Search found 132 matches

by Kishan Shah 2G
Fri Mar 13, 2020 5:58 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible System
Replies: 2
Views: 86

Re: Irreversible System

The questions would have to say isothermal irreversible, so you would use the deltaS=nRln(V2/V1) formula. The delta S obtained is the delta S of the system. For a irreversible system, the graph is a sharp vertical dip, which means the surroundings do not have time to react to this change, so the del...
by Kishan Shah 2G
Fri Mar 13, 2020 5:09 pm
Forum: Student Social/Study Group
Topic: Tips for Staying Focused
Replies: 8
Views: 209

Re: Tips for Staying Focused

Yeah same with me. I am usually really focused before finals week but there is a lot going on in terms of panic and new news. I try and get through some work but it seems like there are constant distractions every few minutes.
by Kishan Shah 2G
Fri Mar 13, 2020 2:25 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius equation
Replies: 2
Views: 36

Re: Arrhenius equation

You would have to be given the constant A, the rate constant, and the temperature to solve for activation energy.
by Kishan Shah 2G
Mon Mar 09, 2020 8:27 am
Forum: Administrative Questions and Class Announcements
Topic: Review session on Friday
Replies: 3
Views: 46

Re: Review session on Friday

I don't think they bruincast the review session. However, they have a worksheet that they usually go through and they post it on chemistry community and then they will post the answers sometime after the review session. So if you absolutely can't make it you can still review the content they covered.
by Kishan Shah 2G
Mon Mar 09, 2020 8:26 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Ways to Approach Reaction Mechanisms
Replies: 3
Views: 25

Re: Ways to Approach Reaction Mechanisms

yes, and he said he will teach pre-equilibrium approach to us in todays lecture!
by Kishan Shah 2G
Mon Mar 09, 2020 8:26 am
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 2
Views: 42

Re: Final

Last quarter the final was around 8 questions which a few parts to each one. It roughly covered each topic we had learned. However, it did not take 3 hours to finish. As Brian said, I had a lot of time to check my work before I turned it in.
by Kishan Shah 2G
Mon Mar 09, 2020 8:24 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration cells
Replies: 4
Views: 62

Re: Concentration cells

I don't remember there being a question where you had to utilize solubility rules. I think for concentration cells there was a HW problem that said if you change one of the ions in your salt bridge what would happen, and I think you were chagning NO3- to Cl- and if PbCl2 forms its insoluble so the s...
by Kishan Shah 2G
Mon Mar 09, 2020 8:23 am
Forum: First Order Reactions
Topic: Units for t
Replies: 13
Views: 127

Re: Units for t

You can use whichever units you would like but, as Brian said, make sure the units match up in all of your terms before solving.
by Kishan Shah 2G
Mon Mar 09, 2020 8:22 am
Forum: First Order Reactions
Topic: First Order Equation
Replies: 3
Views: 30

Re: First Order Equation

Yes there are multiple ways of expressing the equation. The first one is the linearized form and thats the one that Lavelle put on the Kinetics syllabus. I prefer to use that one since its easy to graph and see the linear line.
by Kishan Shah 2G
Mon Mar 02, 2020 8:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Deciding Where Reactions Occur
Replies: 2
Views: 37

Re: Deciding Where Reactions Occur

Reduction occurs at the cathode and oxidation occurs at the anode.
by Kishan Shah 2G
Mon Mar 02, 2020 8:57 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox (from worksheet 6-8 workshop)
Replies: 2
Views: 51

Re: Balancing redox (from worksheet 6-8 workshop)

Since we know that this is in acidic solution. We also know that Chromium is being reduced, we can conclude that hydrogen ions will be in our reactants and water will be in our products. Also the electrons will be on the reactants side. After we determine what our products and reactants are, we basi...
by Kishan Shah 2G
Mon Mar 02, 2020 8:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagrams
Replies: 2
Views: 32

Re: cell diagrams

Yes, that is correct. No coefficients in your cell diagram. Use platinum in instances when you have no solids in your redox reactions.
by Kishan Shah 2G
Mon Mar 02, 2020 8:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams and Metal Solids
Replies: 2
Views: 29

