Search found 52 matches

by Cynthia Ulloa
Sun Mar 17, 2019 10:01 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: steady state approximation
Replies: 1
Views: 78

steady state approximation

does anyone know if we used the steady state approximation or was it just the pre-equilibrium approximation?
by Cynthia Ulloa
Sun Mar 17, 2019 1:42 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: catalyst vs intermediate
Replies: 3
Views: 101

Re: catalyst vs intermediate

intermediates are produced and then used up in another reaction. a catalyst appears at the beginning and then again at the end. A catalyst can also be a part of the rate law while an intermediate can't.
by Cynthia Ulloa
Sat Mar 16, 2019 11:42 pm
Forum: First Order Reactions
Topic: Finding Order of Reactions
Replies: 1
Views: 79

Finding Order of Reactions

When setting up our rate rations to find the order of reaction, does it matter which rates we take from the experimental data? and how do we decide which to put as our numerator?
by Cynthia Ulloa
Sat Mar 16, 2019 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Shifting K with changes in volume
Replies: 4
Views: 128

Re: Shifting K with changes in volume

If the volume increases, the pressure with decrease and it will shift to the side with more moles. If the volume decreases, the pressure will increase and there will be a shift to the side with less moles.
by Cynthia Ulloa
Thu Mar 14, 2019 5:06 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Ranking species
Replies: 3
Views: 55

Ranking species

On test 2, there were a few questions that asked us to rank the given species in order of increasing oxidation power going from second oxidation state to neutral. Can someone explain how I would go about this?
by Cynthia Ulloa
Thu Mar 14, 2019 4:55 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 1
Views: 45

Concentration Cells

what is a concentration cell and can you give an example please? I want to get a better understanding
by Cynthia Ulloa
Thu Mar 14, 2019 12:14 am
Forum: Phase Changes & Related Calculations
Topic: steam at 100ºC burn worse
Replies: 2
Views: 87

steam at 100ºC burn worse

Why does steam at 100ºC cause a worse burn than boiling water at 100ºC?
by Cynthia Ulloa
Wed Mar 13, 2019 11:56 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell diagrams
Replies: 6
Views: 73

Re: cell diagrams

Also for cell diagrams don't forget to include the H+ as well!
by Cynthia Ulloa
Wed Mar 13, 2019 11:40 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bomb calorimeter
Replies: 6
Views: 129

Bomb calorimeter

can someone explain what the difference between a regular calorimeter and a bomb calorimeter is?
by Cynthia Ulloa
Mon Mar 11, 2019 11:44 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: stability of reactants and products
Replies: 3
Views: 52

stability of reactants and products

How do we describe the stability of reactants and products when we look at which reaction is favored?
by Cynthia Ulloa
Thu Mar 07, 2019 5:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating Eºcell
Replies: 2
Views: 39

Calculating Eºcell

I am looking over my Test 2 and I realized I made a couple of mistakes when calculating for Eºcell. I just want to get clarification on whether we switch the sign of a reaction when we flip it in order to use Eºcell = Eºcathode - Eºanode?
by Cynthia Ulloa
Thu Mar 07, 2019 5:02 pm
Forum: General Rate Laws
Topic: Ratios and Rate laws
Replies: 2
Views: 76

Ratios and Rate laws

I am still confused on how we can use ratios when working with rate laws. Can someone give me an example of how we would set this up?
by Cynthia Ulloa
Thu Mar 07, 2019 12:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ecell
Replies: 13
Views: 198

Re: Ecell

Use Ecell= Eº(cathode) - Eº(anode) and you might have to flip one of the equations. I believe the professor will provide us with the sheet that has the E values for each half reaction so you would just plug in accordingly.
by Cynthia Ulloa
Thu Mar 07, 2019 11:56 am
Forum: General Rate Laws
Topic: Deriving rate laws
Replies: 2
Views: 57

Re: Deriving rate laws

No, I just think you need to be able to understand the equations and how to use them
by Cynthia Ulloa
Thu Mar 07, 2019 11:52 am
Forum: First Order Reactions
Topic: Using ln[A]
Replies: 2
Views: 48

Using ln[A]

Can someone explain to me why we would use ln[A] instead of [A] like we do for the rest of the orders?
by Cynthia Ulloa
Tue Feb 26, 2019 9:50 pm
Forum: Balancing Redox Reactions
Topic: oxidation Numbers
Replies: 2
Views: 47

oxidation Numbers

I am having trouble finding the oxidation numbers from elements. Can someone explain to me how we find them? I know there are a few rules, but I am still confused
by Cynthia Ulloa
Mon Feb 25, 2019 11:29 am
Forum: Balancing Redox Reactions
Topic: determining charges
Replies: 1
Views: 25

determining charges

Can someone explain how we read the total charges on the reactions and when we would need to add electrons to either side?
by Cynthia Ulloa
Mon Feb 25, 2019 10:55 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 1
Views: 30

