## Search found 67 matches

Sat Mar 17, 2018 11:27 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: catalysts and intermediates
Replies: 2
Views: 194

### catalysts and intermediates

how do we know the affect of a catalyst on an overall reaction if its only in one step? and how do we know how many intermediates?
Wed Mar 14, 2018 9:26 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: delta s surrounding and system
Replies: 3
Views: 1622

### delta s surrounding and system

why is delta s surround negative and system positive?
Wed Mar 14, 2018 9:25 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: chapter 9, number 13
Replies: 2
Views: 223

### Re: chapter 9, number 13

ohhhh THANKSSSS
Wed Mar 14, 2018 6:13 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: chapter 9, number 13
Replies: 2
Views: 223

### chapter 9, number 13

In 9.13, the problem says 3.00 liters of Nitrogen gas at 18.5 degrees c was compressed suddenly and irreversibly to .500 liters by driving in a piston. The temperature changed to 28.1 degrees c. calculate the total change in entropy. So I know that I need to independently calculate delta s for the c...
Wed Mar 14, 2018 5:46 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: delta s surroundings
Replies: 3
Views: 343

### delta s surroundings

why does delta s surroundings = -q rev/time x t but, delta s = q rev/t
Wed Mar 14, 2018 12:16 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: oxidation and reduction agents
Replies: 1
Views: 228

### oxidation and reduction agents

How do we know which part of the anode is the reduction agent and which part of the cathode is the oxidizing agent?
Wed Mar 14, 2018 12:15 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: steady state and pre equilibrium
Replies: 2
Views: 220

### steady state and pre equilibrium

do we need to know these to concepts and if so can someone explain them?
Tue Mar 13, 2018 9:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: question 6 on test 2
Replies: 2
Views: 268

### question 6 on test 2

For the question that says H+/H2 and Ni+2/Ni, doesn't both sets have a reducing agent and an oxidizing agent??
Tue Mar 13, 2018 8:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Identifying highest reducing/oxidizing power
Replies: 3
Views: 222

### Re: Identifying highest reducing/oxidizing power

I think a reduction potential chart has to be given.
Tue Mar 13, 2018 8:47 pm
Forum: Administrative Questions and Class Announcements
Topic: Lecture Friday
Replies: 4
Views: 404

### Re: Lecture Friday

when did he say that?
Tue Mar 13, 2018 8:47 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 2
Views: 184

### Re: Catalysts

A catalyst in a different phase than R is heterogeneous.
A catalyst in the same phase as R is homogeneous.
Tue Mar 13, 2018 8:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Daniell cells?
Replies: 1
Views: 181

### Re: Daniell cells?

what is a Daniell cell?
Wed Mar 07, 2018 9:58 pm
Forum: First Order Reactions
Topic: unique rate [ENDORSED]
Replies: 1
Views: 166

### unique rate[ENDORSED]

what is a unique rate and how do you find it?
Wed Mar 07, 2018 9:04 pm
Forum: Second Order Reactions
Topic: 15.39
Replies: 2
Views: 362

### 15.39

for 15.39 b, why does the solutions manual have ".37[a] initial as part of the solution. Where is the .37 coming from?
Sun Mar 04, 2018 5:14 pm
Forum: General Rate Laws
Topic: higher order rate laws
Replies: 1
Views: 144

### higher order rate laws

would Lavelle ever expect us to derive integrated rate laws greater than second order?
Sun Mar 04, 2018 5:12 pm
Forum: Zero Order Reactions
Topic: slope
Replies: 9
Views: 1322

### Re: slope

Taking the integral when solving for the integrated rate law for a second order reaction produces a double negative which turns into a positive. Integrating the integrated rate law for each order will demonstrate this.
Sun Mar 04, 2018 5:10 pm
Forum: General Rate Laws
Topic: half life equation
Replies: 1
Views: 139

### half life equation

does a half life pertain to a substance in general or an AMOUNT of substance? for ex: does mercury have one half life or do different amounts of mercury have different half lives?
Sun Mar 04, 2018 5:08 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: kinetics an thermodynamics
Replies: 3
Views: 253

### kinetics an thermodynamics

We will ever use both kinetics and thermodynamics in the same problem?
Sun Mar 04, 2018 5:07 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Rate Constant Units
Replies: 9
Views: 679

### Re: Rate Constant Units

using either the integrated rate law or the half life eqn can help you figure out the units for the rate constant without having to memorize anything. If you plug in the units for everything but k, you can figure out what k has to be for the equations to work.
Sun Mar 04, 2018 5:05 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: reaction mechanism
Replies: 2
Views: 177

### reaction mechanism

how does the slow step determine the overall rate? and how do you know how many steps there are?
Tue Feb 20, 2018 9:15 pm
Forum: Balancing Redox Reactions
Topic: 14.5 a)
Replies: 5
Views: 284

### 14.5 a)

on part a of 14.5, I do not get why we add OH when balancing the half reaction.
Tue Feb 13, 2018 9:57 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Gibbs free energy
Replies: 3
Views: 197

