Search found 65 matches

by Rachel Yoo 1F
Wed Mar 13, 2019 1:07 am
Forum: General Rate Laws
Topic: writing rate law
Replies: 2
Views: 21

Re: writing rate law

I believe it is because the rate law is in terms of the products so reactants are the ones affecting the production rate
by Rachel Yoo 1F
Wed Mar 13, 2019 1:04 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 #6 part c
Replies: 1
Views: 30

Test 2 #6 part c

Did anyone get #6 part c right and if you did could you give me the answer and how you got it because I got a and b right but c wrong and I'm not sure what I did wrong
by Rachel Yoo 1F
Wed Mar 13, 2019 12:54 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 2
Views: 28

Re: Arrhenius Equation

Are the k reaction rates swithced too? Because if k is switched too then it is fine
by Rachel Yoo 1F
Fri Mar 08, 2019 12:44 pm
Forum: Zero Order Reactions
Topic: Differentiating Zero and One Order Reactions
Replies: 2
Views: 26

Re: Differentiating Zero and One Order Reactions

The 1st order reaction should look like an exponential decay function
by Rachel Yoo 1F
Tue Mar 05, 2019 5:34 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Homework 15.17 6th Edition
Replies: 1
Views: 27

Re: Homework 15.17 6th Edition

check to see the order for the reactant C. If reactant C iz zero order, than it doesn't matter what concentration C is because it has no effect on the rate
by Rachel Yoo 1F
Tue Mar 05, 2019 11:59 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.15
Replies: 1
Views: 25

6N.15

Calculate the potential of a cell constructed with two nickel electrodes. The electrolyte in one compartment is 1.0 M Ni(NO3)2. In the other compartment, NaOH has been added to a Ni(NO3)2 solution until the pH = 11 at 298 K. Use Table 6I.1 I got the [OH-} concentration but I'm not really sure how to...
by Rachel Yoo 1F
Mon Feb 25, 2019 4:40 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Homework question
Replies: 3
Views: 28

Re: Homework question

in this equation n = the number of moles of electrons being transferred
by Rachel Yoo 1F
Mon Feb 25, 2019 4:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M5 part a
Replies: 2
Views: 42

6M5 part a

For the cell diagram the answer doesn't include a platinum(s) on the anode side when there is no solid. It only has Hg(l) and Hg2 2+(aq). I thought we had to always include Pt(s) when there's no solid so why does the answer not include it on this side?
by Rachel Yoo 1F
Mon Feb 25, 2019 4:30 pm
Forum: Student Social/Study Group
Topic: Topic 6N
Replies: 1
Views: 81

Topic 6N

For the people with 7th edition textbooks will anything in topic 6N be in test 2?
by Rachel Yoo 1F
Wed Feb 20, 2019 12:25 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 4J.15
Replies: 2
Views: 40

4J.15

Which of the following compounds become less stable with respect to the elements as the temp is raised: (a) PCl5 (b) HCN (c) NO(g) (d)SO2?
by Rachel Yoo 1F
Wed Feb 20, 2019 12:22 am
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Thermodynamics
Replies: 1
Views: 59

Test 2 Thermodynamics

I read a post saying that thermodynamics will be on test 2 so does that mean isobaric, isothermal, and isochoric equations for test 2?
by Rachel Yoo 1F
Wed Feb 20, 2019 12:19 am
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: S value
Replies: 3
Views: 53

Re: S value

The larger the molecule, the more ways it can rearrange itself and create different shapes. This increases entropy
by Rachel Yoo 1F
Mon Feb 11, 2019 2:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 7th edition 4C.13
Replies: 1
Views: 37

Re: 7th edition 4C.13

I dont think it matters whether you use specific heat of molar heat as long as your consistent in what you use.
For this problem make sure you include the energy it takes to change the solid to a liquid into the equation
by Rachel Yoo 1F
Mon Feb 11, 2019 1:49 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 3/2 R and 5/2 R
Replies: 3
Views: 53

