Search found 92 matches

by Nathan Tran 4K
Sun Mar 17, 2019 1:15 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Heat Capacity Intensive or Extensive?
Replies: 1
Views: 115

Heat Capacity Intensive or Extensive?

I've seen some chem mods say it is intensive and others say it is extensive. I believe it is extensive because it is not standardized to grams or moles and as such depends on how much "stuff" there is. Is this wrong?
by Nathan Tran 4K
Sat Mar 16, 2019 12:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: What is a porous disk?
Replies: 3
Views: 41

What is a porous disk?

Does anyone know what a porous disk is? What is the use?
by Nathan Tran 4K
Sat Mar 16, 2019 12:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: what is an electrolyte?
Replies: 1
Views: 36

what is an electrolyte?

What is an electrolyte in the context of a cell diagram? Can you give an example?
by Nathan Tran 4K
Thu Mar 14, 2019 1:43 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Concentration changes on Cell Potential
Replies: 1
Views: 47

Concentration changes on Cell Potential

Can someone explain how cell potential changes with changes of concentrations of reactants and products? What is the justification behind these changes?
by Nathan Tran 4K
Thu Mar 14, 2019 12:42 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: How to Find Reverse Activation Energy for Endothermic Processes?
Replies: 1
Views: 42

How to Find Reverse Activation Energy for Endothermic Processes?

How do you find the reverse activation energy for endothermic processes?
by Nathan Tran 4K
Wed Mar 13, 2019 12:22 am
Forum: Second Order Reactions
Topic: 2nd order rates
Replies: 6
Views: 140

Re: 2nd order rates

Yes, that is true. The total rate order involves summing the exponents of each reactant.
by Nathan Tran 4K
Tue Mar 12, 2019 11:57 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Log vs Ln
Replies: 2
Views: 45

Re: Log vs Ln

Oh apologies, I realized the simplification is different so the values probably somehow cancel out. Follow up question, how was this derivation solved?
by Nathan Tran 4K
Tue Mar 12, 2019 11:52 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Log vs Ln
Replies: 2
Views: 45

Log vs Ln

In the constants and equations sheet, there is an equation that simplifies the scalar quantity of ln(Q). However, it changes the ln to log. Can you do this? This seems fundamentally different?
by Nathan Tran 4K
Sun Mar 10, 2019 11:23 pm
Forum: General Rate Laws
Topic: Graphs
Replies: 2
Views: 43

Re: Graphs

I don't think we have to memorize the graphs per se, but it is important that we learn how to derive the relationships for the graphs. We do this by rearranging our dA and dt terms so we can integrate. Then, we change the graph to some form similar to y=mx + b. The graphs allow us to make evaluation...
by Nathan Tran 4K
Sun Mar 10, 2019 11:17 pm
Forum: First Order Reactions
Topic: reaction orders
Replies: 3
Views: 37

Re: reaction orders

If for example, a reaction is forming something, the reactant would have to be a negative reaction order. We can also see this as the reverse reaction of something that is decomposing--this is why the equilibrium constant has concentration of products in the denominator.
by Nathan Tran 4K
Sun Mar 10, 2019 11:10 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units of k
Replies: 7
Views: 150

Re: Units of k

The units are different because the reaction order affects the exponent--a first reaction order means an exponent of 1, a second reaction order means an exponent of 2, etc. Because we are raising the concentration (moles/Liter) to a different power, the units change accordingly. For example, by rais...
by Nathan Tran 4K
Sun Mar 10, 2019 11:05 pm
Forum: First Order Reactions
Topic: Pseudo rate laws
Replies: 2
Views: 38

Re: Pseudo rate laws

Essentially, because the concentration of one reactant is so high, we can neglect the excess reactant to make the rate law easier to work with. So for a second order reaction involving two concentrations, if one of the concentrations is high, we can ignore it, and say the reaction is a pseudo first ...
by Nathan Tran 4K
Thu Mar 07, 2019 9:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Electrode
Replies: 2
Views: 63

Re: Inert Electrode

There are inert electrodes like mercury, but for the purposes of this class, I am sure platinum is the main one we should be concerned with.
by Nathan Tran 4K
Thu Mar 07, 2019 9:48 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What does unique rate of reaction mean?
Replies: 6
Views: 121

Re: What does unique rate of reaction mean?

