Search found 102 matches

by Ryan Laureano 3I
Fri Mar 12, 2021 12:34 am
Forum: Student Social/Study Group
Topic: STEM Clubs!
Replies: 7
Views: 76

Re: STEM Clubs!

ICGS specializes in genetics and deals with research and presentations. You get to travel over your breaks and meet many medical professionals!
by Ryan Laureano 3I
Fri Mar 12, 2021 12:27 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Are catalysts consumed?
Replies: 29
Views: 110

Re: Are catalysts consumed?

What I learned in biology is that catalysts are attached to the reaction and then detached. Thus the catalyst is never consumed by the reaction (as in it still is there after the reaction takes place). I think a better way of phrasing this is the catalyst is used and then discarded (it is on the rea...
by Ryan Laureano 3I
Fri Mar 12, 2021 12:22 am
Forum: Student Social/Study Group
Topic: How are y'all doing?
Replies: 46
Views: 184

Re: How are y'all doing?

Since finals are just around the corner, I'm not feeling stressed per say, but I have definitely kicked into a different gear in terms of studying. I don't want to dwell on how important my exams are so I'll just go about this just like any other exam. Other than that I'm chilling. How are you feeli...
by Ryan Laureano 3I
Fri Mar 12, 2021 12:19 am
Forum: Student Social/Study Group
Topic: Doubts about Pre-Med or Pre-Professional School
Replies: 17
Views: 79

Re: Doubts about Pre-Med or Pre-Professional School

Hey! I just wanted to let you know Savana that the majority of people I've talked to, including myself, doubt their future plans. I for sure have thought about leaving the pre med major but what keeps me going is knowing what I'm doing this for: I want to be a doctor to positively impact others (I k...
by Ryan Laureano 3I
Sat Mar 06, 2021 12:39 am
Forum: Second Order Reactions
Topic: Termolecular
Replies: 28
Views: 585

Re: Termolecular

Three reactants are colliding in the reaction but this is not so common.
by Ryan Laureano 3I
Sat Mar 06, 2021 12:25 am
Forum: General Rate Laws
Topic: Derivation of integrated rate laws and half-life equations
Replies: 7
Views: 25

Re: Derivation of integrated rate laws and half-life equations

You don't have to memorize the derivation per say but I do recommend understanding how it is derived since the equations sheet does not have the equations labeled.
by Ryan Laureano 3I
Sat Mar 06, 2021 12:06 am
Forum: Student Social/Study Group
Topic: Playlist
Replies: 83
Views: 430

Re: Playlist

Upside down by Jack Johnson is very nostalgic and just an overall classic song to play (its the curious george song).
by Ryan Laureano 3I
Thu Mar 04, 2021 11:54 pm
Forum: First Order Reactions
Topic: 0.693 ?
Replies: 29
Views: 138

Re: 0.693 ?

ln(2)
by Ryan Laureano 3I
Thu Mar 04, 2021 11:43 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order of Reaction
Replies: 4
Views: 24

Re: Order of Reaction

The order of the reaction is the sum of the order of the reactants (n,m,l). The order of the reactants can be solved algebraically given experimental values (think of the table in the lecture about initial concentrations and rxn rates).
by Ryan Laureano 3I
Fri Feb 26, 2021 9:41 pm
Forum: Student Social/Study Group
Topic: Chem 14B Final
Replies: 86
Views: 283

Re: Chem 14B Final

Go to as many UA office hours as you can.
by Ryan Laureano 3I
Thu Feb 25, 2021 11:56 pm
Forum: Balancing Redox Reactions
Topic: Sapling 7/8 #4
Replies: 2
Views: 47

Sapling 7/8 #4

Can someone explain what this feedback means for number 4 on this week's sapling?

"Once you have formed the net ionic redox equation, add Cl− ions to both sides of the equation and adjust the number of protons to transform the equation into the neutral molecular form"
by Ryan Laureano 3I
Thu Feb 25, 2021 11:49 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in NFE
Replies: 41
Views: 408

Re: n in NFE

N is the number of electrons after you balance the redox reactions.
by Ryan Laureano 3I
Thu Feb 25, 2021 6:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Eºcell
Replies: 11
Views: 64

Re: Eºcell

To add on think about the equation delta g naught = -nFE naught. For a spontaneous reaction (delta g naught is negative) E naught has to be positive.
by Ryan Laureano 3I
Thu Feb 25, 2021 6:42 pm
Forum: Administrative Questions and Class Announcements
Topic: When is Sapling HW due?
Replies: 22
Views: 75

Re: When is Sapling HW due?

