Search found 96 matches
- Sat Mar 17, 2018 10:57 am
- Forum: Phase Changes & Related Calculations
- Topic: Test #1
- Replies: 4
- Views: 609
Re: Test #1
^@Nicole No, phase changes such as vaporization and melting are endothermic ( you need to add heat to an ice cube in order for it to change phase to liquid) while freezing and condensation are exothermic (I remember it as think of a glass of water. If you somehow took out all the heat in the water i...
- Sat Mar 17, 2018 10:02 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: When do you use LNQ vs LogQ?
- Replies: 1
- Views: 788
When do you use LNQ vs LogQ?
When using the Nernst equation when do you use LnQ vs Log Q? I know the equation has Ln Q but some work I have seen has LogQ
- Thu Mar 15, 2018 10:52 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 14.97? Finding Ka?
- Replies: 1
- Views: 289
14.97? Finding Ka?
I found the equilibrium constant to be K=6.14 x 10^-6. But it asks you to find Ka? I don't understand what Ka is supposed to represent and the solutions says its 2.5x10^3 What is Ka?
- Thu Mar 15, 2018 9:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Could someone explain 14.55 please?
- Replies: 2
- Views: 397
Could someone explain 14.55 please?
14.55 A 1.0 m NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction. (c) With no overpotential or passivity at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis? I don't rememb...
- Thu Mar 15, 2018 12:23 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 d?
- Replies: 1
- Views: 329
14.13 d?
How do you know which Au is going to be the anode and which one is going to be the cathode? I thought in lecture today Lavelle said that the half-reaction with "more positive/less negative" value would be reversed to become the anode? So why does the solutions manual make: Au3+ (aq) +3e- -...
- Thu Mar 15, 2018 12:19 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.17?
- Replies: 2
- Views: 397
14.17?
Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride.
Why doesn't the solutions manual include potassium or chloride ? I am confused
Why doesn't the solutions manual include potassium or chloride ? I am confused
- Wed Mar 14, 2018 10:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: I'm confused on the formula for calculating cell potential?
- Replies: 1
- Views: 380
I'm confused on the formula for calculating cell potential?
So on the equation sheet and in the textbook, it says the cell formula for calculating cell potential is Eo= Eo (right electrode, cathode)- Eo (left electrode,anode)?? But then on other websites it says to find the standard cell potential you ADD them not subtract them ? Look at these websites: http...
- Wed Mar 14, 2018 9:39 pm
- Forum: Balancing Redox Reactions
- Topic: 14.15 a?
- Replies: 2
- Views: 320
Re: 14.15 a?
Ok and then what???
- Wed Mar 14, 2018 8:30 pm
- Forum: Balancing Redox Reactions
- Topic: 14.15 a?
- Replies: 2
- Views: 320
14.15 a?
I don't understand how to find the half reactions when given: AgBr(s) --> Ag+(aq) + Br-(aq), a solubility equilibrium. I understand that at a cathode (reduction)occurs and anode (oxidation) occurs. I just don't understand the books explanation? Does Ag and Br in AgBr(s) each have a charge of 0? Or d...
- Tue Mar 13, 2018 6:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.57? I don't understand the way the solutions manual solved the problem?
- Replies: 1
- Views: 328
8.57? I don't understand the way the solutions manual solved the problem?
8.57 Determine the reaction enthalpy for the hydrogenation of ethyne to ethane, C2H2(g) +2 H2(g)--> C2H6(g), from the following data: DeltaHc(C2H2, g) = -1300. kJ·mol1 DELTA Hc(C2H6, g) = -1560. kJ·mol1 DELTA Hc(H2, g)= - 286 kJ·mol1 So I used the formula: DELTA H rxn= Sum of H produc...
- Tue Mar 13, 2018 4:41 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 9.31? Determining which one has a higher entropy?
- Replies: 1
- Views: 1105
9.31? Determining which one has a higher entropy?
A) Iodine vapor or bromine vapor?
How can you determine which substance has a higher entropy since they are both in the same state?
C) What is meant by "polymerization of ethylene"? How does knowing this information help you determine which has the higher entropy value?
Thanks!
How can you determine which substance has a higher entropy since they are both in the same state?
C) What is meant by "polymerization of ethylene"? How does knowing this information help you determine which has the higher entropy value?
Thanks!
- Sun Mar 11, 2018 6:42 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.67?
- Replies: 5
- Views: 1228
15.67?
Could someone explain to me very simply what they are asking, and what the solution is telling me to do. I do not understand at all
- Sun Mar 11, 2018 5:14 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.51? Molecularity?
- Replies: 3
- Views: 827
15.51? Molecularity?
