## Search found 65 matches

Sat Mar 16, 2019 12:44 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12956

How do you solve #8 on worksheet 9? How do you find the half-life given that 99% of the reactant decomposes in 137 min?
Fri Mar 15, 2019 6:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 2
Views: 103

### Re: Cell Diagram

use comma when the the reactants are in the same state/phase and the line when they are not. so if you had Mn4+ (aq) and Mn2+ (aq) it would be a comma separating the two. If Mn2+ was a gas then use the line.
Fri Mar 15, 2019 6:45 pm
Forum: General Rate Laws
Topic: Rate constants
Replies: 1
Views: 58

### Rate constants

What is the difference between the rate and rate constants?
Wed Mar 13, 2019 10:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration cell
Replies: 1
Views: 113

### Concentration cell

In a concentration cell, why does reduction take place on the electrode with a higher concentration? (w/same components)
Sun Mar 10, 2019 8:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 6
Views: 211

### Re: Cell diagram

What doesn't get put in the cell diagram? Is it just solids and H2O liquid? Does H+ get put in the cell diagram?
Sun Mar 10, 2019 8:24 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 12
Views: 475

### Re: Test 2

What happens if Gibbs free energy is zero exactly?
Sun Mar 10, 2019 8:23 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Final Material
Replies: 4
Views: 163

### Re: Final Material

If you look on his website, it's under the header "Audio-Visual Focus-Topics, Assessments & Surveys". There's four of them to complete.
Thu Feb 28, 2019 7:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cathode vs anode
Replies: 4
Views: 218

### Re: cathode vs anode

whichever half-rxn is oxidized (loses e-, oxidation number incr) is the anode and the half-rxn that is reduced (gain e-, oxidation number decr) is the cathode
Thu Feb 28, 2019 7:01 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculations using the Van't Hoff Equation
Replies: 2
Views: 237

### Re: Calculations using the Van't Hoff Equation

For that problem I used deltaG= deltaGo + RTlnQ which further is deltaG=-RTlnK + RTlnQ. I don't know really what the applications of the Van't Hoff equation.
Thu Feb 28, 2019 6:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.15 6th Edition
Replies: 2
Views: 113

### Re: 11.15 6th Edition

What does it mean if Gibbs free energy is 0 exactly?
Thu Feb 28, 2019 6:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.17
Replies: 3
Views: 201

### Re: 11.17

Since the reaction is not at equilibrium, you need to use deltaG=deltaGo + RTlnQ which can be further written as deltaG=-RTlnK + RTlnQ
Fri Feb 22, 2019 8:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Units of Delta G
Replies: 5
Views: 522

### Re: Units of Delta G

The units are either kJ or J due to the fact that delta G is deltaH- T*deltaS
Fri Feb 22, 2019 8:55 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 8
Views: 311

### Re: Spontaneity

Gibbs free energy can be used to determine the "spontaneity" of a reaction due to the fact Gibbs free energy change is the total energy change of the system.
Fri Feb 22, 2019 8:53 pm
Forum: Balancing Redox Reactions
Topic: Test 2 Textbook Sections
Replies: 2
Views: 165

### Re: Test 2 Textbook Sections

It covers in chapter 14, everything up to but not including Nernst Equation which is section 14.9 in the 6th edition textbook.
Fri Feb 22, 2019 8:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridges
Replies: 3
Views: 146

### Re: Salt Bridges

I thought that the salt bridges have porous disks which allow only for the transfer of ions between solutions and keeps the solution inside the bridge completely separate. Correct me if I'm wrong.
Fri Feb 22, 2019 8:49 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm Question
Replies: 8
Views: 289

### Re: Midterm Question

I used C=5/2R and I got full credit, maybe it doesn't matter that much?
Fri Feb 22, 2019 8:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 7
Views: 354

### Re: Test 2

It covers Gibb Free Energy and Thermochemistry up until today's lecture.
Thu Feb 07, 2019 11:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.53 Bomb Calorimeter 6th Ed
Replies: 1
Views: 106

### Re: 8.53 Bomb Calorimeter 6th Ed

Bomb calorimeters are insulated and essential makes the system isolated which is a reason that volume is fixed because if it weren't then an external force like a piston could compress the volume, but in an isolated system, nothing exchanges with the surroundings. using the equation q=-C(cal) x delt...
Thu Feb 07, 2019 11:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 2
Views: 237

### Re: Midterm

We get an equations sheet, so probably not? All the related and derived equations we need should be given to us.
Thu Feb 07, 2019 11:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 6th edition Question 8.67
Replies: 2
Views: 168

