Search found 44 matches

by RyanTran2F
Sat Mar 17, 2018 12:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Conditions of Galvanic Cell Setups
Replies: 1
Views: 62

Standard Conditions of Galvanic Cell Setups

What are the standard conditions of a galvanic cell? Is it only that solutes are at 1 mol/L or are there more requirements? Thanks :)
by RyanTran2F
Fri Mar 16, 2018 5:20 pm
Forum: *Nucleophiles
Topic: Nucleophiles on the final?
Replies: 3
Views: 318

Re: Nucleophiles on the final?

Would we need to know where and how to draw the arrows? Thanks :)
by RyanTran2F
Thu Mar 15, 2018 4:43 pm
Forum: *Electrophilic Addition
Topic: Possible Questions
Replies: 1
Views: 268

Possible Questions

On questions about electrophilic addition, would we be given the diagrams of the molecules and reaction and then be asked to draw arrows or will we have to do all of this by ourselves? Are there any other types of questions that this technique/method will need to be used in? Thank you :)
by RyanTran2F
Tue Mar 13, 2018 5:24 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Test 1 #3
Replies: 4
Views: 258

Test 1 #3

The question asks if heat is being transferred when "A balloon filled with gas is expanded to a larger volume and lower pressure while maintaining the same temperature." The answer is Yes but I am not too sure how to arrive at this answer. Is it since we need to do work on the system to in...
by RyanTran2F
Sun Mar 11, 2018 6:00 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.85
Replies: 1
Views: 85

15.85

Why is the answer in Part b not 2I + Ar -> I2 + Ar (disregard charges on the molecules)? I understand that Ar is on both sides so they can cancel and we get the answer provided in the Answer Key but then why is it in the rate law and not the elementary step? Thanks :)
by RyanTran2F
Sun Mar 11, 2018 5:57 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.79
Replies: 3
Views: 137

15.79

Hi can someone explain how the answer key got the answer in Part A? I did not quite understand the explanation provided. The question asks, "In the reaction of HBr with the reactive intermediate CH3CH=CHCH2+, at low temperatures the predominant species is CH3CHBrCH=CH2, but at high temperatures...
by RyanTran2F
Sun Mar 11, 2018 2:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units
Replies: 3
Views: 188

Units

When we find reaction enthalpies based on bond enthalpies, we multiply the enthalpy (kJ/mol) to break a bond by the number of bonds (mol) so why does the answer in the answer key sometimes have units as kj/mol (ex. 8.75)? Would it be acceptable if we just put units as kJ? Thanks :)
by RyanTran2F
Mon Mar 05, 2018 4:20 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate Laws of Elementary Reactions
Replies: 4
Views: 120

Rate Laws of Elementary Reactions

If the elementary reaction is A + B -> P then the rate of this step is Rate = k[A][B] where each is first order and the overall rate is second order. However, previously in class, we learned that overall reactions can have Rate = k[A]^n [B]^m (and we use initial rates to find the powers), so is the ...
by RyanTran2F
Mon Mar 05, 2018 4:16 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Molecularity
Replies: 3
Views: 93

Molecularity

When we talk about molecularity, is it ONLY used to describe the number of species in an elementary step or will it ever be used to describe a regular overall reaction? Thanks :)
by RyanTran2F
Mon Mar 05, 2018 4:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Elementary Reactions
Replies: 2
Views: 89

Elementary Reactions

Are we given the elementary reactions or will we have to figure out all the components on our own? Thanks :)
by RyanTran2F
Fri Mar 02, 2018 11:50 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Method of Initial Rates and Differential Rate Law
Replies: 1
Views: 103

Method of Initial Rates and Differential Rate Law

Hi just to make sure, is this a correct statement to make: the Differential Rate Law (Rate = -1/a * d[R]/dt = k[R]^n) is related to (and are associated with) the method of initial rates since this method helps us find the n (and other powers if there were more parts to the rate law) and the k? Thank...
by RyanTran2F
Tue Feb 20, 2018 7:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Chapter 14 Outline Questions
Replies: 1
Views: 83