Week 7/8 homework is due the 28th.
by Ryan Laureano 3I
Sun Feb 21, 2021 11:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Textbook Question 4D.7
Replies: 9
Views: 53

Re: Textbook Question 4D.7

I think sapling is missing some information here but I just assumed SATP (298K and 1 atm).
by Ryan Laureano 3I
Sun Feb 21, 2021 10:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 30
Views: 98

Re: Salt Bridge

The salt bridge keeps electrical neutrality in the circuit. Without one, the solution would have a positive and negative side.
by Ryan Laureano 3I
Sun Feb 21, 2021 10:55 pm
Forum: General Science Questions
Topic: MT 2 grades
Replies: 34
Views: 189

Re: MT 2 grades

I'm pretty sure sometime in week 8. Last time it was on Wednesday so i'm guessing around then.
by Ryan Laureano 3I
Wed Feb 17, 2021 11:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Textbook Question 4D.7
Replies: 9
Views: 53

Re: Textbook Question 4D.7

Use the first law of thermodynamics: delta U=q+w. Use the ideal gas law pv=nrt to find-p*deltav (note that temperature is 298k and you would manipulate it so that -p*delta v=-delta n*r*t). Work is equal to -p*delta v and q is equal delta h at constant pressure.
by Ryan Laureano 3I
Tue Feb 16, 2021 11:27 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Textbook Problem 5J.13
Replies: 3
Views: 9

Re: Textbook Problem 5J.13

Pay attention to what happens as the temperature goes up (the equilibrium constant goes down). Now apply this to how the products and reactants are affected (which way does the reaction shift?).
by Ryan Laureano 3I
Tue Feb 16, 2021 10:59 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Textbook 4A.9
Replies: 1
Views: 28

Re: Textbook 4A.9

I'm guessing you're using incorrect values for the heat capacities. Copper is .385 and water is 4.18. Otherwise I'd just make sure your algebra and general calculations are correct.
by Ryan Laureano 3I
Fri Feb 12, 2021 3:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling Week 5 and 6 #19
Replies: 4
Views: 31

Re: Sapling Week 5 and 6 #19

Solve for q using the partial pressures. Then use that for delta G = delta G standard + RTln(Q). Make sure the units check out!
by Ryan Laureano 3I
Fri Feb 12, 2021 12:10 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4F.9
Replies: 3
Views: 17

Re: 4F.9

I checked the answer key and the equation is manipulated so that it is p1/p2 instead of p2/p1. This is apparently because pressure is the inverse of volume. So .5 would actually still be p2 just in the denominator instead of numerator. Hope that clears some confusion.
by Ryan Laureano 3I
Wed Feb 10, 2021 10:55 pm
Forum: Calculating Work of Expansion
Topic: Negative vs Positive Work
Replies: 13
Views: 69

Re: Negative vs Positive Work

Think of anything going out of the system as negative and anything going in the system as positive. As a gas is being compressed, work is being done on the system meaning work is positive. In expansion, the system does work to the surroundings thus it is negative work.
by Ryan Laureano 3I
Tue Feb 09, 2021 10:50 pm
Forum: Student Social/Study Group
Topic: Points needed to pass?
Replies: 76
Views: 523

Re: Points needed to pass?

I know that you can miss a maximum of 28 points to keep an A in the class (not A-). I don't know for the other grades, but you can use the syllabus and the point distribution and put that information into RogerHub calculator to find out what you need for your desired grade. Keep in mind the grade di...
by Ryan Laureano 3I
Tue Feb 09, 2021 10:48 pm
Forum: Calculating Work of Expansion
Topic: How to know which equations to use?
Replies: 11
Views: 82

Re: How to know which equations to use?