I am so glad that you have recognized this. I make an active goal to engage in pragmatism, especially in the realm of kinematics. Are you saying you divide the rate of A by the stoichiometric coefficient of A?
by Nathan Tran 4K
Thu Mar 07, 2019 9:37 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What does unique rate of reaction mean?
Replies: 6
Views: 121

What does unique rate of reaction mean?

What does the textbook mean when it asks us to find the unique rate of reaction? What is the process of solving for it?
by Nathan Tran 4K
Thu Mar 07, 2019 4:02 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Why does F/RT equal this value?
Replies: 1
Views: 48

Why does F/RT equal this value?

I'm trying to figure out why F/RT equals 1/.02569 V. On number 14.35 of the book, it says this is so. I am confused because I am getting a different value. I plugged in 96485 for F, 8.314 for R, and 298.15 for T. For reference, this is number 14.35 and the solutions manual simplifies F/RT to this va...
by Nathan Tran 4K
Tue Feb 19, 2019 11:24 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy
Replies: 7
Views: 85

Re: Gibbs free energy

In terms of the equations, gibbs' free energy sees a relationship with enthalpy and entropy where delta G = Delta H - T * Delta. Heat is a measurement of how much energy is transferred, but in terms of energy that is not able to do work, whereas Gibbs free energy is a measurement of how much work so...
by Nathan Tran 4K
Tue Feb 19, 2019 11:17 am
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: Third Law concept and problem types
Replies: 2
Views: 134

Re: Third Law concept and problem types

We use the third law to identify changes in entropy in systems, surroundings, etc. Applications would be calculating delta s in terms of isothermal, isobaric, and isochoric conditions, calculating S in terms of Boltzmann's equation, and finding relationships in terms of delta s of the system, surrou...
by Nathan Tran 4K
Tue Feb 19, 2019 11:14 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: System vs Surroundings
Replies: 7
Views: 173

Re: System vs Surroundings

Usually, the system is the actual thing we are dealing with in the question. For example, if we are looking at the piston and identifying characteristics like work, heat, etc., the piston is the system, while the surroundings is what is supplying heat or what the system is losing heat to or the surr...
by Nathan Tran 4K
Mon Feb 11, 2019 3:51 pm
Forum: Calculating Work of Expansion
Topic: Why are Work and Heat Considered Path Dependent?
Replies: 1
Views: 34

Why are Work and Heat Considered Path Dependent?

I know what the difference between state functions and path dependent functions are. However, how would we rationalize the fact that work and heat are path dependent using our formulas or just conceptually?
by Nathan Tran 4K
Sat Feb 09, 2019 7:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.57 6th Edition
Replies: 1
Views: 39

8.57 6th Edition

On 8.57 of the 6th edition, we are given Standard Delta H with a subscript of c. I assumed we could use this value as the standard enthalpy of formation, but the answer manual is using Hess' law. How do you do this? And what does the subscript c mean?
by Nathan Tran 4K
Sat Feb 09, 2019 7:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.9 7th Ed.
Replies: 1
Views: 39

Re: 4D.9 7th Ed.

Hi, so you know standard enthalpy formation is based off the moles of each reactant and product. Refer to table 8.4 to find the enthalpy of the whole reaction. Remember that diatomic molecules will have an enthalpy of zero, that product enthalpy will be negative and that reactant enthalpy will be po...
by Nathan Tran 4K
Sat Feb 09, 2019 6:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Is there a significance with 298 degrees Kelvin?
Replies: 5
Views: 197

Is there a significance with 298 degrees Kelvin?

In 8.49 of the 6th edition, we're asked to find the change in internal energy, knowing the reactions' change in enthalpy, and given the change in moles. We're not given a temperature, but we need a temperature to solve for work, or -p times delta V. We can solve for this using the ideal gas law. The...
by Nathan Tran 4K
Sat Feb 09, 2019 6:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Closed, Open, and Isolated Systems
Replies: 5
Views: 74

Re: Closed, Open, and Isolated Systems

The application of what people said before comes from the equation, delta U = q + w. If for example, something is isolated, that means that there can be no change in energy or matter, so delta U is zero.
by Nathan Tran 4K
Sat Feb 09, 2019 6:21 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Positive or Negative Entropy Change
Replies: 2
Views: 56