### 6th edition Question 8.67

The question asks to estimate the enthalpy of formation of compounds in the liquid state. After finding the deltaH of the gas, what equation are we supposed to use to find the deltaH of the liquid? In class we learned that the enthlapy of vaporization is the H(vapor)-H(liquid) to go from liquid to a...
Sat Feb 02, 2019 9:11 pm
Forum: Student Social/Study Group
Topic: Absent on 1/30; in need of notes
Replies: 4
Views: 236

### Re: Absent on 1/30; in need of notes

We have a note taker for this class on studysoup.com, I think her name is Celine Hoh. She uploads the notes there if you need them.
Sat Feb 02, 2019 9:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy & Constant Pressure and Volume
Replies: 2
Views: 123

### Re: Enthalpy & Constant Pressure and Volume

Thanks for explaining this! I was also kind of confused about deltaH.
Fri Feb 01, 2019 8:11 pm
Forum: Ideal Gases
Topic: pV=nRT
Replies: 12
Views: 1006

### Re: pV=nRT

What does the R in this equation stand for?
Fri Jan 25, 2019 6:19 pm
Forum: Phase Changes & Related Calculations
Topic: Modules
Replies: 17
Views: 493

### Re: Modules

No, they are not counted towards your grade at all. The modules are just for you to refer to if you need extra help or want to review basics. In my opinion, its good to do them, especially the quizzes for extra practice.
Fri Jan 25, 2019 6:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What not to count
Replies: 9
Views: 395

### Re: What not to count

As stated before, don't use solid or pure liquid concentrations in the equilibrium constant equation. For water, you would only put it in the equation if it is in the gas phase.
Fri Jan 25, 2019 6:14 pm
Forum: Phase Changes & Related Calculations
Topic: Lecture 1/23
Replies: 3
Views: 156

### Re: Lecture 1/23

In addition, the definition of state property is that its a value determined by its current state and is not dependent on the path taken to obtain that state. State property can be added and subtracted. Other state properties are energy, pressure, volume, temperature, density, and heat capacity.
Tue Jan 15, 2019 12:35 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Hmwrk 11.33 6th edition
Replies: 1
Views: 59

### Re: Hmwrk 11.33 6th edition

In my solutions manual it says that Q<K. When you solve for Q, you should get 6.9 which is smaller than K of 1.7 x 10^6. Therefore, bc Q<K, the rxn will form more constants (favor forward rxn).
Tue Jan 15, 2019 12:31 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition Question 11.45
Replies: 2
Views: 78

### 6th edition Question 11.45

For part (C), can someone explain why Cl2 is thermodynamically more stable? Does the equilibrium constant have anything to do with determining wheter Cl2 rxn or F2 rxn is more stable?
Fri Jan 11, 2019 10:59 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Kc to Kp
Replies: 4
Views: 668

### Re: Converting Kc to Kp

To convert, use p=(conc)RT --> Conc=P/(RT). In Module 2, the PCl problem in the video, Lavelle talks about conversion there if you need more assistance.
Fri Jan 11, 2019 10:51 am
Forum: General Science Questions
Topic: Week 1 Homework
Replies: 5
Views: 229

### Re: Week 1 Homework

Celine Hoh 4H wrote:Can we submit our hw during discussion?

I think for this week's homework only, everybody turns it in after lecture. But, for every other hw assignment, it will be due in discussion.
Fri Jan 11, 2019 10:49 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium
Replies: 3
Views: 137

### Re: equilibrium

If you know what the equilibrium constant of the reaction is, you can use it (plus some extra given info), to figure out the individual equilibrium concentrations of products and reactants. Hope that answers your question!
Thu Dec 06, 2018 10:06 pm
Forum: Administrative Questions and Class Announcements
Replies: 135
Views: 31567

will there be more worksheets for the recently covered material like acids and bases and coordination compounds ? Thanks
Thu Dec 06, 2018 9:59 pm
Forum: Naming
Topic: Final Exam
Replies: 9
Views: 430

### Re: Final Exam

I would just remember both. What is the chemical formula for EN and EDTA?
Thu Dec 06, 2018 9:53 pm
Forum: Naming
Topic: Naming with bis-
Replies: 5
Views: 256

### Re: Naming with bis-

what were the other names we had to remember besides bis when the other prefixes are already used in the name?
Mon Nov 26, 2018 11:16 pm
Forum: Lewis Structures
Topic: Question 3.45
Replies: 4
Views: 201

### Re: Question 3.45

Hanniel U 1A wrote:Does that mean atoms after row three can? Does this relate to the atomic number?