A good place to start is figuring out what is given by the question as well as what you need to find. With this information you can determine which equations are beneficial. Sometimes you'll use one equation to get information you need for another equation. As for memorizing the equations, I think i...
by Ryan Laureano 3I
Fri Feb 05, 2021 11:07 pm
Forum: Student Social/Study Group
Topic: Equations
Replies: 7
Views: 50

Re: Equations

I find it helpful to know where the equation comes from. Derive it and manipulate it to fit what you are looking for. Also don't forget which units are there.
by Ryan Laureano 3I
Fri Feb 05, 2021 9:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Thermochemistry Equations?
Replies: 7
Views: 55

Re: Thermochemistry Equations?

I actually remembered a quick trick for gibbs free energy. delta g = -RTlnK or ratlink
This may or may not help but its good to know.
by Ryan Laureano 3I
Fri Feb 05, 2021 9:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Thermochemistry Equations?
Replies: 7
Views: 55

Re: Thermochemistry Equations?

Yeah just to add on, when you know how these equations are derived its easier to remember them. You can manipulate equations to make new ones. Just keep in mind what the units are and if they cancel out!
by Ryan Laureano 3I
Fri Feb 05, 2021 9:04 pm
Forum: Student Social/Study Group
Topic: Study routine.
Replies: 51
Views: 145

Re: Study routine.

Definitely read the book. A lot of the midterm and final content is straight from the book and sometimes Dr. Lavelle will spend little or no time on a topic he puts in the exams during his lectures.
by Ryan Laureano 3I
Sun Jan 31, 2021 10:10 pm
Forum: Student Social/Study Group
Topic: Work Life Balance
Replies: 44
Views: 218

Re: Work Life Balance

Try to meditate at least 5 minutes a day.
by Ryan Laureano 3I
Sun Jan 31, 2021 10:08 pm
Forum: Student Social/Study Group
Topic: Favorite Music
Replies: 105
Views: 517

Re: Favorite Music

You should listen to Luke Chiang
by Ryan Laureano 3I
Wed Jan 27, 2021 11:25 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Textbook Problem 5J.1
Replies: 1
Views: 14

Re: Textbook Problem 5J.1

For the first three, use Le Chatelier's principle to analytically solve them (i.e. what happens to the products and reactants as a result of the change in partial pressure or concentration). The last one is dealing with equilibrium. Does equilibrium change when concentrations change?
by Ryan Laureano 3I
Tue Jan 26, 2021 7:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 1 Zoom Proctoring
Replies: 14
Views: 137

Re: Midterm 1 Zoom Proctoring

I would assume so because that way we wouldn't need an external camera. I would just wait for your TA to email you.
by Ryan Laureano 3I
Tue Jan 26, 2021 7:18 pm
Forum: Phase Changes & Related Calculations
Topic: Midterm Scratch Paper? [ENDORSED]
Replies: 5
Views: 58

Re: Midterm Scratch Paper? [ENDORSED]

Last quarter we were allowed one piece of blank scratch paper for the midterms and I imagine that is the same for this quarter.
by Ryan Laureano 3I
Sat Jan 23, 2021 7:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids in Ice Tables
Replies: 11
Views: 51

Re: Solids in Ice Tables

You wouldn't include anything that is irrelevant so solids and liquid concentrations are not included.
by Ryan Laureano 3I
Thu Jan 21, 2021 11:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying for Midterm #1
Replies: 63
Views: 231

Re: Studying for Midterm #1

Take advantage of the resources Dr. Lavelle provides. Also study groups helps me a lot so I would look to form those :)
by Ryan Laureano 3I
Thu Jan 21, 2021 11:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: reaction direction
Replies: 3
Views: 11

Re: reaction direction

Left or right refers to reactants or products. Due to Le Chatelier's principle, an increase of one causes an increase in the other and a decrease in one causes a decrease in another. Changes in K can shift reactions left or right depending on what the change is. For example, in an exothermic reactio...
by Ryan Laureano 3I
Tue Jan 19, 2021 10:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constants and solubility
Replies: 2
Views: 22

Equilibrium constants and solubility

I was looking at the learning targets for the chemical equilibrium unit and I came across "Use equilibrium constants to predict solubility". Can someone explain what that means and how to do it?
by Ryan Laureano 3I
Tue Jan 19, 2021 10:21 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Rounding E Values in ICE charts
Replies: 17
Views: 84

Re: Rounding E Values in ICE charts

If the K value is smaller than 1x10^-3 than you can ignore its effect when subtracting k from a concentration.
by Ryan Laureano 3I
Sat Jan 16, 2021 4:02 pm
Forum: Ideal Gases
Topic: Kc vs. Kp
Replies: 32
Views: 160