For 15.51, I don't understand why the overall reaction ( 2NO+Br2 --> 2NOBr) is considered to be bimolecular according to the solutions manual? Wouldn't it be trimolecular, which makes the rate law= k[NO]^2[Br2] ? I thought you include the coefficients when writing a rate law for a reaction and also ...
- Sun Mar 11, 2018 5:08 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: K
- Replies: 7
- Views: 851
Re: K
Hi Cameron,
K can be altered by change in energy or activation energy.
Your friend,
Adriana
K can be altered by change in energy or activation energy.
Your friend,
Adriana
- Sat Mar 10, 2018 10:17 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Michelis-Menten Mechanism?
- Replies: 2
- Views: 375
Michelis-Menten Mechanism?
Hello, I am confused as to what this mechanism/ equation is used for? Could someone explain this to me simply? Thank you
- Sat Mar 10, 2018 9:17 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Collision theory and transition state theory?
- Replies: 2
- Views: 313
Collision theory and transition state theory?
What are the most important concepts we need to know about these two theories? Thank you!
- Sat Mar 10, 2018 9:17 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: How does a homogeneous catalyst affect (a) the rate law; (b) the equilibrium constant? [ENDORSED]
- Replies: 5
- Views: 1121
How does a homogeneous catalyst affect (a) the rate law; (b) the equilibrium constant? [ENDORSED]
This was a self-test question in the book:
How does a homogeneous catalyst affect (a) the rate law; (b) the equilibrium constant?
Could someone please explain in simple terms? Thank you!
How does a homogeneous catalyst affect (a) the rate law; (b) the equilibrium constant?
Could someone please explain in simple terms? Thank you!
- Sat Mar 10, 2018 9:11 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Why aren't homogeneous catalysts consumed by the reaction? [ENDORSED]
- Replies: 1
- Views: 324
Why aren't homogeneous catalysts consumed by the reaction? [ENDORSED]
So I know that catalysts by definition lower the activation energy of a reaction and are not consumed by the reaction itself. However, in a homogeneous reaction (say its liquid catalyst in liquid reactant) the book says that the catalyst is absorbed by the liquid. How come then the catalyst isn't co...
- Sun Mar 04, 2018 2:08 pm
- Forum: General Rate Laws
- Topic: How to know when to use which formula?
- Replies: 2
- Views: 394
How to know when to use which formula?
How do you know if you have to solve for k or any variable really to use "[A]= -kt + [A0]" vs "ln[A]=-kt+ln[A0]" ??
- Sun Mar 04, 2018 1:49 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 15.23?
- Replies: 3
- Views: 473
15.23?
In part C, why isn't [A]t going to be equal to .034? Why do we have to multiply it by two and then subtract that from the concentration of [A] 0 ?
- Sat Mar 03, 2018 6:52 pm
- Forum: General Rate Laws
- Topic: 15.17
- Replies: 1
- Views: 282
15.17
Could someone explain for parts a and b how do they know which experiments is ok to solve for the rate and order? Does it matter which ones you use?
- Sat Mar 03, 2018 4:39 pm
- Forum: General Rate Laws
- Topic: 15.13 part a?
- Replies: 3
- Views: 510
15.13 part a?
So since the formation of HI is second- order wouldn't the formula for finding the rate = k x concentration^2?
The solutions says " From the units of the rate constant, it follows that the reaction is second-order; therefore, rate= k [H2] [I]
The solutions says " From the units of the rate constant, it follows that the reaction is second-order; therefore, rate= k [H2] [I]
- Sat Mar 03, 2018 3:41 pm
- Forum: General Rate Laws
- Topic: 15.3 partb ?
- Replies: 3
- Views: 485
15.3 partb ?
Hello this is a stupid question but (hey it'll be easy points for someone to answer!) Ok for 15.3 part b when you are finding the rate of formation of O2, the solutions manual has O2= (6.2 x -3) (1 mol O2/ 2 mol NO2) So is the general structure for that formula a rate law ? Why do they multiply the ...
- Wed Feb 21, 2018 10:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.17 Potassium Permanganate?
- Replies: 3
- Views: 359
Re: 14.17 Potassium Permanganate?
Ok thank you but how do you know Mn changes to 2+ ??
- Wed Feb 21, 2018 9:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.17 Potassium Permanganate?
- Replies: 3
- Views: 359
14.17 Potassium Permanganate?
When acidifying the potassium permanganate the solutions manual doesn't include potassium ? What happened to it? And chloride in iron chloride?
Also, how do you know Mn is +2 in the product side??
Also, how do you know Mn is +2 in the product side??
- Wed Feb 21, 2018 9:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When writing cell diagrams, how do you know when to include an additional element at the electrode?
- Replies: 5
- Views: 572
When writing cell diagrams, how do you know when to include an additional element at the electrode?
