiabatic system?
by Henry_Phan_4L
Sat Feb 02, 2019 7:02 pm
Forum: Phase Changes & Related Calculations
Topic: Negative work
Replies: 11
Views: 139

Negative work

Can negative work be done on a system? Does increasing the volume count as negative work?
by Henry_Phan_4L
Sat Feb 02, 2019 6:58 pm
Forum: Phase Changes & Related Calculations
Topic: Drawing a heating curve
Replies: 6
Views: 83

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??
by Henry_Phan_4L
Sat Feb 02, 2019 6:50 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: calorimeters
Replies: 7
Views: 102

Re: calorimeters

The energy of the reaction should be contained inside the bomb calorimeter.
by Henry_Phan_4L
Sun Jan 27, 2019 5:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE
Replies: 19
Views: 253

Re: ICE

Concentration at equilibrium, so you basically add I and C to get the expected concentration at eq
by Henry_Phan_4L
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: 101

Catalysts in Kc

Why doesn't a catalyst affect the equilibrium constant?
by Henry_Phan_4L
Sun Jan 27, 2019 5:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Lecture Slides
Replies: 5
Views: 98

Re: Lecture Slides

No
by Henry_Phan_4L
Wed Jan 23, 2019 5:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition, 12.69
Replies: 3
Views: 57

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...
by Henry_Phan_4L
Sun Jan 20, 2019 1:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion Section Test
Replies: 4
Views: 83

Re: Discussion Section Test

All of them should be short answer. They want to see you do the calculations.
by Henry_Phan_4L
Sun Jan 20, 2019 1:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Water in K
Replies: 3
Views: 70

Re: Water in K

Can water be in the form (aq) or does it only usually occur as a liquid or gas?
by Henry_Phan_4L
Sun Jan 20, 2019 1:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations Effect on K
Replies: 8
Views: 91

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?
by Henry_Phan_4L
Tue Jan 15, 2019 1:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp
Replies: 7
Views: 124

Re: Kp

you wouldn't need to convert, but make sure to keep all the units the same because Kp is a ratio.
by Henry_Phan_4L
Tue Jan 15, 2019 1:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature Relation
Replies: 3
Views: 56

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.
by Henry_Phan_4L
Tue Jan 15, 2019 1:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw
Replies: 2
Views: 51

Re: Kw

Kw is like [H3O+] and [-OH] combined, which equals 1.0 x 10-14
by Henry_Phan_4L
Tue Jan 15, 2019 1:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw
Replies: 2
Views: 48

Re: Kw

Could the pH be higher at a different temperature?
by Henry_Phan_4L
Tue Jan 15, 2019 1:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q vs. K
Replies: 5
Views: 83

Re: Q vs. K

Can Q fluctuate around K so that it could be higher at one point and lower at another point?
by Henry_Phan_4L
Tue Jan 15, 2019 1:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ksp
Replies: 2
Views: 48

Re: Ksp

Ksp is the degree at which a solid will dissolve in solution. We haven't talked about it in class yet.
by Henry_Phan_4L
Sun Dec 09, 2018 9:22 am
Forum: Naming
Topic: -ate in naming
Replies: 7
Views: 186

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.
by Henry_Phan_4L
Sun Dec 09, 2018 12:02 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: sig figs
Replies: 4
Views: 80

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.
by Henry_Phan_4L
Sun Dec 02, 2018 10:18 am
Forum: Bronsted Acids & Bases
Topic: Are Bronsted and Lewis acids the same thing?
Replies: 2
Views: 56

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?
by Henry_Phan_4L
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: 38

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.
by Henry_Phan_4L
Sun Dec 02, 2018 10:14 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Final pH
Replies: 3
Views: 54

Re: Final pH

pH and pOH are inversely related. The molal ratio of H30+ and -OH in solution is equal to 10^-14.
by Henry_Phan_4L
Thu Nov 22, 2018 11:44 am
Forum: Determining Molecular Shape (VSEPR)
Topic: I3- molecular shape
Replies: 2
Views: 57

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.
by Henry_Phan_4L
Thu Nov 22, 2018 11:39 am
Forum: Dipole Moments
Topic: Repulsion
Replies: 2
Views: 73

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.
by Henry_Phan_4L
Thu Nov 22, 2018 11:35 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw vs Tetrahedral Bipyramidal
Replies: 2
Views: 39

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.
by Henry_Phan_4L
Sun Nov 18, 2018 8:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar molecules
Replies: 2
Views: 65

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.
by Henry_Phan_4L
Sat Nov 17, 2018 10:42 pm
Forum: Ionic & Covalent Bonds
Topic: polar/nonpolar
Replies: 3
Views: 86

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.
by Henry_Phan_4L
Sat Nov 17, 2018 10:42 pm
Forum: Ionic & Covalent Bonds
Topic: polar/nonpolar
Replies: 3
Views: 86

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.
by Henry_Phan_4L
Sat Nov 17, 2018 10:28 pm
Forum: Hybridization
Topic: Electron promotion
Replies: 2
Views: 107

