Search found 67 matches
- Wed Mar 13, 2019 2:10 pm
- Forum: Student Social/Study Group
- Topic: class pictures
- Replies: 15
- Views: 4059
class pictures
Hey friends, attached are the pictures of the 1pm Lecture!
- Wed Mar 13, 2019 2:09 pm
- Forum: First Order Reactions
- Topic: Integrated Rate Laws (7b.1/ 15.21)
- Replies: 3
- Views: 359
Re: Integrated Rate Laws (7b.1/ 15.21)
thank you both!
- Mon Mar 11, 2019 9:32 pm
- Forum: First Order Reactions
- Topic: Integrated Rate Laws (7b.1/ 15.21)
- Replies: 3
- Views: 359
Integrated Rate Laws (7b.1/ 15.21)
We are given that this is a first order reaction, 2A -> B + C, given that [A]0 = 0.153 mol/L and that after 115sec the conc. of B rises to 0.034 mol/L. How would we go about solving for [A]?
- Mon Mar 11, 2019 8:05 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: solving for rates with charts
- Replies: 3
- Views: 415
Re: solving for rates with charts
Ahhh!! thank you so much! I kept reading other explanations but yours was much clearer!
- Sun Mar 10, 2019 7:21 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: solving for rates with charts
- Replies: 3
- Views: 415
solving for rates with charts
What is the best way to approach problems asking to solve for rates and orders given a chart?
- Tue Mar 05, 2019 8:28 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: n in Nernst
- Replies: 4
- Views: 580
n in Nernst
How does one find n to plug into the Nernst?
- Tue Mar 05, 2019 8:05 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 7th Edition 6N.3c
- Replies: 2
- Views: 337
Re: 7th Edition 6N.3c
I was wondering this too. How would you go about solving for Q?
- Sun Mar 03, 2019 6:26 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Pt inert electrode
- Replies: 9
- Views: 1823
Re: Pt inert electrode
We use Pt (s) when the reaction lacks a conducting metal, so if we have (aq)|(g)||(aq)(aq) we would add Pt(s) to both sides
- Tue Feb 26, 2019 9:00 pm
- Forum: Balancing Redox Reactions
- Topic: oxidizing agent and reducing agent
- Replies: 15
- Views: 1391
Re: oxidizing agent and reducing agent
what is reduced is the oxidizing agent and what is being oxidized in the reducing agent. Its basically flipped
- Mon Feb 25, 2019 8:05 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 5G.15 (7th Ed.)/ 11.17 (6th ed.)
- Replies: 1
- Views: 268
5G.15 (7th Ed.)/ 11.17 (6th ed.)
Can someone explain why the solution manual is using the formula deltaG=-RTlnK + RTlnQ instead of deltaG= deltaGnot + RTlnQ.
- Sun Feb 24, 2019 10:21 pm
- Forum: Balancing Redox Reactions
- Topic: E dependency on moles
- Replies: 2
- Views: 342
E dependency on moles
Why dont we multiply the E value in relation to the number of moles ?
- Sun Feb 24, 2019 10:20 pm
- Forum: Balancing Redox Reactions
- Topic: Which Equation to Flip?
- Replies: 9
- Views: 4894
Re: Which Equation to Flip?
Flip the anode because we should be looking at its reverse reaction
- Sun Feb 24, 2019 10:19 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: E standard
- Replies: 3
- Views: 421
Re: E standard
In some aspects no, however, if the reaction is reversed then the sign is flipped other than that I think that it remains the same.
- Sun Feb 17, 2019 9:45 pm
- Forum: Phase Changes & Related Calculations
- Topic: Slope of heating curve
- Replies: 8
- Views: 3367
Re: Slope of heating curve
the slope refers to the rate, so lower heat capacities = steeper slope because it can reach the next phase quicker and higher heat capacity, more shallow because more energy and time is needed to reach next phase change
- Sun Feb 17, 2019 9:42 pm
- Forum: Phase Changes & Related Calculations
- Topic: Negative and Positive values of delta H and w
- Replies: 6
- Views: 3874
Re: Negative and Positive values of delta H and w
-delta H means the system is exothermic and is releasing heat (surrounding absorb that heat) and + delta H means the system is endothermic and requires heat
- Wed Feb 13, 2019 2:11 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 1 atm to 101.3 J/(atm*L)
- Replies: 2
- Views: 1605
1 atm to 101.3 J/(atm*L)
will we be required to know this conversion or will it be given in the problem?
- Sun Feb 10, 2019 11:29 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Mondays class
- Replies: 3
- Views: 439
Mondays class
Will class be review or will we be continuing learning different material/ expanding?