For example 14.13 part b when writing the cell diagram how do you know to include Platinum since the problem didn't indicate you needed it?
- Wed Feb 21, 2018 3:46 pm
- Forum: Balancing Redox Reactions
- Topic: 14.5 a, balancing redox O3 to O2?
- Replies: 1
- Views: 861
14.5 a, balancing redox O3 to O2?
I balanced the elements and have: H20 + O3 --> O2 + 2OH But the solution manual has + 2e- on the left side. If both O3 and O2 have a neutral charge how do you know which is oxidized/reduced?? Shouldn't the two electrons be on the right side because O3 has a charge of -6 and O2 has a charge of -4 (-4...
- Tue Feb 20, 2018 10:33 pm
- Forum: Balancing Redox Reactions
- Topic: 14.1 ???
- Replies: 1
- Views: 213
14.1 ???
The following redox reaction is used in acidic solution in the Breathalyzer test to determine the level of alcohol in the blood.. Hi I know this is going to be a stupid question for y'all but I don't understand how by looking at the reaction you know that Cr is reduced and C is oxidized. Why isn't H...
- Mon Feb 19, 2018 2:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Hydrogen Electrode (SHE)?
- Replies: 1
- Views: 224
Standard Hydrogen Electrode (SHE)?
Can someone explain simply what SHE (standard hydrogen electrodes) are and how exactly does it work? I'm reading about it in 14.6, page 578 but I am very confused. Thank you
- Mon Feb 19, 2018 2:39 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.29
- Replies: 3
- Views: 463
Re: 14.29
I think the phase depends on if it is ionized or not. Ionized elements (they have a charge) are written (aq), where an element in its neutral state has its standard state. For example the oxidation of hydrogen would be H2 (g)/ H+ (aq).
Hope this helped!
Hope this helped!
- Fri Feb 16, 2018 7:29 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Explaining 14.4 (Cell potential and gibbs)
- Replies: 2
- Views: 297
Explaining 14.4 (Cell potential and gibbs)
Hello can someone please explain to me what I just read in simpler terms please (page 572): "There is a hidden assumption in the derivation of Eq. 1. Maximum nonexpansion work is obtained when a cell is operating reversibly. Therefore, Eq. 1 applies only when the pushing power of the cell is ba...
- Tue Feb 13, 2018 7:54 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: ) Which has higher molar entropy, Lead (82Pb) or Carbon (6C)? Why?
- Replies: 1
- Views: 277
) Which has higher molar entropy, Lead (82Pb) or Carbon (6C)? Why?
Could someone explain this please? It is 3H from the practice midterm
- Tue Feb 13, 2018 7:53 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: spontaneity of rev vs irrev
- Replies: 2
- Views: 263
Re: spontaneity of rev vs irrev
Irreversible processes have increasing delta S, so I think it depends on what your temperature and enthalpy are?
Reversible processes have DELTA S=0, so a reversible process will be spontaneous if it is exothermic.
I hope this helped!
Reversible processes have DELTA S=0, so a reversible process will be spontaneous if it is exothermic.
I hope this helped!
- Tue Feb 13, 2018 4:39 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Useful Table of Thermodynamic definitions!!
- Replies: 2
- Views: 636
Useful Table of Thermodynamic definitions!!
Hi everyone, I am making a little table for thermodynamic definitions and including examples and the equations to use. I am mixing up the definitions and get a little confused on when to use which equation and also how to identify in a word problem what kind of thermodynamic equations are being done...
- Sat Feb 10, 2018 3:15 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 9.89 What do aqueous solutions with negative entropiees have in common? [ENDORSED]
- Replies: 1
- Views: 156
9.89 What do aqueous solutions with negative entropiees have in common? [ENDORSED]
Some entries for Sm in Appendix 2A are negative. What is common about these entries, and why would the entropy be negative?
I read the book's explanation and I do not understand what they are talking about when they mention aqueous solutions and reference points
I read the book's explanation and I do not understand what they are talking about when they mention aqueous solutions and reference points
- Sat Feb 10, 2018 2:26 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 9.81? Why is Fe2O3 more thermodynamically stable than Fe3O4?
- Replies: 1
- Views: 1030
9.81? Why is Fe2O3 more thermodynamically stable than Fe3O4?
9.81 Which is the thermodynamically more stable iron oxide in air, Fe3O4(s) or Fe2O3(s)? Justify your selection. The solutions manual states that Fe2O3 is more stable but I don't understand the explanation. I thought that since Fe3O4 has a higher entropy (it has more particles), than Delta G is more...
- Fri Feb 09, 2018 4:14 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 9.69? I am in need of guidance please :)))
- Replies: 1
- Views: 467
9.69? I am in need of guidance please :)))
9.69 Coupled reactions are used in organisms to drive important biochemical processes. Individual chemical reactions may be added together to form a net reaction, and the overall reaction Gibbs free energy is the sum of the individual Gibbs free energies of reaction. For example, ATP is the primary ...
