## Search found 29 matches

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: 181

### 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: 426

### 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: 440

### 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: 330

### 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: 447

### 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].

Thu Mar 01, 2018 9:12 pm
Forum: General Rate Laws
Topic: Reactions higher than the second order [ENDORSED]
Replies: 3
Views: 233

### 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: 2168

### 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: 154

### 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: 181

### 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: 775

### 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
Replies: 3
Views: 300

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: 271

### 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: 2838

### 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: 202

### 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: 5
Views: 2317

### 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: 272

### Re: Denate

And the common polydentates include:
1)Bidentate: C2O4^2- and ethylenediamine (H2NCH2CH2NH2)
2) Tridentate: Diethylenetriamine
Thu Nov 30, 2017 7:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Denate
Replies: 3
Views: 272

### 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: 3
Views: 744

### 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: 384

### 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: 435

### 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: 414

### 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: 764

### 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: 289

### 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: 214

### 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: 339

### 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: 675

### Re: Octets

What is a resonance hybrid?
Tue Oct 31, 2017 7:41 pm
Forum: Electronegativity
Topic: Electronegativity [ENDORSED]
Replies: 5
Views: 450

### 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
Replies: 4
Views: 365

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: 8047
Views: 1413046

### Re: Post All Chemistry Jokes Here

https://goo.gl/images/1Emecf