Search found 52 matches

by Angela Cong 3C
Sun Feb 10, 2019 10:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 47
Views: 426

Re: Midterm [ENDORSED]

The notes area also extremely important. If you can, try to memorize even the small details that might seem arbitrary. I remember in 14a Lavelle put some questions on the test that were briefly mentioned in class.
by Angela Cong 3C
Sun Feb 10, 2019 10:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 47
Views: 1679

Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!

Yah for number six, im confused as well. Internal energy is dependent on temperature and the work function for a reversible reaction has temperature for one of the unknown variables. Is there a way around this?
by Angela Cong 3C
Sun Feb 03, 2019 7:18 pm
Forum: Phase Changes & Related Calculations
Topic: Work
Replies: 2
Views: 11

Re: Work

There are also other work equations such as work=-P*delta V where work is done by the system causing energy to decrease
by Angela Cong 3C
Sun Feb 03, 2019 5:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Predicting Spontaneity
Replies: 4
Views: 26

Re: Predicting Spontaneity

There are charts that you can search up in which it gives you if T is a high number when delta H is positive and so is delta s then it will be spontaneous and so on. It can somewhat help you conceptually. However, essentially if you just plug in big or small values for the equation you can get a gag...
by Angela Cong 3C
Sun Feb 03, 2019 5:34 pm
Forum: Calculating Work of Expansion
Topic: R constant
Replies: 3
Views: 15

Re: R constant

The R constant can be determined with which equation you have to use. For example in the pV=nrt function it will be 8.314*10^7 while the rydberg formula for finding energy states would be 1.097*10^7.
by Angela Cong 3C
Sun Feb 03, 2019 5:27 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: constant pressure/volume vs specific/molar heat capacities
Replies: 4
Views: 23

Re: constant pressure/volume vs specific/molar heat capacities

the information given is always the biggest clue, what units are and what fits into the equation will help you solve for what you need to find.
by Angela Cong 3C
Tue Jan 29, 2019 10:42 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 5
Views: 29

Re: Heat Capacity

When they ask you the question the information should be enough for you to determine whether or not to calculate specific, molar, or just plain heat capacity
by Angela Cong 3C
Tue Jan 29, 2019 10:31 am
Forum: Phase Changes & Related Calculations
Topic: Different enthalpy calculation methods
Replies: 4
Views: 29

Re: Different enthalpy calculation methods

The information present in the question given will allow you to determine which method to use
by Angela Cong 3C
Mon Jan 28, 2019 10:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 3
Views: 38

Re: Hess's Law

you will be given the enthalpy with the initial rxns but just keep in mind you will also need to use that to find the final reaction enthalpy.
by Angela Cong 3C
Mon Jan 28, 2019 10:23 pm
Forum: Phase Changes & Related Calculations
Topic: Steam
Replies: 11
Views: 67

Re: Steam

steam does cool down but it's still immediately displacing the energy that was necessary to change water into steam in the heating curve.
by Angela Cong 3C
Mon Jan 28, 2019 10:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law (Method 1)
Replies: 4
Views: 35

Re: Hess's Law (Method 1)

they're almost similar to math equations. Whatever you do to one you have to do to another, so if the rxn in the second equation is multiplied by two or divided by two you much also do the same to the enthalpy. It will be more convenient to keep track of if you add them together
by Angela Cong 3C
Wed Jan 23, 2019 2:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Does [H3O+][OH-] always equal 10^-14?
Replies: 9
Views: 52

Re: Does [H3O+][OH-] always equal 10^-14?

even if kw is not equal to 1*10^-14, [H3O+][OH-] is still equal to kw and to find concentration, you just sqaureroot the kw
by Angela Cong 3C
Sat Jan 19, 2019 9:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ignoring solids
Replies: 6
Views: 30

Re: ignoring solids

The change in liquids such as water is so small in even in equilibrium there is large excess of it so it would cancel out in K and thus is not included. Solids also don’t affect the constant and is left out as well
by Angela Cong 3C
Sat Jan 19, 2019 9:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure
Replies: 4
Views: 25

Re: Pressure

There is no change since the number of moles balance on both sides. Equilibrium would not shift either way
by Angela Cong 3C
Sun Jan 13, 2019 2:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic Reactions
Replies: 9
Views: 68

Re: Exothermic Reactions

in the modules he also mentioned you can tell if a reaction is exo or endo by looking at the lewis structure depending on whether or not they form or break bonds
by Angela Cong 3C
Sun Jan 13, 2019 2:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant Eq.
Replies: 4
Views: 24

Re: Equilibrium Constant Eq.

the concentrations and ratio do not change since youre using the concentration of product over reactant to find the ratio which is the equilibrium constant
by Angela Cong 3C
Sun Jan 13, 2019 2:40 pm
Forum: Administrative Questions and Class Announcements
Topic: HW 2 Due Date
Replies: 4
Views: 31