- Fri Feb 09, 2018 4:06 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Question 9.55
- Replies: 2
- Views: 399
Re: Question 9.55
I'm going to use 55 part a to answer your question. So you CAN find ΔH°using: ΔH°reaction= sum of ΔH°products- sum of ΔH°reactants . If you plug in the known standard enthalpy values into the equation, you'll get: ΔH°products= -46.11 kJ/mol -[0+0]. So since the known ΔH° values for H2 and O2 you don...
- Fri Feb 09, 2018 2:38 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 9.55?
- Replies: 1
- Views: 237
9.55?
9.55 Write a balanced chemical equation for the formation reaction of (a) NH3(g); (b) H2O(g); (c) CO(g); (d) NO2(g). For each reaction, determine H, S, and G from data in Appendix 2A When I go to the appendix and I'm looking at the DELTA H standard for NH3, how do I know whether to use the NH3...
- Thu Feb 08, 2018 7:03 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 9.47
- Replies: 2
- Views: 345
9.47
When using the Ideal Gas Law to find the number of moles, how does one know for V which volume to use (initial or final?)
- Thu Feb 08, 2018 6:44 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.43 Using Cp vs Cv?
- Replies: 2
- Views: 401
9.43 Using Cp vs Cv?
Hello, number 43 I thought we were supposed to use Cp because the question asks you to find entropy change with a change in temperature and constant pressure. Using the formula Delta S= nCln (T2/T1), the solution manual uses the heat capacity of water instead of the (5/2R) for C. Why is that ???? Ho...
- Sun Feb 04, 2018 4:50 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.35?
- Replies: 2
- Views: 487
9.35?
"Container A is filled with 1.0 mol of the atoms of an ideal monatomic gas. Container B has 1.0 mol of atoms bound together as diatomic molecules that are not vibrationally active. Container C has 1.0 mol of atoms bound together as diatomic molecules that are vibrationally active. The container...
- Sat Feb 03, 2018 6:09 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Question on 9.15?
- Replies: 1
- Views: 130
Question on 9.15?
"The enthalpies of reactants and products are both affected by a temperature rise, and the difference between their values changes only a little with temperature"
Can someone explain this to me please
Can someone explain this to me please
- Sat Feb 03, 2018 1:50 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Why does an exothermic process lead to an increase in entropy?
- Replies: 3
- Views: 414
Why does an exothermic process lead to an increase in entropy?
I thought an exothermic process would lead to a decrease in entropy due to the fact that it is losing heat. When a substance loses heat then wouldn't it go from gas to liquid to solid and therefore entropy is decreasing?
- Sat Feb 03, 2018 1:25 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: What does it mean for a reaction to be "thermodynamically favored?"
- Replies: 6
- Views: 31405
What does it mean for a reaction to be "thermodynamically favored?"
I saw somewhere that reactions with a negative enthalpy change are exothermic and thus more favorable than reactions with a positive enthalpy change (endothermic). But according to the 2nd Law of Thermodynamics (states that reactions tend to go from low to high entropy) then why is a reaction with a...
- Mon Jan 29, 2018 5:54 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 2. At the temperature of a phase transition, the transfer of heat is reversible."
- Replies: 2
- Views: 339
2. At the temperature of a phase transition, the transfer of heat is reversible."
Hello I am reading in 9.4:
"2. At the temperature of a phase transition, the transfer of heat is reversible."
Can someone explain to me what is meant by this please?
"2. At the temperature of a phase transition, the transfer of heat is reversible."
Can someone explain to me what is meant by this please?
- Mon Jan 29, 2018 5:50 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Adiabatic and enthalpy related?
- Replies: 2
- Views: 410
Re: Adiabatic and enthalpy related?
I think Delta H is going to be 0 because there is no transfer of heat taking place.
Also this link I found helpful
https://chemistry.stackexchange.com/que ... tic-system
Also this link I found helpful
https://chemistry.stackexchange.com/que ... tic-system
- Mon Jan 29, 2018 5:36 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Calculating change in entropy for a process? (9.3)
- Replies: 2
- Views: 331
Calculating change in entropy for a process? (9.3)
In 9.3, page 325 it reads: "To calculate a change in entropy for a process, we find a reversible path between the initial and final states. It is immaterial whether the actual process is irreversible or reversible. Because entropy is a state function, the change for that path will be the same a...
- Mon Jan 29, 2018 4:53 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Would someone be able to share today's lecture notes please?
- Replies: 1
- Views: 340
Would someone be able to share today's lecture notes please?