Atoms after and in row three can have an expanded octet because of their d orbitals.
Mon Nov 26, 2018 11:06 pm
Forum: Hybridization
Topic: problem 4.91
Replies: 1
Views: 135

### Re: problem 4.91

The hybridizations of sp of 2 of the 6 C atoms want to be in a linear arrangement with 180 degree angles but can't because of the constrainment of being in a 6-membered ring whose angles are close to 120 degrees. This makes benzyne highly reactive with these hybridzations.
Mon Nov 26, 2018 11:02 pm
Forum: Resonance Structures
Topic: Delocalization
Replies: 6
Views: 753

### Re: Delocalization

Delocalization means that the electron pair is distributed over several pairs of atoms and can't be identified with just one pair of atoms.
Mon Nov 19, 2018 4:03 pm
Forum: Hybridization
Topic: 6th edition Prob 4.43
Replies: 1
Views: 116

### 6th edition Prob 4.43

Why does the bond angle between two hybrid orbital increase
as the s-character of the hybrids is increased?
Mon Nov 19, 2018 1:58 pm
Forum: Hybridization
Topic: Hybridization
Replies: 3
Views: 140

### Re: Hybridization

Hybridization is the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory. Like Lavelle said in class, its easier to start by figuring...
Mon Nov 19, 2018 1:55 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Lengths
Replies: 10
Views: 583

### Re: Bond Lengths

First, realize that nitrate's lewis structure has resonance and is the reason why the bond lengths are averaged. This blend of single and double bond lengths accounts for this averaged length.
Mon Nov 19, 2018 1:52 pm
Forum: Photoelectric Effect
Topic: Difference between ionization energy and threshold energy
Replies: 1
Views: 445

### Re: Difference between ionization energy and threshold energy

Ionization energy is energy required to remove an electron off an isolated atom or molecule. Threshold energy is basically same thing but its the minimum energy required to remove an electron and is the work function (in photoelectric effect).
Fri Nov 16, 2018 6:32 pm
Forum: Hybridization
Topic: Test 3
Replies: 5
Views: 341

### Re: Test 3

In one of his posts, he said "Test 3 covers: End of bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see syllabus and outlines for details). Hope that helps!
Wed Nov 14, 2018 2:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs Angular
Replies: 3
Views: 161

### Re: Bent vs Angular

They are synonymous, our TA said if you write either one it will be counted correct although they are using the term angular for the most part.
Wed Nov 14, 2018 2:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Q4B
Replies: 4
Views: 287

### Midterm Q4B

Can someone explain why electron diffraction by a crystal supports de Broglie's hypothesis of the wave nature of matter? Thanks!
Wed Nov 14, 2018 12:00 am
Forum: Industrial Examples
Topic: Favorite Industrial Example
Replies: 3
Views: 512

### Re: Favorite Industrial Example

Actually, I have a question for you. What are coordination compounds and what is one example do you know of? This is the first I've ever heard of that term so I'm curious.
Fri Nov 09, 2018 11:03 pm
Forum: Dipole Moments
Topic: Dipole
Replies: 8
Views: 397

### Re: Dipole

Luc Galaif wrote:What exactly does the term "dipole" mean?

A dipole is a separation of electrical charges and these molecular dipoles occur due to the unequal sharing of electrons between atoms in a molecule.
Fri Nov 09, 2018 10:58 pm
Forum: *Shrodinger Equation
Topic: Shrodinger Equation
Replies: 2
Views: 339

### Re: Shrodinger Equation

This equation uses the wave function to describe valence electrons in an atom and uses the concept that valence electrons with wavelike properties and indeterminacy in momentum and position, can be described by wave function.
Fri Nov 09, 2018 10:56 pm
Forum: Lewis Structures
Topic: 6th edition ch3 3.99
Replies: 1
Views: 164

### Re: 6th edition ch3 3.99

Once you total the number of valence electrons and distribute them, you will find a Lewis structure with triple-single-single-triple bonds between the N, another Lewis structure with double-double-single-triple bond, and a triple-single-double-double bond. There are 4 lone pairs as well on each of t...
Fri Nov 09, 2018 10:26 pm
Forum: Lewis Structures
Topic: Lewis Structure
Replies: 10
Views: 406

### Re: Lewis Structure

Make sure that the atoms are also balanced on opposing sides of the central atom and as said above, calculate the total number of valence electrons and don't forget to follow octet rule.
Sun Nov 04, 2018 7:40 pm
Forum: Lewis Structures
Topic: Question 3.41(c) (6th edition)
Replies: 1
Views: 85

### Question 3.41(c) (6th edition)

part (C): For the Lewis structure of glycine, H2C(NH2)COOH, does it matter where (the position) the Hydrogens attached to the N are?
Thu Nov 01, 2018 11:31 pm
Forum: Resonance Structures
Topic: 6th Edition 3.21
Replies: 2
Views: 120

### Re: 6th Edition 3.21

I think you can write both out because they are the same configurations.
Thu Nov 01, 2018 10:57 pm
Forum: Ionic & Covalent Bonds
Topic: Group Me
Replies: 2
Views: 151