Re: 3/2 R and 5/2 R

3/2 R=Cv
5/2R=Cp
this is used in the equation to find heat
q=ncdeltaT
those values only apply to ideal gases
by Rachel Yoo 1F
Mon Feb 11, 2019 1:46 pm
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM 7th ed
Replies: 1
Views: 47

Re: MIDTERM 7th ed

It will cover everything until 4J I believe because he said entropy is on the midterm
by Rachel Yoo 1F
Sun Feb 10, 2019 11:24 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 48
Views: 766

Re: Midterm [ENDORSED]

If you go to any TA office hour, they will tell you what topics are on the midterm and generally help with any questions you have for the midterm.
by Rachel Yoo 1F
Mon Feb 04, 2019 5:00 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Thermodynamic equations
Replies: 1
Views: 39

Thermodynamic equations

I'm struggling with trying to understand which equation to use when I'm reading the homework problems so does anyone have any tips or advice on how to memorize which work,q, or delta u equation to use for the different types of different processes?
by Rachel Yoo 1F
Mon Feb 04, 2019 2:53 pm
Forum: Administrative Questions and Class Announcements
Topic: Final from 14A
Replies: 2
Views: 106

Final from 14A

Does anyone know when we will receive our finals from last quarter?
by Rachel Yoo 1F
Mon Feb 04, 2019 2:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14 BL
Replies: 5
Views: 120

Chem 14 BL

Does anyone know if Chem 14BL should be taken with Chem 14C? If not when is it recommended to take Chem 14 BL?
by Rachel Yoo 1F
Mon Jan 28, 2019 11:17 pm
Forum: Phase Changes & Related Calculations
Topic: 7th edition 4a.3 part c
Replies: 1
Views: 38

7th edition 4a.3 part c

air in a bicycle pump is compressed by pushing in the handle. the inner diameter of the pump is 3.0cm and the pump is depressed 20. cm with a pressure of 2.0 atm. part c) what is the change in internal energy of the system?
by Rachel Yoo 1F
Mon Jan 28, 2019 11:09 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Memorizing bond enthalpies
Replies: 5
Views: 81

Re: Memorizing bond enthalpies

What are the common bond enthalpies that I should memorize?
by Rachel Yoo 1F
Mon Jan 28, 2019 11:07 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW Week4
Replies: 4
Views: 57

HW Week4

So I'm trying to do the problems in the 7th edition book section 4A but I don't really think Lavelle's lecture today or last Friday covered section 4A. Which sections did Lavelle cover so far in thermochemistry so I can do for this week's hw?
by Rachel Yoo 1F
Mon Jan 21, 2019 3:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th Edit 6D15
Replies: 1
Views: 30

Re: 7th Edit 6D15

Since its a weak acid you have to make an ICE Table. You can find the Ka values on the tables in section 6C.
by Rachel Yoo 1F
Mon Jan 21, 2019 3:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 & homework
Replies: 2
Views: 45

Re: Test 1 & homework

For problem 6D.13 I used tables 6c1, 6c2, and 6c3 to find ka and kb values
by Rachel Yoo 1F
Mon Jan 21, 2019 3:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th Edit 6D.7
Replies: 1
Views: 22

Re: 7th Edit 6D.7

For part a with the H+ concentration, you can also use the Table 6c1 and 6c2 to find Ka for HClO. Use ICE table to set up an equation and find the initial concentration of the weak acid
by Rachel Yoo 1F
Mon Jan 14, 2019 3:37 pm
Forum: Ideal Gases
Topic: When is pv=nrt used? [ENDORSED]
Replies: 5
Views: 96

Re: When is pv=nrt used? [ENDORSED]

You can use PV=NRT in any situation when given any three out of the four: pressure, volume, number of moles, or temperature. R=.08206. In this instance, we use it to convert Kc to Kp or vice versa
by Rachel Yoo 1F
Mon Jan 14, 2019 3:31 pm
Forum: Ideal Gases
Topic: Using Kc or Kp
Replies: 13
Views: 121

Re: Using Kc or Kp

Kp is for partial pressure with units like atm, bar, torr, etc. Kc is for concentrations and will have mol/L for units
by Rachel Yoo 1F
Mon Jan 14, 2019 3:27 pm
Forum: General Science Questions
Topic: Lecture Powerpoints
Replies: 9
Views: 165