Hello, I was not able to go to lecture today. Would someone be able to share their notes or summarize what we learned about in today's lecture (1/29/18)?
Thank you :)
Thank you :)
- Wed Jan 24, 2018 3:39 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Lecture 1/24 (Wednesday) [ENDORSED]
- Replies: 5
- Views: 577
Re: Lecture 1/24 (Wednesday) [ENDORSED]
Why are these equations derived?
- Wed Jan 24, 2018 1:27 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: What are the types of calorimeters we learned about/ covered in class?
- Replies: 4
- Views: 465
What are the types of calorimeters we learned about/ covered in class?
I know about the bomb calorimeter, which measures the heat of a reaction via combustion (burning an object). Is there another kind we learned about?
- Wed Jan 24, 2018 12:48 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Lecture 1/24 (Wednesday) [ENDORSED]
- Replies: 5
- Views: 577
Lecture 1/24 (Wednesday) [ENDORSED]
Hello, for today's lecture could someone summarize what Lavelle was talking about with the integral equations, and where can we find that section in the book?
Thank you :)
Thank you :)
- Wed Jan 24, 2018 12:35 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: C(deltaT) vs mC(deltaT)
- Replies: 4
- Views: 2921
Re: C(deltaT) vs mC(deltaT)
What is the difference between heat capacity and specific heat ?
- Tue Jan 23, 2018 8:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: When can we pick up our finals from Chem 14A?
- Replies: 3
- Views: 765
When can we pick up our finals from Chem 14A?
Where can we pick up last quarter's final
- Sun Jan 21, 2018 2:31 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 8.31? Molar heat capacity of a monatomic idea gas at constant pressure?
- Replies: 1
- Views: 273
8.31? Molar heat capacity of a monatomic idea gas at constant pressure?
So for part a) for the molar heat capacity of a monatomic ideal gas at constant pressure is Cp,m= 5/2 R. Why? Where did this value come from? ( in the solutions I see it is 20.8J/mol x C) ?
Also same for part b) the molar heat capacity of a monatomic ideal gas at constant value is 3/2R. Why??:???????
Also same for part b) the molar heat capacity of a monatomic ideal gas at constant value is 3/2R. Why??:???????
- Sun Jan 21, 2018 2:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Why is enthalpy a state function? Why is heat not a state function?
- Replies: 5
- Views: 10055
Re: Why is enthalpy a state function? Why is heat not a state function?
What does it mean by not depending on "paths taken"?
- Sun Jan 21, 2018 1:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Why is enthalpy a state function? Why is heat not a state function?
- Replies: 5
- Views: 10055
Why is enthalpy a state function? Why is heat not a state function?
Can someone please explain what exactly is a state function? I've found definitions online but I still don't get it. And why is enthalpy a state function and heat is not a state function?
Thank you
Thank you
- Sat Jan 20, 2018 4:50 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard State [ENDORSED]
- Replies: 2
- Views: 160
Re: Standard State [ENDORSED]
I am pretty sure that you have to memorize them. For example the noble gases are gas in standard state with the exception of Br2 (liquid) and Iodine (solid). If it was an element we don't usually talk about, I think they would give us on the test
- Sat Jan 20, 2018 4:33 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard enthalpies of formation?
- Replies: 1
- Views: 125
Standard enthalpies of formation?
Could someone explain to me in simple terms so I can understand what is standard enthalpy of formation? I've read about it but I don't get it??? Or any videos or links that would help explain it to me pls
- Sat Jan 13, 2018 2:55 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Table 8.3 in the book (page 284, 8.11)
- Replies: 1
- Views: 262
Table 8.3 in the book (page 284, 8.11)
So why is that that the values for boiling and freezing point are expressed in Kelvin while Delta H fus and Delta H vap are expressed in kJmol -1???
- Sat Jan 13, 2018 2:53 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of physical change?
- Replies: 3
- Views: 1078
Enthalpy of physical change?
In the book chapter 8.11, there is a part: The difference in molar enthalpy between the vapor and the liquid states is called the enthalpy of vaporization... The enthalpy of vaporization of most substances changes little with temperature. *** For water at its boiling point, 100 C, Hvap 40.7 kJm...
- Fri Jan 12, 2018 4:36 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat capacity at constant volume (Cv) vs Heat capacity at constant pressure (Cp)?
- Replies: 1
- Views: 174
Heat capacity at constant volume (Cv) vs Heat capacity at constant pressure (Cp)?
So the equation for Cv= Delta U/ Delta T and the equation for Cp= Delta H/ Delta T My question is: how come in the equation for Cv it has Delta U (change in internal energy) while the equation for Cp it has Delta H (change in enthalpy)? How do those differences help determine Cv vs Cp? I think if so...
- Wed Jan 10, 2018 5:16 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lecture?