Chapter 14 Outline Questions

How do you define emf and why does it represent a maximum value? Is it just the potential difference between the cathode and anode? How do we know if a metal will dissolve (do we just make a redox reaction with the metal at anode or cathode then see if the reaction is spontaneous in that direction)?...
by RyanTran2F
Tue Feb 20, 2018 6:57 pm
Forum: Balancing Redox Reactions
Topic: 14.15 part b
Replies: 2
Views: 147

Re: 14.15 part b

Why is O2 included in the cell diagram even though it was not in the overall cell reaction? Thanks :)
by RyanTran2F
Mon Feb 19, 2018 11:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.15 Parts b and c [ENDORSED]
Replies: 2
Views: 151

14.15 Parts b and c [ENDORSED]

On Part b, If we know the overall reaction is H+ (aq) + OH- (aq) -> H2O (l) then how did we have O2 and OH- on the anode side of the cell diagram and H+ and O2 on the cathode side? Where did the O2 come from? On Part b, where did we get KOH(aq) in the cell diagram? Thanks :)
by RyanTran2F
Sun Feb 18, 2018 6:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 141

Cell Diagrams

When writing cell diagrams, does the order matter for things on the same side of the ||? Sometimes the book would write it in the same order as it was in the reaction equation (ex. anode side of || would have Au(s) | Au3+ (aq)), but at other times the order would be switched (anode is still on left ...
by RyanTran2F
Fri Feb 16, 2018 9:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 106

Re: Cell Diagrams

Yea I think the book also always had the anode on the left and the cathode on the right (similar to how it is in the galvanic cell picture)
by RyanTran2F
Fri Feb 16, 2018 9:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic vs Concentration
Replies: 3
Views: 119

Re: Galvanic vs Concentration

Galvanic cells often have equal molarities of 2 electrodes but concentration cells have different molarities with the same type of electrode on both sides. About your other 2 questions, I am not too sure but I think this is just another way of using the relationship between chemical and electrical e...
by RyanTran2F
Fri Feb 16, 2018 9:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Potential in Galvanic/Voltaic Cells
Replies: 2
Views: 50

Re: Potential in Galvanic/Voltaic Cells

And to add on to that, this is true for the concentration cell, not the voltaic cell which we learned previously which usually had equal molarities on both sides and different electrodes.
by RyanTran2F
Sat Feb 10, 2018 1:40 pm
Forum: Phase Changes & Related Calculations
Topic: Units [ENDORSED]
Replies: 2
Views: 163

Re: Units [ENDORSED]

I think in class Dr. Lavelle uses 1 atm instead of 1 bar. Also if you are required to interchange between 2 units of pressure, I think he would give you that information on the Constants and Equations Sheet. I hope that helps :)
by RyanTran2F
Sat Feb 10, 2018 1:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Practice Midterm Winter 2018
Replies: 10
Views: 2039

Re: Practice Midterm Winter 2018

Will the work and answers to the questions be posted online after the session? It would be great if they could post a pdf of the work and answers or just have pictures of the work they did during the session. Thanks :)
by RyanTran2F
Wed Feb 07, 2018 1:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Half Reactions
Replies: 6
Views: 195

Half Reactions

If a question asks for the half reactions, do we write it in the order it was given in the equation or always write it as a reduction process (similar to the reaction in the table)? Thanks :)
by RyanTran2F
Sun Feb 04, 2018 11:47 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium Value K
Replies: 3
Views: 149

Equilibrium Value K

At equilibrium, K can be 1, >1, or <1. If K>1 then products are favored and ΔG is negative (the reaction favors the products). We also learned that a reaction proceeds spontaneously towards equilibrium (which is when ΔG = 0) so then does that mean, based on the equation learned in class, that at equ...
by RyanTran2F
Sun Feb 04, 2018 11:36 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Units of ΔS
Replies: 3
Views: 248