Re: Positive or Negative Entropy Change

I feel like there are a lot of ways to evaluate the change of signs for entropy--heat conventions is one of them, but because there are so many derivations of heat, you could also look at entropy change through different variables (this is good because then if you're not given heat or do not know ho...
by Nathan Tran 4K
Sat Feb 09, 2019 6:11 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 48
Views: 949

Re: Midterm [ENDORSED]

I would say review notes, read textbook for unfamiliar concepts, do lots of homework problems, and go to review sessions! Lavelle has so many resources!
by Nathan Tran 4K
Sun Feb 03, 2019 11:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Entropy
Replies: 3
Views: 67

Re: Entropy

This is a bit of a manipulation of our equation Delta u = q + w. If we know that there is a constant volume, we can assume there is zero work. As such, delta u = qp. We learned that qp is the same as delta H so u = delta H.
by Nathan Tran 4K
Sun Feb 03, 2019 11:36 pm
Forum: Calculating Work of Expansion
Topic: Different ways to derive work
Replies: 3
Views: 45

Re: Different ways to derive work

I might also add that it would be helpful to know the equation Delta U = qp + w, where work can be rearranged. It's helpful to know as many derivations of the same term as possible.
by Nathan Tran 4K
Sun Feb 03, 2019 11:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 3
Views: 60

Re: Hess's Law

Hess's Law allows us to manipulate equations where one constituent appears in one equation's reactants while the same constituent appears in another equation's products. As such, you can cancel out the constituent by adding the equations together. In doing so, you must also add up the enthalpies. In...
by Nathan Tran 4K
Tue Jan 22, 2019 12:17 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Justifying what is favored based off temperature changes and Delta H
Replies: 2
Views: 48

Justifying what is favored based off temperature changes and Delta H

How do you justify that an increase in temperature for endothermic reactions favors product and vice versa for exothermic reactions? Can we reason this out without just memorizing?
by Nathan Tran 4K
Tue Jan 22, 2019 11:37 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Given Equilibruim Partial Pressures and a Volume
Replies: 2
Views: 45

Given Equilibruim Partial Pressures and a Volume

If you are given equilibrium partial pressures and an overall volume, can you just ignore the overall volume, assuming you're finding Kp? In other words, would the overall volume just be extraneous information?
by Nathan Tran 4K
Tue Jan 22, 2019 11:30 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th Edition 11.61
Replies: 1
Views: 43

6th Edition 11.61

I have a question regarding sig figs. In 11.61, all the initial concentrations are given in three sig figs, but the Kc is given in two sig figs (the value is 0.56). The question asks to find the equilibrium concentrations of all the reactants and products. Why does the answer manual have the answers...
by Nathan Tran 4K
Tue Jan 22, 2019 11:16 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.3 7th Edition (When to use P vs molecular formula/concentrations)
Replies: 5
Views: 64

Re: 5G.3 7th Edition (When to use P vs molecular formula/concentrations)

Also, it could depend on what phase your reactants and products are in if you are not given actual values.
by Nathan Tran 4K
Tue Jan 22, 2019 11:15 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.3 7th Edition (When to use P vs molecular formula/concentrations)
Replies: 5
Views: 64

Re: 5G.3 7th Edition (When to use P vs molecular formula/concentrations)

If the question just asks for K, you can use either, but it is probably better to use what you are given. In this case, I am sure you were given partial pressure which is why you got a Kp value. However, if the question asked for Kc, you would need to convert your partial pressures to concentration ...
by Nathan Tran 4K
Tue Jan 22, 2019 12:03 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What does Kc have to be less than for you to estimate?
Replies: 3
Views: 54

What does Kc have to be less than for you to estimate?

What value does Kc have to be less than for you to estimate, meaning you can negate the -x term when employing ice method to solving for concentrations of products given initial reactant concentration? Is it less than 10^-3 or something else? Just making sure!
by Nathan Tran 4K
Wed Jan 16, 2019 7:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th Edition 12.23
Replies: 1
Views: 19

6th Edition 12.23

The question asks you to find the concentration of H3O+ given the Kw as 2.1(10)^-14. I realized that the concentration of H3O+ would be the same as the concentration of OH- so I made 2.1(10)^-14 equal to x^2. I ended up solving for x and got 1.45(10)^-7, but of course, in interest of sig figs, round...
by Nathan Tran 4K
Tue Jan 15, 2019 5:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: If you calcuate Kp and Kc for the same reaction, will they be the same?
Replies: 2
Views: 42

If you calcuate Kp and Kc for the same reaction, will they be the same?

