Search found 41 matches
- Sun Jan 17, 2021 11:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: reverse rxn equilibrium
- Replies: 4
- Views: 251
Re: reverse rxn equilibrium
Hello I think it would just depend on the concentrations/amount of reactions and products that you are dealing with. Also another important factor would be if the conditions of the reverse reaction are the same as the forward reaction i.e. temperature.
- Sun Jan 17, 2021 11:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: +/- x in the ice box
- Replies: 4
- Views: 295
Re: +/- x in the ice box
When setting up your ICE box, if the initial concentration of either the products or reactants is equal to zero, then the change in molarity would be positive. If the initial change has any given number other than zero, the change is then negative. I hope this helps.
- Sun Jan 17, 2021 11:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Box
- Replies: 10
- Views: 494
Re: ICE Box
Hello, the way that I go about it is that if the initial change is not zero, then the change in molar concentration would have to be negative. If the initial change is zero when setting up the ICE box, then the change in their molar concentrations would be positive.
- Sun Jan 17, 2021 11:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Changes in K
- Replies: 4
- Views: 260
Re: Changes in K
Hello, by changing the temperature, you are able to speed up or slow down a reaction. So this does in fact change the value of K.
- Sat Jan 16, 2021 6:44 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Using the ICE table
- Replies: 36
- Views: 1314
Re: Using the ICE table
Hello! Yes you are correct. You can use the ICE table whenever it asks you to calculate the equilibrium composition. Also just like Hana said, is to keep the initial, change, and the equilibrium molar concentrations all together and organized.
- Thu Jan 07, 2021 6:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Q
- Replies: 53
- Views: 1919
Re: K vs. Q
And yes to clarity both have the same ratio [Products]/[Reactants].
- Thu Jan 07, 2021 6:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Q
- Replies: 53
- Views: 1919
Re: K vs. Q
Hello Lilly!
The time when we would use the reaction quotient (Q) would be any time during the reaction and like you stated, the K constant is used for when at an equilibrium! Hope this helps!
The time when we would use the reaction quotient (Q) would be any time during the reaction and like you stated, the K constant is used for when at an equilibrium! Hope this helps!
- Thu Jan 07, 2021 5:49 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4210
Re: PV=nRT
FionaHunter21 wrote:So is R the same constant as the one we used before on the equation sheet?
Hey Fiona, the R constant would be gas constant which is 0.082057 L atm mol^-1 K^-1.
Hope this helps!
- Thu Jan 07, 2021 5:43 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4210
Re: PV=nRT
when do you know you are allowed to use this formula? Hey Leslie, Just like Alexandra said, you can use this idea gas formula to convert from the concentration Kc to the partial pressure Kp, and vise versa. In order to do that, you would divide V (the volume) by both sides to isolate the P (or Kp);...
- Thu Jan 07, 2021 5:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: concentration or partial pressure
- Replies: 7
- Views: 303
Re: concentration or partial pressure
Hello Emma, Looks like you are on the right track to solve this problem since you do not need to convert the initial values of Cl2 and BCl because the problem is asking for the concentrations (Kc). Now if you wanted to convert it to the partial pressure (Kp), then for that instance, you would need t...
- Thu Jan 07, 2021 5:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Partial pressure vs concentration
- Replies: 6
- Views: 329
Re: Partial pressure vs concentration
Hey Anya, I believe that you can use both the partial pressure (Kp) in the equilibrium or the concentration (Kc) to solve for an equation composed of all gases. If you end up starting the problem with the partial pressure (Kp) you can always use the ideal gas law of PV=nRT to convert/ solve for the ...
- Thu Jan 07, 2021 5:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How do you know when to use Kc vs Kp?
- Replies: 9
- Views: 522
Re: How do you know when to use Kc vs Kp?
I believe that if you are asked to use K to calculate the concentration of a species at equilibrium, and if the reaction is in a gas phase, we would need to use its partial pressure (Kp). After this, we can use PV=nRT, or once solved P=n/V(RT) ---> P=conc(RT) to covert Kp to find the concentration Kc.
- Sun Mar 11, 2018 3:03 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: reversible/irreversible
- Replies: 2
- Views: 374
Re: reversible/irreversible
The difference is that during a reversible process, the system will always be at equilibrium with its surroundings. For an irreversible process, there will always be an entropy change.
