Search found 118 matches

by Edmund Zhi 2B
Sun Mar 15, 2020 4:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Athena
Replies: 34
Views: 1522

Re: Athena

thank you dr lavelle!
by Edmund Zhi 2B
Sat Mar 14, 2020 7:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: intermediates
Replies: 8
Views: 31

Re: intermediates

Reaction intermediates are formed but are consumed later on to produce the actual products and are therefore not part of the net overall reaction
by Edmund Zhi 2B
Sat Mar 14, 2020 7:02 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: lnA
Replies: 3
Views: 19

Re: lnA

A lot of questions don't give us the value of A how do we go about calculating it or is it not necessary?
by Edmund Zhi 2B
Thu Mar 12, 2020 10:09 pm
Forum: Zero Order Reactions
Topic: Elementary Reactions
Replies: 5
Views: 27

Re: Elementary Reactions

I believe that coefficients determine the order of reactants in the rate law when we are dealing with elementary reactions. Elementary reactions are when chemical species react directly to form products with a single reaction step and single transition state. I believe this is correct, yes. They ar...
by Edmund Zhi 2B
Thu Mar 12, 2020 7:34 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What was your favorite chem topic?
Replies: 24
Views: 79

Re: What was your favorite chem topic?

I thought coordination compounds were cool
by Edmund Zhi 2B
Tue Mar 10, 2020 3:21 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7C.7: Rate laws
Replies: 2
Views: 18

Re: 7C.7: Rate laws

We are not being asked to find both the forward and reverse, we are only being asked to find the rate for the formation of NOBr, which is the forward reaction.
by Edmund Zhi 2B
Sun Mar 08, 2020 6:00 pm
Forum: First Order Reactions
Topic: 7B.1
Replies: 1
Views: 18

7B.1

A certain beta blocker is eliminated in a first-order process with a rate constant of 7.6 * 10^-3 min^-1 at normal body temperature (37 C). A patient is given 20. mg of the drug. What mass of the drug remains in the body 5.0 h after administration? How do we use the integrated rate law/rate low to f...
by Edmund Zhi 2B
Sat Mar 07, 2020 11:54 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: temperature and k
Replies: 5
Views: 48

Re: temperature and k

If you're talking about k as in the initial rate, increasing temperature increases k because it increases the movement of the molecules and causes them to interact and collide more frequently.
by Edmund Zhi 2B
Sat Mar 07, 2020 11:52 am
Forum: Zero Order Reactions
Topic: Difference
Replies: 5
Views: 56

Re: Difference

The differences are just the effect that the concentration of one reactant has on the overall reactant rate, that is, whether or not a change in concentration will have no effect on the rate, have a linear change, or cause a squared rate of change
by Edmund Zhi 2B
Sat Mar 07, 2020 11:50 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: k' vs k'
Replies: 3
Views: 268

Re: k' vs k'

They are simply the same notation
by Edmund Zhi 2B
Tue Mar 03, 2020 11:53 pm
Forum: First Order Reactions
Topic: Finding Order of Reactions
Replies: 4
Views: 237

Re: Finding Order of Reactions

The order of reactions are determined by comparing different experiments. By keeping all but one reactant constant, you can determine the order of the varying reactant by seeing it's effect on the initial rate.
by Edmund Zhi 2B
Mon Mar 02, 2020 11:35 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: lnQ vs logQ
Replies: 5
Views: 43

lnQ vs logQ

Using either would be ok, right? As long as we use the correct constants (ex 0.025693/n vs 0.0592/n)
by Edmund Zhi 2B
Mon Mar 02, 2020 4:46 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.15 anode or cathode
Replies: 1
Views: 37

6N.15 anode or cathode

We are given 1.0M Ni2+ in one solution, and I have calculated that 6.5 x 10*-12 M of Ni2+ is in the other compartment. How do I determine which is the anode and which is the cathode?
by Edmund Zhi 2B
Sun Mar 01, 2020 2:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Partial Pressures in Q
Replies: 2
Views: 24

Partial Pressures in Q

When we include partial pressures in the value of Q, why do they have to be in atmospheres? For example, in Question 5N.3 (c), we are given 250torr and 125 torr but the answer key divides them by 760 to convert to atm.
by Edmund Zhi 2B
Sun Mar 01, 2020 11:03 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.1: reading the cell diagram
Replies: 6
Views: 49