- Sun Feb 10, 2019 11:28 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm #1 14B
- Replies: 17
- Views: 2230
Re: Midterm #1 14B
also, does any one know where we can get more practice problems besides Lyndon's?
- Sun Feb 10, 2019 11:27 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm #1 14B
- Replies: 17
- Views: 2230
Re: Midterm #1 14B
when is his review session?
- Sun Feb 10, 2019 11:26 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: How to Calculate Degeneracy
- Replies: 5
- Views: 557
Re: How to Calculate Degeneracy
i also agree that it is the number of particles to the number of different positions they can occupy
- Sun Feb 03, 2019 7:13 pm
- Forum: Phase Changes & Related Calculations
- Topic: Water vapor vs boiling water burns
- Replies: 3
- Views: 488
Water vapor vs boiling water burns
I remember that Dr. Lavelle mentioned that water vapor burns are more painful, however, can someone explain as to why they are worse/ more painful?
- Tue Jan 29, 2019 11:38 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Work
- Replies: 4
- Views: 533
Re: Work
i think we look at the absolute values to determine which does more work. the sign is associated with what is doing the work; for example work is positive if its being done on a system and negative if its being done by a system.
- Tue Jan 29, 2019 10:35 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: 6th Edition Problem 8.21
- Replies: 8
- Views: 868
Re: 6th Edition Problem 8.21
hi becky, how did you derive this equation?
- Sun Jan 27, 2019 9:10 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 7
- Views: 933
Re: Phase Changes
melting and vaporization are considered endothermic because molecules must be broken up using heat, the definition of being an endothermic reaction.
- Sun Jan 27, 2019 9:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy signs
- Replies: 13
- Views: 1743
Re: Enthalpy signs
enthalpy is positive for endothermic because there is the need for heat, while enthalpy is negative for exothermic because heat is being released (exo=exit/out)
- Sun Jan 27, 2019 9:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy signs
- Replies: 13
- Views: 1743
Re: Enthalpy signs
enthalpy is positive for endothermic because there is the need for heat, while enthalpy is negative for exothermic because heat is being released (exo=exit)
- Sun Jan 27, 2019 9:04 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Properties
- Replies: 5
- Views: 491
Re: State Properties
remember state properties are only looking at the initial and final and nothing in between.
- Sun Jan 20, 2019 10:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in Temperature
- Replies: 8
- Views: 1149
Re: Changes in Temperature
since K is temp. dependent, if a rxn needs heat (endothermic) the products will be favored. if a rxn is releasing heat (exothermic) the reactants will be favored. I see it as if you need heat you need more energy to produce, and if you give off heat, you are favoring your reactants
- Sun Jan 20, 2019 10:01 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: amphoteric
- Replies: 2
- Views: 357
Re: amphoteric
I thought NH3 was amphoteric because it can act as both a base and an acid depending on what it reacts with
for example in 2Na + 2NH3 = 2NaNH2 + H2, NH3 acts as an acid because it donates a proton
in NH3 + HCl = NH4+Cl-, NH3 is accepting a proton meaning it acts as a base
for example in 2Na + 2NH3 = 2NaNH2 + H2, NH3 acts as an acid because it donates a proton
in NH3 + HCl = NH4+Cl-, NH3 is accepting a proton meaning it acts as a base
- Wed Jan 16, 2019 2:20 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: "Shifting"
- Replies: 15
- Views: 1802
Re: "Shifting"
I too recall him saying 'shifting' is used more when referring when the reaction is not at equilibrium and prefers the term 'leans towards right/left' to indicate if it favors products or reactants.
- Thu Jan 10, 2019 8:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Chart for HW problem 11.49 6th Edition
- Replies: 4
- Views: 366
Re: ICE Chart for HW problem 11.49 6th Edition
Thank you both!
- Thu Jan 10, 2019 7:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Chart for HW problem 11.49 6th Edition
- Replies: 4
- Views: 366
Re: ICE Chart for HW problem 11.49 6th Edition
thank you for your explanation! My point of confusion is using the quadratic formula in the chart. May you please explain..
- Wed Jan 09, 2019 11:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Qc
- Replies: 4
- Views: 44316
Kc and Qc
What is the difference between Kc and Qc? I know K has the brackets while Q uses partial pressures, however, what is the distinction?
- Wed Jan 09, 2019 11:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Chart for HW problem 11.49 6th Edition
- Replies: 4
- Views: 366
ICE Chart for HW problem 11.49 6th Edition
How would one understand to complete an ICE chart for problem 11.49? I have gotten the initial for NH3 but how would we know what steps to follow after? (First time seeing ICE charts :( )
- Wed Jan 09, 2019 11:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: ChemComm. Account
- Replies: 1
- Views: 242
ChemComm. Account
It might be a redundant question, but do we need to create a new account or do anything in particular for 14B to make sure our posts get recorded? Do we continue using the same account we created for 14A? (just want to make sure to not lose my points..)
