Search found 54 matches
- Tue Mar 13, 2018 12:19 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.63
- Replies: 3
- Views: 540
Re: 15.63
I had the same question, and I was also wondering if the solutions made a mistake when it wrote down that K was 3130 and it actually meant 310 K. Thank you!
- Tue Mar 13, 2018 12:14 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Hw 15.67
- Replies: 5
- Views: 1618
Re: Hw 15.67
In this equation you cancel out A, but if you didn't what is A and what do you plug into the equation for it?
- Tue Mar 13, 2018 12:13 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.61
- Replies: 3
- Views: 661
Re: 15.61
I think that when you look at K it is K = k/k', but when you are looking at ln then it is ln(k'/k)
- Tue Mar 13, 2018 12:11 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Adsorption
- Replies: 3
- Views: 628
Re: Adsorption
If the catalyst is the solid in the reaction and the reaction occurs in the surface of the solid, can it be assumed that the catalyst is the excess substance in the reaction? Or will this not always be the case?
- Sat Mar 03, 2018 12:50 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Straight line
- Replies: 7
- Views: 1766
Re: Straight line
It is also important to note that the slopes of these graphs will be either -k or k
- Sat Mar 03, 2018 12:48 pm
- Forum: General Rate Laws
- Topic: Finding reaction rate [ENDORSED]
- Replies: 5
- Views: 787
Re: Finding reaction rate [ENDORSED]
There was a question in which the answer was in mmol. I guess this is ok as long as what you are solving for maintains the units you used.
- Sat Mar 03, 2018 12:47 pm
- Forum: General Rate Laws
- Topic: Rate Law dependent on Reactants [ENDORSED]
- Replies: 4
- Views: 774
Re: Rate Law dependent on Reactants [ENDORSED]
How would we take into account temperature and activation energy when calculating k? Also, I'm confused about all the meanings we have given K in this class. Is k here the rate or the equilibrium constant?
- Sat Mar 03, 2018 12:44 pm
- Forum: General Rate Laws
- Topic: 15.3 C
- Replies: 8
- Views: 1619
Re: 15.3 C
All you have to do to change and correct your answer if find the rate PER mole
- Sat Mar 03, 2018 12:42 pm
- Forum: General Rate Laws
- Topic: Deriving integrated rate laws
- Replies: 4
- Views: 600
Re: Deriving integrated rate laws
Does the y=mx+b form refer to anything else than the graphs we looked at in class?
- Sat Mar 03, 2018 12:41 pm
- Forum: General Rate Laws
- Topic: Unique Reaction Rates [ENDORSED]
- Replies: 45
- Views: 163753
Re: Unique Reaction Rates [ENDORSED]
Does this mean that even if all the stoichiometric coefficients were different, because of the concentrations of each species then all rates would be the same? And does unique rate refer to the equality of all rates or of one species only?
- Sat Mar 03, 2018 12:36 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Overall order
- Replies: 4
- Views: 791
Re: Overall order
The order of each individual reactant or product serves to solve for the reactions used in class. But I don't see what the overall order would be used for.
- Sat Mar 03, 2018 12:32 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: What is Free Energy of Activation
- Replies: 11
- Views: 3608
Re: What is Free Energy of Activation
When you say it includes both entropy and enthalpy are you saying that because when one calculates Gibbs free energy you use both in the equation? Would both of the values used be referring to the activation energy?
- Thu Feb 22, 2018 3:53 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation Energy
- Replies: 4
- Views: 995
Re: Activation Energy
If the amount of energy that is needed to make a reaction happen is small, then no matter how much you raise temperature, the reaction will occur regardless because it only needs a small increase in order to occur.
- Thu Feb 22, 2018 3:40 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Diamond and graphite
- Replies: 8
- Views: 3546
Re: Diamond and graphite
Diamond turns into graphite spontaneously, but that does not mean it occurs fast. In fact, it happens very very slowly, for kinetics rather than thermodynamics is controlling this reaction. The diamond is kinetically stable with respect to graphite, yet thermodynamically unstable.