Re: 6M.1: reading the cell diagram

705121606 wrote:I also had trouble with this one, I read on another chemistry community question that when the ecell is negative we have to flip the cell around


Update: I looked at the solutions manual and they did consider the cell to be flipped. Guess the textbook is wrong
by Edmund Zhi 2B
Sat Feb 29, 2020 9:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.1: reading the cell diagram
Replies: 6
Views: 49

6M.1: reading the cell diagram

In this question, we are given M(s)|M2+(aq)||Cu^2+(aq)|Cu(s) as the cell diagram and are asked to find E(M2+/M) given E(cell) = -0.689. Now normally, we would consider the right side to be the cathode, right? So in that case, we setup the equation to as E(cell) = E(cathode) - E(anode) -0.689 = 0.337...
by Edmund Zhi 2B
Thu Feb 27, 2020 3:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Strength of reducing agents [ENDORSED]
Replies: 1
Views: 62

Strength of reducing agents [ENDORSED]

I'm just curious as why Li is a stronger reducing agent than K, which is a stronger reducing agent than Na (I know based off the half-reaction cell potentials). Why isn't it the other way around if there is more shielding in the lower alkalines and they become more likely to be oxidized, lose an ele...
by Edmund Zhi 2B
Thu Feb 27, 2020 3:22 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Homework 6M.5
Replies: 2
Views: 28

Homework 6M.5

For part a, we are given

2NO3- + 8H+ + 6Hg -> 3Hg2 2+ + 2NO + 4H2O.

In the answer key's cell, they do not include NO at all, instead, they include NO3- and O in the cathode. Why is this?
by Edmund Zhi 2B
Thu Feb 27, 2020 2:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Coefficients in Calculating Cell Potential?
Replies: 3
Views: 15

Coefficients in Calculating Cell Potential?

Are we supposed to ignore coefficients and balancing everything when we calculate cell potentials? If so why?
by Edmund Zhi 2B
Thu Feb 27, 2020 2:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to tell which is anode/cathode based on standard reduction potentials E
Replies: 5
Views: 18

How to tell which is anode/cathode based on standard reduction potentials E

According to the textbook, "In general, the more positive the standard potential, the more strongly oxidizing is the oxidizing member of the redox couple and the more likely that member will be to undergo reduction itself." Does this mean that when given two half reactions, we put the more...
by Edmund Zhi 2B
Tue Feb 25, 2020 9:38 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Difference in G's
Replies: 2
Views: 34

Re: Difference in G's

Delta G is dependent on other variables, where as ΔG°is a fixed value, where the fixed values are at standard conditions.
by Edmund Zhi 2B
Sat Feb 22, 2020 2:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 6L.3 part d
Replies: 1
Views: 27

Homework 6L.3 part d

In the anode, we are given O2(g) and H+(aq) in contact with each other. I'm confused as to why we put O2 and H+ on the same side of the half reaction...can someone explain how do we determine the half-reaction for these types of problems?
by Edmund Zhi 2B
Fri Feb 21, 2020 1:38 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Voltage of 0
Replies: 3
Views: 20

Voltage of 0

What are different causes of a galvanic cell reaching a voltage of 0?
by Edmund Zhi 2B
Fri Feb 21, 2020 1:35 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard hydrogen electrode [ENDORSED]
Replies: 3
Views: 98

Re: Standard hydrogen electrode [ENDORSED]

So then are values of E just relative to the value determined by the half reaction involving hydrogen?
by Edmund Zhi 2B
Fri Feb 21, 2020 1:33 am
Forum: Balancing Redox Reactions
Topic: Oxidation number of Ozone
Replies: 10
Views: 60

Re: Oxidation number of Ozone

In compounds with only one element the oxidation number is 0
by Edmund Zhi 2B
Fri Feb 21, 2020 1:33 am
Forum: Balancing Redox Reactions
Topic: oxidation numbers
Replies: 8
Views: 40

Re: oxidation numbers

Use common oxidations states such as that of very electronegative atoms like oxygen, nitrogen, and fluorine, and then fill in the rest to make sure that the charges add up to the overall charge of the molecule
by Edmund Zhi 2B
Wed Feb 12, 2020 5:06 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: State and path functions [ENDORSED]
Replies: 1
Views: 41