Re: Lecture Powerpoints

They aren't online so if you ever miss a lecture I would say to either ask a friend for their notes on the lecture or go into his office hours and ask what you topics you missed.
by Rachel Yoo 1F
Wed Jan 09, 2019 11:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Giving Qc or Qp when asked for Q
Replies: 5
Views: 66

Giving Qc or Qp when asked for Q

For questions like 5G.11 when it asks you to write the reaction quotient Q for a certain equation, does it matter to answer with Qc or Qp?
by Rachel Yoo 1F
Mon Jan 07, 2019 9:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem Community ID
Replies: 1
Views: 38

Re: Chem Community ID

Just change your username by clicking on your name on the top right corner of the page and click user control panel
by Rachel Yoo 1F
Mon Jan 07, 2019 9:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Aqueous in K expression
Replies: 4
Views: 64

Aqueous in K expression

I know that we don't include solids and liquid in our K expression but what if its aqueous ?
by Rachel Yoo 1F
Wed Dec 05, 2018 1:59 am
Forum: Identifying Acidic & Basic Salts
Topic: Proton Transfer Reaction
Replies: 1
Views: 27

Re: Proton Transfer Reaction

The cation/anion and water would be the reactants and depending on which reactant is the acid, it will donate the H+ to the base
by Rachel Yoo 1F
Wed Dec 05, 2018 1:55 am
Forum: Bronsted Acids & Bases
Topic: J.9
Replies: 2
Views: 42

J.9

The question is to identify the salt that is produce from the acid-base neutralization reaction between potassium hydroxide and acetic acid. write the complete ionic equation for each reaction. I am confused as how to approach the problem and what salts can be produced
by Rachel Yoo 1F
Wed Dec 05, 2018 1:52 am
Forum: Bronsted Acids & Bases
Topic: Acids
Replies: 3
Views: 60

Re: Acids

For our class right now I believe that we are focusing on Bronsted acids
by Rachel Yoo 1F
Mon Nov 26, 2018 10:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Cis and Trans
Replies: 10
Views: 125

Re: Cis and Trans

The cis configuration is polar which means it can create dipole dipole interactions and create a stronger bond compared to the trans configuration
by Rachel Yoo 1F
Mon Nov 26, 2018 10:30 pm
Forum: Hybridization
Topic: Question from textbook
Replies: 4
Views: 53

Re: Question from textbook

It has 3 bonds and two lone pairs which means its hybridization is sp3d
by Rachel Yoo 1F
Mon Nov 26, 2018 10:27 pm
Forum: Lewis Structures
Topic: Question 3.45
Replies: 4
Views: 68

Re: Question 3.45

Nitrogen is in row 2 which means it cant disobey the octet rule. By adding a double bond to chlorine, it would make nitrogen not follow this rule.
by Rachel Yoo 1F
Mon Nov 19, 2018 6:58 pm
Forum: Hybridization
Topic: Unhybridized orbitals
Replies: 10
Views: 159

Unhybridized orbitals

Today in lecture Dr. Lavelle talked about unhybridized 2p orbitals but I was unsure of what unhybridized orbitals are and the difference between these and hybridized orbitals.
by Rachel Yoo 1F
Mon Nov 19, 2018 6:41 pm
Forum: Lewis Structures
Topic: Lewis Structure of Carbon Monoxide
Replies: 3
Views: 56

Re: Lewis Structure of Carbon Monoxide

When drawing lewis structures, it is good to first make sure every element has a complete octet( unless it's in row 3 or after). Then I would start paying attention to how to create the most stable structure.
by Rachel Yoo 1F
Mon Nov 19, 2018 6:37 pm
Forum: Hybridization
Topic: D-orbital
Replies: 5
Views: 82

Re: D-orbital

Yes Dr. Lavelle said in class that it was fine if you put d before or after the sp
by Rachel Yoo 1F
Tue Nov 13, 2018 5:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 8
Views: 162