- Sun Mar 11, 2018 1:55 am
- Forum: General Rate Laws
- Topic: graphs
- Replies: 8
- Views: 942
Re: graphs
I would know them just in case, especially since Dr. Lavelle did go over them during lecture. In the textbook, these graphs are found on page 631 in Chapter 15.6.
- Sun Mar 11, 2018 1:53 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: units
- Replies: 4
- Views: 738
Re: units
I'm pretty sure that we will only have to use SI units, therefore, only mol, L, and s. But then again, I am not 100% sure.
- Thu Mar 01, 2018 9:18 pm
- Forum: General Rate Laws
- Topic: Rate Law dependent on Reactants [ENDORSED]
- Replies: 4
- Views: 745
Re: Rate Law dependent on Reactants [ENDORSED]
The rate constant (k) depends on the temperate and activation energy.
- Thu Mar 01, 2018 9:16 pm
- Forum: Second Order Reactions
- Topic: The graph of second order [ENDORSED]
- Replies: 5
- Views: 1748
Re: The graph of second order [ENDORSED]
For the graph of the second order reaction:
1/[A] concentrations increase over time and [A] concentrations decrease over time.
If you were to graph this, you would end up getting a positive slope, since the y-axis of the graph is 1/[A].
Hope this made sense!
1/[A] concentrations increase over time and [A] concentrations decrease over time.
If you were to graph this, you would end up getting a positive slope, since the y-axis of the graph is 1/[A].
Hope this made sense!
- Thu Mar 01, 2018 9:12 pm
- Forum: General Rate Laws
- Topic: Reactions higher than the second order [ENDORSED]
- Replies: 3
- Views: 476
Re: Reactions higher than the second order [ENDORSED]
Will we be talking about negative order, mixed order, or fractional order?
- Sun Feb 18, 2018 11:28 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation (log vs. ln)
- Replies: 5
- Views: 6469
Re: Nernst Equation (log vs. ln)
I believe that you should use the log or ln stated for each version of the equation given just to avoid an error but to be truthful I'm not entirely sure if there is a difference.
- Sun Feb 18, 2018 11:22 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: About the standard cell potentials for aqueous solutions
- Replies: 2
- Views: 331
Re: About the standard cell potentials for aqueous solutions
I'm not completely sure what you mean by "which equation to use?" Maybe like Cassidy said, it would be best to provide a specific example.
- Sun Feb 18, 2018 11:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 4
- Views: 428
Re: Salt Bridge
A salt bridge is an inverted U-tube that contains an electrolyte and it connects the two half-cells in a galvanic cell. The importance of the salt bridge is to maintain electrical neutrality.
- Mon Jan 29, 2018 6:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy: State Function? [ENDORSED]
- Replies: 4
- Views: 2793
Re: Gibbs Free Energy: State Function? [ENDORSED]
The Gibbs energy is defined solely in terms of state functions, and so G is a state function. The temperature and pressure are constant, and with that we can already predict using Gibbs free energy the spontaneity of a process sole in terms of the properties of a system.
- Mon Jan 29, 2018 6:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: homework/reading schedule
- Replies: 3
- Views: 527
Re: homework/reading schedule
If you go onto the class website for Chem 14b, there are a few outlines for what we should be learning from each chapter and also what homework problems we should do. Since we are still reviewing the first law and the second law of thermodynamics in lectures, I would do homework problems from both c...
- Mon Jan 29, 2018 6:48 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 4
- Views: 528
Re: Reversible vs Irreversible
Reversible expansion is one that can be reversed by an infinitely small change in a variable. An example of this at work would be when a gas expands reversibly, the pressure on the outside is matched to the pressure of the gas during the expansion. This example could be directed in either direction,...
- Fri Jan 26, 2018 8:57 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy of gas vs liquid vs solid
- Replies: 7
- Views: 8650
Re: Entropy of gas vs liquid vs solid
Liquids have more energy and entropy than solids. When there is an increased number of gas molecules, there is also an increase in entropy.
- Fri Jan 26, 2018 8:44 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Relation of degeneracy and entropy
- Replies: 2
- Views: 380
Re: Relation of degeneracy and entropy
The number of possible states for a system of given energy is called the degeneracy and it is denoted by g in the equation S=k ln (g). So when there is an increase in the degeneracy the energy level is higher versus when the degeneracy decreases, the energy level is lower.