State and path functions [ENDORSED]

Aren't work (w) and heat (q) the only path functions? Can't we just think about that instead of trying to remember all the state functions?
by Edmund Zhi 2B
Wed Feb 12, 2020 3:02 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Constant pressure and volume
Replies: 1
Views: 22

Re: Constant pressure and volume

This situation would probably never happen because it's not possible to add heat and have no change in pressure or volume.
by Edmund Zhi 2B
Mon Feb 10, 2020 5:31 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: equipartition theorem
Replies: 2
Views: 34

Re: equipartition theorem

Are we required to know this for the exam? I don't see it in our learning objectives but there have been homework problems on it
by Edmund Zhi 2B
Mon Feb 10, 2020 4:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework 4.15
Replies: 1
Views: 27

Homework 4.15

Hydrochloric acid oxidizes zinc metal in a reaction that produces hydrogen gas and chloride ions. A piece of zinc metal of mass 8.5 g is dropped into an apparatus containing 800.0 mL of 0.500 m HCl(aq). If the initial temperature of the hydrochloric acid solution is 25C, what is the final temperatur...
by Edmund Zhi 2B
Sun Feb 09, 2020 9:22 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Writing balanced equation for formation reactions
Replies: 4
Views: 25

Writing balanced equation for formation reactions

Why do we use fractions when writing balanced equations for these questions involving Gibbs free energy and formation? These coefficients affect answers and calculations greatly and I was wondering if using answers that we calculated using a different balanced equation is still acceptable (homework ...
by Edmund Zhi 2B
Sun Feb 09, 2020 9:20 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs LS7A
Replies: 2
Views: 18

Re: Gibbs LS7A

We aren't required to know the second equation for the midterm; this is covered in chapter 5, which Lavelle hasn't gone over yet
by Edmund Zhi 2B
Sun Feb 09, 2020 9:08 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy units
Replies: 7
Views: 65

Re: Entropy units

Just make sure that in calculations, if you end up with L * atm, multiply it by a conversion to joules. It's 101.3 I believe
by Edmund Zhi 2B
Sun Feb 09, 2020 9:07 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy on midterm
Replies: 5
Views: 30

Re: Gibbs Free Energy on midterm

Basically we need to know all of chapter 4. The concepts he hasn't covered are all part of chapter 5.
by Edmund Zhi 2B
Sun Feb 09, 2020 1:33 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4H.1 part B
Replies: 4
Views: 31

4H.1 part B

We are asked to find which has higher molar entropy, NH3 or Ne. Why is the answer NH3 even though Ne has a higher molar mass, and heavier molecules have more entropy. I suspect it might be because NH3 is more complex, but then, which characteristic of molecules do we look at first when determining w...
by Edmund Zhi 2B
Fri Feb 07, 2020 3:52 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Calculating entropy using positive or negative delta H
Replies: 2
Views: 28

Calculating entropy using positive or negative delta H

In different problems I have to let deltaS = deltaH/T, or -deltaH/T. What is the difference between positive and negative delta H and how do I conceptualize it? Does it have to do with which viewpoint you're taking, the system or surroundings? How do I tell?
by Edmund Zhi 2B
Fri Feb 07, 2020 3:45 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Conceptualizing Cv, Cp
Replies: 2
Views: 28

Conceptualizing Cv, Cp

I know that Cp = Cv + nR, and for monoatomic ideal gases that Cv = 3/2R, but I'm struggling to understand WHY this is so. Why is a change in entropy based on change in temperature at a constant pressure GREATER than entropy change at constant volume. Can someone please help me understand this concep...
by Edmund Zhi 2B
Fri Feb 07, 2020 3:11 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy
Replies: 2
Views: 17

Re: Entropy

I think you mean "change in entropy." The reason why entropy is always increasing in the universe is because of the big bang theory and how the universe is always expanding, and therefore occupying a forever increasing number of possible states.
by Edmund Zhi 2B
Sun Feb 02, 2020 10:11 pm
Forum: Calculating Work of Expansion
Topic: Thermochemistry and thermodynamics
Replies: 3
Views: 25