Re: Cell Diagrams and Metal Solids

I'm not sure. I have only seen Carbon(graphite) and Platinum. I would stick with platinum just to be safe.
by Kishan Shah 2G
Mon Mar 02, 2020 8:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: EMF
Replies: 1
Views: 20

Re: EMF

It is basically the difference in potentials that gives rise to an electrical current. I'm not sure about the second part of your question though.
by Kishan Shah 2G
Mon Feb 24, 2020 10:35 am
Forum: Administrative Questions and Class Announcements
Topic: Hw 8
Replies: 10
Views: 121

Re: Hw 8

Usually you can do the hw on material that he has taught within the past week of your discussion time.
by Kishan Shah 2G
Mon Feb 24, 2020 10:32 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 6
Views: 69

Re: Test 2

Second page of the thermodynamics outline(outline 4), and the all of outline 5. We will begin to learn kinetics but it will not be on the test.
by Kishan Shah 2G
Mon Feb 24, 2020 10:16 am
Forum: Administrative Questions and Class Announcements
Topic: Outlines for Thermodynamics and Electrochem
Replies: 1
Views: 37

Re: Outlines for Thermodynamics and Electrochem

Hmm. I am not having that problem. Maybe try using a different web browser. I am also not sure how to post images on chemistry community.
by Kishan Shah 2G
Mon Feb 24, 2020 10:14 am
Forum: Balancing Redox Reactions
Topic: OIL RIG
Replies: 4
Views: 71

Re: OIL RIG

Yeah thats another good way. I may just end up using it!
by Kishan Shah 2G
Mon Feb 24, 2020 10:08 am
Forum: Administrative Questions and Class Announcements
Topic: Test 2 info
Replies: 8
Views: 131

Re: Test 2 info

We will begin learning kinetics on Friday, but it will not be on the test.
by Kishan Shah 2G
Mon Feb 24, 2020 10:07 am
Forum: Administrative Questions and Class Announcements
Topic: Thermo
Replies: 3
Views: 48

Re: Thermo

I agree with those above. I also thing its smart to go about and create a little study guide as you move through the text, lecture notes, and homework problems, outlining which situations in which to use certain equations and rules and exceptions. Repetition of the problems is key as the more proble...
by Kishan Shah 2G
Mon Feb 17, 2020 5:06 pm
Forum: Balancing Redox Reactions
Topic: Why do we split equations?
Replies: 12
Views: 113

Re: Why do we split equations?

There is no other reason, other than the fact that it helps to visualize and see what is being oxidized and reduced.
by Kishan Shah 2G
Mon Feb 17, 2020 5:06 pm
Forum: Balancing Redox Reactions
Topic: Why do we split equations?
Replies: 12
Views: 113

Re: Why do we split equations?

There is no other reason, other than the fact that it helps to visualize and see what is being oxidized and reduced.
by Kishan Shah 2G
Mon Feb 17, 2020 5:05 pm
Forum: Administrative Questions and Class Announcements
Topic: 14BL and 14C
Replies: 8
Views: 101

Re: 14BL and 14C

I think it is definitely manageable, however I do know that 14BL is a lot of calculations and it takes time. So if you think that learning OCHEM along with doing chemistry labs is too much then split it up.
by Kishan Shah 2G
Mon Feb 17, 2020 5:04 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Constant R
Replies: 15
Views: 260

Re: Constant R

The best way to determine when to use which instead of memorizing them is to look at the units to see which units you are working with and what you want to end up with.
by Kishan Shah 2G
Mon Feb 17, 2020 5:03 pm
Forum: Ideal Gases
Topic: pv=nrt
Replies: 19
Views: 244

Re: pv=nrt

Yes, you would just need to plug in 0 degrees celsius and 1 atm.
by Kishan Shah 2G
Mon Feb 17, 2020 5:02 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Cv vs Cp
Replies: 17
Views: 274

