Search found 91 matches

by Kishan Shah 2G
Tue Jan 28, 2020 12:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Thermochemistry Textbook HW
Replies: 4
Views: 20

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: 17

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: 12

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: 12
Views: 23

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: 20

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: 31

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: 18

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: 21

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: 18

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: 37

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: 24

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: 17

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: 28

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: 27

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: 68

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: 23

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: 22

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: 42

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: 27

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: 33

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: 34

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: 49

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: 39

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: 150

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: 86

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: 35

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: 35

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: 74

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: 34

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: 19

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: 120

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: 35

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: 73

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: 93

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: 39

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: 117

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: 44

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: 86

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: 17

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: 32

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: 60

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: 16

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: 29

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: 86

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: 198

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: 72

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: 49

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: 104

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: 151

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: 38

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: 101

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: 53

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: 356

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: 29

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: 66

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: 66

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: 62

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: 23

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: 44

Re: Review Sessions

I had the same question. I emailed my TA and am awaiting a response.
by Kishan Shah 2G
Mon Oct 28, 2019 10:33 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 11
Views: 97

Re: Midterm

The format should be similar to first test but longer. It will cover fundamentals, quantum, and chemical bonding.
by Kishan Shah 2G
Mon Oct 28, 2019 10:28 am
Forum: Lewis Structures
Topic: Lewis Structure of Ions
Replies: 6
Views: 36

Re: Lewis Structure of Ions

Yes make sure you place the bracket, however Dr. Lavelle stated in class that the placement of the charge whether its inside or outside the brackets does not matter.
by Kishan Shah 2G
Mon Oct 28, 2019 10:27 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Transition Metals
Replies: 2
Views: 35

Re: Transition Metals

Usually the question will denote which form of the cation it is. However another easy way to tell is to take a look at the anion it is bonded to in order to determine what the charge would have to be on the cation for the molecule to have a net neutral charge.
by Kishan Shah 2G
Wed Oct 23, 2019 10:40 pm
Forum: Lewis Structures
Topic: lewis drawings
Replies: 8
Views: 93

Re: lewis drawings

I am not sure. However, this would be a great question to ask in Dr. Lavelle's office hours.
by Kishan Shah 2G
Wed Oct 23, 2019 10:38 pm
Forum: Resonance Structures
Topic: defintion
Replies: 7
Views: 67

Re: defintion

Yes, resonance structures are molecules that can be drawn in different configurations that still represent the same molecule. The example in class today shows clearly shows the true meaning of a resonance structure.
by Kishan Shah 2G
Wed Oct 23, 2019 10:36 pm
Forum: Trends in The Periodic Table
Topic: bond length
Replies: 9
Views: 69

Re: bond length

So far I know of no way to calculate bond lengths and I don't know if Lavelle will teach us a method to. I also do not think him going over it in class today roughly means we have it know it. I think he went over it just to reinforce basic concepts.
by Kishan Shah 2G
Wed Oct 23, 2019 10:33 pm
Forum: Trends in The Periodic Table
Topic: Location of elements
Replies: 12
Views: 103

Re: Location of elements

Yes, its the best to know them and its not too hard to memorize which parts of the periodic table are solid, liquid, and gas.
by Kishan Shah 2G
Wed Oct 23, 2019 10:32 pm
Forum: Ionic & Covalent Bonds
Topic: Double Bond vs Single Bond Length
Replies: 6
Views: 112

Re: Double Bond vs Single Bond Length

Correct, the lewis structure is just a rough model and Dr. Lavelle did say that the actual length is 1.24 angstrom. The double bonds and triple bonds contain more electrons, thereby exerting a stronger force on the nuclei of the atoms and this pulls the atoms closer together hence shorter bond lengt...
by Kishan Shah 2G
Wed Oct 23, 2019 10:28 pm
Forum: SI Units, Unit Conversions
Topic: Sharing of electrons
Replies: 3
Views: 81

Re: Sharing of electrons

The concept of electrons lying on the internuclear axis is not as hard to understand as it sounds. When two atoms are sharing electrons, the electrons they are sharing, otherwise known as the electrons that are represented by bond lines in lewis structures, are shared along this axis or space that c...
by Kishan Shah 2G
Wed Oct 23, 2019 10:09 pm
Forum: Ionic & Covalent Bonds
Topic: What topic are we on?
Replies: 11
Views: 105

Re: What topic are we on?