If you calculate Kp and Kc of the same chemical equation with the same conditions, would the values of Kp and Kc be the same? There is the logic that because both Kp and Kc are simply rations of products/reactants, they would be the same. If they are not the same, why not?
by Nathan Tran 4K
Tue Jan 15, 2019 5:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Changes to K value
Replies: 9
Views: 115

Re: Changes to K value

The reason why only temperature changes the K value is because the other variables e.g. pressure only really change the initial concentration of reaction or product. However, because of this, the Q value changes which will shift the chemical equation.
by Nathan Tran 4K
Tue Jan 15, 2019 5:34 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic Reaction
Replies: 9
Views: 134

Re: Exothermic vs. Endothermic Reaction

I know the triangle on top of the arrow indicates there is heat involved, so you know that equation can be endothermic or exothermic. However, to determine whether a reaction is exothermic or endothermic, I would assume we would be given delta H or some variation of it.
by Nathan Tran 4K
Tue Jan 08, 2019 12:05 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: H20's Concentration in Gas Phase?
Replies: 1
Views: 34

H20's Concentration in Gas Phase?

Over lecture and in the textbook, we went over the idea that liquids and solids have concentrations we can ignore in context to finding the equilibrium constant--or in other words, concentrations of 1. Because H20 is a universal solvent, this makes sense. But what if H20 is in the gas phase? During ...
by Nathan Tran 4K
Mon Jan 07, 2019 11:57 pm
Forum: Ideal Gases
Topic: R in PV=nRT
Replies: 11
Views: 174

Re: R in PV=nRT

It's essentially a constant usually equal to 8.315 JK^-1mol^-1. I am sure it will be on our constant sheet.
by Nathan Tran 4K
Mon Jan 07, 2019 11:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Large/Small Equilibrium Constant
Replies: 2
Views: 31

Re: Large/Small Equilibrium Constant

If I remember correctly, a larger equilibrium constant occurs due to a larger concentration of product than the concentration of reactant. This is because Kc = [Product]/[Reactant]. Alternatively, a smaller equilibrium constant occurs due to a larger concentration of reactant than that of product.
by Nathan Tran 4K
Sun Dec 09, 2018 6:10 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why HF is a weaker acid than HCl
Replies: 12
Views: 349

Re: Why HF is a weaker acid than HCl

This comparison is different because in your first comparison, you are comparing bond lengths, but in your second comparison, you are comparing the electronegativity. The reason why we compare electronegativity in your latter comparison is because H is attached to O in both molecules; thus, comparin...
by Nathan Tran 4K
Sun Dec 09, 2018 6:05 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Boiling point
Replies: 4
Views: 163

Re: Boiling point

In this question, it is specified that H2Se has a higher boiling point. Normally, we cannot determine which intermolecular force dominates, but in this question, we know that since the LDF and the dipole dipole forces contradict each other, the LDF is more dominant. It's a really weird nuance!
by Nathan Tran 4K
Sun Dec 09, 2018 6:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination compound shape
Replies: 3
Views: 177

Re: coordination compound shape

The shape is determined by how many ligands are attached. Even more so, we have to consider whether something is polydentate. For example, three bidentate ligands would be octahedral in shape.
by Nathan Tran 4K
Sun Dec 09, 2018 5:53 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 900496

Re: Post All Chemistry Jokes Here

Did you know that oxygen went for a second date with potassium?

How did it go?

It went OK2!
by Nathan Tran 4K
Fri Dec 07, 2018 10:49 pm
Forum: Bronsted Acids & Bases
Topic: Why Can't Double Bonded O's Accept Protons?
Replies: 1
Views: 44

Why Can't Double Bonded O's Accept Protons?

