Search found 70 matches

by josephperez_2C
Sat Mar 16, 2019 10:35 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n value
Replies: 3
Views: 10

Re: n value

In electrochemistry, the equation is deltaG = -nFE, and n is equal to the change in electrons in the redox half reactions.
by josephperez_2C
Sat Mar 16, 2019 10:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: kB
Replies: 1
Views: 5

Re: kB

kB is Boltzmann's constant and is provided on the equations sheet. (1.38 * 10^-23 J/K)
by josephperez_2C
Sat Mar 16, 2019 10:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Determining n
Replies: 6
Views: 27

Re: Determining n

"Delta n as in moles" would be the change in moles from there reactant to product side. For the combustion reaction CH4 + 2O2 > 2H2O + CO2, delta n would be negative 2 because water is a liquid.
by josephperez_2C
Sat Mar 16, 2019 5:05 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst
Replies: 14
Views: 63

Re: Nernst

Just making sure, n could never equal 0 since there is always a transfer of electrons right?
by josephperez_2C
Sat Mar 16, 2019 5:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Ecell Always Positive
Replies: 3
Views: 12

Re: Ecell Always Positive

We have the equation deltaG = -nFEcell. For galvanic cells, the reaction is spontaneous and therefore Ecell must be positive because deltaG is negative. Not sure if this was a bit roundabout but that's how I think of it.
by josephperez_2C
Sat Mar 16, 2019 5:00 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates
Replies: 1
Views: 8

Intermediates

How do we determine intermediates in a reaction?
by josephperez_2C
Sat Mar 16, 2019 12:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Nernst Equation
Replies: 2
Views: 6

Re: Nernst Equation

I believe you can use the 0.05916V equation when the temperature is at 25 degrees C. Just remember q would equal 10^((-n(E-E))/0.05916) since its log.
by josephperez_2C
Sat Mar 16, 2019 12:32 pm
Forum: Calculating Work of Expansion
Topic: Integrate Rate Law
Replies: 2
Views: 11

Integrate Rate Law

Hello guys. Can anyone help me find a practice problem in the book where we are given conditions for an integrated rate problem (ln[A] vs time gives a straight line) and we have to fint the order? Or something of that nature? I remember a problem in class but I can’t find one in the book that’s quit...
by josephperez_2C
Sun Mar 10, 2019 11:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Final Exam
Replies: 23
Views: 130

Re: Final Exam

chemical equilibrium will be on the final exam as it covers everything we have covered in class so far
by josephperez_2C
Sun Mar 10, 2019 11:47 pm
Forum: Zero Order Reactions
Topic: Graphs
Replies: 8
Views: 44

Re: Graphs

first, second, and zero order reactions have linear plots
by josephperez_2C
Sun Mar 10, 2019 11:44 pm
Forum: Second Order Reactions
Topic: Temperature
Replies: 6
Views: 38

Re: Temperature

temperature effects the rate constant
by josephperez_2C
Sun Mar 03, 2019 11:56 pm
Forum: Balancing Redox Reactions
Topic: OH-
Replies: 5
Views: 52

Re: OH-

You add OH- in a basic solution to the side of the reaction that has less hydrogen accordingly.
by josephperez_2C
Sun Mar 03, 2019 11:54 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: how is kinetics different?
Replies: 17
Views: 103

Re: how is kinetics different?

Kinetics relates to how quickly a reaction reaches equilibrium while Thermodynamics relates to the energy stored in a reaction.
by josephperez_2C
Sun Mar 03, 2019 11:52 pm
Forum: General Rate Laws
Topic: The value of K
Replies: 5
Views: 25

Re: The value of K

K is not constant per reaction because it fluctuates wit temperature.
by josephperez_2C
Sun Feb 24, 2019 11:47 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in -nFE
Replies: 6
Views: 40

Re: n in -nFE

Number of electrons transferred, it signifies whether or not the system is gaining or losing energy.
by josephperez_2C
Sun Feb 24, 2019 11:46 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Units
Replies: 5
Views: 41

Re: Gibbs Free Energy Units

If the question gives certain values per mol then you know to use kJ/mol.
by josephperez_2C
Sun Feb 24, 2019 11:44 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 9
Views: 72

Re: Test 2

Know entropy and enthalpy as well because there a lot of questions that encompass those as well as GFE.
by josephperez_2C
Sun Feb 17, 2019 11:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gases
Replies: 3
Views: 29

Re: Gases

I believe the negative delta g that we typically see when deaing with gases is due to the fact that the entire process is spontaneous.
by josephperez_2C
Sun Feb 17, 2019 11:24 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Intensive vs extensive
Replies: 4
Views: 28