- Thu Feb 22, 2018 3:30 pm
- Forum: General Rate Laws
- Topic: Convention of the Negative Sign [ENDORSED]
- Replies: 1
- Views: 397
Convention of the Negative Sign [ENDORSED]
I understand why in class we were told that since the concentration of the reactants decreases, then a negative sign is placed in front of the equation so that the resulting answer is positive. However, why not keep it in order to have it be an indicator that the species is in fact a reactant? If th...
- Wed Feb 14, 2018 10:19 pm
- Forum: Balancing Redox Reactions
- Topic: Salt Bridges
- Replies: 14
- Views: 1352
Re: Salt Bridges
How would the charges of each side be balanced using a porous disk? Also, a single line in the shorthand equation serves as a porous disk too instead of two lines signifying a salt bridge, and when the reactants and products of one half equation are in the same state you separate them by a comma.
- Wed Feb 14, 2018 10:16 pm
- Forum: Balancing Redox Reactions
- Topic: 14.1 Question
- Replies: 2
- Views: 449
Re: 14.1 Question
How I usually do it is that I use the simple reduction and oxidation reactions and once I have those down into one overall reaction, I balance the charges adding H protons, and balance the H and Os adding water.
- Wed Feb 14, 2018 10:14 pm
- Forum: Balancing Redox Reactions
- Topic: Standard Reduction Potentials Concept
- Replies: 4
- Views: 2544
Re: Standard Reduction Potentials Concept
I understand that all values are for standard reduction potentials, but when using the Ecell=Ecathode-Eanode we plug in both values for the reduction potential of the equations from the anode and cathode even when we know the reaction at the anode is actually the reverse reaction since it is actuall...
- Sat Feb 10, 2018 1:22 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Free expansion
- Replies: 2
- Views: 471
Re: Free expansion
So no work is done but there still is a change in internal energy due to the change in volume?
- Sat Feb 10, 2018 1:19 pm
- Forum: Calculating Work of Expansion
- Topic: Work Equations [ENDORSED]
- Replies: 9
- Views: 1439
Re: Work Equations [ENDORSED]
Will the problem always say that the reaction is isothermal? Or will it not always be the case and how does this change your way of approaching the problem?
- Sat Feb 10, 2018 1:09 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Degeneracy (W) [ENDORSED]
- Replies: 8
- Views: 1270
Re: Degeneracy (W) [ENDORSED]
I have seen some problems in which W also sometimes is calculated using Avogadro's number. When would this be the case instead of doing 2^molecules in the system?
- Sat Feb 10, 2018 1:07 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible an Irreversible [ENDORSED]
- Replies: 4
- Views: 802
Re: Reversible an Irreversible [ENDORSED]
Is it correct to think that in a reversible expansion, the deltaStotal would be zero, and that in an irreversible expansion the deltaSsurrounding would be zero?
- Thu Feb 01, 2018 4:43 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Bomb calorimeter
- Replies: 7
- Views: 814
Re: Bomb calorimeter
Also, an easy way to remember that it is bomb calorimeter is that since the volume does not change, pressure builds up inside against the constant volume!
- Thu Feb 01, 2018 4:40 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Second Law of Thermodynamics [ENDORSED]
- Replies: 5
- Views: 1004
Re: Second Law of Thermodynamics [ENDORSED]
So according to the law, disorder increases until equilibrium is reached? So disorder does not always increase?
- Thu Feb 01, 2018 4:37 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Lunchbox?
- Replies: 3
- Views: 574
Re: Lunchbox?
Hi! I guess the lunchbox, if it is completely sealed and no matter was taken from its inside it could be isolated? As long as no matter and energy are lost then it would be.
- Mon Jan 22, 2018 12:02 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Question 8.103
- Replies: 1
- Views: 315
Question 8.103
Can someone explain why the solution manual states that the average kinetic energy expression is 3/2RT, when the constants sheet states nRT? Can we assume this is an ideal gas and that there is only one mol so it matches up with the J/mol?
- Sun Jan 21, 2018 11:59 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.99
- Replies: 6
- Views: 645
Re: Problem 8.99
How does calculating limiting reactant impact this problem?
- Sun Jan 21, 2018 11:59 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.99
- Replies: 6
- Views: 645
Re: Problem 8.99
In the previous explanation for this question, how is the ZnCl2 separated? Should we say they are separated into their ionized versions and calculate the enthalpies of each? Isn't the product ZnCl2 and we should use bond enthalpies of two ZnCl bonds? And how is the enthalpy of formation of 2Cl somet...