Gibbs Free Energy

How is the stability of a reaction related to its spontaneity?
by Cynthia Ulloa
Sun Feb 24, 2019 1:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 1
Views: 29

Platinum

Can someone explain to me what the purpose of platinum is? And how do we know when to use it?
by Cynthia Ulloa
Sun Feb 24, 2019 1:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidation and Reduction
Replies: 3
Views: 46

Oxidation and Reduction

When writing our half reactions, will our oxidized reaction always have the e- on the right side? and the reduction reaction will have the e- on the left?
by Cynthia Ulloa
Wed Feb 20, 2019 4:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 5
Views: 68

Salt Bridge

Can someone re-explain to me the purpose of a salt bridge?
by Cynthia Ulloa
Tue Feb 12, 2019 11:47 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 4
Views: 86

Bond Enthalpies

Will the structures be given to us on the midterm or are we expected to know how to draw them?
by Cynthia Ulloa
Tue Feb 12, 2019 9:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: strong and weak acids
Replies: 5
Views: 164

strong and weak acids

Can someone explain why solutions of weak acids have a higher pH?
by Cynthia Ulloa
Mon Feb 11, 2019 4:06 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Higher Molar Entropy
Replies: 3
Views: 85

Higher Molar Entropy

How do we determine which molecules will have a higher molar entropy? and what is residual entropy?
by Cynthia Ulloa
Sun Feb 10, 2019 11:20 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molecular Interlude
Replies: 5
Views: 155

Re: Molecular Interlude

Andre_Galenchik_2L wrote:Don't we need to know that the Cp for a single atom is 5R/2 and the Cv for a single atom is 3R/2?

Yeah, that is what I thought as well
by Cynthia Ulloa
Sun Feb 10, 2019 11:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 5
Views: 86

Hess's Law

There are a few homework problems where we have to make several chemical reactions to solve for Hess's Law. Will we be expected to know how to make them or will the test provide them for us?
by Cynthia Ulloa
Sun Feb 10, 2019 10:31 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 11
Views: 282

Re: Phase Changes

whitneyhawthorne_2C wrote:Understanding it would definitely make problem solving easier so I would try to as much as you can. I took some notes in my discussion with the graph labeled, a picture of it is shown below. Hope it helps!

thank you so much!
by Cynthia Ulloa
Sun Feb 10, 2019 10:30 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.41
Replies: 1
Views: 46

8.41

"A 50.0-g ice cube at 0.0 degree C is added to a glass containing 400.0 g of water at 45.0 degree C. What is the final temperature of the system (see Tables 8.2 and 8.3)? Assume that no heat is lost to the surroundings." Can someone tell me how to go about this problem? I know we will have...
by Cynthia Ulloa
Sun Feb 10, 2019 8:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molecular Interlude
Replies: 5
Views: 155

Molecular Interlude

Will we have to memorize the Cv,m and Cp,m for the rotational motions? e.g. 3R for for nonlinear molecules
by Cynthia Ulloa
Sun Feb 10, 2019 1:12 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 11
Views: 282

Phase Changes

Would it be a good idea to understand 100% the phase changes graph that was shown in class?
by Cynthia Ulloa
Sun Feb 10, 2019 1:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: methods
Replies: 8
Views: 136

Re: methods

Eruchi Okpara 2E wrote:How do you know which bonds need to be broken?

if you draw out the lewis structures you will be able to cross out any new bonds formed or any bonds that were broken. This method will make it easier to go about these problems involving bond enthalpies
by Cynthia Ulloa
Sun Feb 10, 2019 1:07 pm
Forum: Calculating Work of Expansion
Topic: Degeneracy
Replies: 3
Views: 59

Degeneracy

Hello y'all, I am still a bit confused as to what degeneracy is and why it is important for thermodynamics? can someone re-explain? thanks!
by Cynthia Ulloa
Sat Feb 02, 2019 6:33 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Reaction Constant P
Replies: 3
Views: 62

Reaction Constant P

Can someone briefly re-explain what would happen to our internal energy when our P is constant and the moles of a gas change versus when our P is constant and solids and liquids are involved? I more or less understand what the Professor said at Friday's lecture, but I just want clarification.
by Cynthia Ulloa
Sat Feb 02, 2019 5:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Compression of Gas
Replies: 4
Views: 74

Compression of Gas

When we compress a gas, are we adding heat?
by Cynthia Ulloa
Mon Jan 28, 2019 10:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv and Cp
Replies: 3
Views: 67

Cv and Cp

Would it be specified when to use Cv vs Cp or vice versa? Or how would we go about when to use one over the other?
by Cynthia Ulloa
Sun Jan 27, 2019 4:11 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 3
Views: 43