Re: Intensive vs extensive

It is extensive because its magnitude is dependent on the amount of a substance in a given thermodynamic state
by josephperez_2C
Sun Feb 17, 2019 11:17 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Midterm Grades
Replies: 35
Views: 289

Re: Midterm Grades

In 14A we received them about a week after we took it after lecture.
by josephperez_2C
Mon Feb 04, 2019 12:05 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Internal energy
Replies: 5
Views: 53

Re: Internal energy

the internal energy of a system is the energy within the system, of the entire system, as well as the potential energy of the system as a whole due to external force fields
by josephperez_2C
Mon Feb 04, 2019 12:02 am
Forum: Phase Changes & Related Calculations
Topic: Heat
Replies: 6
Views: 70

Re: Heat

When heat is absorbed from the solution q for the solution has a negative value
When heat is absorbed by the solution, q for the solution has a positive value
by josephperez_2C
Mon Feb 04, 2019 12:01 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies
Replies: 2
Views: 32

Re: Enthalpies

ΔH°= standard enthalpy change
ΔH°r = standard enthalpy change of reaction
ΔH°f = standard enthalpy change of formation
ΔH°c = the standard enthalpy change of combustion
by josephperez_2C
Sun Feb 03, 2019 11:59 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Cup of Tea
Replies: 17
Views: 169

Re: Cup of Tea

A system which can interchange mass and energy is considered an open system. A cup of tea is susceptible to the environment.
by josephperez_2C
Sun Feb 03, 2019 11:56 pm
Forum: Phase Changes & Related Calculations
Topic: State Function
Replies: 10
Views: 75

Re: State Function

State functions are "variables" that define the state of a system
by josephperez_2C
Sun Feb 03, 2019 11:47 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: w=PdeltaV
Replies: 5
Views: 43

Re: w=PdeltaV

V=(Abase)(H)=A*D
by josephperez_2C
Sun Feb 03, 2019 11:44 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 11
Views: 149

Re: Le Chatelier's Principle

Increasing the partial pressure of a reactant shifts reactions towards the products, decreasing the partial pressure of a reactants shifts the reactions towards the reactants.
by josephperez_2C
Sun Feb 03, 2019 11:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 3
Views: 36

Re: Hess's Law

Hess's law basically states that enthalpy changes are additive. Enthalpy change at each step of a multi-step reaction can be added to give Total Enthalpy Change.
by josephperez_2C
Sun Feb 03, 2019 11:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bomb Calorimeter
Replies: 5
Views: 49

Re: Bomb Calorimeter

I think it was just important to know that the constant V (calorimetry) is associated with it. The problems will say something like "In a constant P calorimeter," so I doubt we'll have to know exactly how it works.
by josephperez_2C
Sun Feb 03, 2019 11:15 pm
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 4
Views: 39

Re: Heating Curve

Someone explained it to me like this: the energy required for water to go from a liquid to a gas is called the heat of vaporization, and when steam hits your skin, a lot of energy will be released as it condenses into a liquid
by josephperez_2C
Sun Feb 03, 2019 11:13 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: qv vs qp
Replies: 9
Views: 71

Re: qv vs qp

q(v) is heat at constant volume and q(p) is heat at constant pressure
by josephperez_2C
Sun Feb 03, 2019 11:08 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 48
Views: 631

Re: Midterm [ENDORSED]

In my experience the best way to prepare for professor Lavelle's exams is the practice problems that are assigned. It might sound a bit arbitrary but what I like to do is actually repeat and quickly jot down the steps to each problem after I've completed it. It's worked well for me and I also think ...
by josephperez_2C
Sun Jan 20, 2019 6:55 pm
Forum: Ideal Gases
Topic: Ideal Gas as Approximation
Replies: 2
Views: 33

Re: Ideal Gas as Approximation

It is considered an approximation because deviations from ideal gas behavior are small.
by josephperez_2C
Sun Jan 20, 2019 6:44 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endo/exothermic rxns
Replies: 5
Views: 47

Re: endo/exothermic rxns

We can come to certain conclusions that are more obvious, such as H2 -> 2H being endothermic, because H2 has lower energy than the 2 H's. However, because we are given more complex chemical reactions, it's not always possible.
by josephperez_2C
Sun Jan 20, 2019 6:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ionization and deprotonation
Replies: 3
Views: 21

Re: Ionization and deprotonation

They mean the same thing but I believe we will be more likely to see percent ionization on a test.
by josephperez_2C
Sun Jan 13, 2019 8:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 3
Views: 41

Re: ICE Tables

Yes. I believe you can use ICE tables if asked to find equilibrium partial pressures.
by josephperez_2C
Sun Jan 13, 2019 7:05 pm
Forum: Student Social/Study Group
Topic: New to Lavelle
Replies: 32
Views: 502