I encountered this problem I 12.127 in the 6th edition book where the question asked how many protons could interact with thymine. My question is how come double bonded O can't accept H. Someone told me that it was because this would make O have a formal charge of +1, but when you add the proton to ...
by Nathan Tran 4K
Fri Dec 07, 2018 9:24 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Chem 6th Edition 12.25
Replies: 2
Views: 79

Chem 6th Edition 12.25

Hi, I need help with question 12.25 with figuring out the concentration of H3O+. I understand how to calculate everything else, but I don't understand why there would even be a concentration of H3O+ if we are just dealing with a Bronsted base. In the solution manual, it mentions Kw. How would you do...
by Nathan Tran 4K
Tue Dec 04, 2018 5:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Ligands
Replies: 2
Views: 75

Re: Identifying Ligands

You can determine if a molecule is a ligand by first looking for a coordination sphere. If there is a bracket, there is a coordinating covalent compound, which means there are ligands. You can probably also look for them by looking for a transitional metal. Transitional metals can bond with 6 ligand...
by Nathan Tran 4K
Tue Dec 04, 2018 5:22 pm
Forum: Naming
Topic: Which nonmetal do we name first if the ligand has 2 of them?
Replies: 1
Views: 15

Re: Which nonmetal do we name first if the ligand has 2 of them?

I believe it's safe to assume that when we name ligands, we can just go left to right because the ligands are already in alphabetical order in the chemical equation. When we write the chemical notation for coordinating compounds, we start with the transitional metal, and then name the compounds base...
by Nathan Tran 4K
Mon Dec 03, 2018 9:31 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Is there a difference between concentration and molarity?
Replies: 2
Views: 61

Is there a difference between concentration and molarity?

I noticed when we did pH computations, we used the concentration of specific ions or molecules. When we did this, we used M, which is the unit for molarity of moles/liters. However, I always understood concentration as g/L of Kg/L. What is the difference between molarity and concentration? Is there ...
by Nathan Tran 4K
Sat Dec 01, 2018 6:56 pm
Forum: Naming
Topic: 6th Edition 17.29
Replies: 2
Views: 30

Re: 6th Edition 17.29

I actually bought an answer solution in the book form, so my solutions manual is a physical copy.
by Nathan Tran 4K
Sat Dec 01, 2018 6:39 pm
Forum: Naming
Topic: 6th Edition 17.29
Replies: 2
Views: 30

6th Edition 17.29

On 17.29, in the chapter 6 edition, it says in the answer manual that the CN portion of the coordinating compound will be cyano (not including everything else). However, on page 742 of the book with the chart of common ligands, it says that CN is cyanido. How come the answer solution changed cyanido...
by Nathan Tran 4K
Wed Nov 28, 2018 1:46 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: 4.46
Replies: 4
Views: 111

Re: 4.46

As stated before, you will need to find the total sigma and pi bonds in the molecule. This will involve counting the single bonds for sigma bonds and characterizing the excess bonds as pi bonds.
by Nathan Tran 4K
Wed Nov 28, 2018 1:16 am
Forum: Dipole Moments
Topic: Drawing dipole moments
Replies: 3
Views: 70

Re: Drawing dipole moments

I know what you're talking about when you say the textbook and lectures are different when it comes to drawing dipole. I would stick with what Lavelle said though. You are right about how we draw it--the arrow points to the more electronegative atom while the "tail" is near the less electr...
by Nathan Tran 4K
Wed Nov 28, 2018 12:37 am
Forum: Dipole Moments
Topic: Polarity of Asymmetrical Molecules
Replies: 4
Views: 89

Re: Polarity of Asymmetrical Molecules

No, these shapes cannot be nonpolar because of the inherent asymmetry of the molecules. The lone pair in each shape pushes the other atoms so bond lengths are slightly different than that of their arrangement structure counterparts. Thus, the dipole vectors will not cancel out.
by Nathan Tran 4K
Sun Nov 25, 2018 12:48 am
Forum: Octet Exceptions
Topic: Why Doesn't I Break Octet in IO3-
Replies: 1
Views: 144

Why Doesn't I Break Octet in IO3-

I am currently working on number 4.13, question C in the 6th Edition book. When drawing the lewis structure of IO3-, I noticed the solution manuals had three single bonds for each I-O and one lone pair which means I has a formal charge of +2 and each O has a formal charge of -1. Sure, this makes I h...
by Nathan Tran 4K
Sat Nov 24, 2018 4:06 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distortion and London Dispersion Forces
Replies: 2
Views: 75