Re: Cv vs Cp

Basically, Cv represents the heat capacity at constant volume, so a bomb calorimeter per say. Cp represents heat capacity at constant pressure, so an irreversible expansion. Cv is 3/2R and Cp is 5/2R
by Kishan Shah 2G
Mon Feb 17, 2020 5:00 pm
Forum: Van't Hoff Equation
Topic: K rather than Kc
Replies: 10
Views: 169

Re: K rather than Kc

This is a good question. When I was doing my calculations I used the same value for both but my calculations could be wrong. Does anyone know?
by Kishan Shah 2G
Thu Feb 13, 2020 1:28 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: constant pressure and volume
Replies: 3
Views: 80

Re: constant pressure and volume

Constant volume means there is no work done. At constant pressures, q is equal to delta H and work is -PdeltaV.
by Kishan Shah 2G
Thu Feb 13, 2020 1:27 am
Forum: General Science Questions
Topic: Tutoring
Replies: 6
Views: 148

Re: Tutoring

What does AAP stand for?
by Kishan Shah 2G
Thu Feb 13, 2020 1:26 am
Forum: Student Social/Study Group
Topic: Number of Chemistry Community Posts
Replies: 33
Views: 717

Re: Number of Chemistry Community Posts

Personally, you can go under "your posts" tab and check the date on which you posted. This is the most definite way to check if you have completed the required number of posts in the right time period.
by Kishan Shah 2G
Thu Feb 13, 2020 1:25 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Significance of open, closed, isolated
Replies: 11
Views: 261

Re: Significance of open, closed, isolated

In my opinon. The most applicable scenario in which we would use our knowledge about closed, isolated, and open systems in when assessing whether there are changes in heat and work. For example since a bomb calorimeter is an isolated system there is no work done on the system.
by Kishan Shah 2G
Thu Feb 13, 2020 1:23 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: deltaU for an ideal gas
Replies: 2
Views: 52

Re: deltaU for an ideal gas

Exactly what was said above. Dr. Lavelle just used those in derivations and to explain concepts to us. We don't actually need to solve problems using them.
by Kishan Shah 2G
Thu Feb 13, 2020 1:21 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous
Replies: 23
Views: 355

Re: Spontaneous

A negative delta G value or a positive detla S universe (total) value.
by Kishan Shah 2G
Thu Feb 13, 2020 1:20 am
Forum: Student Social/Study Group
Topic: Notes from 2.10.20
Replies: 3
Views: 63

Re: Notes from 2.10.20

Dr. Lavelle didn't lecture on any topics. He rather went over past exam questions in preparation for our midterm.
by Kishan Shah 2G
Mon Feb 03, 2020 10:43 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: reversing signs
Replies: 5
Views: 47

Re: reversing signs

You can reverse the sign of enthalpy change when doing Hess's law and you are trying to determine the overall reaction by manipulating the equations.
by Kishan Shah 2G
Mon Feb 03, 2020 10:41 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Degeneracy
Replies: 4
Views: 31

Re: Degeneracy

I think the problem he did in his lecture was a good example. You have to identify the number of orientations the molecule can be in. Lets say its 3. Then you raise this number to the power of how many molecules of it there are. That is your W (degeneracy) in the boltzmann equation.
by Kishan Shah 2G
Mon Feb 03, 2020 10:39 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff
Replies: 6
Views: 75

Re: Van't Hoff

Has Dr. Lavelle taught this yet?
by Kishan Shah 2G
Mon Feb 03, 2020 10:39 pm
Forum: Phase Changes & Related Calculations
Topic: -w vs w
Replies: 15
Views: 149

Re: -w vs w

Basically work is represented by "w". negative work means that the system has lost energy since it has itself done work. positive work means that the system has gained energy because something else has done work on the system.
by Kishan Shah 2G
Mon Feb 03, 2020 10:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Lyndon Bui Workshops
Replies: 7
Views: 151

Re: Lyndon Bui Workshops

I attended lyndon's review session earlier today, and he said he will be posting the worksheet later this week. He usually comes and announces it in lecture. I'm assuming he will do this either on Wednesday or Friday.
by Kishan Shah 2G
Mon Feb 03, 2020 10:36 pm
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 6
Views: 65