Re: Units of ΔS

Hey, If J/k mol is given for enthalpy, and there is no value of mol that needs to be accounted for, then the entropy would also be in J/k mol. In some cases, such as when calculating standard reaction entropy, and you are given the amount of moles per product or reactant, then the answer would like...
by RyanTran2F
Sat Feb 03, 2018 9:21 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Units of ΔS
Replies: 3
Views: 248

Units of ΔS

Why does the answer key sometimes solve for ΔS and say units is J/K but sometimes J/K mol? When do we add on the "per mole" and will we be marked down if we do not have it? Thanks :)
by RyanTran2F
Fri Feb 02, 2018 6:18 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.47 [ENDORSED]
Replies: 2
Views: 107

9.47 [ENDORSED]

Is ΔU = 0 in Part B because of it is an irreversible pathway? I do not understand how the answer key knew ΔU = 0. Thanks :)
by RyanTran2F
Fri Feb 02, 2018 5:37 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.35 [ENDORSED]
Replies: 5
Views: 169

9.35 [ENDORSED]

The answer key says, "The change in entropy for container A is greater than that for container B or C due to the greater number of particles." Is this saying container A has more particles? If so, how does container A have more particles? Thanks :)
by RyanTran2F
Fri Feb 02, 2018 5:10 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.15 and 9.19
Replies: 2
Views: 100

9.15 and 9.19

So in 9.15 we used ΔH boiling and melting points when the thing we are boiling/melting is at its boiling/melting point. If the thing was not at the correct temperature then we would have to account for the energy needed to get it to the boiling/melting point, the energy to boil/melt it, and the ener...
by RyanTran2F
Tue Jan 30, 2018 8:37 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible vs. Reversible Pathways
Replies: 3
Views: 129

Re: Irreversible vs. Reversible Pathways

I think they use reversible pathways since, like Salman said, they change very slowly and in small steps. This way we can add up the changes in each step to get the total entropy. Hope that helps :)
by RyanTran2F
Tue Jan 30, 2018 8:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Page 331 - Figure 9.7
Replies: 1
Views: 103

Re: Page 331 - Figure 9.7

In Part A it is saying that the molecules are at 0 K (no thermal energy) and are fixed so this is when you only examine the picture in the top left since that is the original (and only) microstate that the system can be in. In Part B, the molecules are able to have different microstates so you would...
by RyanTran2F
Tue Jan 30, 2018 8:27 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Graph of G
Replies: 2
Views: 88

Graph of G

In lecture on Monday we had a picture of a graph of G and the system is at equilibrium when the slope is 0. What do the rest of the slopes mean? Does a negative slope (to the left of the equilibrium point) mean that the reaction is spontaneous at that point? Thanks :)
by RyanTran2F
Sat Jan 27, 2018 3:29 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sign of ΔS
Replies: 3
Views: 159

Sign of ΔS

On #9.1A why did the answer key say ΔS = -qrev/T and then have the answer as a positive value? When do we use a negative sign in the formula? I thought it was when entropy decreases but then on #9.5 the answer key also used a negative in 1 value but not the other? So how do you know if we should mak...
by RyanTran2F
Sat Jan 27, 2018 3:24 pm
Forum: Calculating Work of Expansion
Topic: Irreversible Pathway Picture
Replies: 3
Views: 153

Re: Irreversible Pathway Picture

So if the external environment was not a vacuum then, to move the piston, there would be work done and this would not be simply due to entropy but because work was done to push the piston against the external pressure? Thanks :)
by RyanTran2F
Fri Jan 26, 2018 3:32 pm
Forum: Calculating Work of Expansion
Topic: Irreversible Pathway Picture
Replies: 3
Views: 153