Re: Thermochemistry and thermodynamics

You might be struggling because we haven't gone over too many practice problems in class. If your TA is able to provide practice problems, or when Lavelle goes over some in class once thermochem and thermodynamics are completely covered, I think you'll have more of an understanding of how to do ever...
by Edmund Zhi 2B
Sun Feb 02, 2020 11:37 am
Forum: Phase Changes & Related Calculations
Topic: Multiple Phase Changes
Replies: 4
Views: 32

Re: Multiple Phase Changes

When substances change phases, their specific heats also change. If this is water, for example, the specific heats of water and steam are different and therefore need to be calculated separately and then added together for total heat added.
by Edmund Zhi 2B
Sat Feb 01, 2020 9:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Textbook question 4C.3
Replies: 3
Views: 55

Re: Textbook question 4C.3

I actually got the same thing as the answer key. At first, I was getting the same things as you were. If I am correct, you're using 7/2R, and then 5/2R, following the example 4C.1 on page 266. However, these values of Cv,m and Cp,m are for a diatomic gas, Kr in the question is a monoatomic gas. Ther...
by Edmund Zhi 2B
Sat Feb 01, 2020 4:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4C.3
Replies: 2
Views: 25

Re: 4C.3

Moreover, Cv,m is 3/2R for a monoatomic gas (this is for part B)
by Edmund Zhi 2B
Sat Feb 01, 2020 4:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4C.3
Replies: 4
Views: 66

Re: 4C.3

For part a, I believe it's 343K for the final temperature and 935.1J for the change in enthalpy, and part b it's 374K for the final temperature and 947.6J for the change in enthalpy. Wouldn't the change in enthalpy just be 765J because in example 4C.1 on page 266, the solution states that "the...
by Edmund Zhi 2B
Sat Feb 01, 2020 3:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework 4C.1 comparing molar heat capacities
Replies: 1
Views: 10

Homework 4C.1 comparing molar heat capacities

Which gas has the higher molar heat capacity, NO or NO2?

How are we supposed to know this/figure this out, and where in the textbook does it talk about this or are we supposed to apply other concepts from other units?
by Edmund Zhi 2B
Sat Feb 01, 2020 1:57 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated vs Closed [ENDORSED]
Replies: 34
Views: 235

Re: Isolated vs Closed [ENDORSED]

An insulated water bottle can be considered isolated because neither matter nor energy can be exchanged with the surroundings
by Edmund Zhi 2B
Sat Jan 25, 2020 4:52 pm
Forum: Ideal Gases
Topic: R Constant
Replies: 26
Views: 149

Re: R Constant

The R constant will vary based on the other units given to us within a problem. Our formula sheet should always have a value of R that we will need to use in any problem on an exam.
by Edmund Zhi 2B
Mon Jan 20, 2020 10:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 6E.1 Rounding Error?
Replies: 1
Views: 30

Homework 6E.1 Rounding Error?

Calculate the pH of 0.15 m H2SO4(aq). Here is my work for this problem: 0.15M H2SO4 generates 0.15M H3O+ (to be added in later in the problem) and 0.15M HSO4-. Ka of HSO4- is 1.2 * 10^-2 1.2 * 10^-2 = x^2/(0.15-x) 0 = x^2 + 0.012x -0.0018, used quadratic equation to solve for x = [H3O+] = 0.0368 Add...
by Edmund Zhi 2B
Mon Jan 20, 2020 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.15
Replies: 1
Views: 38

Re: 6D.15

You write the equation as [Al(H2O)6]3+ + H2O <-> [Al(H2O5)OH]2+ + H3O+. A proton leaves one of the water molecules surrounding the Aluminum and is transferred to another water molecule not attached to the Al. That's why I wrote the compound on the right as [Al(H2O5)OH]2+, to show where the proton wa...
by Edmund Zhi 2B
Mon Jan 20, 2020 2:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 6D.5 part d answer key error?
Replies: 2
Views: 26

Homework 6D.5 part d answer key error?

For part D on this problem, where we are asked to find the pH, pOH, and percentage protonation of 0.0073 M codeine given that the pKa of its conjugate acid is 8.21, I'm getting the correct answer for pH and pOH, 3.96 and 10.04, but I'm getting a percentage of 1.5% instead of the answer key's 2.5%. I...
by Edmund Zhi 2B
Sat Jan 18, 2020 4:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Exercise 6A.19
Replies: 4
Views: 51

Re: Exercise 6A.19

I am getting 3.2 x 10^-15 as well, I believe there is an error in the answer key
by Edmund Zhi 2B
Sat Jan 18, 2020 3:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5E.2 table??
Replies: 3
Views: 22

Re: 5E.2 table??