- Replies: 3
- Views: 285
What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lecture?
Hello, I do not understand what Lavelle was doing with the Lewis structures and bond enthalpy in class today (1/10) . Could someone please explain ?
- Sat Dec 09, 2017 2:44 pm
- Forum: Bronsted Acids & Bases
- Topic: 12.25?
- Replies: 3
- Views: 1697
Re: 12.25?
how do you know ba(oh)2 is a small base
- Fri Dec 08, 2017 11:42 pm
- Forum: Bronsted Acids & Bases
- Topic: 12.25?
- Replies: 3
- Views: 1697
12.25?
Calculate the initial molarity of Ba(OH)2 and the molarities of Ba2+, OH- and H3O+ in an aqueous solution that contains .43g of Ba(OH)2 in .100L
I do not understand how to begin this problem. Please help
I do not understand how to begin this problem. Please help
- Fri Dec 08, 2017 9:35 pm
- Forum: Bronsted Acids & Bases
- Topic: 12.17 How can you determine if an oxide is acidic, basic, or amphoteric
- Replies: 1
- Views: 751
12.17 How can you determine if an oxide is acidic, basic, or amphoteric
Ok so I understand that: -An acidic oxide is an oxide that reacts with water to form a solution of a Bronstead acid. (Co2+ H2CO3) -A basic oxide is an oxide that reacts with water to form a solution of hydroxide ions -Amphoteric are substances that react with both bases and acids How can I determine...
- Fri Dec 08, 2017 12:24 am
- Forum: Bronsted Acids & Bases
- Topic: Do we need to memorize table 12.2 and 12.3? [ENDORSED]
- Replies: 3
- Views: 615
Do we need to memorize table 12.2 and 12.3? [ENDORSED]
Table 12.2 and 12.3 lists basicity and acidity constants for acids and bases. Do we need to know these constants for the final or would they be given if we need them?
- Thu Dec 07, 2017 10:02 pm
- Forum: Bronsted Acids & Bases
- Topic: "Do you expect the pH of pure water to increase or decrease with increasing temperature?"
- Replies: 1
- Views: 354
"Do you expect the pH of pure water to increase or decrease with increasing temperature?"
Hi I'm reading through the book right now and I saw this on page 472. It doesn't provide an answer but I was wondering if this is important? Thank you
- Thu Dec 07, 2017 7:39 pm
- Forum: Amphoteric Compounds
- Topic: Is water both amphoteric and amphiprotic? [ENDORSED]
- Replies: 2
- Views: 1535
Is water both amphoteric and amphiprotic? [ENDORSED]
Or is water JUST amphiprotic? Also can someone distinguish/explain the difference between the two more clearly? Thank you!
- Sun Nov 26, 2017 5:22 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: #4.29? Determining which isomer has the largest dipole moment?
- Replies: 2
- Views: 629
#4.29? Determining which isomer has the largest dipole moment?
Between figures 1 and 2 I understand they are polar because the Cl creates dipole moments. Between the two figures, how do you determine which one has the larger dipole moments?
- Sun Nov 26, 2017 3:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chem equilibrium module 4, Question #13?
- Replies: 1
- Views: 207
Chem equilibrium module 4, Question #13?
13. State whether the equilibrium shifts towards products, reactants, or neither when the given change occurs. 2 HI(g) + Cl2(g) ⇌ 2 HCl(g) + I2(s) delta H° = -238.0 kJ.mol-1 i. The volume of the system is compressed. ii. The temperature of the system is decreased. A. i = Products, ii = Products B. ...
- Sun Nov 26, 2017 3:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Post Assessment Equilibrium Part 2 #30
- Replies: 2
- Views: 2271
Re: Post Assessment Equilibrium Part 2 #30
Hello, Ok So you first calculated everything to molarity values which is good. You should have gotten the concentration of H20 to be .05 M. So you are given an initial concentration value of H20 and equilibrium concentration value of H2. Kc= [H2][CO]/[H20] (Omit C in your setup as it is a pure solid...
- Sun Nov 26, 2017 11:25 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equilibrium module Part 2 #27?
- Replies: 2
- Views: 307
Re: Chemical Equilibrium module Part 2 #27?
That was helpful thank you!
- Sun Nov 26, 2017 11:22 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: How can you determine if a complex is a polydentate?
- Replies: 5
- Views: 1108
- Sat Nov 25, 2017 7:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equilibrium module Part 2 #27?
- Replies: 2
- Views: 307
Chemical Equilibrium module Part 2 #27?
27. A mixture of 2.5 moles H2O and 100 g of C are placed in a 50 L container and allowed to come to equilibrium subject to the following reaction: C(s) + H2O (g) ⇌ CO (g) + H2 (g) The equilibrium concentration of hydrogen is found to be [H2] = 0.040 M. What is the equilibrium concentration of water,...