Re: HW 2 Due Date

yes. only homework one is due during class the rest of the homeworks are all due during your discussion section
by Angela Cong 3C
Thu Dec 06, 2018 10:15 pm
Forum: Naming
Topic: Common Names
Replies: 1
Views: 20

Common Names

For the final exam, would we need to know the common names of metals? Such as ferrate or ferrous for iron and cuprous for copper?
by Angela Cong 3C
Thu Dec 06, 2018 9:55 pm
Forum: Naming
Topic: Final Exam
Replies: 9
Views: 108

Final Exam

For the final exam, would we need to know the chemical formula for ethylenediamine or do we just need to write en?
by Angela Cong 3C
Thu Dec 06, 2018 2:17 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 3566

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Thank you so much to my favorite UA. I greatly appreciate your practice problems!
by Angela Cong 3C
Sun Dec 02, 2018 10:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: repulsion
Replies: 3
Views: 33

Re: repulsion

In bonding and vsepr models, the central atom dictates shape since its the atom that pairs with all other valence electrons. The other lone pairs are not significant enough in repulsion to affect the shape since they are essentially on the outskirts of the atom. The lone pairs on the central atom ho...
by Angela Cong 3C
Sun Dec 02, 2018 10:11 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: ionization of weak bases
Replies: 1
Views: 35

Re: ionization of weak bases

The backwards reaction causes the equation to produce reactants that are on the left side of the equation as well as products. They are not strong enough to completely dissociate
by Angela Cong 3C
Sun Dec 02, 2018 10:09 pm
Forum: Bronsted Acids & Bases
Topic: Fundamentals J.1 Bronsted Acids and Bases
Replies: 2
Views: 37

Re: Fundamentals J.1 Bronsted Acids and Bases

The lewis structures could also help you visualize which atoms give or receive an electron. Depending on the lone pairs and the electronegativity of the atom you can get an idea of which ones will be more likely to donate.
by Angela Cong 3C
Sun Dec 02, 2018 10:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 186
Views: 39281

Re: Saying Thank You to Dr. Lavelle

Dear Dr. Lavelle,
Thank you for your explanations in chem that make the material more understandable. I never thought it would be a subject that I would understand and your jokes are pretty funny! I look forward to next quarter with you in chem 14b :) Happy holidays
by Angela Cong 3C
Mon Nov 26, 2018 7:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR shape
Replies: 4
Views: 32

Re: VSEPR shape

The lone pairs also play a part in determining molecular shape due to their repulsion. For trigonal pyramidal there is only one lone pair while t shaped has two
by Angela Cong 3C
Mon Nov 26, 2018 7:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Bond Angles
Replies: 6
Views: 4319

Re: Seesaw Bond Angles

would we also need to include the 180 degree angle when they ask for the bond angles?
by Angela Cong 3C
Mon Nov 19, 2018 5:41 pm
Forum: Hybridization
Topic: Ethene Hybridization
Replies: 4
Views: 24

Re: Ethene Hybridization

im confused too, if its occupying three orbitals then wouldnt that make it sp3 instead of sp2 and have another electron in an unhybridized orbital?
by Angela Cong 3C
Mon Nov 19, 2018 5:26 pm
Forum: Sigma & Pi Bonds
Topic: Double Bonds and Triple Bonds
Replies: 2
Views: 45

Re: Double Bonds and Triple Bonds

the sigma bond is the first bond between the two elements and thus any bond created after that can only pair side by side, creating the different pi bonds. The triple bond has the same concept where the electrons pair side by side.
by Angela Cong 3C
Mon Nov 19, 2018 4:55 pm
Forum: Hybridization
Topic: Sigma and Pi Bonds [ENDORSED]
Replies: 12
Views: 113

Re: Sigma and Pi Bonds [ENDORSED]

pi bonds are bonded side by side different than sigma bonds, because of the physical structure, rotating the molecule along the sigma bond would cause the pi bond to snap.
by Angela Cong 3C
Mon Nov 19, 2018 4:47 pm
Forum: Hybridization
Topic: Labeling Compounds
Replies: 4
Views: 29

Re: Labeling Compounds

you can think of it as kind of the "_" that are drawn for the electron orbitals. There are only three p orbitals and thats why it does not go higher than sp3
by Angela Cong 3C
Mon Nov 19, 2018 3:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs and bonding
Replies: 4
Views: 49

Re: Lone pairs and bonding

Because lone pairs are unbound electrons, they have a much larger electron cloud and repulsion energy, thus push down the other electron densities such as the bond angles. In class lavelle showed us that by replacing a molecule (taking it off the stick), the area becomes much more occupied and resul...
by Angela Cong 3C
Mon Nov 19, 2018 3:43 pm
Forum: Sigma & Pi Bonds
Topic: Rotating Pi bonds
Replies: 3
Views: 26