I ran into the same problem as well but I don't think anything in the 5E.1 table is meant to help us with the problem?
by Edmund Zhi 2B
Sat Jan 18, 2020 1:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 3
Views: 21

Re: 5.33

Adding X atoms would cause more reactants to form to relieve stress on the equilibrium from an increase in products, but in the image there are actually less X2 molecules in container 2, so that answer is incorrect.
by Edmund Zhi 2B
Sat Jan 18, 2020 1:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effect of Temperature on Halogen Reaction (Homework 5J.11)
Replies: 3
Views: 33

Effect of Temperature on Halogen Reaction (Homework 5J.11)

For part b on homework 5J.11, we are given reactoin X2(g) <-> 2X(g), where x is a halogen and we want to find out if the reaction will shift left or right with a temperature increase. How do we know? Where in the book can we read about this?
by Edmund Zhi 2B
Sat Jan 18, 2020 1:36 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.9b
Replies: 8
Views: 41

Re: 5J.9b

I like to think of this mathematically in terms of the equilibrium constant. Because a number in the denominator is decreasing, O2, which is also in the denominator, must increase to compensate for this to maintain the same K.
by Edmund Zhi 2B
Wed Jan 15, 2020 9:58 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 5I.25
Replies: 4
Views: 40

Re: Homework 5I.25

Also having trouble with this problem. I follow your work until you plug into the Kc formula. Could you explain how you solved for x? Could you also explain why you omitted the x variable in the denominator with 0.06? I didn't mean to omit it; there should be an x variable there. I solved for x by ...
by Edmund Zhi 2B
Tue Jan 14, 2020 10:31 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 5I.25
Replies: 4
Views: 40

Re: Homework 5I.25

Ok, I realized that I was dividing by the wrong number and I got the same answers as the book. However, I came up with 2 different values of x: 0.0423, and 0.0189. These numbers are both positive, so how do I determine which one to use? The book uses 0.0189 EDIT: I think I figured it out, it's becau...
by Edmund Zhi 2B
Tue Jan 14, 2020 10:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 5I.25
Replies: 4
Views: 40

Homework 5I.25

I've set up an ice table so that the equilibrium concentrations are as follows: [SO2] = 0.02M - x [NO2] = 0.04M - x [NO] = 0.02 + x [SO3] = 0.03 + x And I've set up the equilibrium concentration as Kc = [NO][SO3]/[SO2][NO2], and letting these equal 85. My expanded equation for Kc is (x^2 + 0.05x + 0...
by Edmund Zhi 2B
Fri Jan 10, 2020 5:41 pm
Forum: Ideal Gases
Topic: K value
Replies: 14
Views: 79

Re: K value

Another way to derive the meaning is to think about the actual formula of K, [products]/[reactants]. If K is high (greater than 10^3), this means that [products] is a greater value than [reactants] and thus a large K means that equilibrium lies on the right, the side of the products. Same concept ap...
by Edmund Zhi 2B
Fri Jan 10, 2020 5:39 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q
Replies: 10
Views: 45

Re: Q

Yup, it is a ratio!
by Edmund Zhi 2B
Fri Jan 10, 2020 5:36 pm
Forum: Ideal Gases
Topic: R in PV=nRT
Replies: 34
Views: 448

Re: R in PV=nRT

There are different values and units that will vary based on the units of the other variables given in a certain equation. We will probably get these on the formula sheet just like lavelle's 14a
by Edmund Zhi 2B
Fri Jan 10, 2020 5:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using Kc Vs Kp
Replies: 18
Views: 132

Re: Using Kc Vs Kp

I believe you should look at the states of matter and try and determine from that
by Edmund Zhi 2B
Fri Jan 10, 2020 5:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K expression involving solids/liquids
Replies: 7
Views: 49

Re: K expression involving solids/liquids

Pure substances do not have concentrations and do not impact equilibrium constants because they have no concentration that changes in the reaction
by Edmund Zhi 2B
Fri Jan 10, 2020 5:31 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Today's Lecture
Replies: 3
Views: 31

Re: Today's Lecture

It is consistent with the short reasoning. The short reasoning is just a simplified version of the true complex explanation that he showed in class. The short reasoning was used in high school to introduce us to the concept
by Edmund Zhi 2B
Sat Dec 07, 2019 8:21 pm
Forum: Polyprotic Acids & Bases
Topic: HW 6C.17 Which is the stronger base?
Replies: 4
Views: 86

Re: HW 6C.17 Which is the stronger base?