Re: Heating Curve

The flat lines on a heating curve represent the deltaH(fusion) or the deltaH(vaporization) depending on where the horizontal line is. The increasing diagonal lines are representing the q=mcAT as we are heating the substance with a certain heat capacity.
by Kishan Shah 2G
Sat Feb 01, 2020 11:32 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated vs Closed [ENDORSED]
Replies: 34
Views: 725

Re: Isolated vs Closed [ENDORSED]

An isolated system is something where matter and energy cannot enter or leave the system. A closed system is where only energy, but not matter, can enter or leave the system. And an open system is where both matter and energy can enter or leave the system. That being said, an insulated water bottle ...
by Kishan Shah 2G
Tue Jan 28, 2020 12:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Thermochemistry Textbook HW
Replies: 4
Views: 61

Re: Thermochemistry Textbook HW

Just took a look and that is right. 4D has Hess's law, and 4E is bond enthalpies, all of which we have covered. 4C may have some problems as well.
by Kishan Shah 2G
Tue Jan 28, 2020 12:48 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A and B
Replies: 2
Views: 32

Re: 4A and B

You could read through the 4A and 4B focuses, but I would wait until he covers it in class. It seems as if he is going out of order for this unit.
by Kishan Shah 2G
Tue Jan 28, 2020 12:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4E.5
Replies: 2
Views: 33

Re: 4E.5

The way you calculate the enthalpy of these reactions is always (Delta H(Bonds Broken) - DeltaH(Bonds Formed)). So if you break a C-H bond lets just say, but then reform it, they will cancel out according to our equation. That is what is happening in this problem because the Bonds Form release energ...
by Kishan Shah 2G
Tue Jan 28, 2020 12:45 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 244

Re: ICE BOX

yes, the cutoff is 10^-3.

However, I would advise only to use the short cut when the value is 10^-5 since you don't want to take a chance and have your answer be off by a few digits. On the test I would always check your answer using the quadratic formula if you used the short cut.
by Kishan Shah 2G
Tue Jan 28, 2020 11:02 am
Forum: Administrative Questions and Class Announcements
Topic: Thermochemistry Textbook HW
Replies: 4
Views: 61

Re: Thermochemistry Textbook HW

Yeah I do know that the Hess's Law HW problems are from 4d. Other than that I am also confused on which hw problems we should be doing.
by Kishan Shah 2G
Thu Jan 23, 2020 9:07 pm
Forum: Ideal Gases
Topic: Partial Pressure
Replies: 4
Views: 62

Re: Partial Pressure

A very simple way to convert from concentration to pressure is (Pressure = Concentration * RT)
by Kishan Shah 2G
Thu Jan 23, 2020 8:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ice Tables
Replies: 3
Views: 46

Re: Ice Tables

I do not fully understand the scope of your question but I'll answer to the best of my ability. If they ask for final equilibrium concentrations and you begin with a certain amount of reactant, lets say 0.1, then the E section for that reactant would be 0.1-x, so you would plug x back in to find the...
by Kishan Shah 2G
Thu Jan 23, 2020 8:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: removing H2 from N2 + 3H2 -> 2NH3
Replies: 7
Views: 125

Re: removing H2 from N2 + 3H2 -> 2NH3

If H2 is removed from this chemical reaction. That means that the Q>K and the reaction will shift toward the reactants. Basically the system wants to compensate for the decrease in H2, so it will produce more reactants (H2 and N2) to raise the amount of H2 back so that Q=K
by Kishan Shah 2G
Thu Jan 23, 2020 8:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical equation
Replies: 5
Views: 83

Re: Chemical equation

In those instances in which you are not given a chemical equation, you need to use the context clues to generate an equation. Usually you will have to come up with the equations yourself only for Acid-Base equilibrium problems, in which the acid or base and water are almost always the reactants and ...
by Kishan Shah 2G
Thu Jan 23, 2020 8:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q<K
Replies: 11
Views: 89