Distortion and London Dispersion Forces

I was reviewing my notes, and saw that increasing electrons increases the distortion, which in turn increases london dispersion force. To me, this seems counterintuitive because I typically attribute the increase in electrons to an increase in atomic radius, which I associate with weaker bonds. Can ...
by Nathan Tran 4K
Wed Nov 21, 2018 4:04 pm
Forum: Sigma & Pi Bonds
Topic: Clarification of Pi Bonds and Rotation
Replies: 3
Views: 56

Clarification of Pi Bonds and Rotation

Can someone clarify the point Lavelle made about rotating with pi bonds? I recall he used two pencils to try to rotate the atoms, but I think he said something along the lines of "if there is a pi bond, it means there can be no rotation." Could someone clarify this concept?
by Nathan Tran 4K
Wed Nov 21, 2018 3:52 pm
Forum: Hybridization
Topic: Hybridization
Replies: 6
Views: 75

Re: Hybridization

Hybridization occurs because it rectifies the problem of unequal energy in bonds that unhybridized models imply. Let's look at the molecule CH4. If we were to look at the C-H bonds, we would do so by drawing the valence electrons in the outermost shell of Carbon in its ground state. Thus, we would s...
by Nathan Tran 4K
Wed Nov 21, 2018 3:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: predicting dipole moments
Replies: 4
Views: 79

Re: predicting dipole moments

As Ashley said, the systematic approach is to first look if there are any dipole moments. We can look for dipole moments by looking at the symmetry of the molecule and the vectors of the dipoles. If the molecule is asymmetrical, we know there is a dipole dipole force. If it is symmetrical and the di...
by Nathan Tran 4K
Sun Nov 18, 2018 6:54 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Distortion
Replies: 1
Views: 66

Re: Electron Distortion

Electron distortion refers to an interaction between a cation or anion where a cation (because of the positive charge) alters the electron cloud of the anion. In this sense, electron distortion is very important in ionic bonds. The power a cation has to distort the electron cloud of an anion refers ...
by Nathan Tran 4K
Sun Nov 18, 2018 12:14 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability vs Polarizing Power Trends
Replies: 1
Views: 114

Polarizability vs Polarizing Power Trends

What is this trend on the periodic table for polarizability and polarizing power and how do you justify these trends using ideas like more shells and greater effective nuclear charge?
by Nathan Tran 4K
Fri Nov 16, 2018 1:13 am
Forum: Lewis Structures
Topic: Picking Central Atom Special Cases
Replies: 2
Views: 56

Picking Central Atom Special Cases

When we draw the lewis structure for for ClO2, we usually pick the atom with the lowest ionization energy. However, between the two atoms, there is a conflicting trend where Cl gets more rightward and gets more downward in comparison to O. This is counterintuitive because ionization energy increased...
by Nathan Tran 4K
Thu Nov 15, 2018 11:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Vsepr Formula
Replies: 7
Views: 76

Re: Vsepr Formula

In addition, when we are working with VSEPR theory, we might be asked to put the molecule in the form AXnEm. This helps us predict the actual 3d shape of the molecule while a lewis structure really only predicts the molecule in the 2d plane. Also, the lewis structure has things like single bonds, do...
by Nathan Tran 4K
Thu Nov 15, 2018 10:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double/Triple Bonds
Replies: 5
Views: 121

Re: Double/Triple Bonds

Lavelle discussed in lecture that the number of bonds should not affect the regions of electron density. Thus, with the information we have now, it is best to assume that double and triple bonds do not affect shape. However, of course there may be nuances to this, but I think that we can stick to th...
by Nathan Tran 4K
Thu Nov 15, 2018 10:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Vespr Formula
Replies: 6
Views: 99

Re: Vespr Formula

Also, to add a quick thing--it's actually VSEPR, not VESPR. This is because VSEPR stands for valence shell, electron pair, repulsion theory. As stated above, the basic formula AXnEm where A represents the central atom with an implicit subscript of 1, X represents a ligand (the atom attached to the c...
by Nathan Tran 4K
Wed Nov 14, 2018 11:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Octet Rule
Replies: 6
Views: 165

Re: Octet Rule

Another common exception to the octet rule that we don't often talk about is hydrogen just because it's so intuitive to make a single bond without completing its octet. It's one we don't think about often breaking the octet, but one that does nonetheless.
by Nathan Tran 4K
Mon Nov 12, 2018 10:22 pm
Forum: Ionic & Covalent Bonds
Topic: Noncovalent Interactions
Replies: 4
Views: 85