BrO- is more likely to pick up a hydrogen because it is the conjugate base of a weak acid and equilibrium will be more likely to lie the left. This makes it a STRONGER base than C17H19O3N since it is considered a weak base and is not too likely (but still can) pick up a proton with the lone pair on ...
by Edmund Zhi 2B
Wed Dec 04, 2019 4:03 pm
Forum: Biological Examples
Topic: Biological Examples
Replies: 4
Views: 52

Re: Biological Examples

You should also know that hemoglobin is mostly used for oxygen transport, while myoglobin is used mostly for oxygen storage.
by Edmund Zhi 2B
Wed Dec 04, 2019 3:27 pm
Forum: Lewis Acids & Bases
Topic: Hw 6.5
Replies: 4
Views: 46

Hw 6.5

In the reaction, H2O2 + SO3 -> H2SO5, how do you identify which one is the lewis acid and which one is the lewis base? I know what the definitions are, but how do you determine which of the reactions is the electron "donor" and which one is the "acceptor" since they merge into on...
by Edmund Zhi 2B
Wed Dec 04, 2019 1:14 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6C19 parts a and c
Replies: 3
Views: 31

Re: 6C19 parts a and c

The reason why we use electronegativity to determine that HClO is a stronger acid than HBrO is because the hydrogen isn't bonded to the halogen, it's bonded to the oxygen. Now, considering electronegativity, we see that the more electronegative atom will delocalize the electrons/charge more, causing...
by Edmund Zhi 2B
Wed Dec 04, 2019 12:25 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.9
Replies: 5
Views: 47

Re: 6B.9

I got an answer that is different from the textbook as well and is the same as the ones you all got. I've checked my work multiple times. Maybe there's an error in the solutions?
by Edmund Zhi 2B
Tue Dec 03, 2019 9:37 pm
Forum: Biological Examples
Topic: Biological Examples
Replies: 4
Views: 52

Re: Biological Examples

Sara Richmond 1D wrote:What specific biological examples would we know for the final? And what should we know about them?

Box 9C.1 in the textbook may have examples that we could be tested on.
by Edmund Zhi 2B
Tue Dec 03, 2019 11:37 am
Forum: Naming
Topic: Iron vs Ferrate
Replies: 5
Views: 33

Iron vs Ferrate

Why do we sometimes use Ferrate in the name and sometimes use Iron? How do we distinguish between the two?
by Edmund Zhi 2B
Mon Dec 02, 2019 12:23 am
Forum: Conjugate Acids & Bases
Topic: Definition
Replies: 7
Views: 53

Re: Definition

They are sort of opposites of each other.
by Edmund Zhi 2B
Mon Dec 02, 2019 12:22 am
Forum: Biological Examples
Topic: Cisplatin
Replies: 15
Views: 120

Re: Cisplatin

Are we going to have to apply this knowledge for the final or do we just have to memorize it?
by Edmund Zhi 2B
Fri Nov 29, 2019 9:21 pm
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 118

Re: HCl vs HF

HCl is larger and less electronegative than HF. The bond length is therefore longer and less strong, and easier to dissociate in water, where as the H and F are very tightly bonded in H-F
by Edmund Zhi 2B
Fri Nov 29, 2019 9:12 pm
Forum: Conjugate Acids & Bases
Topic: Water as an Acid/Base
Replies: 20
Views: 479

Re: Water as an Acid/Base

Yes because water is amphoteric and you would have to look at what it's reacting with
by Edmund Zhi 2B
Fri Nov 29, 2019 9:11 pm
Forum: Bronsted Acids & Bases
Topic: Strong acids and bases
Replies: 2
Views: 23

Re: Strong acids and bases

Yes I believe so because you have to know that these have 100% dissociation rate, any other acid we would probably be given the dissociation rates in the problem
by Edmund Zhi 2B
Sun Nov 24, 2019 11:39 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Cis vs Trans
Replies: 21
Views: 230