Re: Test 3

Test 3 is on the week after Thanksgiving
by Rachel Yoo 1F
Tue Nov 13, 2018 5:11 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Stable Vs. Formal
Replies: 4
Views: 153

Re: Stable Vs. Formal

I think stable charge refers to the formal charge of the most stable structure for the specific molecule
by Rachel Yoo 1F
Tue Nov 13, 2018 4:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 5
Views: 101

Re: Bond Angles

I think bond angles is something you just need to memorize by VSEPR
by Rachel Yoo 1F
Thu Nov 08, 2018 12:50 am
Forum: Dipole Moments
Topic: Polar and Nonpolar
Replies: 7
Views: 122

Re: Polar and Nonpolar

Polar bonds have an unequal sharing of electrons while nonpolar bonds do have equal sharing
by Rachel Yoo 1F
Thu Nov 08, 2018 12:35 am
Forum: Lewis Structures
Topic: Electron Pairs 3.61
Replies: 2
Views: 30

Re: Electron Pairs 3.61

To know how to solve the problem, you want to find the most stable lewis structure so guess and check until you find a structure with the lowest formal charge.
by Rachel Yoo 1F
Thu Nov 08, 2018 12:25 am
Forum: Dipole Moments
Topic: Dipole-Dipole vs Induced Dipole
Replies: 5
Views: 79

Re: Dipole-Dipole vs Induced Dipole

A dipole induced dipole means that the molecule by itself doesn't have a dipole moment but with the bonding of a second molecule, it will have become dipole,
by Rachel Yoo 1F
Tue Oct 30, 2018 11:25 pm
Forum: Ionic & Covalent Bonds
Topic: 2B.1 Part B
Replies: 2
Views: 42

2B.1 Part B

The question asks to draw the lewis structure for COCl2. I drew mine and put oxygen in the middle but when I checked the answers carbon was the central atom. How would you be able to know this?
by Rachel Yoo 1F
Tue Oct 30, 2018 11:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cu+ electron configuration
Replies: 2
Views: 59

Re: Cu+ electron configuration

Since the question is asking for the electron configuration of Cu+ it means that Cu lost an electron. Originally it would be [ar]3d84s2 but the 2 electrons from the 4s shell move to the 3d shell making the electron configuration [Ar]3d10
by Rachel Yoo 1F
Tue Oct 30, 2018 11:13 pm
Forum: Ionic & Covalent Bonds
Topic: 2A.15
Replies: 2
Views: 47

Re: 2A.15

The way I figure it out is I first look at the position of the element. If it is in Group1-3 it will lose the electron, so it will have a positive charge. If its in Group 15-17 it will gain electrons and have a negative charge. The amount of electrons it loses/gains represents the number.
by Rachel Yoo 1F
Mon Oct 22, 2018 11:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Test 2 Question
Replies: 3
Views: 91

Re: Test 2 Question

Also where did you get the study guide
by Rachel Yoo 1F
Mon Oct 22, 2018 11:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Test 2 Question
Replies: 3
Views: 91

Re: Test 2 Question

I think it might be talking about e-p distribution and that the p orbital has a 0 probability of electron density
by Rachel Yoo 1F
Mon Oct 22, 2018 11:56 pm
Forum: Trends in The Periodic Table
Topic: Periodic Table
Replies: 2
Views: 36

Re: Periodic Table

The ionization energy(energy required to lose one electron) of p-block are quite high because they need one more to fill a shell . So they are less reactive than s-blocks in which has a low ionization energy
by Rachel Yoo 1F
Mon Oct 22, 2018 11:53 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework 1E.13
Replies: 1
Views: 29

Re: Homework 1E.13

The f orbital is included after the 6s2 orbital is filled. When looking at the periodic table, you can see that the f block starts in period 6.
by Rachel Yoo 1F
Tue Oct 16, 2018 5:13 pm
Forum: Properties of Light
Topic: property of light
Replies: 2
Views: 40

Re: property of light

Photons do influence the amount of energy. Each photon is like a packet of energy so if the light produces a certain amount of photons, the energy radiation is influenced upon that.
by Rachel Yoo 1F
Tue Oct 16, 2018 5:07 pm
Forum: Properties of Light
Topic: Change in the electrical field
Replies: 1
Views: 37