Re: Rotating Pi bonds

Pi bonds break if they are rotated. This is due to their rigidness and the way that they are bonded side by side, different than sigma bonds.
by Angela Cong 3C
Sun Nov 11, 2018 11:05 pm
Forum: Properties of Light
Topic: Test 3
Replies: 24
Views: 314

Re: Test 3

Dr. Lavelle should tell us in class soon but so far it's going to be everything after the midterm like the lewis structures, bond energy, types of bonds and such
by Angela Cong 3C
Sun Nov 11, 2018 10:54 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge on central atom
Replies: 5
Views: 56

Re: Formal charge on central atom

additionally, the central atom is alway the least electronegative so the surrounding atoms bonded would much rather have the more negative charge
by Angela Cong 3C
Sun Nov 11, 2018 10:51 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7023
Views: 771975

Re: Post All Chemistry Jokes Here

Chemistry is Fluorine, Uranium, Nitrogen
by Angela Cong 3C
Sun Nov 04, 2018 2:34 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal planes
Replies: 6
Views: 65

Re: Nodal planes

would we need to know the difference between angular and radial planes on the midterm?
by Angela Cong 3C
Sat Nov 03, 2018 8:39 pm
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 4202

Re: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]

hello! does anyone know how soon the solutions sheet will be up?
by Angela Cong 3C
Sun Oct 28, 2018 10:46 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 13
Views: 70

Re: Lewis Structures

Dr. Lavelle also mentioned Li and Be in addition to H and He as never fulfilling the octet rule
by Angela Cong 3C
Sun Oct 28, 2018 10:45 pm
Forum: Lewis Structures
Topic: Lewis Structures with Polyatomic Species
Replies: 2
Views: 26

Re: Lewis Structures with Polyatomic Species

The four H atoms are on the outside of N and since N has five valence electrons, there will be a bond connecting the two NH4 structures with the SO4
by Angela Cong 3C
Sun Oct 28, 2018 10:39 pm
Forum: Ionic & Covalent Bonds
Topic: Octet Rule
Replies: 7
Views: 69

Re: Octet Rule

The exceptions are H, He, Li, and Be since they will always be the elements giving their electrons instead of receiving them
by Angela Cong 3C
Sun Oct 28, 2018 10:37 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7023
Views: 771975

Re: Post All Chemistry Jokes Here

If avagrado calls, tell him to leave his number ;)
by Angela Cong 3C
Sun Oct 21, 2018 8:53 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 3
Views: 39

Re: Nodal Planes

Since the nodal plane is a plane, don't the electrons cross over it at one point to the orbital on the other side? I understand that there's zero possibility but in cases of the p orbital where there's two orbital won't the electron have to circulate both?
by Angela Cong 3C
Sun Oct 21, 2018 8:49 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7023
Views: 771975

Re: Post All Chemistry Jokes Here

Chemistry? More like Chemystery
by Angela Cong 3C
Sun Oct 21, 2018 8:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 86
Views: 25186

Re: Advice from a Medical Student [ENDORSED]

Thank you so much for all your advice! This will definitely help us all out years from now :)
by Angela Cong 3C
Sun Oct 14, 2018 4:59 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7023
Views: 771975

Re: Post All Chemistry Jokes Here

Take all your lame chemistry jokes, and Barium.
by Angela Cong 3C
Sun Oct 14, 2018 4:57 pm
Forum: Administrative Questions and Class Announcements
Topic: Test #2
Replies: 3
Views: 113

Re: Test #2

Test 2 will begin Tuesday Oct 23rd in our discussion, similar to how Test 1 was. So it would be the 10/22-10/26, depending on what day your discussion is. @danny
by Angela Cong 3C
Sun Oct 14, 2018 4:52 pm
Forum: Properties of Electrons
Topic: Photoelectric Experiment
Replies: 9
Views: 66

Re: Photoelectric Experiment

I understand the difference between intensity and frequency but in an actual experiment, how would you physically raise the frequency of the of the light source?
by Angela Cong 3C
Sun Oct 07, 2018 2:53 pm
Forum: Significant Figures
Topic: Sig Figs & Molar Mass
Replies: 4
Views: 46

Re: Sig Figs & Molar Mass

I'm pretty sure you're suppose to use the least amount of sig figs found in the problem to avoid any "false accuracy". If there isn't any numbers given in the problem then a good amount would be three sig figs.
by Angela Cong 3C
Sun Oct 07, 2018 2:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Registering/Creating Your Chemistry Community Account
Replies: 17
Views: 15270

Re: Registering/Creating Your Chemistry Community Account

Is there a system where they can automatically track if we had posted or not?
by Angela Cong 3C
Sun Oct 07, 2018 2:42 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7023
Views: 771975

Re: Post All Chemistry Jokes Here

I tried to tell a chemistry joke but it got no reaction

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