Re: Cis vs Trans

In cis molecules, different side groups are on the same side. In trans molecules, the side groups are on opposite sides, like a trans plane. These exist in compounds with a double bond, which can't rotate.
by Edmund Zhi 2B
Sat Nov 23, 2019 4:47 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Gas Phase Question
Replies: 5
Views: 96

Re: Gas Phase Question

Argon's more electrons can potentially form stronger London dispersion forces than the fewer electrons in Neon
by Edmund Zhi 2B
Sat Nov 23, 2019 4:45 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: What are coordination compounds
Replies: 2
Views: 33

What are coordination compounds

Can someone clarify what coordination compounds are and why they are important/exist?
by Edmund Zhi 2B
Mon Nov 18, 2019 11:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW 2E.13a VSEPR formula
Replies: 1
Views: 26

HW 2E.13a VSEPR formula

For I3- ,why is the VSEPR formula X2E3 and not AX2E3? Would saying the latter be incorrect?
by Edmund Zhi 2B
Mon Nov 18, 2019 11:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: I3-
Replies: 1
Views: 21

Re: I3-

The three lone pairs are actually able to hang around the equator of the molecule, forming a triangle. The other two I atoms can form a 180 degree angle around the axial plane, minimizing repulsion between them.
by Edmund Zhi 2B
Mon Nov 18, 2019 1:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles with different atoms surrounding a central atom
Replies: 1
Views: 22

Bond angles with different atoms surrounding a central atom

In atoms such as CH2F2, where not all the atoms surrounding the central atom are the same, how are bond angles affected? Are they all still about 109.5 degrees or does the greater size of fluorine repel the hydrogens a little bit? If so, which bond angle is greater? H-C-F, H-C-H, or F-C-F? How do we...
by Edmund Zhi 2B
Sun Nov 17, 2019 6:50 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Hydrogen Bonding
Replies: 5
Views: 33

Re: Hydrogen Bonding

Hydrogen bonding is not the bond between hydrogen and another atom. It is the bond that occurs due to a difference in dipole moments between a partial positive hydrogen and a partial negative N, O, or F.
by Edmund Zhi 2B
Sun Nov 17, 2019 6:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Influence of Lone Pair e- on Model
Replies: 5
Views: 50

Re: Influence of Lone Pair e- on Model

Having a lone pair has a greater effect on repulsion because if you think about it, only one atom will be fighting for electrons, where as if there was a bond, two atoms would be exhibiting a nuclear force on the electrons. This means that the lone pair will be pulled closer to the nucleus, and the ...
by Edmund Zhi 2B
Wed Nov 13, 2019 4:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VESPR Model of H2O
Replies: 12
Views: 96

Re: VESPR Model of H2O

We haven't gone over molecules with lone pairs yet. But in H2O, there are 4 regions of electrons. The two lone pairs repel the bonding pairs and the shape is actually bent.
by Edmund Zhi 2B
Wed Nov 13, 2019 4:46 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: HW 3F.15
Replies: 2
Views: 50

HW 3F.15

Can someone please explain why AsF3 has a boiling point of 63C while AsF5 has a boiling point of -53C?
by Edmund Zhi 2B
Wed Nov 13, 2019 4:44 pm
Forum: Bond Lengths & Energies
Topic: Boiling Points (HW 3F.5)
Replies: 2
Views: 28

Boiling Points (HW 3F.5)

Can someone please explain why CHI3 has a higher melting point than CHF3?
by Edmund Zhi 2B
Sun Nov 10, 2019 1:36 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonding
Replies: 3
Views: 45

Re: Hydrogen Bonding

I think the numbers that Lavelle gave in lectures are just averages or typical values to give us an idea of relative strengths. Keep in mind that these numbers are experimentally determined.
by Edmund Zhi 2B
Sun Nov 10, 2019 1:30 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Can polar molecules be more polar than another?
Replies: 5
Views: 38

Re: Can polar molecules be more polar than another?

Molecules are more polar than other molecules when the differences in electronegativity are greater. For example, C-H is a less polar bond than O-H.
by Edmund Zhi 2B
Sun Nov 10, 2019 1:29 pm
Forum: Dipole Moments
Topic: BOND STRENGTH
Replies: 4
Views: 35

Re: BOND STRENGTH

Number of bonds shouldn't be what you're looking at, it should be the differences in electronegativity.
by Edmund Zhi 2B
Tue Nov 05, 2019 4:30 pm
Forum: DeBroglie Equation
Topic: Do neutrons have diffraction patterns?
Replies: 2
Views: 63

Do neutrons have diffraction patterns?