Re: Kc vs. Kp

You solve Kp the same way as Kc. If you wanted to convert between Kc and Kp you use Kp=Kc(RT)^(change in moles). You don't need to convert because kp uses partial pressures.
by Ryan Laureano 3I
Sat Jan 16, 2021 3:59 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Textbook Question 6D.3
Replies: 3
Views: 32

Re: Textbook Question 6D.3

It's most likely that it's a sig fig problem. Generally if the answer is reasonably close to what you got, I would just assume sig figs. Your line of reasoning is correct, which is good.
by Ryan Laureano 3I
Sat Jan 16, 2021 3:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: hw question #4
Replies: 5
Views: 64

Re: hw question #4

Use ICE box to find x which you then use to find the partial pressure of the products and reactants. Then add up the partial pressures to get the total pressure of the system.
by Ryan Laureano 3I
Fri Jan 15, 2021 10:24 pm
Forum: Ideal Gases
Topic: Equilibrium Constant (Q and K)
Replies: 13
Views: 79

Re: Equilibrium Constant (Q and K)

To add on, Q is the reaction quotient at a given point in the reaction. Comparing Q and K can show which way the reaction is going to tend to (products or reactants). When they are equal the reaction is at equilibrium.
by Ryan Laureano 3I
Fri Jan 15, 2021 10:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conjugate Seesaw ??
Replies: 5
Views: 18

Re: Conjugate Seesaw ??

Conjugate seesaw refers to the fact that the stronger the acid, the weaker its conjugate base is and the stronger the base, the weaker its conjugate acid is. It is important in understanding acids and bases in relation to equilibrium.
by Ryan Laureano 3I
Fri Jan 08, 2021 10:14 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 5
Views: 16

Re: Inert Gas

Inert gases are noble gases. Adding them into a reaction changes the total pressure but not the partial pressures of the other gases, thus equilibrium is unchanged.
by Ryan Laureano 3I
Thu Jan 07, 2021 10:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 1&2 Sapling Homework Problem 9
Replies: 2
Views: 35

Re: Week 1&2 Sapling Homework Problem 9

You put 1M instead of .1M. Try fixing that first and then use ICE box.
by Ryan Laureano 3I
Thu Jan 07, 2021 10:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Problem 5G.1
Replies: 2
Views: 17

Re: Textbook Problem 5G.1

If there is a high concentration of reactants it is more likely for these reactants to come in contact with each other thus creating a product. Therefore, in equilibrium (when the concentration of reactants and products stops changing) you will see a increase in the product concentration compared to...
by Ryan Laureano 3I
Wed Jan 06, 2021 10:38 pm
Forum: Ideal Gases
Topic: Gas constant R
Replies: 26
Views: 162

Re: Gas constant R

Any constants in this class will be provided on the constants and equations sheet. Dr. Lavelle doesn't expect us to remember these but rather how to apply them. As for your question, R is a constant that is given.
by Ryan Laureano 3I
Wed Jan 06, 2021 5:45 pm
Forum: Ideal Gases
Topic: What makes an ideal gas an ideal gas?
Replies: 9
Views: 92

Re: What makes an ideal gas an ideal gas?

To add on to everyone above, an ideal gas for example won't turn into liquid if the temperature was lowered. That's how Dr. Lavelle portrayed it in his lecture and I think it's worth remembering.
by Ryan Laureano 3I
Fri Dec 11, 2020 5:08 pm
Forum: Lewis Acids & Bases
Topic: Aluminum Chloride naming in today's review
Replies: 4
Views: 53

Re: Aluminum Chloride naming in today's review

I'm pretty sure the prefixes are used to specify the number of atoms. Without the prefixes, the name would just refer to the elements within the compound.
by Ryan Laureano 3I
Fri Dec 11, 2020 5:03 pm
Forum: Sigma & Pi Bonds
Topic: Benzene Sigma/Pi Bonds
Replies: 3
Views: 20

Re: Benzene Sigma/Pi Bonds

Benzene has 12 bonds overall: 9 single and three triple bonds. In one single bonds is a sigma bond and in a pi bond exists a sigma bond and a pi bond. Therefore the three double bonds adds three sigma bonds and three pi bonds. Thus the total is 12 sigma and 3 pi bonds.
by Ryan Laureano 3I
Tue Dec 08, 2020 11:26 pm
Forum: Bronsted Acids & Bases
Topic: Amphoteric compounds
Replies: 8
Views: 82