- Wed Jan 17, 2018 11:04 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Self-Test 8.5B
- Replies: 3
- Views: 388
Re: Self-Test 8.5B
Did you use an equation provided by the equations sheet? OR can we also think about this logically? I am finding it really hard to think about what to subtract or add from something else with the way things are worded.
- Wed Jan 17, 2018 11:00 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Q 8.13
- Replies: 9
- Views: 1040
Re: Q 8.13
Does it matter if we are talking about work or heat? I understand that when heat is lost it is negative, but what about work? I am confused about these two terms
- Wed Jan 17, 2018 10:56 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: U and H
- Replies: 3
- Views: 479
U and H
Can someone please clarify the difference between deltaU and deltaH and how they relate to each other in the equation deltaU = deltaH-pdeltaV
- Wed Jan 10, 2018 7:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy is a state property
- Replies: 13
- Views: 1883
Re: Enthalpy is a state property
We can also think about state properties in the way Dr Lavelle showed us in class with the mountain image. In class, the path the hikers took to get from point A to B did not matter, which is what the rest was saying about the initial and final points.
- Wed Jan 10, 2018 7:39 pm
- Forum: Phase Changes & Related Calculations
- Topic: Supercooling and Superheating
- Replies: 2
- Views: 372
Re: Supercooling and Superheating
Do you think we will be asked to pdo problems in which the delta Hs refer to supercooling and superheating problems? Would they be solved the same way or do some specific rules apply?
- Wed Jan 10, 2018 7:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endo and Exothermic Ways to Remember
- Replies: 28
- Views: 11640
Re: Endo and Exothermic Ways to Remember
Adding to what everyone else has said and like someone said, it is also important to see how these terms refer to a reaction. If the reaction is exothermic, you are releasing heat, meaning that on the products side of your reaction you could add heat. Meanwhile, if the reaction is endothermic, you a...
- Tue Dec 05, 2017 10:49 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Problem 12.69
- Replies: 8
- Views: 2951
Re: Problem 12.69
How do you go about solving the problem (a) is you only have Kb of NH3 and it is on the products side? Are you supposed to solve for Ka or should you keep Kb and work to the other side?
- Tue Dec 05, 2017 4:42 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: 12.57
- Replies: 3
- Views: 541
Re: 12.57
Can someone please explain how to do this problem? I've been trying to do it for over thirty minutes now.
- Sun Nov 26, 2017 9:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.41
- Replies: 2
- Views: 455
11.41
Can someone please explain what method we are supposed to use to solve 41?
- Sun Nov 26, 2017 9:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.31 and 11.33
- Replies: 2
- Views: 435
11.31 and 11.33
Hi! I was doing questions 31 and 33 from chapter 11 and run into some controversy. While the answer for 31 says that if Q is less than K then more products will be formed, the answer to 33 says that if Q is greater than K then more product will be formed too. Is this a problem with the answers?
- Mon Nov 20, 2017 6:30 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Homework question 17.33
- Replies: 4
- Views: 459
Homework question 17.33
Hi, can someone please explain how to solve for questions b and c of this question? Why is b) a mono or bidentate when there are so many free electron pairs, and why in is it a monodentate in part c) if there are also multiple free electron pairs that could form bonds?
- Mon Nov 20, 2017 6:28 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Homework Q17.37
- Replies: 2
- Views: 432
Re: Homework Q17.37
Hi, can someone please go through what bonds of the molecule one should look at to determine coordination compounds for these molecules? I was tried to do it by free electron pairs but I can't get the right answers.
- Mon Nov 13, 2017 7:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 13.a)
- Replies: 3
- Views: 527
Re: 13.a)
I read the previous answer to this question, but in the answers it places both electron lone pairs on the same side of the Iodine central atom, not on opposite sides. Is this because the answer booklet placed the electrons arbitrarily? Or because they actually do go on one side of the Iodine.
- Mon Nov 13, 2017 7:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 13.a)
- Replies: 3
- Views: 527
13.a)
I don't understand why the Iodine chain would be linear if there are two lone pairs bonded to the central atom. Shouldn't it be bent/angular instead of linear?