Based on Dr. Lavelle's last email 2 weeks ago he said that as we transition from fundamentals to quantum, that transition week's homework could be from either units. I do not believe that just because he taught chemical bonds today in class that we have to turn in chemical bonds hw since people in T...
by Kishan Shah 2G
Wed Oct 23, 2019 10:04 pm
Forum: Trends in The Periodic Table
Topic: Exceptions
Replies: 3
Views: 31

Re: Exceptions

As the above two replies stated, ionization energies increase as you move toward the bottom left of the periodic table. This is due to the fact that these electrons are further away from the nucleus so they are more easily removable, and the fact that these elemental atoms have an inclination to los...
by Kishan Shah 2G
Sat Oct 19, 2019 12:03 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: HW 1D.23
Replies: 2
Views: 26

Re: HW 1D.23

The first one can have 3. The second can have 1. The third can have 4. The fourth can have 1.
by Kishan Shah 2G
Sat Oct 19, 2019 11:51 am
Forum: Einstein Equation
Topic: HW 1B.15c
Replies: 1
Views: 39

Re: HW 1B.15c

We know its kinetic energy, since the photon needs to contain enough energy to eject the electron from the surface as well as to cause it to move at 3.6 x 10^3 km*s^-1 . The energy involved, therefore, is kinetic energy. I was also confused at first on why we use Kinetic Energy, and in my opinion th...
by Kishan Shah 2G
Sat Oct 19, 2019 11:48 am
Forum: Properties of Light
Topic: Unit for Wavelength
Replies: 34
Views: 163

Re: Unit for Wavelength

Usually when you are doing calculations using the equations related to this unit and you cancel out all the units you are left with meters when you are solving for wavelength. However, a lot times the questions want you to convert this answer into nanometers since the most common way to report wavel...
by Kishan Shah 2G
Sat Oct 19, 2019 11:44 am
Forum: DeBroglie Equation
Topic: 1B.19
Replies: 1
Views: 20

Re: 1B.19

The answer for this question just ends up being that the wavelength of a proton and a neutron are identical to 3 significant figures. The solutions guide doesn't actually end calculating the final answer as a percentage of either the proton/neutron's weight. You just have to use the equation to find...
by Kishan Shah 2G
Tue Oct 15, 2019 8:18 am
Forum: DeBroglie Equation
Topic: Three Fundamental Equations
Replies: 3
Views: 35

Re: Three Fundamental Equations

The way I decide which equation to use is that I first write down all the formulas on a separate piece of paper in front of me. Then under the problem, I write down all my given values. Then I look at what value the question is asking for. Then it is easier to determine which equation(s) to use to g...
by Kishan Shah 2G
Tue Oct 15, 2019 8:15 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: HW Problem 1.A.15
Replies: 3
Views: 45

Re: HW Problem 1.A.15

The way that I approached the questions was that I used the Rydberg Equation after determining that this was an instance of the Lyman Series. So we know the frequency, we know the Rydberg constant, we know n(1)=1 due to the fact its a Lyman series. So we solve for n2. Once we determine n2, we know t...
by Kishan Shah 2G
Sat Oct 12, 2019 10:14 am
Forum: Photoelectric Effect
Topic: Energy classification
Replies: 2
Views: 20

Re: Energy classification

Yes, it is called "work function" or "threshold energy." The equation is (Energy of Incoming Photon = Energy to Remove + Excess Energy). The energy to remove an electron is indeed the threshold energy.
by Kishan Shah 2G
Sat Oct 12, 2019 10:09 am
Forum: Properties of Light
Topic: Color of Light
Replies: 2
Views: 35

Re: Color of Light

Yes, the color of light is determined by wavelength. This can be seen directly on page 6 in the textbook. There are something called spectral lines, which were discovered by Johann Balmer, that are light rays that are emitted when electrons are excited from one energy level to the next. The color of...
by Kishan Shah 2G
Sat Oct 12, 2019 10:05 am
Forum: General Science Questions
Topic: Tutoring
Replies: 3
Views: 48

Re: Tutoring

I do not know of any private tutors for this course, but I am sure there are many out there. Website like Wyzant are helpful for finding tutors for different subjects. However, I do know for a fact that the Step-Up and Workshops held by Dr. Lavelle's UAs are extremely helpful for learning the topics...
by Kishan Shah 2G
Thu Oct 10, 2019 4:26 pm
Forum: Balancing Chemical Reactions
Topic: compound state in chem rxn
Replies: 3
Views: 66

Re: compound state in chem rxn

Usually the problem with either state the state of the compound or element, but sometimes they may not for really simple equations. For example, if Oxygen is a product, it is usually in its diatomic gaseous form and it may not always be given to you.
by Kishan Shah 2G
Thu Oct 10, 2019 4:19 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: # of molecules and formula units?
Replies: 5
Views: 87

Re: # of molecules and formula units?