Re: Noncovalent Interactions

Another thing to add that I have down in my notes is that greater force in interactions leads to greater melting points. But as reiterated before, your understanding thus far seems spot on!
by Nathan Tran 4K
Mon Nov 12, 2018 10:16 pm
Forum: Electronegativity
Topic: Electronegativity Graph
Replies: 4
Views: 136

Re: Electronegativity Graph

I noticed what Christopher noticed as well. Could it have something to do with the fact that this decrease tends to cluster more to the right of the transitional metals? I am looking at a periodic table with the actual electronegativities for each element and it seems like this is somewhat of a trend.
by Nathan Tran 4K
Mon Nov 12, 2018 10:06 pm
Forum: Ionic & Covalent Bonds
Topic: London Van Der Waals Force?
Replies: 5
Views: 133

London Van Der Waals Force?

I recall my TA saying that all molecules undergo London Van Der Waals Forces in some way, and that for example, diploe-dipole forces are just stronger forces of this nature. What exactly are these London Van Der Waals Forces and are they synonymous to dispersion and induced diploe-induced dipole for...
by Nathan Tran 4K
Mon Nov 12, 2018 10:01 pm
Forum: Ionic & Covalent Bonds
Topic: What is Distortion?
Replies: 3
Views: 59

What is Distortion?

During Lavelle's lecture, we learned that higher distortion results in greater interaction potential energy which ultimately leads to higher boiling points. What exactly is distortion though?
by Nathan Tran 4K
Fri Nov 02, 2018 11:00 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: How to Find Number of Nodal Planes?
Replies: 1
Views: 84

How to Find Number of Nodal Planes?

How does one find the number of nodal planes given principle quantum number and the subshells? So how does the number of nodal planes relate to s-,p-,d-,and,f- and other things like that?
by Nathan Tran 4K
Thu Nov 01, 2018 11:55 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity Trend: Contrasting Trends
Replies: 1
Views: 56

Electronegativity Trend: Contrasting Trends

For trends like electronegativity, what do we do if the atom we are comparing gets more rightward but more downward in position? Does one of the values (period versus group) affect the electronegativity more significantly?
by Nathan Tran 4K
Thu Nov 01, 2018 11:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How to Find Unpaired Electrons?
Replies: 2
Views: 228

Re: How to Find Unpaired Electrons?

Furthermore, will we be expected to know how to do so on the test?
by Nathan Tran 4K
Thu Nov 01, 2018 11:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How to Find Unpaired Electrons?
Replies: 2
Views: 228

How to Find Unpaired Electrons?

How do you find the number of unpaired electrons?
by Nathan Tran 4K
Thu Nov 01, 2018 11:33 pm
Forum: Resonance Structures
Topic: Definition of resonance
Replies: 7
Views: 117

Re: Definition of resonance

Moreover, to add on to all of these answers, the "true" model for the bonds would be a blend of all the resonance structures, meaning that every bond between nitrogen and oxygen has characteristics of both a single bond and a double bond. Drawing multiple lewis structures of the same molec...
by Nathan Tran 4K
Thu Nov 01, 2018 11:28 pm
Forum: Resonance Structures
Topic: 6th Edition 3.21
Replies: 2
Views: 59

Re: 6th Edition 3.21

Just writing the ground state as [Ar] would be an acceptable answer, as the charge of plus 2 means the Calcium atom lost two electrons, equal in valence electrons to that of the noble gas Argon.
by Nathan Tran 4K
Sat Oct 27, 2018 12:34 am
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 8
Views: 139

Re: Atomic Radius

Knowing the trend like you mentioned is probably something we need to know, but knowing the actual values will be given, as we are not expected to memorize the values of atomic radii.
by Nathan Tran 4K
Mon Oct 22, 2018 1:15 pm
Forum: Properties of Light
Topic: Chem Homework 1.55 Mistake?
Replies: 2
Views: 85

Re: Chem Homework 1.55 Mistake?

That makes sense, thank you!
by Nathan Tran 4K
Mon Oct 22, 2018 1:37 am
Forum: Properties of Light
Topic: Chem Homework 1.55 Mistake?
Replies: 2
Views: 85

Chem Homework 1.55 Mistake?