Re: Q<K

As Kyle said, if Q<K then there is more reactants at that instance, so in order to reach equilibrium (Q=K), the reaction needs to proceed toward the products.
by Kishan Shah 2G
Mon Jan 13, 2020 11:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: volume and K value
Replies: 3
Views: 44

Re: volume and K value

Changing the volume changes the pressure. This can cause the reaction to lean toward the reactants or products but it does not change the equilibrium constant value.
by Kishan Shah 2G
Mon Jan 13, 2020 11:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Updating my account
Replies: 2
Views: 34

Re: Updating my account

Click on the "Register Alias and Password) link at the top menu bar once you are logged in, and you will be able to change your alias to the new discussion section you are in
by Kishan Shah 2G
Mon Jan 13, 2020 11:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effect of Inert Gases
Replies: 9
Views: 73

Re: Effect of Inert Gases

Increasing pressure by inserting an inert gas will not change the way the reaction leans. Only increasing pressure by reducing volume will affect the reactant quotient which will change the direction that the reaction favors.
by Kishan Shah 2G
Mon Jan 13, 2020 11:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying tips
Replies: 10
Views: 70

Re: Studying tips

I would recommend you read the textbook, complete all the HW problems, revisit your lecture notes, and browse Chemistry Community. If you do these things well you will be prepared for the test.
by Kishan Shah 2G
Mon Jan 13, 2020 2:16 pm
Forum: Ideal Gases
Topic: When to use this equation
Replies: 14
Views: 156

Re: When to use this equation

In the context of equilibrium, you use this equation to convert from pressure to concentration. So if you want to calculated K(p) and you are given concentration values, you can use PV=nRT to convert to partial pressure values for that reactant or product. The same applies for converting from pressu...
by Kishan Shah 2G
Mon Jan 13, 2020 2:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solid and Liquid
Replies: 5
Views: 49

Re: Solid and Liquid

Yes, the concentration change of solids and liquids is insignificant. If you think about it, if they do not affect the concentrations of reactants/products, then they serve no purpose in the equilibrium constant.
by Kishan Shah 2G
Sun Jan 12, 2020 11:18 pm
Forum: Ideal Gases
Topic: Q vs. K
Replies: 10
Views: 94

Re: Q vs. K

Q and K are calculated using the same rules and formula. However Q is used when you are given initial concentration/pressure values, and K is used when you are given equilibrium concentration/pressure values. You can compare Q and K to determine in which direction the reaction will proceed.
by Kishan Shah 2G
Mon Jan 06, 2020 5:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kc
Replies: 4
Views: 61

Re: Calculating Kc

Basically solids and liquids have a constant concentration. There may be very tiny changes in volume of them but its not enough to affect our calculations. The activity of solids and liquids at equilibrium is 1, so therefore it doesn't affect equilibrium concentrations.
by Kishan Shah 2G
Mon Jan 06, 2020 5:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K threshold
Replies: 2
Views: 54

Re: K threshold

Threshold is 10^-4
by Kishan Shah 2G
Mon Jan 06, 2020 4:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reactant Quotient vs Equilibrium Constant
Replies: 3
Views: 58

Reactant Quotient vs Equilibrium Constant

How can you identify when to calculate a reactant quotient vs an equilibrium constant. Also, are the rules for calculating them the same (ex: do you omit solids and liquids for reactant quotient as well?)
by Kishan Shah 2G
Mon Jan 06, 2020 4:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 5H.3
Replies: 3
Views: 59

Re: Question 5H.3

This equation can be broken down into two smaller equation. By looking at the chart it becomes evident of what those two equations are. Then identify K values at the correct temperature for these reactions and multiply K values together for the overall K for the reaction.
by Kishan Shah 2G
Mon Jan 06, 2020 4:52 pm
Forum: Ideal Gases
Topic: ICE Table Variables
Replies: 6
Views: 94

Re: ICE Table Variables

Always use variables in your change row. the coefficient for your change variable corresponds to the coefficient in the chemical equation. Use a negative sign to indicate using up of reactants and a positive sign to indicate production of products.
by Kishan Shah 2G
Tue Dec 03, 2019 12:53 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: dipole dipole
Replies: 7
Views: 88