Amphoteric compounds

I'm having trouble distinguishing which compounds are amphoteric. I know the meaning of amphoteric, but I can't really determine which compounds are. Any help would be appreciated.
by Ryan Laureano 3I
Tue Dec 08, 2020 10:55 pm
Forum: Identifying Acidic & Basic Salts
Topic: acidic/basic solution of salts
Replies: 4
Views: 39

Re: acidic/basic solution of salts

Fluorine has a strong interaction with the hydrogen in water while potassium has no attraction to any element in water. Thus potassium does not split up hydrogen ions in the water.
by Ryan Laureano 3I
Tue Dec 08, 2020 10:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Radial and Planar Nodes
Replies: 2
Views: 26

Re: Radial and Planar Nodes

Radial has a spherical shape and planar has a flat shape (think of the x,y, or z planes).
by Ryan Laureano 3I
Thu Dec 03, 2020 10:31 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate acids vs conjugate base
Replies: 12
Views: 85

Re: Conjugate acids vs conjugate base

Conjugate acid is the original formula plus a hydrogen ion. Conjugate base is minus a hydrogen ion.
by Ryan Laureano 3I
Thu Dec 03, 2020 10:26 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelates and Polydentates
Replies: 2
Views: 21

Re: Chelates and Polydentates

All coordination compounds with polydentate ligands are considered chelates.
by Ryan Laureano 3I
Wed Dec 02, 2020 7:01 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: The HCl + H2O example
Replies: 4
Views: 32

Re: The HCl + H2O example

The HCl - H2O forces are stronger than the HCl - HCl forces. Therefore the hydrogen ion is more attracted to the oxygen and breaks away from the chlorine atom, leaving the chlorine ion with an electron from the hydrogen. I hope that helps.
by Ryan Laureano 3I
Wed Dec 02, 2020 6:51 pm
Forum: Naming
Topic: Sapling 1
Replies: 34
Views: 209

Re: Sapling 1

When arranging ligands in alphabetical order, you always use the ligand name without the prefix.
by Ryan Laureano 3I
Sat Nov 28, 2020 11:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E #13c
Replies: 2
Views: 18

Re: 2E #13c

I have had many occurrences where the book is incorrect. By your description, it seems like there shouldn't be a formal charge on iodine. I am pretty sure you are correct and I would not pay too much attention to this problem. You think the book would be correct for the price you pay for it :/
by Ryan Laureano 3I
Sat Nov 28, 2020 11:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 11
Views: 74

Re: Bond Angles

I think it would just be helpful to look at a VSEPR chart. I am pretty sure Dr. Lavelle doesn't expect us to know the exact number, just if and why the bond angle is greater than or less than a specific number.
by Ryan Laureano 3I
Sat Nov 28, 2020 11:25 pm
Forum: Lewis Structures
Topic: Delocalized Pi Bonds
Replies: 3
Views: 61

Re: Delocalized Pi Bonds

Delocalized pi bonds are bonds that can move across multiple atom nuclei. Therefore they are in resonance structures.
by Ryan Laureano 3I
Wed Nov 25, 2020 10:33 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: When Ligands appear?
Replies: 3
Views: 34

Re: When Ligands appear?

Ligands are molecules that donate electron lone pairs (lewis base). They appear in transition metal complexes. A ligand can be thought of as what the central atom is bonding to.
by Ryan Laureano 3I
Wed Nov 25, 2020 10:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Atom Angles
Replies: 3
Views: 77

Re: Atom Angles

I searched it up and apparently they were discovered through various spectroscopic methods and diffraction methods. I don't think it is important to know how the geometry was found other than through experimentation.
by Ryan Laureano 3I
Sun Nov 22, 2020 8:46 pm
Forum: Sigma & Pi Bonds
Topic: Delocalized pi bonds
Replies: 2
Views: 34

Re: Delocalized pi bonds

A delocalized pi bond means a pi bond that can move over two or more nuclei. It is a free moving bond.
by Ryan Laureano 3I
Sun Nov 22, 2020 8:43 pm
Forum: Hybridization
Topic: Sapling#11
Replies: 6
Views: 33