- Sat Nov 25, 2017 6:34 pm
- Forum: Ideal Gases
- Topic: Units of Partial Pressure
- Replies: 7
- Views: 969
Re: Units of Partial Pressure
^ No, in the problems we've been doing in the book, partial pressure from Kp is in atm not Pascals
- Sat Nov 25, 2017 4:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chem Equilibrium Module Question #27 & #29?
- Replies: 1
- Views: 175
Chem Equilibrium Module Question #27 & #29?
27. For a reaction with K > 1 what do we know? I put B. The initial concentration of product(s) is higher than the initial concentration of reactant(s). I understand that K>1 means that the reaction lies to the right because then the initial concentration of products must be greater than initial con...
- Sat Nov 25, 2017 4:03 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Determining how many binding sites a ligand has
- Replies: 1
- Views: 384
Re: Determining how many binding sites a ligand has
A ligand (polydentate) can bond 2 to 9 max. To determine the number of binding sites a ligand has, count the number of atoms that have lone pairs and can act as donor atoms. For example, if there are two donor atoms then it has two binding sites and thus is a bidentate ligand (like ethylenediamine)
- Fri Nov 24, 2017 12:20 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Determining whether a complex is tetrahedral or square-planar?
- Replies: 2
- Views: 1196
Determining whether a complex is tetrahedral or square-planar?
I understand that a complex with coordination number 4 can either be a tetrahedral or square-planar complex. How can you know which one it will be exactly? I read the book definitions: -Tetrahedral complex-"the four ligands are found at the vertices of the tetrahedron, as in the [CoCl4]^2-"...
- Fri Nov 24, 2017 12:17 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: How can you determine if a complex is a polydentate?
- Replies: 5
- Views: 1108
How can you determine if a complex is a polydentate?
I understand that a polydentate ligands are able to occupy more than 1 binding site simultaneously. How can you determine if a complex is a polydentate and if so, the type (bidentate, tridentate) and if it will form a chelate? I already memorized the ones mentioned in our book such as EDTA and theyl...
- Tue Nov 21, 2017 9:55 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: #4.25 Predicting Polarity of a molecule?
- Replies: 1
- Views: 1255
#4.25 Predicting Polarity of a molecule?
So I drew the Lewis Structure for a) CH2Cl2 and drew it out with C as the central atom and two Cl attached to it (single bond) and two H atoms attached to it (single bond). How can I predict polarity? I know that a molecule is nonpolar when the dipoles cancel each other out and polar when the dipole...
- Wed Nov 15, 2017 5:07 pm
- Forum: Sigma & Pi Bonds
- Topic: When looking at at molecule how can I determine when they will form sigma and pi bonds?
- Replies: 3
- Views: 491
When looking at at molecule how can I determine when they will form sigma and pi bonds?
I understand what sigma and pi bonds are, but there is an example in the text asking how many sigma and pi bonds there are in a) CO2 and b) CO?
I do not understand how I can determine the number of sigma and pi bonds there are in these molecules.
I do not understand how I can determine the number of sigma and pi bonds there are in these molecules.
- Wed Nov 15, 2017 5:04 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Understanding sigma and pi bonds?
- Replies: 8
- Views: 817
Understanding sigma and pi bonds?
So I have a general understanding of what a sigma and pi bonds are. Correct me if I am wrong but what I understand so far is: A sigma bond forms when the electron orbitals from different atoms overlap along the internuclear axis. They are cylindrically symmetrical with no nodal planes containing the...
- Wed Nov 15, 2017 4:58 pm
- Forum: Octet Exceptions
- Topic: Why do octets expand?
- Replies: 4
- Views: 571
Re: Why do octets expand?
Nonmetal atoms in period 3 or later can expanded their valence shells because they have empty d-orbitals where they can store electrons.
For example, Sulfur e-configuration is: [Ne] 3s2 3p4. However, it has a 3d orbital available for bonding
For example, Sulfur e-configuration is: [Ne] 3s2 3p4. However, it has a 3d orbital available for bonding
- Sun Nov 05, 2017 9:48 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 3.9 and 3.11 in the homework? I am confused as to what it is they are asking
- Replies: 3
- Views: 797
3.9 and 3.11 in the homework? I am confused as to what it is they are asking
So 3.9 asks "Which M2+ ions (where M is a metal) are predicted to have the following ground-state electron configurations: a) [Ar] 3d7 b) [Ar]3d6 and so on. So for a) I got Co2+ and b) Fe2+ because those are the neutral electron configurations for those metals. And then I check the answer in th...