In our lesson about the wave properties of electrons, we learned that electrons passing through a crystal also show diffraction patterns, indicating that electrons exhibit wave characteristics too, just like light. However, we never applied this to protons and neutrons, and in the audio-visual focus...
by Edmund Zhi 2B
Mon Nov 04, 2019 8:02 pm
Forum: Photoelectric Effect
Topic: Details about the photoelectric experiment
Replies: 3
Views: 72

Details about the photoelectric experiment

On the audio-focus visual assessments, there are a lot of questions asking about the specifics of the experiment itself, like its purpose and stuff about its conditions (ex whether or not it needs to be done on a vacuum). Will we have to know these specifics for the midterm because the problems from...
by Edmund Zhi 2B
Sat Nov 02, 2019 4:25 pm
Forum: Octet Exceptions
Topic: expanded octet for P
Replies: 2
Views: 34

Re: expanded octet for P

Asking this question is like asking why the elements in the 2p block don't use 3s for expanded octets. But what you're saying does make sense, and I am equally as confused. I think we are supposed to focus on this part of the definition of the expanded valence model: that there are EMPTY d orbitals ...
by Edmund Zhi 2B
Sat Nov 02, 2019 4:08 pm
Forum: Electronegativity
Topic: Oxygen and Electronegativity
Replies: 5
Views: 34

Re: Oxygen and Electronegativity

Elements such as Oxygen and Fluorine in the upper right hand corner of the periodic table exhibit high electronegativity because 1) Basically, they are really close to filling their valence shell (the 2p orbitals) 2) Increased electrostatic attraction to the nucleus due to more protons than the elem...
by Edmund Zhi 2B
Fri Nov 01, 2019 3:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge vs Actual Charge
Replies: 2
Views: 39

Formal Charge vs Actual Charge

Does the sum of all the formal charges on individual atoms in a compound (the most stable version) ALWAYS equal the actual charge on the entire compound? Like in periodate, where the formal charges on all the oxygens are -1, and the central iodine has a charge of +3, making the sum of the formal cha...
by Edmund Zhi 2B
Tue Oct 29, 2019 11:14 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge and Covalent Bonds
Replies: 3
Views: 36

Re: Formal Charge and Covalent Bonds

Keep in mind the difference between Formal Charge versus oxidation states. What formal charge attempts to do is determine the lowest possible energy configuration for a covalent compound. That is, the most stable. If you're thinking about oxidation states, it is an exaggeration of a charge in a mole...
by Edmund Zhi 2B
Tue Oct 29, 2019 11:11 am
Forum: Resonance Structures
Topic: Resonance vs. Resonance Hybrid
Replies: 2
Views: 34

Re: Resonance vs. Resonance Hybrid

You could think of resonance structures as the underlying idea behind molecules, resonance hybrids are what occur in actuality
by Edmund Zhi 2B
Sun Oct 27, 2019 7:39 pm
Forum: Ionic & Covalent Bonds
Topic: Charges
Replies: 4
Views: 43

Re: Charges

The charge on a molecule is determined by counting the number of electrons that are actually in the compound and then subtracting the sums of all the valence electrons of the individual atoms.
by Edmund Zhi 2B
Sat Oct 26, 2019 11:38 am
Forum: Lewis Structures
Topic: Homework 2B.5 - hypobromite
Replies: 1
Views: 31

Homework 2B.5 - hypobromite

I have found that two versions of the lewis structure have formal charges close to 0. In one, I have Bromine double bonded to an Oxygen atom (this means that Bromine has expanded its octet into the d orbital) with 6 valence electrons on Bromine and 4 on Oxygen. I believe I have done everything right...
by Edmund Zhi 2B
Sat Oct 26, 2019 11:35 am
Forum: Lewis Structures
Topic: HW question 2B.3
Replies: 2
Views: 40

Re: HW question 2B.3

You could also take a look at the formal charges (after making sure all electrons are there) and find that they would not be close to 0. The most optimal lewis structures have formal charges close to 0.

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