Re: dipole dipole

Yes. The molecule needs to be polar in order to for it to have dipole dipole interactions since the dipole on one molecule can form an IMF with the dipole on the other molecule.
by Kishan Shah 2G
Tue Dec 03, 2019 12:52 pm
Forum: Trends in The Periodic Table
Topic: Question
Replies: 17
Views: 574

Re: Question

They have the same trend but they mean different things. Electronegativity refers to the amount of pull that an atom can have on an outside electron because it wants the electron. Ionization energy means the amount of energy it takes to remove one electron from an atom.
by Kishan Shah 2G
Tue Dec 03, 2019 12:51 pm
Forum: Biological Examples
Topic: cisplatin
Replies: 5
Views: 121

Re: cisplatin

The Cl atoms don't directly attach to the DNA. The Cl atoms are replaced by nitrogen atoms when the cisplatin binds to guanine on the DNA. This is now going into too much depth. Just know its general function.
by Kishan Shah 2G
Tue Dec 03, 2019 12:50 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Resonance and Formal Charge
Replies: 4
Views: 144

Re: Resonance and Formal Charge

Different resonance structures may have different formal charges for the atoms that are double bonded in one and are single bonded in the other. Just look at the overall charge of the molecule and make sure your formal charges add up.
by Kishan Shah 2G
Tue Dec 03, 2019 12:42 pm
Forum: Polyprotic Acids & Bases
Topic: Why is HClO4 stronger than H3PO4?
Replies: 3
Views: 86

Re: Why is HClO4 stronger than H3PO4?

Because the conjugate base of HClO4, which is ClO4 is more stable than the conjugate base of H3PO4, so HClO4 is more likely to disassociate more in solution as H+ ions and ClO4- anions. Eventhough it is polyprotic, to my knowledge it really has no effect on acidity strength. Here is a formal explana...
by Kishan Shah 2G
Tue Dec 03, 2019 12:40 pm
Forum: *Particle in a Box
Topic: Hydrogen Atom
Replies: 7
Views: 332

Re: Hydrogen Atom

When it absorbs a hydrogen atom, then it absorbs energy so the energy change is positive meaning it gained energy.
by Kishan Shah 2G
Sat Nov 30, 2019 12:11 pm
Forum: Bronsted Acids & Bases
Topic: 6A.17b
Replies: 5
Views: 64

Re: 6A.17b

SO3 is basic, not acidic. Acidic oxides are oxides that reacts with water to form a solution of a Bronsted acid. SO3 is an example of an acidic oxide because when it reacts with water, it forms H2SO4. SO3 + H20 --> H2SO4. Since H2SO4 is an acid, SO3 is an acidic oxide. It is also useful to not that...
by Kishan Shah 2G
Fri Nov 29, 2019 11:55 pm
Forum: Naming
Topic: 9C.3d
Replies: 1
Views: 37

Re: 9C.3d

Na[Fe(OH2)2(C2O4)2]
by Kishan Shah 2G
Tue Nov 26, 2019 5:02 pm
Forum: Student Social/Study Group
Topic: Test 2 and Final
Replies: 18
Views: 226

Re: Test 2 and Final

The TA's will decide when to give back Test 2. The final will cover everything since day 1 of class.
by Kishan Shah 2G
Tue Nov 26, 2019 5:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Video Modules
Replies: 5
Views: 81

Re: Video Modules

Nope! Lavelle only posts video modules for quantum and fundamentals.
by Kishan Shah 2G
Tue Nov 26, 2019 5:00 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity Formula / Calculation
Replies: 5
Views: 1745

Re: Molarity Formula / Calculation

Try not to get too caught up in the wordiness of the questions. You need to break everything down so you have just moles of whatever atom/compound you want to find the molarity of and the volume of the solution. Then divide the number of moles by the number of liters to get the concentration.
by Kishan Shah 2G
Tue Nov 26, 2019 4:58 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Hydrogen Bonding/Pi bonds
Replies: 11
Views: 269