- Sun Nov 05, 2017 9:32 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 3.5 Give the ground state configuration expected for each of the following ions:
- Replies: 3
- Views: 2793
3.5 Give the ground state configuration expected for each of the following ions:
Hello, I am confused for question: 3.5 Give the ground state electron configuration expected for each of the following ions: a) Cu+ b) Bi3+ c) Ga3+ d) Tl3+ So originally I thought the question was asking me what is the regular configuration for them since it said ground state (so I wrote the neutral...
- Mon Oct 30, 2017 2:52 pm
- Forum: *Shrodinger Equation
- Topic: "Describe the interpretation of atomic orbitals in terms of probability"
- Replies: 1
- Views: 444
"Describe the interpretation of atomic orbitals in terms of probability"
Hello, I am reviewing for tomorrow's test and I looked on the Chapter 2 Outline for what we should know. One of the points we should know states "Describe interpretation of atomic orbitals in terms of probability". Is a fair statement to describe atomic orbitals in terms of probability: &q...
- Sat Oct 28, 2017 5:07 pm
- Forum: *Shrodinger Equation
- Topic: "Hydrogen occupies a unique position in the periodic table..." ??? [ENDORSED]
- Replies: 1
- Views: 645
"Hydrogen occupies a unique position in the periodic table..." ??? [ENDORSED]
So this statement found in the book (2.7 page 49) "Hydrogen occupies a unique position in the periodic table. It has one s-electron, and so it belongs in Group 1; but it is also one electron short of a noble-gas configuration, and so it can act like a member of Group 17". I am confused as ...
- Sat Oct 28, 2017 5:03 pm
- Forum: *Shrodinger Equation
- Topic: Concept [ENDORSED]
- Replies: 1
- Views: 262
Re: Concept [ENDORSED]
Hi, I think you only need to understand the theory part of the equation and NOT how to calculate using it. So the most important thing to understand about Schrodinger's is that it calculates the wavefunction for a given particle (electron) and corresponding energy. What this means is that the wavefu...
- Sun Oct 22, 2017 9:05 pm
- Forum: Properties of Light
- Topic: Heisenberg's indeterminacy principle
- Replies: 2
- Views: 419
Re: Heisenberg's indeterminacy principle
For sure, H is Planck's Constant which is 6.626 x 10^-34 Jxs^-1. It relates the energy in one quantum (photon) of electromagnetic radiation to the frequency.
- Sat Oct 21, 2017 10:43 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Module #23?
- Replies: 4
- Views: 710
Re: Heisenberg Module #23?
"In order to find the speed, you must use the values given to you and plug it into the Heisenberg equation. The only value you should be missing is speed since for the momentum part of the equation is equal to (mass)(velocity). The rest of the equation is either constants or given to you in the...
- Sat Oct 21, 2017 9:39 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Module #23?
- Replies: 4
- Views: 710
Heisenberg Module #23?
You are caught in a radar trap and hope to show that the speed measured by the radar gun is in error due to the Heisenberg uncertainty principle. If you assume that the uncertainty in your position was +/- 5 m when your speed was measured, and that the car has a mass of 2150 kg, what is your calcula...
- Fri Oct 13, 2017 4:07 pm
- Forum: General Science Questions
- Topic: What is Rydberg's Constant?
- Replies: 1
- Views: 1313
What is Rydberg's Constant?
Hi, I am a bit confused on what is Rydberg's Constant, is it 3.29x10^15? Because I watched a video on Khan Academy and R is 1.097x10^7? And when you google "Rydberg's Constant" that is what comes up
- Thu Oct 12, 2017 11:10 am
- Forum: Properties of Light
- Topic: When is the Date of Test #2?
- Replies: 1
- Views: 319
Re: When is the Date of Test #2?
The tests are going to begin starting next week in discussions 10/17. So if your discussion is next Wednesday, it'll be then. If your discussion is on Tuesday, it'll be then
- Wed Oct 11, 2017 11:51 pm
- Forum: General Science Questions
- Topic: Photoelectric Module #29 [ENDORSED]
- Replies: 1
- Views: 488
Photoelectric Module #29 [ENDORSED]
Hello I am having trouble with this question and would like some guidance please. 29. B. How much energy is required to remove an electron from one sodium atom? (Work function for sodium is 150.6 kJ.mol-1. ) Hello, so I understood how to do the previous question and found the kinetic energy of the e...
- Mon Oct 09, 2017 11:20 pm
- Forum: General Science Questions
- Topic: Rusty on High School Chem [ENDORSED]
- Replies: 347
- Views: 416380
Re: Rusty on High School Chem [ENDORSED]
I took high school chemistry my sophomore year of high school and have not taken AP Chemistry. Since I am a bit "rusty", something that helped me review what I learned about chemistry was outlining the chapters, completing the modules, doing the homework problems, and going to the night st...