- Tue Jan 23, 2018 7:44 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy Calculations (9.1)
- Replies: 7
- Views: 4536
Re: Entropy Calculations (9.1)
In this case, the q would be negative because the enthalpy (the amount of heat released or absorbed at a constant pressure) in this question is being released. The enthalpy value is equivalent to q= delta H and if the reaction is exothermic (which it is in this question because it is giving off heat...
- Thu Nov 30, 2017 7:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Denate
- Replies: 3
- Views: 420
Re: Denate
And the common polydentates include:
1)Bidentate: C2O4^2- and ethylenediamine (H2NCH2CH2NH2)
2) Tridentate: Diethylenetriamine
3) Hexadentate: edta
1)Bidentate: C2O4^2- and ethylenediamine (H2NCH2CH2NH2)
2) Tridentate: Diethylenetriamine
3) Hexadentate: edta
- Thu Nov 30, 2017 7:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Denate
- Replies: 3
- Views: 420
Re: Denate
Common monodentates include: H20, CN-, SCN-, X-, NH3, NO2-, OH-.
- Thu Nov 30, 2017 7:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating Equilibrium
- Replies: 4
- Views: 1906
Re: Calculating Equilibrium
Remember that the equilibrium constant Kc is defined as Kc= [C]^c[D]^d/[A]^a[B]^b
- Wed Nov 15, 2017 3:19 pm
- Forum: Hybridization
- Topic: Diapole
- Replies: 4
- Views: 715
Re: Diapole
In the example of water, (H2o) there are two dipole moments, a partial positive with both hydrogen atoms and a partial negative dipole over the Oxygen atom. This configuration overall is considered non-polar even know there is a dipole moment.
- Wed Nov 15, 2017 3:07 pm
- Forum: Hybridization
- Topic: Notation
- Replies: 6
- Views: 754
Re: Notation
I think that the only time we have write out this fully is when we are asked to write out the full and complete (extended) electron configuration rather than just the ground state electron.
- Wed Nov 08, 2017 12:37 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 3.5 b) [ENDORSED]
- Replies: 5
- Views: 722
Re: 3.5 b) [ENDORSED]
If that is what is easiest for you. Just remember that in the answer, the n number should be in increasing order of energy levels. By doing this, it will be easier to write out the electron configurations for cations and anions.
- Wed Nov 08, 2017 12:34 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: The valence electron of Cu and Br
- Replies: 2
- Views: 1123
Re: The valence electron of Cu and Br
The easiest way for me to count valence electrons is to count the group numbers instead of the period numbers.
- Wed Nov 08, 2017 12:33 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Midterm
- Replies: 2
- Views: 392
Re: Midterm
I do not think that we have to know the VSEPR formulas or shapes for this midterm because that is mainly in chapter 4 and the midterm will cover the fundamentals and chapters 1-3.
- Wed Nov 08, 2017 12:30 am
- Forum: Lewis Structures
- Topic: Where to place lone pairs
- Replies: 2
- Views: 378
Re: Where to place lone pairs
If the lewis dot structure happens to be a square planar shape, you can place one pair of lone pairs on either ends of the central atom (top and bottom) but if the VSEPR shape is for instance T-shaped, then you can place the pairs of lone pairs both on the top of the central atom but as far away fro...
- Wed Nov 08, 2017 12:26 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Central Atom
- Replies: 4
- Views: 609
Re: Central Atom
The least electronegative element tends to be the central atom when creating the lewis dot structures because they tend to be more stable this way. However, there is an exception with H2O because oxygen is more electronegative than hydrogen but in this case, oxygen is still the central atom.
- Tue Oct 31, 2017 9:15 pm
- Forum: Octet Exceptions
- Topic: Octets
- Replies: 8
- Views: 1073
Re: Octets
What is a resonance hybrid?
- Tue Oct 31, 2017 7:41 pm
- Forum: Electronegativity
- Topic: Electronegativity [ENDORSED]
- Replies: 5
- Views: 734
Re: Electronegativity [ENDORSED]
Fluorine on the periodic table is the first element in that group and it is pretty far to the right so it does still follow the electronegativity trend of increasing across the periods and up a group.
- Sun Oct 29, 2017 2:32 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius vs. Ionic Radius [ENDORSED]
- Replies: 4
- Views: 838
Re: Atomic Radius vs. Ionic Radius [ENDORSED]
Atomic radius is half the distance between centers of neighboring atoms and ionic radius is two ions that are joined by an ionic bond.
- Mon Oct 02, 2017 5:26 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2989447
Re: Post All Chemistry Jokes Here
https://goo.gl/images/1Emecf
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