### Re: Group Me

Thank you! I've been looking for people to study with!
Sat Oct 27, 2018 11:38 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 2
Views: 201

I don't know how this formula is derived but I think R and r stand for the radii of each of the particles.
Sat Oct 27, 2018 11:31 am
Forum: Administrative Questions and Class Announcements
Topic: Modules & Assessments
Replies: 1
Views: 124

### Re: Modules & Assessments

I hope they are updated too, but khan academy and other sites have great videos to look at as well.
Sat Oct 27, 2018 11:29 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 7
Views: 434

### Re: Midterm

I think it will cover all those topics up to how far we get in lecture. I would just start reviewing everything we've covered so far.
Thu Oct 18, 2018 10:21 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 16
Views: 358

### Re: Work Function

Vanessa Reyes_4C wrote:For problem 1.69b do you have to convert electron volts to joules, and then use the E=hc/frequency equation?

Yes, you have to make sure all your SI units are correct before doing the problem.
1eV=1.602 x 10^-19 J
Sun Oct 14, 2018 4:13 pm
Forum: Properties of Light
Topic: 1A.3 7th edition
Replies: 1
Views: 66

### Re: 1A.3 7th edition

The extent of change refers to the slope of the wave; so think about what happens to the amplitude of the waves if frequency(the number of cycles/Hertz per sec) decreases. Does the extent of change (slope of the wave) increase or decrease?
Sun Oct 14, 2018 4:00 pm
Forum: Properties of Light
Topic: Photons
Replies: 4
Views: 124

### Re: Photons

In lecture, someone asked the same question and Professor Lavelle said it can happen where two photons combine to eject an electron but it's SUPER rare for this to happen which is why we use 1 photon to eject 1 electron as it happens most commonly.

I hope this helps.
Fri Oct 12, 2018 10:03 am
Forum: Properties of Light
Topic: Do I need to memorize the Light Spectrum? [ENDORSED]
Replies: 13
Views: 385

### Re: Do I need to memorize the Light Spectrum?[ENDORSED]

It is advisable to know the general idea and the main categories such as UV, visible, and infrared.
Mon Oct 08, 2018 4:42 pm
Forum: SI Units, Unit Conversions
Topic: SI Units
Replies: 10
Views: 407

### Re: SI Units

Do all our final answers need to be converted to the base SI unit (ex:meter, kilogram, mole) or do we just use the closest prefix to it? And if we leave our answer in the base SI unit and do not use a prefix simplifying the value would our answer be wrong even if both answers would be mathematicall...
Mon Oct 08, 2018 4:23 pm
Forum: Student Social/Study Group
Topic: Missed today's lecture (10/8) could anyone share their notes?
Replies: 3
Views: 223

### Re: Missed today's lecture (10/8) could anyone share their notes?

Of course!
Today's topics included the quantum mechanics description of light, the photoelectric effect, and the experiments leading to the discovery of the photoelectric effect.
Mon Oct 08, 2018 12:19 pm
Forum: Administrative Questions and Class Announcements
Replies: 135
Views: 31567

Where are the posted answers for this worksheet?
Thanks
Wed Oct 03, 2018 10:57 pm
Forum: SI Units, Unit Conversions
Topic: SI Units
Replies: 10
Views: 407

### Re: SI Units

Here is some we have to know: Mass (kg) Length(m) Time(s)
Giga - 10^9
mega- 10^6
kilo - 10^3
deci- 10^-1
centi- 10^-2
milli- 10^-3
micro- 10^-6
nano- 10^-9
pico-10^-12

We went over these in lecture; hope that this list is helpful
Wed Oct 03, 2018 10:52 pm
Forum: SI Units, Unit Conversions
Topic: Problem E.9 in textbook
Replies: 3
Views: 261

### Re: Problem E.9 in textbook

use molar mass to find out the moles of the Epsom salts 5.15 g H14MgO11S / 246.466 g*mol^-1 = .02089 mol H14MgO11S use the ratio of 11 mols oxygen to 1 mol of Epsom salts and then multiply by Avogadro's number to find how many atoms of oxygen .02089 mol H14MgO11S * (11 mol O / 1 mol H14MgO11S) *(6.0...
Wed Oct 03, 2018 10:37 pm
Forum: SI Units, Unit Conversions
Topic: Naming Compounds
Replies: 9
Views: 521

### Re: Naming Compounds

Another thing to note is hydrate refers to water, so it's formula is simply H20. It helps to break down the name into parts and figure out what they mean individually and then put it all together at the end.

Ex. hepta/ hydrate
Hepta means 7
Hydrate refers to water

Therefore heptahydrate is 7H20