Re: Hydrogen Bonding/Pi bonds

Hydrogen Bonds and pi ponds really have nothing to do with each other in my knowledge.
by Kishan Shah 2G
Tue Nov 26, 2019 4:57 pm
Forum: Naming
Topic: Final Exam
Replies: 3
Views: 53

Re: Final Exam

Dr. Lavelle provided his own chart. I think it is linked above in one of the other replies!
by Kishan Shah 2G
Tue Nov 26, 2019 4:56 pm
Forum: Sigma & Pi Bonds
Topic: Question on Test 2
Replies: 11
Views: 336

Re: Question on Test 2

For this question, you had to be able to identify that all the single bonds had a sigma bond in it and that all the double bonds that a sigma bond and a pi bond in it. When counting the number of hydrogen bonding sites you need to include the H-bonds already present and the lone pairs on N,O, or F.
by Kishan Shah 2G
Tue Nov 19, 2019 8:43 am
Forum: Determining Molecular Shape (VSEPR)
Topic: How to know which angles are smaller
Replies: 8
Views: 80

Re: How to know which angles are smaller

@Leila: The shape of AX2E is bent. The bond angles are 120 degrees. For AX2E2 it is still bent, but the bond angles are 109.5 degrees since the two lone pairs push the two atoms further away from them therefore decreasing the angle.
by Kishan Shah 2G
Tue Nov 19, 2019 8:37 am
Forum: Dipole Moments
Topic: Dipole Induced- Dipole Induced
Replies: 13
Views: 298

Re: Dipole Induced- Dipole Induced

I think you mean to say "induced-dipole induced-dipole." Yes this is the weakest form of interaction since it is synonymous with LDF and Van der Waals forces. So technically it is present to some extent in all molecules. Contrary, "Dipole-Induced-Dipole" is an interaction between...
by Kishan Shah 2G
Tue Nov 19, 2019 8:35 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Ion-Dipole
Replies: 2
Views: 41

Re: Ion-Dipole

The easiest way to explain ion-dipole interaction, is the salt in water example. Lets take NaCl for example. The sodium has a positive charge and the chlorine has a negative charge. So the water molecules will surround the the NaCl ion in such an orientation that the positive hydrogen atom in water ...
by Kishan Shah 2G
Tue Nov 19, 2019 8:31 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Pi and Sigma bonds
Replies: 5
Views: 88

Re: Pi and Sigma bonds

I think the general idea behind pi and sigma bonds that we need to know is determining how many of each there are in a large molecule of some sort. So the basic rule of a single bond having 1 sigma bond, a double bond having 1 sigma and 1 pi bond, and a triple bond having 1 sigma and 2 pi bonds is u...
by Kishan Shah 2G
Tue Nov 19, 2019 8:29 am
Forum: Dipole Moments
Topic: Cancelling Dipole Moments
Replies: 4
Views: 113

Re: Cancelling Dipole Moments

Can someone explain more in depth why CH2Cl2 is polar?
by Kishan Shah 2G
Tue Nov 19, 2019 8:28 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Strength of Intermolecular Forces
Replies: 3
Views: 34

Re: Strength of Intermolecular Forces

What Camellia said is correct. However, yesterday I came across the idea that HCl has a stronger bond than HBr since the bond length in HCl is shorter and stronger since Cl has a smaller atomic radii than Br does. How do you know which reasoning to use?
by Kishan Shah 2G
Wed Nov 13, 2019 2:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Topics on Outlines for Test 2
Replies: 3
Views: 41

Re: Topics on Outlines for Test 2

To my knowledge Test 2 will only contain information from the end of Chemical Bonds outline and from the Molecular Shape and Structure outline. This is also a good question to ask your TA's
by Kishan Shah 2G
Wed Nov 13, 2019 2:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Week 9 homework
Replies: 11
Views: 165

Re: Week 9 homework

That is probably a good question to ask our TAs as I am also wondering the same thing.
by Kishan Shah 2G
Wed Nov 13, 2019 2:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Class grading
Replies: 12
Views: 268