Re: Sapling#11

There are four orbitals needed to be filled. SP3 is the hybridization notation that fits this.
by Ryan Laureano 3I
Sat Nov 21, 2020 10:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: sigma and pi bonds
Replies: 4
Views: 29

Re: sigma and pi bonds

For now, I think those are the only bonds that we should focus on. In the lectures, Dr. Lavelle describes how single bonds are sigma, double bonds have one sigma and one pi, and triple bonds have one sigma and two pi bonds.
by Ryan Laureano 3I
Tue Nov 17, 2020 5:32 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: ElectronConfigurations
Replies: 3
Views: 17

Re: ElectronConfigurations

You would utilize the Noble gas configuration. I think it would be better to use the shortcut method so it is easier to follow.
by Ryan Laureano 3I
Mon Nov 16, 2020 5:49 pm
Forum: Student Social/Study Group
Topic: Studying for Midterm 2
Replies: 4
Views: 31

Re: Studying for Midterm 2

I would attend as many UA sessions as possible. Also go over the textbook problems Dr. Lavelle suggests on his website. Study groups also are helpful because you can both teach and learn with your peers. Any combination of this should be enough. Good luck!
by Ryan Laureano 3I
Fri Nov 13, 2020 7:15 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Number
Replies: 8
Views: 92

Re: Oxidation Number

I would just think of it conceptually. If you know where the element is in the periodic table, you can deduce how many electrons it gains or loses. For example, the group 2 elements would have an oxidation number of +2 because it loses two electrons to fulfill the octet rule.
by Ryan Laureano 3I
Fri Nov 13, 2020 6:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone-Lone Pair vs Lone Bonding Pair vs Bonding-Bonding Pair?
Replies: 5
Views: 51

Re: Lone-Lone Pair vs Lone Bonding Pair vs Bonding-Bonding Pair?

Lone lone pair is the repulsion between two lone pairs. Lone bonding pair is the repulsion between a lone pair and a bond. Bonding bonding pair is the repulsion between two bonds.
by Ryan Laureano 3I
Fri Nov 13, 2020 6:09 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures on Midterm
Replies: 31
Views: 171

Re: Drawing Lewis Structures on Midterm

Total formal charge is the same for a molecule regardless of electron distribution. I'm pretty sure you are talking about individual atoms, in which case you would draw for the lowest formal charge unless told otherwise.
by Ryan Laureano 3I
Thu Nov 12, 2020 6:11 pm
Forum: Quantum Numbers and The H-Atom
Topic: angular momentum equation
Replies: 2
Views: 36

Re: angular momentum equation

I checked the 14A website and it doesn't seem to be under the outline 3 unit. My guess is that we wouldn't be tested on it. If you really want to know, I would email your TA just to make sure. Hope that helps.
by Ryan Laureano 3I
Thu Nov 12, 2020 6:05 pm
Forum: Lewis Structures
Topic: Resonance Hybrid
Replies: 5
Views: 70

Re: Resonance Hybrid

Dominant contribution refers to stability of the lewis structure. It's basically asking which structure is more stable between the two. More stable structure contribute more to resonance hybrids and have formal charges close to 0.
by Ryan Laureano 3I
Fri Nov 06, 2020 11:22 pm
Forum: Lewis Structures
Topic: Using sapling to draw lewis structures
Replies: 3
Views: 21

Re: Using sapling to draw lewis structures

There is a tab for elements and you just drag the elements to the canvas. For bonds, you pick the type (single, double, or triple) and connect it between the two elements. To put electron pairs, just press that button and click on the element you want to add electrons to. Lastly, you can add formal ...
by Ryan Laureano 3I
Thu Nov 05, 2020 6:08 pm
Forum: Lewis Structures
Topic: Formal Charge
Replies: 5
Views: 28

Re: Formal Charge

Formal charges of zero are more stable. The lower absolute value of the formal charge means higher stability.
by Ryan Laureano 3I
Wed Nov 04, 2020 10:18 pm
Forum: Resonance Structures
Topic: 2C.17
Replies: 2
Views: 35

Re: 2C.17

It is asking for which lewis bond structure has the lowest energy and is the most stable. To solve this, compare the formal charges of the structures.
by Ryan Laureano 3I
Wed Nov 04, 2020 9:19 pm
Forum: Ionic & Covalent Bonds
Topic: Ions
Replies: 5
Views: 69