As Anjali noted, they indeed have different meanings, however for the sake of Unit 1 material, you can consider them the same since Avogadro's constant will be used to solve problems that ask either for formula units or number of molecules.
by Kishan Shah 2G
Wed Oct 09, 2019 2:00 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Ratio Rounding
Replies: 6
Views: 70

Re: Empirical Ratio Rounding

Usually you will intuitively know if the number is able to be rounded to a whole number or not. Usually my values that I round accurately to a whole number are within .05 of the whole number. If they are not whole numbers, in which it can happen, write the empirical formula down with the decimal sub...
by Kishan Shah 2G
Tue Oct 08, 2019 7:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Finding Textbook Questions on the Quantum World
Replies: 4
Views: 46

Re: Finding Textbook Questions on the Quantum World

To answer your first question. The quantum questions for 1A begin on page 9 and are at the end of the reading for section A. As for turning in fundamentals problems vs quantum problems for hw this week, Dr. Lavelle's email this week said fundamentals questions "and/or" quantum questions. S...
by Kishan Shah 2G
Tue Oct 01, 2019 6:27 pm
Forum: SI Units, Unit Conversions
Topic: Units
Replies: 5
Views: 85

Units

Hello all. This may be a question that you won't be able to answer definitively, however I thought it was worth a try to ask anyways. Does anybody know to what extent we have to know prefixes for the various types of units and how to convert from them back to standard units(eg: microgram to gram, na...
by Kishan Shah 2G
Mon Sep 30, 2019 10:27 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.17 Homework Problem
Replies: 3
Views: 44

Re: G.17 Homework Problem

It is the same calculation as part A, except you need to use the molar mass for CuSO4 x 5H2O in this part. This molar mass is 249.68 grams/mol.
by Kishan Shah 2G
Mon Sep 30, 2019 10:26 pm
Forum: Limiting Reactant Calculations
Topic: Using mols or grams
Replies: 4
Views: 67

Re: Using mols or grams

Yes. I don't see a problem using this method. I think Dr. Lavelle stated to use mols because it is easier to see visually, but you could do grams as well. The answer would be the same.
by Kishan Shah 2G
Mon Sep 30, 2019 10:21 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's Number
Replies: 4
Views: 61

Re: Avogadro's Number

I personally use 6.022 x 10^23 and my answers are correct when I use this value. In addition, because Dr. Lavelle uses this value, I recommend going with it.
by Kishan Shah 2G
Mon Sep 30, 2019 10:15 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Units
Replies: 4
Views: 53

Re: Formula Units

I can give you a definitive answer to the first part of your question. Yes, formula units do mean the same thing as atoms. As for the second question, I would assume that formula units do not change for dissolved ionic compounds due to the fact that atoms are neither being created nor destroyed duri...
by Kishan Shah 2G
Mon Sep 30, 2019 10:11 pm
Forum: Empirical & Molecular Formulas
Topic: Percent Mass Composition
Replies: 7
Views: 140

Re: Percent Mass Composition

Adding on, if the total mass of the compound is given and the respective masses of each element are given like the example regarding Vitamin C in class, then you need to divide each respective mass by the total mass given and then find the percent mass composition. From this point on you can continu...
by Kishan Shah 2G
Sun Sep 29, 2019 10:57 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework Problem G.11
Replies: 2
Views: 26

Re: Homework Problem G.11

Personally, I would simply convert 4.50 mmol glucose to mol which translates into .0450 mol of glucose. Then I would multiply this value by the reciprocal of the molarity of glucose given (M= 0.278).
by Kishan Shah 2G
Sun Sep 29, 2019 10:48 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework Question G.5
Replies: 4
Views: 98

Re: Homework Question G.5

Hi, you would begin to solve the problem by converting 50 mg of sodium carbonate to grams of sodium carbonate. Then, you would need to convert this mass of sodium carbonate to moles of sodium carbonate by dividing by the molar mass of the compound. Finally, you would need to take this value and mult...

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