Re: Electron promotion

Do we need to know electron promotion for the test?
by Henry_Phan_4L
Sat Nov 10, 2018 9:42 pm
Forum: Bond Lengths & Energies
Topic: Energy of Intermolecular forces
Replies: 2
Views: 74

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.
by Henry_Phan_4L
Sat Nov 10, 2018 9:35 pm
Forum: Student Social/Study Group
Topic: Last Friday's Lecture
Replies: 4
Views: 147

Re: Last Friday's Lecture

Is there any way to access it without the textbook?
by Henry_Phan_4L
Fri Nov 09, 2018 2:57 pm
Forum: Bond Lengths & Energies
Topic: bond angles
Replies: 3
Views: 68

Re: bond angles

I think the bond angles just depend on the covalent bonds and lone pairs.
by Henry_Phan_4L
Sun Nov 04, 2018 1:30 am
Forum: Ionic & Covalent Bonds
Topic: determining bond strength
Replies: 3
Views: 92

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.
by Henry_Phan_4L
Sun Nov 04, 2018 1:27 am
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 4
Views: 91

Re: Drawing Lewis Structures

I think you should draw the possible resonance structures and put the double sided arrow in between them.
by Henry_Phan_4L
Sun Nov 04, 2018 1:26 am
Forum: Lewis Structures
Topic: Triangle Bond?
Replies: 2
Views: 36

Triangle Bond?

Can the oxygen atoms in O3 bind to each other in a triangle? Is this possible?
by Henry_Phan_4L
Sun Oct 28, 2018 8:57 am
Forum: *Shrodinger Equation
Topic: Threshold Energy
Replies: 4
Views: 227

Re: Threshold Energy

Schrodinger's equation doesn't have anything to do with the photoelectric effect. Therefore, threshold energy would not be used.
by Henry_Phan_4L
Sun Oct 28, 2018 8:54 am
Forum: Properties of Electrons
Topic: Degeneracy
Replies: 11
Views: 367

Re: Degeneracy

Would the degeneracy be the same as the quantum number l then?
by Henry_Phan_4L
Sun Oct 28, 2018 8:52 am
Forum: Lewis Structures
Topic: Periodic Table Trends
Replies: 5
Views: 93

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.
by Henry_Phan_4L
Sun Oct 21, 2018 8:02 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: H-Atom Equation
Replies: 2
Views: 57

Re: H-Atom Equation

The jump in energy is negative, so the negative sign cancels it out.
by Henry_Phan_4L
Sun Oct 21, 2018 7:48 pm
Forum: Einstein Equation
Topic: Energy of photon [ENDORSED]
Replies: 12
Views: 416

Re: Energy of photon [ENDORSED]

Chem_Mod wrote:Yes, E = hv or E = hc/.



How did you get that second equation?
by Henry_Phan_4L
Tue Oct 16, 2018 11:15 pm
Forum: Properties of Light
Topic: Expected to know?
Replies: 6
Views: 130

Re: Expected to know?

Yes, but generally you should know that the visible light spectrum is 300 to 700 nm.
by Henry_Phan_4L
Sun Oct 14, 2018 8:49 pm
Forum: Photoelectric Effect
Topic: SI Unit for Work Function
Replies: 4
Views: 159

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?
by Henry_Phan_4L
Sat Oct 13, 2018 3:00 pm
Forum: Properties of Light
Topic: Frequency Equations
Replies: 2
Views: 51

Re: Frequency Equations

You might be talking about the equation that combines E=hv with c=λv. Substitute v to get E=hc/λ.
by Henry_Phan_4L
Sat Oct 13, 2018 2:58 pm
Forum: Photoelectric Effect
Topic: Properties of Light
Replies: 5
Views: 98

Re: Properties of Light

Energy is higher when the wavelength is smaller or the frequency is higher.
by Henry_Phan_4L
Sat Oct 13, 2018 2:56 pm
Forum: Limiting Reactant Calculations
Topic: Test 1
Replies: 5
Views: 284

Re: Test 1

Do we get our homework back too? I'd like it back so I can review.
by Henry_Phan_4L
Sat Oct 13, 2018 2:54 pm
Forum: Properties of Light
Topic: light frequency
Replies: 3
Views: 49

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.
by Henry_Phan_4L
Fri Oct 05, 2018 4:09 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 91
Views: 8926

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?
by Henry_Phan_4L
Fri Oct 05, 2018 4:02 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: MOLARITY
Replies: 13
Views: 450

Re: MOLARITY

Molarity is moles of solute in liters of solution. The unit for molarity is mol/L.
by Henry_Phan_4L
Fri Oct 05, 2018 4:01 pm
Forum: Empirical & Molecular Formulas
Topic: When finding empirical formula
Replies: 4
Views: 122

Re: When finding empirical formula

Find the percent composition and then convert to moles.
by Henry_Phan_4L
Wed Oct 03, 2018 2:55 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles and Atomic Masses/Weights
Replies: 4
Views: 119

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...

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