Re: Change in the electrical field

A lower frequency means a longer wavelength. Since the wavelengths are longer, it allows less oscillations to be completed in a time frame compared to a small wavelength. "extent of the change" means the slope so since the wavelength is longer, the slope changes less.
by Rachel Yoo 1F
Tue Oct 16, 2018 4:59 pm
Forum: DeBroglie Equation
Topic: 1B.9
Replies: 3
Views: 73

Re: 1B.9

Use the 32J/s to find the total amount of J in 2 seconds. Then use the equation E=(hc)/lambda to find the energy of one photon. With this you should be able to find the number of photons of a violet light. Then you can find the number of moles of photons by using Avogadro's number
by Rachel Yoo 1F
Sun Oct 14, 2018 10:55 am
Forum: Photoelectric Effect
Topic: 1B.15 Part C
Replies: 2
Views: 66

1B.15 Part C

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6*10^3 km*s^-1. part c. what is the wavelength of the radiation that caused photoejection of the electron? I got part a and b but I'm not really sure how to do this part but I tried both the equations lambda=c/v and...
by Rachel Yoo 1F
Tue Oct 09, 2018 10:08 pm
Forum: Properties of Light
Topic: Homework Problem 1A.9
Replies: 2
Views: 39

Re: Homework Problem 1A.9

To find the wavelength you first convert the frequency of MHz to Hz. Then using the equation c=(lambda)v, you can find the wavelength.
by Rachel Yoo 1F
Mon Oct 08, 2018 10:44 pm
Forum: Properties of Light
Topic: Chapter 1 Question 1.3
Replies: 3
Views: 57

Re: Chapter 1 Question 1.3

the "extent of the change" refer to the slopes of the wavelength and because the wavelengths are longer, it allows less oscillations to be completed within a time frame
by Rachel Yoo 1F
Mon Oct 08, 2018 10:36 pm
Forum: Properties of Light
Topic: Chem Homework Question Number 1.9
Replies: 1
Views: 26

Re: Chem Homework Question Number 1.9

I have the 7th edition and the chart on Table 1A.1 says that a 1m wavelength is both microwave and radio wave
by Rachel Yoo 1F
Wed Oct 03, 2018 10:51 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Steps General Question
Replies: 3
Views: 53

Re: Limiting Reactant Steps General Question

When finding empirical or molecular formula, its important that we know the mass percentage of each element. For example, we find the mass percentage is H 4.58%, O 54.5%, and C 40.9%. Since these percentages all equal to 100% it is the easiest procedure to imagine the sample mass being 100g because ...
by Rachel Yoo 1F
Wed Oct 03, 2018 10:45 pm
Forum: Significant Figures
Topic: Significant Figures
Replies: 10
Views: 199

Re: Significant Figures

When adding and subtracting, you use the least number of sig figs AFTER the decimal place.
For example, 1.823+9.75=11.57

9.57 has only 2 sig figs after the decimal place which means the answer will only have 2 sig figs after the decimal.
by Rachel Yoo 1F
Wed Oct 03, 2018 10:34 pm
Forum: SI Units, Unit Conversions
Topic: Prefixes
Replies: 2
Views: 52

Re: Prefixes

In my opinion, the prefixes that will most likely be used is kilo, deci, centi, and milli but like the comment above I think its probably best to memorize them all.
by Rachel Yoo 1F
Tue Oct 02, 2018 9:28 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 35850

Re: Rusty on High School Chem [ENDORSED]

Doing the modules posted on Dr. Lavelle's website is actually really good review. The videos are him teaching the topics/lectures and he gives good and easy examples to follow along.
by Rachel Yoo 1F
Tue Oct 02, 2018 9:27 pm
Forum: SI Units, Unit Conversions
Topic: Audio-Visual Focus-Topics, Assessments & Surveys
Replies: 10
Views: 214

Re: Audio-Visual Focus-Topics, Assessments & Surveys

Yea when I did the modules they don't ask for our name or UID so I'm assuming that its just review for self benefit. It was actually a good refresher from summer break.

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