Re: Ions

It depends on the quantum level of the element. If the element is in the 3d orbital for example, the electron is taken from 4s since n=4 is higher than n=3 (the 4s orbitals are filled before 3d). However, if the n is the same the electrons are taken from the highest subshell occupied (In order: f, d...
by Ryan Laureano 3I
Tue Nov 03, 2020 5:55 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Inner Core
Replies: 4
Views: 75

Re: Inner Core

The inner core is the portion of electrons in the inner shells of the atom. They are the electrons that are not valence electrons. In your example, [Ar] represents the inner core and is used as a shortcut to write the electron configuration. The 4s is the valence which is important to know for bondi...
by Ryan Laureano 3I
Fri Oct 30, 2020 10:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Sapling Question on number of electrons
Replies: 6
Views: 110

Re: Sapling Question on number of electrons

Yeah you would assume the maximum of 2 electrons, so the answer would be 2. Pay attention to the wording of this question as it asks how many electrons 'can' exist there. Hope that helps!
by Ryan Laureano 3I
Thu Oct 29, 2020 10:29 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Plane Importance
Replies: 9
Views: 53

Re: Nodal Plane Importance

Nodal planes help us determine how orbitals are positioned and thus what shapes they take.
by Ryan Laureano 3I
Thu Oct 29, 2020 10:27 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy v. Work Function
Replies: 3
Views: 35

Re: Ionization Energy v. Work Function

I am not really sure, but I would assume it's because the atoms in the gaseous state have different chemical properties compared to the solid state. This would account for difference in work function and ionization energy. That's a good question that you could probably search up but I don't think it...
by Ryan Laureano 3I
Tue Oct 27, 2020 10:51 pm
Forum: Empirical & Molecular Formulas
Topic: Book problem E15
Replies: 2
Views: 59

Re: Book problem E15

M is a mystery metal which you need to find by looking at its molar mass. Subtract the molar mass of OH from the compound and you would get the molar mass of M. Then correspond that molar mass to an existing element on the periodic table. Lastly add the molar mass of Sulfide which is S^2. Hope that ...
by Ryan Laureano 3I
Tue Oct 27, 2020 10:41 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra: Post-Module Survey
Replies: 2
Views: 23

Re: Atomic Spectra: Post-Module Survey

I believe the rydberg equation goes final and then initial. So you would be using 4 first.
by Ryan Laureano 3I
Fri Oct 23, 2020 4:30 pm
Forum: *Shrodinger Equation
Topic: Understanding of Shrodinger Equation
Replies: 3
Views: 56

Re: Understanding of Shrodinger Equation

I think the wave functions vary depending on the location of the electron. Other than that, your understanding of the squared wave function I believe is correct. Also I think it is important to know that probability density is different from probability in the sense that probability density requires...
by Ryan Laureano 3I
Thu Oct 22, 2020 5:52 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: How the Heisenberg Indeterminacy Equation Proves Electrons are not in the Nucleus
Replies: 2
Views: 21

Re: How the Heisenberg Indeterminacy Equation Proves Electrons are not in the Nucleus

From my understanding, the uncertainty refers to how accurate it is. In this case, a uncertainty velocity that is higher than the speed of light means the difference between the actual and observed velocities is higher than the speed of light. That means the electron is moving much higher than the s...
by Ryan Laureano 3I
Tue Oct 20, 2020 6:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Video Learning Modules?
Replies: 5
Views: 32

Re: Video Learning Modules?

I think Dr. Lavelle stated that he would add more modules if we wanted them. So I think posting to this forum can help spread that sentiment. I personally also want more modules because it helps to get ahead of the lecture and allows me to make my own pace. Also we might not be quite done with this ...
by Ryan Laureano 3I
Mon Oct 19, 2020 7:10 pm
Forum: DeBroglie Equation
Topic: Deriving De Broglie Equation
Replies: 2
Views: 38

Deriving De Broglie Equation

When deriving the De Broglie equation, how can we substitute c (the speed of light constant) with v (velocity). If the speed of light is constant, how can we substitute it with a value that can be changed?
by Ryan Laureano 3I
Mon Oct 19, 2020 7:03 pm
Forum: DeBroglie Equation
Topic: 1B27
Replies: 3
Views: 48