Re: New to Lavelle

I always make sure to take really good notes in class because while it sounds trivial, lecture is probably one the best resources for doing well on the exams. Also one tip for navigating chem community is going into Quicklinks on the top left and clicking on active topics to respond to questions.
by josephperez_2C
Sun Jan 13, 2019 6:44 pm
Forum: Ideal Gases
Topic: bar or atm
Replies: 8
Views: 88

Re: bar or atm

I believe we can use either but I know my TA said that since the textbook uses bar so would she. Just make sure you know that they are pretty much equal
by josephperez_2C
Sun Dec 09, 2018 1:48 am
Forum: Biological Examples
Topic: coordination compounds
Replies: 2
Views: 43

Re: coordination compounds

^ you can refer to that chart and also Lyndon Bui mentioned that we should know cisplatin because Lavelle mentioned it in class. It's used to treat cancers.
by josephperez_2C
Sun Dec 09, 2018 1:40 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 3
Views: 52

Re: Polydentate

Polydentate simply means ligands with more than one bonded atom. I believe you can just look at the amount of bonds, so an atom with 4 bonds is tetradentate for example.
by josephperez_2C
Sun Dec 09, 2018 1:37 am
Forum: Bronsted Acids & Bases
Topic: Bronsted acid
Replies: 4
Views: 58

Re: Bronsted acid

It is a strong acid because it loses an H+. It's equation of dissociation is HBr(aq) -> H+(aq) + Br-(aq).
by josephperez_2C
Sun Dec 09, 2018 1:35 am
Forum: Electronegativity
Topic: Polarizing Power and Polarizability
Replies: 2
Views: 50

Re: Polarizing Power and Polarizability

Li+ is the smallest cation and also has one less shell than Mg2+
by josephperez_2C
Thu Dec 06, 2018 4:48 pm
Forum: Naming
Topic: OH2 vs H2O
Replies: 5
Views: 53

Re: OH2 vs H2O

They are the same and you can write it in both ways.
by josephperez_2C
Thu Dec 06, 2018 4:46 pm
Forum: Air Pollution & Acid Rain
Topic: acid rain
Replies: 4
Views: 66

Re: acid rain

I believe it is 2NO2 + H2O -> HNO2 +HNO3
by josephperez_2C
Thu Dec 06, 2018 4:41 pm
Forum: Naming
Topic: Spelling
Replies: 4
Views: 47

Re: Spelling

There is no such thing as a dumb question. It is spelled ammine.
by josephperez_2C
Thu Dec 06, 2018 4:40 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Final Exam
Replies: 7
Views: 96

Re: Final Exam

Yes I remember my TA going over this in section.
by josephperez_2C
Thu Dec 06, 2018 4:37 pm
Forum: Naming
Topic: Naming Metals
Replies: 2
Views: 24

Re: Naming Metals

Yes this is just a rule. For example sulfate is SO42−.
by josephperez_2C
Thu Dec 06, 2018 4:30 pm
Forum: Hybridization
Topic: lone pairs
Replies: 20
Views: 152

Re: lone pairs

Each lone pair is considered a region of electron density so they should be taken into account.
by josephperez_2C
Thu Dec 06, 2018 4:29 pm
Forum: Student Social/Study Group
Topic: Studying
Replies: 7
Views: 139

Re: Studying

I am mostly studying my notes and going over practice problems. I think it really helps to compare notes with other students to see if you missed anything.
by josephperez_2C
Thu Dec 06, 2018 4:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam
Replies: 22
Views: 300

Re: Final Exam

The final will be cumulative with an emphasis on the later topics.
by josephperez_2C
Thu Dec 06, 2018 4:25 pm
Forum: Administrative Questions and Class Announcements
Topic: How to find my posts
Replies: 28
Views: 15516

Re: How to find my posts

'Quick links' top left -> 'your posts'
by josephperez_2C
Thu Dec 06, 2018 4:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent Structures
Replies: 12
Views: 113

Re: Bent Structures

They are all polar.
by josephperez_2C
Sun Nov 18, 2018 8:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Thanksgiving Wednesday Class
Replies: 19
Views: 271

Re: Thanksgiving Wednesday Class

I think the case might be that not every lecture is on the same pace but I could be wrong. From Friday's lecture at noon, he said that we were ahead of schedule and that we would have no class on Wednesday.
by josephperez_2C
Sun Nov 18, 2018 7:58 pm
Forum: Dipole Moments
Topic: Test
Replies: 15
Views: 175