(This question requires the solution manual in hand) In the solution manual for 1.55, the way the question is solved is v/c = wavelength. However, this means frequency = speed of light times wavelength which makes no sense. Am I misinterpreting this problem, misinterpreting the solution manual, or i...
by Nathan Tran 4K
Mon Oct 22, 2018 1:34 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Chem Homework 1.45 Question Mistake?
Replies: 3
Views: 154

Chem Homework 1.45 Question Mistake?

In question 1.45, the bowling ball is rolling down an alley at 5 plus or minus 5 meters per second. In Lavelle's lecture, I recall the uncertainty in position would be 10 because the maximum value is 10 meters per second while the minimum value is 0 meters per second. However, in the solution manual...
by Nathan Tran 4K
Sat Oct 20, 2018 6:59 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Post Module Question
Replies: 1
Views: 65

Post Module Question

I need help with the following question: 18. The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. Comme...
by Nathan Tran 4K
Thu Oct 18, 2018 2:16 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Absorption Spectroscopy versus Atomic Emission Spectroscopy
Replies: 3
Views: 63

Atomic Absorption Spectroscopy versus Atomic Emission Spectroscopy

Hi, I need help with the following question on the module: 13. In the above experiment if only the absorbed wavelengths of light are detected what is the experiment called? What is the spectrum called? I know this is a question about the definition but why is it not: A. Atomic absorption spectroscop...
by Nathan Tran 4K
Sun Oct 14, 2018 6:14 pm
Forum: Properties of Light
Topic: Wave vs. Particle Behavior
Replies: 5
Views: 87

Re: Wave vs. Particle Behavior

The fact that they act as particles manifests in the one to one interaction in the photoelectric experiment. However, diffraction is one of the main characteristics that show that they act as waves.
by Nathan Tran 4K
Mon Oct 08, 2018 9:57 pm
Forum: Properties of Light
Topic: Chem Homework Question Number 1.9
Replies: 1
Views: 28

Chem Homework Question Number 1.9

On number 1.9, in the 6th edition book, the wavelength of the third type of radiation solves to be 1 meter. Looking at an electromagnetic chart, 1 meter is the approximate wavelength of radio waves (or relatively close to that value). However, on the answer key, the radiation event is supposedly &qu...
by Nathan Tran 4K
Mon Oct 08, 2018 5:18 pm
Forum: Properties of Light
Topic: Quanta & Photons
Replies: 5
Views: 97

Re: Quanta & Photons

Doctor Lavelle used a very pertinent example of a water faucet in his discussion of the difference between discrete and quanta variables. Essentially, the holistic view of water exiting a water faucet is comparable to a discrete value because water is seen as continuously flowing. An example of this...
by Nathan Tran 4K
Mon Oct 08, 2018 5:06 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Replies: 135
Views: 28265

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]

This is very helpful! Thank you for this! I'll make sure to study it, and I look forward to seeing you on Sunday!
by Nathan Tran 4K
Mon Oct 01, 2018 9:41 am
Forum: SI Units, Unit Conversions
Topic: Grams/mole
Replies: 12
Views: 312

Re: Grams/mole

Yes, they are the same notation. Negative powers just indicate that the exponent will appear in the denominator. For example, x^(-1) is simply 1/(x)^1. Another way to think of it is looking at the term as the reciprocal of the absolute value of the exponent. Because the grams are multiplied by (mole...
by Nathan Tran 4K
Sun Sep 30, 2018 10:11 pm
Forum: Balancing Chemical Reactions
Topic: Short cuts/methods for balancing equations
Replies: 15
Views: 193

Re: Short cuts/methods for balancing equations

The way I balance equations is I always scan for an element that appears on the reactant side of the equation and product side of the equation once. In doing so, I make sure that there are no other elements affecting the balancing of the element. After this, I look to see if the element I balanced w...
by Nathan Tran 4K
Sat Sep 29, 2018 6:40 pm
Forum: Limiting Reactant Calculations
Topic: Is there a specific way to solve limiting reactant problems?
Replies: 4
Views: 140

Re: Is there a specific way to solve limiting reactant problems?

The way I solve limiting reactant problems is the way you highlighted in your first description. Converting the grams of reactants to moles allows one to compare the moles of the actual reaction to those in the molecular equation. I understand what you mean about comparing the two values as being co...

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