- Fri Dec 07, 2018 10:59 pm
- Forum: Coordinate Covalent Bonds
- Topic: polydentates
- Replies: 5
- Views: 637
polydentates
How do we easily find out if the coordination compound is polydentate?
- Tue Dec 04, 2018 12:33 am
- Forum: Naming
- Topic: Determining oxidation number
- Replies: 5
- Views: 559
Re: Determining oxidation number
Is there an easy way to the oxidation number for ions like sulfate? This is the first time I take chem in my life (HS didnt offer it) so I feel behind in knowing oxidation numbers. Group 1 has an oxidation number of +1 Group 2: +2 Group 13 (with Boron): +3 Group 14: +4/-4 Group 15: -3 Group 16: -2 ...
- Tue Dec 04, 2018 12:30 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: polydentates/ chelates
- Replies: 1
- Views: 272
polydentates/ chelates
Just by looking at a structure and/ or formula, how can we tell if it will be a polydentate or form chelates?
- Mon Dec 03, 2018 9:13 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Problem 12.19 6th ed
- Replies: 3
- Views: 972
Re: Problem 12.19 6th ed
How would we solve for the concentration? I am stuck as to how to even start.
- Mon Dec 03, 2018 9:08 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acids and Bases vs Conjugate acids and bases
- Replies: 1
- Views: 361
Bronsted Acids and Bases vs Conjugate acids and bases
Is there a difference between the Brønsted and conjugated acids and bases? How do you tell them apart?
- Mon Dec 03, 2018 9:05 pm
- Forum: Naming
- Topic: Determining oxidation number
- Replies: 5
- Views: 559
Re: Determining oxidation number
Is there an easy way to the oxidation number for ions like sulfate? This is the first time I take chem in my life (HS didnt offer it) so I feel behind in knowing oxidation numbers.
- Sun Dec 02, 2018 7:26 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted and Lewis Acids and Bases
- Replies: 3
- Views: 225
Re: Bronsted and Lewis Acids and Bases
when talking about bronsted think of protons (sharing of H+ ion):
bronsted base- accepts protons; bronsted acid- donates protons
when talking about lewis think lone electron pairs:
lewis base- donates e- pair; lewis acid- accepts e- pair
bronsted base- accepts protons; bronsted acid- donates protons
when talking about lewis think lone electron pairs:
lewis base- donates e- pair; lewis acid- accepts e- pair
- Sun Dec 02, 2018 7:20 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Chelates: are the rings a part of the coordination sphere?
- Replies: 2
- Views: 287
Re: Chelates: are the rings a part of the coordination sphere?
Yes, because they are attached to the central, causing a share of electrons. They are what create the sphere
- Sun Dec 02, 2018 7:17 pm
- Forum: Hybridization
- Topic: hybridization
- Replies: 13
- Views: 1846
hybridization
Does anyone have an easy way to find the hybridization of the central atom they are able to share? Much appreciated.
- Sun Nov 25, 2018 7:35 pm
- Forum: Lewis Structures
- Topic: Polar vs Nonpolar molecules
- Replies: 7
- Views: 910
Re: Polar vs Nonpolar molecules
using the 3D model its checking for symmetry and not all polar bonds have nonpolar molecules
- Sun Nov 25, 2018 7:29 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length
- Replies: 6
- Views: 635
Re: Bond Length
yes due to the larger amount of overlap between the two orbitals104904344 wrote:And sigma bonds are stronger than pi bonds, right?
- Sun Nov 25, 2018 7:28 pm
- Forum: Sigma & Pi Bonds
- Topic: Why are sigma bonds stronger than pi bonds?
- Replies: 10
- Views: 4725
Re: Why are sigma bonds stronger than pi bonds?
there is more overlap in sigma bonds than in pi bonds which makes for the stronger bond
- Sun Nov 25, 2018 7:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam
- Replies: 22
- Views: 1726
Final Exam
Will the final be cumulative or just from midterm to the end?
- Sun Nov 18, 2018 2:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: electron density/concentration
- Replies: 4
- Views: 505
Re: electron density/concentration
its the same thing, both are where electrons can be found
- Sun Nov 18, 2018 2:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 3
- Replies: 19
- Views: 1421
Re: Test 3
its best to know each shape and the angles corresponding to them
- Sun Nov 18, 2018 2:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 16
- Views: 1245
Re: Bond Angles
I believe he mentioned we should know the general ones like 90, 180, and for bent it should be slightly less than 109.5 but not the exact angle
- Sun Nov 11, 2018 7:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: tetrahedral
- Replies: 3
- Views: 393
tetrahedral
Im sorry, but can someone explain why a structure cannot be tetrahedral planar if it were planar and the angles were 90 degrees apart? Why isnt that a VSEPR shape?