Re: 1B27

I did this problem too, and I ended up getting 6.59x10^-37. I would assume the difference is in how much of planck's constant you use. In this case, I wouldn't worry about the small difference as long as the sig figs are correct. I noticed sapling allows some room for error in rounding.
by Ryan Laureano 3I
Fri Oct 16, 2020 11:31 pm
Forum: Properties of Light
Topic: Wave model vs Photon model
Replies: 3
Views: 46

Re: Wave model vs Photon model

Your summary is correct in that the photoelectric effect shows light having particle properties. Along with diffraction patterns, these examples highlight the wave-particle duality which states every particle or quantum entity exhibits both wave-like and particle-like properties. The photoelectric e...
by Ryan Laureano 3I
Thu Oct 15, 2020 5:23 pm
Forum: Photoelectric Effect
Topic: Sapling Homework Q4 part b
Replies: 3
Views: 27

Re: Sapling Homework Q4 part b

I believe you use the total energy of the photons (which is provided) and divide that by the energy per photon (which you can solve using the E(photon) - work function = E(excess) equation). Let me know if you get the right answer!
by Ryan Laureano 3I
Wed Oct 14, 2020 2:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lyman Series, Balmer Series, and Infrared
Replies: 4
Views: 54

Re: Lyman Series, Balmer Series, and Infrared

It's referred to as the Paschen series, but I don't think this is as important to remember as the Balmer or Lyman series (it's still good to know though!).
by Ryan Laureano 3I
Tue Oct 13, 2020 7:42 pm
Forum: Properties of Light
Topic: Sapling Week 2/3 question 4
Replies: 9
Views: 135

Re: Sapling Week 2/3 question 4

Yeah you would set E(photon) - E (energy remove e-) = E (excess). The excess is the maximum kinetic energy and the energy of the photon can be found using E=hv. From here it's basic algebra. Hope that helps!
by Ryan Laureano 3I
Mon Oct 12, 2020 4:16 pm
Forum: Einstein Equation
Topic: Planck's Constant
Replies: 7
Views: 105

Planck's Constant

I don't know if Professor Lavelle ever covered this, but out of curiosity how was planck's constant (h) derived?
by Ryan Laureano 3I
Fri Oct 09, 2020 1:49 pm
Forum: SI Units, Unit Conversions
Topic: Volume vs. Density
Replies: 6
Views: 62

Re: Volume vs. Density

Extensive properties means it changes as the amount of matter does. Intensive properties remain the same regardless of change in matter. In this case, the amount of matter affects volume but not density.
by Ryan Laureano 3I
Thu Oct 08, 2020 5:11 pm
Forum: DeBroglie Equation
Topic: Wavelike Properties [ENDORSED]
Replies: 9
Views: 148

Wavelike Properties [ENDORSED]

When Professor Lavelle stated in his lecture "All matter has wavelike properties, but it is only noticeable for small mass and high velocity" why is it that cars aren't considered having wavelike properties. Even if it is unnoticeable, isn't the wavelength still there? Or is it considered ...
by Ryan Laureano 3I
Thu Oct 08, 2020 3:34 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs and molar mass
Replies: 18
Views: 133

Re: Sig figs and molar mass

As a general rule for chemistry, whenever there are decimals, it is better to stay true to the original number. For example, hydrogen has a molar mass of 1.008 g/mol (1.00784 g/mol to be exact) and using 1 g/mol instead can have drastic effects in your calculations. I like to keep the number I see o...
by Ryan Laureano 3I
Wed Oct 07, 2020 12:07 am
Forum: Limiting Reactant Calculations
Topic: Sapling Homework Question 10
Replies: 16
Views: 294

Re: Sapling Homework Question 10

If you click on the icon to the left of assignment score, it says 'You lose 0% of the points available to each answer in your question for each incorrect attempt at that answer.' so I believe the homework is graded on completion rather than accuracy.
by Ryan Laureano 3I
Tue Oct 06, 2020 11:56 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Hw Week 1 #10
Replies: 20
Views: 327

Re: Sapling Hw Week 1 #10

Yeah I've been having the same problem too. My theoretical yield is correct but for some reason I can't seem to get the percentage correct. I think its the sig figs but I put multiple answers and all seem to be wrong.

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