Re: Test

The next test is week 9 in section. It might also have some chemical bond material because its needed for molecular structures.
by josephperez_2C
Sun Nov 18, 2018 7:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing structures
Replies: 8
Views: 101

Re: Drawing structures

Lewis structures are the only thing we need to know how to draw in the context of 14a I believe.
by josephperez_2C
Mon Nov 12, 2018 4:49 am
Forum: Dipole Moments
Topic: Hydrogen Bonds
Replies: 20
Views: 187

Re: Hydrogen Bonds

Hydrogen bonds are considered one of the stronger intermolecular attractions, but they are still weaker than covalent and ionic bonds.
by josephperez_2C
Mon Nov 12, 2018 4:47 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Why do the orbitals of an atom only hold a certain amount of electrons?
Replies: 4
Views: 82

Re: Why do the orbitals of an atom only hold a certain amount of electrons?

^simply the way the orbitals are shaped determines the amount of electrons it can hold
by josephperez_2C
Mon Nov 12, 2018 4:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Chapter 4 Homework Number 1
Replies: 6
Views: 61

Re: Chapter 4 Homework Number 1

Lone pairs at the central atom repel shared pairs of electrons and make bond angles varied
by josephperez_2C
Sat Nov 03, 2018 9:34 pm
Forum: Student Social/Study Group
Topic: Studying
Replies: 7
Views: 139

Re: Studying

I'm going over notes from discussion and practice problems from the book. Also the review sessions are really helpful and I know there are some tomorrow!
by josephperez_2C
Sat Nov 03, 2018 9:31 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 3
Views: 81

Re: Unit Conversions

Some unit conversions are given on the equation sheet, such as 1 nm = 10-9 m, so I would just review the ones that aren't on the worksheet.
by josephperez_2C
Sat Nov 03, 2018 9:25 pm
Forum: Administrative Questions and Class Announcements
Topic: What the Midterm Will Cover
Replies: 5
Views: 68

Re: What the Midterm Will Cover

On the midterms review session schedule, it says that it will be all material covered in Fundamentals, Quantum, Bonding to end of 3.11 (6 Ed.) and to end of 2C (7 Ed.).
by josephperez_2C
Sun Oct 28, 2018 11:31 pm
Forum: Ionic & Covalent Bonds
Topic: Octet Rule
Replies: 7
Views: 78

Re: Octet Rule

The octet rule applies to most atoms, but there are exceptions like hydrogen.
by josephperez_2C
Sun Oct 28, 2018 11:26 pm
Forum: Significant Figures
Topic: Sig Figs on MT
Replies: 2
Views: 89

Re: Sig Figs on MT

It won't be a large amount of points taken off but yes you should have the correct amount of sig figs to get full credit. Some questions even have 1 sig fig in them.
by josephperez_2C
Sun Oct 28, 2018 11:25 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 13
Views: 79

Re: Lewis Structures

I believe he said to choose the atom with the lowest ionization energy.
by josephperez_2C
Fri Oct 26, 2018 12:33 pm
Forum: Einstein Equation
Topic: Units
Replies: 6
Views: 145

Re: Units

While there are some units on the equation sheet given, it is probably best to know units as best you can.
by josephperez_2C
Sun Oct 21, 2018 12:19 pm
Forum: Einstein Equation
Topic: Numbers to memorize
Replies: 22
Views: 315

Re: Numbers to memorize

The formula sheet that was given on the first test is the same one that will be given on the second test and third test as well.
by josephperez_2C
Sun Oct 21, 2018 12:17 pm
Forum: Einstein Equation
Topic: Joules per photon?
Replies: 5
Views: 145

Re: Joules per photon?

Joules is the correct unit.
by josephperez_2C
Sun Oct 07, 2018 10:15 pm
Forum: Balancing Chemical Reactions
Topic: Where to start [ENDORSED]
Replies: 10
Views: 256

Re: Where to start [ENDORSED]

It usually helps me to look at the entire equation and see if any atoms are already balanced and then balance the others accordingly.
by josephperez_2C
Sun Oct 07, 2018 10:02 pm
Forum: Administrative Questions and Class Announcements
Topic: WHAT TYPE OF CALCULATOR IS ALLOWED ON EXAMS??
Replies: 5
Views: 146

Re: WHAT TYPE OF CALCULATOR IS ALLOWED ON EXAMS??

A non-programmable calculator is allowed on exams.
by josephperez_2C
Sun Oct 07, 2018 9:52 pm
Forum: Significant Figures
Topic: knowing how many sig figs to use
Replies: 17
Views: 347

Re: knowing how many sig figs to use

You should use the amount of significant figures in your answer that corresponds with the least amount of significant figures in any one given value of the problem.

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