Irreversible Pathway Picture

Hi can someone clarify the picture we saw with the piston on Week 3 Friday's lecture? When it says "No work done" pointing from the piston to the right, is it just saying we do not consider the work being done to push the piston? However there IS work being done right (since we have the eq...
by RyanTran2F
Mon Jan 22, 2018 5:50 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Material in Book but not in Lectures
Replies: 5
Views: 153

Re: Material in Book but not in Lectures

Are his tests always based only on those sections? Thanks :)
by RyanTran2F
Mon Jan 22, 2018 5:48 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.25 Units
Replies: 1
Views: 83

8.25 Units

#8.25: A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter (q = -3.50), resulting in a temperature rise of 7.32 degrees Celsius. In a subsequent experiment, 100.0 mL of 0.200 M HBr(aq) and 100.0 mL of 0.20...
by RyanTran2F
Mon Jan 22, 2018 5:37 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity Units
Replies: 1
Views: 74

Heat Capacity Units

Since the step size between Kelvin and Celsius are the same, when we are calculating a heat capacity, are we always allowed to use either Celsius or Kelvin if the question does not specify? Thanks :)
by RyanTran2F
Mon Jan 22, 2018 5:13 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Material in Book but not in Lectures
Replies: 5
Views: 153

Material in Book but not in Lectures

There are some material from the book in the sections Dr. Lavelle told us to read that were not covered during lectures (ex. 8.7, 8.9, Box 8.2, and 8.21). Will material from these sections be on Tests/Midterms/Final? Thanks :)
by RyanTran2F
Fri Jan 19, 2018 4:18 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Mathematical Derivations of Formulas We Use
Replies: 2
Views: 97

Mathematical Derivations of Formulas We Use

Hi. On Tests/Midterms/Final, will we need to know how to derive the formulas we learned (like how he showed us the derivations in class and in the textbook) or will we only need to know how to use them? Thanks :)
by RyanTran2F
Tue Jan 16, 2018 11:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess Law
Replies: 4
Views: 167

Re: Hess Law

You can also think of it as multiplying the equation and enthalpy values by a fraction (ex. multiplying by 1/2 is same as dividing by 2) so this is a valid technique
by RyanTran2F
Tue Jan 16, 2018 11:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.57
Replies: 2
Views: 93

Re: 8.57

In addition to Cam Bear's response, you can see that the question hints at you having to use combustion equation instead of one of the other 2 methods of solving for enthalpy since the book did not tell you to use a specific table or a page in the Appendix. This means you can only use what is given ...
by RyanTran2F
Tue Jan 16, 2018 10:56 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Is there a way specific way to approach into seeing if open closed or isolated?
Replies: 9
Views: 301

Re: Is there a way specific way to approach into seeing if open closed or isolated?

I think you should just look at whether or not energy is moving from one place to another. If it is then the system is closed and if not then it is an isolated system.
by RyanTran2F
Mon Jan 08, 2018 9:56 pm
Forum: Phase Changes & Related Calculations
Topic: Supercooling and Superheating
Replies: 2
Views: 177

Supercooling and Superheating

In section 8.12 we learned about supercooling and superheating. Can someone explain why these can happen? How does something pass the freezing point and the boiling point before freezing/boiling (respectively)? Thanks :)
by RyanTran2F
Mon Jan 08, 2018 9:52 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy and Temperature [ENDORSED]
Replies: 4
Views: 198

Re: Enthalpy and Temperature [ENDORSED]

I agree with Renee's assumption. In the book in section 8.8, it says that at constant pressure, and with no nonexpansion work ΔH = q. q represents heat, which can be increased by increasing the temperature. So with from equation, we see that with increased temperature, ΔH (enthalpy) will increase as...
by RyanTran2F
Mon Jan 08, 2018 9:45 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 8.3 Reversible Isothermal Expansion
Replies: 3
Views: 224

Re: 8.3 Reversible Isothermal Expansion

I agree with Yashaswi's answer. A reversible process is a process that can be reversed as a result of an infinitely small change. If the external pressure is increased one bit, the volume will decrease and vice versa.

Go to advanced search