- Mon Nov 06, 2017 4:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Materials [ENDORSED]
- Replies: 7
- Views: 877
Re: Midterm Materials [ENDORSED]
Should we be able to know the conversion from eV to Joules for the midterm?
- Mon Nov 06, 2017 4:26 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: H- atom equation for other elements
- Replies: 1
- Views: 266
H- atom equation for other elements
I know that the En equation to determine the energy of an H-atom changing energy levels only works for Hydrogen because it only has one electron, but how would its energy amounts compare to another element, like for example, potassium? I know that since there are more electrons you would need to tak...
- Mon Oct 30, 2017 5:01 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Direction of the Spin Magnetic Quantum Number
- Replies: 5
- Views: 959
Re: Direction of the Spin Magnetic Quantum Number
So does this mean that the +/- signs are relative to each other? And also, when you draw a pair of electrons of a lone electron, do you by convention draw then up or does it not matter meaning you could draw them pointing down?
- Mon Oct 30, 2017 4:59 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Values of Quantum Numbers
- Replies: 3
- Views: 1935
Re: Values of Quantum Numbers
When do you know if you should be using the n-1 equation for l of that s= n=0; p= l=1; etc.? I am really confused because I understand the material but then always get the values wrong when it comes to l because I don't know when to use the equation or the set l values that correspond to n levels.
- Wed Oct 25, 2017 3:55 pm
- Forum: *Particle in a Box
- Topic: What is the equation: En= (n^2*h^2)/(8*m*L^2) used for? [ENDORSED]
- Replies: 5
- Views: 3464
Re: What is the equation: En= (n^2*h^2)/(8*m*L^2) used for? [ENDORSED]
I am having trouble understanding the math questions that we could be asked in the test that could have to do with this concept. I understand the idea, but we have never seen it in class. Will we need to use it in the test?
- Wed Oct 25, 2017 3:48 pm
- Forum: *Shrodinger Equation
- Topic: Using Shrodinger's Equation
- Replies: 4
- Views: 960
Re: Using Shrodinger's Equation
I had the same exact question. I was unsure of how to apply the equation for math problems and did not understand how we were going to be asked this in the test. I am guessing the questions about it will be like the conceptual questions we had on the past two tests.
- Mon Oct 16, 2017 9:44 pm
- Forum: Properties of Electrons
- Topic: De Broglie Equation
- Replies: 3
- Views: 521
Re: De Broglie Equation
When do we use 1/2mv2 for Ek and when do we use de broglies equation for Ek?
- Mon Oct 16, 2017 9:40 pm
- Forum: Properties of Electrons
- Topic: Threshold level and Work Function [ENDORSED]
- Replies: 6
- Views: 1075
Re: Threshold level and Work Function [ENDORSED]
When do we use 1/2mv2 for Ek and when do we use de broglies equation for Ek?
- Tue Oct 10, 2017 12:27 pm
- Forum: Einstein Equation
- Topic: Stefan-Boltzmann Law
- Replies: 2
- Views: 407
Stefan-Boltzmann Law
Can someone please explain the Stephan-Boltzmann law? I am having a hard time understanding how to use it and what it is supposed to tell us.
- Tue Oct 10, 2017 12:25 pm
- Forum: Einstein Equation
- Topic: How does E = hv lead to Einsteins equation E=MC2?
- Replies: 4
- Views: 7231
Re: How does E = hv lead to Einsteins equation E=MC2?
Can someone explain the theory behind these equations? I don't understand what the photon energy is used to represent or what chemistry theories are represented.
- Wed Oct 04, 2017 4:59 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Scientific Notation [ENDORSED]
- Replies: 3
- Views: 707
Re: Scientific Notation [ENDORSED]
If we are converting a number like 0.0380 to scientific notation, we do need to include the last zero in the sense that we'd have to write it as 3.80 x 10^2 right?
- Wed Oct 04, 2017 4:57 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Atomic Mass: Intensive or Extensive Property [ENDORSED]
- Replies: 3
- Views: 2704
Re: Atomic Mass: Intensive or Extensive Property [ENDORSED]
Can someone please clarify the definition or difference between an intensive and extensive property regarding chemistry? I do not understand what they are supposed to reflect.