Bond Enthalpies

Hello, I was wondering if someone can explain to me why bond enthalpy is the least accurate?
by Cynthia Ulloa
Sat Jan 26, 2019 9:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sign changes
Replies: 3
Views: 59

Re: Sign changes

yes, the signs can definitely change when adding them up to get the total. As for the negative and positive signs, they let us know whether the reaction was endothermic, absorbing heat, or exothermic, releasing heat.
by Cynthia Ulloa
Sat Jan 26, 2019 3:39 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 3
Views: 58

Bond Enthalpies

Can someone re-explain how we would use bond enthalpies? Would we only account for the new formations?
by Cynthia Ulloa
Wed Jan 23, 2019 4:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 5
Views: 51

Re: Hess's Law

I think this is a topic we will be covering in 14B soon
by Cynthia Ulloa
Mon Jan 21, 2019 12:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Buffer Solutions
Replies: 2
Views: 66

Buffer Solutions

Hey y'all I am still having trouble understanding what buffer solutions are. Why is it that when we create our ICE tables we disregard the salts? How would we go about these types of problems?
by Cynthia Ulloa
Sun Jan 20, 2019 10:11 pm
Forum: Polyprotic Acids & Bases
Topic: Question 12.79 (Sixth Edition)
Replies: 2
Views: 107

Re: Question 12.79 (Sixth Edition)

Would this be due to H2SO4 being a strong acid? so H3O+ would be the same value since it was completely dissolved
by Cynthia Ulloa
Sun Jan 20, 2019 8:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: PEER LEARNING SESSIONS
Replies: 2
Views: 40

PEER LEARNING SESSIONS

does anyone know if the peer learning sessions will still take place tomorrow due to the holiday?
by Cynthia Ulloa
Sun Jan 20, 2019 4:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.57 6th edition
Replies: 1
Views: 20

11.57 6th edition

Can someone explain why we wouldn't convert to molarity before solving the ICE table? I am confused as to why the solution manual didn't convert to molarity
by Cynthia Ulloa
Sat Jan 19, 2019 10:22 pm
Forum: Ideal Gases
Topic: kc vs kp
Replies: 16
Views: 266

Re: kc vs kp

Kp is specific to the equilibrium constant for partial pressures of gases while Kc is used for molar concentrations such as when working with aqueous elements.
by Cynthia Ulloa
Fri Jan 18, 2019 5:33 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: percentage protonation
Replies: 2
Views: 43

Re: percentage protonation

Percentage protonation is a way for us to check if it was okay to approximate our concentrations rather than use the quadratic formula. So, if the percentage was less than 5%, then we are good to go, but if it is higher than 5%, we are going to have to go back and use the quadratic formula.
by Cynthia Ulloa
Thu Jan 17, 2019 11:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: problem 11.11 6th edition
Replies: 1
Views: 25

problem 11.11 6th edition

Hi y'all I am having trouble understanding this problem. Can someone break it down for me and explain how to go about each one?
by Cynthia Ulloa
Wed Jan 16, 2019 9:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration less than 10^-7
Replies: 4
Views: 43

Concentration less than 10^-7

Towards the end of the lecture today, the professor was talking about what would happen if the concentration was less than 10^-7. Can someone re-explain what he meant by this especially when he brought up using 10^-9?
by Cynthia Ulloa
Sat Jan 12, 2019 9:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.39 6th Ed Multiplying K constants
Replies: 3
Views: 57

Re: 11.39 6th Ed Multiplying K constants

Samantha Kwock 1D wrote:If two reactions are added together to form another reaction, then their K constants are multiplied to give the new reaction's K constant.

can you explain why we would multiply the K constants when we add the reactions? Or is this just a property?
by Cynthia Ulloa
Fri Jan 11, 2019 4:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle [ENDORSED]
Replies: 3
Views: 48

Le Chatelier's Principle [ENDORSED]

In lecture today, Professor Lavelle gave us the reaction N2(g) + 3H2(g) --> 2NH3(g) and described what would happen if we increased N2, increased NH3, and decreased H2. Can someone please explain to me each scenario, I am a bit confused still.
by Cynthia Ulloa
Thu Jan 10, 2019 11:08 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K=1
Replies: 5
Views: 75

Re: K=1

When K = 1, this means that the reaction has reached equilibrium. So, the amount of reactants and products would be the same.
by Cynthia Ulloa
Wed Jan 09, 2019 5:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Bar vs. atm
Replies: 4
Views: 43

Re: Bar vs. atm

They are both a measure of pressure so you can use either one depending on what the question gives you. If they give you pressure in terms of atm then you would use atm or vice versa.
by Cynthia Ulloa
Tue Jan 08, 2019 11:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants for Gases
Replies: 1
Views: 38

Re: Equilibrium Constants for Gases

From my understanding, if we increase the pressure of gases, the equilibrium constant will not be affected. The only way the equilibrium constant would be affected is if we changed the temperature.

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