- Sun Nov 11, 2018 7:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angles and lone pairs
- Replies: 4
- Views: 493
Re: bond angles and lone pairs
I think the bond angles will give you the geometry if they are all the same. If they differ then that may lead to there being lone pairs. But we should get a molecular shape diagram and it'll become apparent if there are lone pairs because it would not follow the basic geometry (no lone pairs)
- Sun Nov 11, 2018 7:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: molecular shapes
- Replies: 13
- Views: 995
Re: molecular shapes
I think we might (should) get like the general shapes and structures on the formula sheet, at least that is what a past chem prof. gave us not to sure
- Sun Nov 04, 2018 4:20 pm
- Forum: Dipole Moments
- Topic: Non-polar molecules
- Replies: 4
- Views: 625
Re: Non-polar molecules
I believe that nonpolar molecules exist as long as the dipoles cancels out and there is not net charge towards an atom. Having at least one dipole moment not canceling out will result in a polar molecule.
- Sun Nov 04, 2018 4:17 pm
- Forum: Bond Lengths & Energies
- Topic: Bond order
- Replies: 4
- Views: 501
Re: Bond order
I believe bond order refers to the number of bonds between two atoms. a single bond would have a bond order of 1, double bonds have a bond order of 2, and triple bonds have a bond order of 3
- Sun Nov 04, 2018 4:15 pm
- Forum: Electronegativity
- Topic: Electron Affinity
- Replies: 3
- Views: 391
Re: Electron Affinity
I believe Sulfur has a higher affinity than Oxygen because sulfur is able to have an expanded octet, meaning it can have more than 8 electrons because it still has the 3d subshell while oxygen strictly follows the octet guideline (can only have 8 electrons).
- Thu Oct 25, 2018 9:30 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 6
- Views: 576
Re: Nodal Planes
So the book says that nodal planes separate the two lobes of a p-orbital where the wave function is 0. How come s orbitals do not have a nodal plane? s orbitals do not have a nodal plane because it is the only orbital that has a symmetrical electron probability distribution and is a spherical shape...
- Thu Oct 25, 2018 9:27 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: electron config. 3d and 4s
- Replies: 5
- Views: 1663
electron config. 3d and 4s
Why is 3d a lower energy level than 4d after Z=20? Isn't the periodic table arranged so that energy levels increase as you go? 1s^2, 2s^2, 2p^6,3s^2,3p^6,4s^2,3d^10,4p^6....?
- Thu Oct 25, 2018 9:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Degeneracy
- Replies: 6
- Views: 589
Degeneracy
What does it mean for energy levels to be degenerate ? Is it that there are multiple orbitals, like in p?
- Mon Oct 15, 2018 8:24 pm
- Forum: SI Units, Unit Conversions
- Topic: Units conversions
- Replies: 1
- Views: 277
Units conversions
During the exams, will we have to memorize 1 J= 1 kg*m*s^-1 or would it be given to us?
- Mon Oct 15, 2018 8:20 pm
- Forum: Properties of Light
- Topic: Mass
- Replies: 4
- Views: 269
Mass
How can light gain a mass when in motion, but has no mass when stationary?
- Mon Oct 15, 2018 8:16 pm
- Forum: Properties of Light
- Topic: Mass of Light
- Replies: 5
- Views: 638
Mass of Light
How is the mass of light calculated? I know it can only have a mass when it is in motion and not when it's stationary.
- Mon Oct 15, 2018 8:15 pm
- Forum: Properties of Light
- Topic: Characteristics of Light
- Replies: 1
- Views: 180
Characteristics of Light
I recall Dr. Lavelle mention how light is able to act as both a particle as well as a wave? How is this possible?
- Wed Oct 03, 2018 10:44 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formula
- Replies: 5
- Views: 362
Re: Empirical Formula
You would want to start off by dividing with the smallest number, then multiply all of the numbers by the same whole number to get the least whole number possible.
- Wed Oct 03, 2018 10:41 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing reactions tips
- Replies: 29
- Views: 2207
Re: Balancing reactions tips
Something I always do when balancing is I always write down each element on both the reactant and product sides along with the amount of each there is and add a coefficient accordingly to balance both sides. Image added just in case wording isn't clear.
- Wed Oct 03, 2018 10:33 pm
- Forum: Significant Figures
- Topic: Sig Figs when finding Mol
- Replies: 4
- Views: 9318
Re: Sig Figs when finding Mol
It's always best to use the most amount of sig figs when continuing a problem, but always refer to the sig fig rules (which is mostly using the least number of sig figs I believe) when writing the final answer.