Re: Class grading

The class is based of points. The max points is 500. The first test was 50 points, the midterm was 120 points, the HW problems are 50 points, and then the rest is consituted by Chem Community participation, Test 2, and the Final. Your final grade will be determined by the amount of points you earned...
by Kishan Shah 2G
Wed Nov 13, 2019 2:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Regrade requests
Replies: 3
Views: 114

Re: Regrade requests

The best course of action would probably be to talk to your TA in the next discussion section or reach out to them via email.
by Kishan Shah 2G
Wed Nov 13, 2019 2:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm grade
Replies: 4
Views: 81

Re: Midterm grade

I do not think our scores will be posted online until the next few days. However, we received our physical test grades back after class from our TA's today.
by Kishan Shah 2G
Wed Nov 13, 2019 2:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Answers
Replies: 10
Views: 171

Re: Midterm Answers

Yes, under the chem14A tab on the website, on the bottom right corner these is a link that says midterms solutions.
by Kishan Shah 2G
Wed Nov 13, 2019 2:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 15
Views: 230

Re: Test 2

3F and latter sections from the Chemical Bonds Outline, and all the sections from the Molecular Shape and Structure Outlines will appear on the test.
by Kishan Shah 2G
Sat Nov 09, 2019 3:18 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Hydrogen bonding
Replies: 8
Views: 101

Re: Hydrogen bonding

The high electronegative atoms will be the only ones strong enough to pull away the electron from hydrogen to form the H-bond.
by Kishan Shah 2G
Sat Nov 09, 2019 3:15 pm
Forum: Bond Lengths & Energies
Topic: Midterm
Replies: 9
Views: 142

Re: Midterm

According to Dr. Lavelle, we should receive them after lecture on Wednesday
by Kishan Shah 2G
Sat Nov 09, 2019 3:14 pm
Forum: Student Social/Study Group
Topic: Test 2
Replies: 3
Views: 104

Re: Test 2

Sure! That would be great
by Kishan Shah 2G
Sat Nov 09, 2019 3:12 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Best Way To Study?
Replies: 56
Views: 1172

Re: Best Way To Study?

Read the textbook in order to fill in gaps in your knowledge from the lecture. Once you think you know the information, then attempt the HW problems to get an accurate representation of how well you know the material.
by Kishan Shah 2G
Fri Nov 08, 2019 4:29 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Shortcut
Replies: 3
Views: 53

Re: Formal Charge Shortcut

An easy way is to count the number of lone electrons, not lone pairs, and add that the number of bonds( so a single bond would be one bond, a double would be two bonds). Then subtract this value from the number of valence electrons for that element.
by Kishan Shah 2G
Fri Nov 08, 2019 4:27 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 11
Views: 134

Re: Bond lengths

This is due to the fact that the electrons are delocalized. Therefore, the bonds in the structure are a blend of single and double bonds, or in another words they have single and double bond character. Therefore the bond lengths are the same.
by Kishan Shah 2G
Fri Nov 08, 2019 4:27 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 11
Views: 134

Re: Bond lengths

This is due to the fact that the electrons are delocalized. Therefore, the bonds in the structure are a blend of single and double bonds, or in another words they have single and double bond character. Therefore the bond lengths are the same.
by Kishan Shah 2G
Mon Oct 28, 2019 10:48 am
Forum: General Science Questions
Topic: homework
Replies: 5
Views: 89

Re: homework

This weeks HW will be on chemical bonds
by Kishan Shah 2G
Mon Oct 28, 2019 10:48 am
Forum: Lewis Structures
Topic: BrF3
Replies: 2
Views: 39

Re: BrF3

Br would be in the center will 3 single bonds to Flourines. Draw in 3 lone pairs for each flourine to complete the octet for them, and add 2 lone pairs onto the Br in the center. In this case, Br is capable is having more than an octet.
by Kishan Shah 2G
Mon Oct 28, 2019 10:43 am
Forum: Administrative Questions and Class Announcements
Topic: Review Sessions
Replies: 2
Views: 71

Re: Review Sessions

I had the same question. I emailed my TA and am awaiting a response.

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