### Gibbs free energy

what is the difference between Delta G and Delta G "not"
Tue Feb 13, 2018 1:32 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: constant pressure
Replies: 2
Views: 305

### constant pressure

When can we assume constant pressure?
Tue Feb 13, 2018 1:10 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: calorimeter problems
Replies: 2
Views: 188

### calorimeter problems

when can we use just q=cdeltaT without moles or mass? does this apply to calorimeter problems?
Mon Feb 12, 2018 10:13 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: entropy of vaporization of water [ENDORSED]
Replies: 3
Views: 612

### entropy of vaporization of water[ENDORSED]

I understand how to do a problem that asks for the entropy of vaporization of water at room temp, yet I do not really get how water has an entropy of vaporization for room temp. Is water vaporizing at room temp. even if it is not physically boiling?
Mon Feb 12, 2018 10:10 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Test 1, #7 and General Question about Heat Transfer
Replies: 2
Views: 181

### Re: Test 1, #7 and General Question about Heat Transfer

your statement is right, but when you wrote the equation the signs are mixed. Your Ta is right with the signs and you are right when you say the ice is gaining heat and the tea is losing heat. But, to show the "release" of heat from the tea it it is -qTea.
Mon Feb 12, 2018 10:04 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: delta u
Replies: 2
Views: 172

### delta u

If temperature does not change, can the internal energy change? If not, can someone please explain?
Sat Feb 10, 2018 1:46 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: delta u [ENDORSED]
Replies: 3
Views: 311

### delta u[ENDORSED]

I just really do not understand delta u: what It means, how to caluculate it, how to know if it equals 0. Can anyone help? thanks
Fri Feb 09, 2018 11:01 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: work
Replies: 2
Views: 166

### work

I am still so confused about work. How does volume affect it?
Fri Feb 09, 2018 10:47 pm
Forum: Calculating Work of Expansion
Topic: irreversible reactions
Replies: 4
Views: 381

### irreversible reactions

what is the conceptual difference of an irreversible and a reversible reaction, and why are most biological reactions irreversible?
Tue Feb 06, 2018 8:18 pm
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: Boltzmann
Replies: 3
Views: 185

### Boltzmann

what does kb mean in the Boltzmann equation?
Sun Feb 04, 2018 10:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 7
Views: 351

### Re: Gibbs Free Energy

Gibbs free energy is a representation of spontaneity it the likeliness for which a reaction will occur on its own. So, as entropy can be called "disorder," Gibbs's free energy can be referred to as how spontaneous a reaction is. However, like "disorder," Dr. Lavelle does not love...
Sun Feb 04, 2018 10:24 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free question
Replies: 2
Views: 160

### Gibbs free question

In class Lavelle went over a problem where we subbed 0 for delta g and solved for the other variables. I know it has something to do with equilibrium, but I am really confused about why and how we were just able to put in a 0. Can someone explain? thanks
Sun Feb 04, 2018 10:22 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sig Figs
Replies: 6
Views: 245

### Re: Sig Figs

sig figs are always important although he does not tend to mark down if they are wrong. If you stick to three, you usually cannot go too wrong.
Sun Jan 28, 2018 11:57 pm
Forum: Phase Changes & Related Calculations
Topic: degeneracy [ENDORSED]
Replies: 7
Views: 396

### Re: degeneracy[ENDORSED]

The higher the degeneracy, the higher the entropy.
Sun Jan 28, 2018 10:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Universe being isolated
Replies: 3
Views: 252

### Re: Universe being isolated

Although Lavelle said in class that we don't REALLY know haha, it is because matter is neither created nor destroyed.
Sun Jan 28, 2018 10:56 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Test question [ENDORSED]
Replies: 16
Views: 885

### Re: Test question[ENDORSED]

The first law of thermodynamics is essentially the law of conservation of mass: matter is neither created nor destroyed. However it is super important to know that as stated by the first law of thermodynamics, the total energy of an isolated system is constant
Mon Jan 22, 2018 3:13 pm
Forum: Phase Changes & Related Calculations
Topic: question 8.49
Replies: 1
Views: 191

### question 8.49

regarding q: 8.49 why do we make -P(delta v) = -(delta n)rt negative on both sides?
Sun Jan 21, 2018 10:04 pm
Forum: Administrative Questions and Class Announcements
Topic: test week 3
Replies: 1
Views: 143

### test week 3

If work and delta u are not gonna be tested computationally, does anyone have any idea what sort of concept questions will be asked?
Mon Jan 15, 2018 9:14 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q 8.13
Replies: 9
Views: 533

### Q 8.13

In question 8.13, why is 947 kj absorbed written as a negative q value?
Mon Jan 15, 2018 9:03 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q 8.11
Replies: 1
Views: 107

### Q 8.11

I thought the value for R was .0821, where is the answer book getting 8.314 J/KxMOL?
Sun Jan 14, 2018 5:36 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: reversible vs irreversible
Replies: 2
Views: 199

### reversible vs irreversible

What are the two equations that are used for reversible and irreversible reactions and how do you differentiate between the processes if not told in the problem?
Sun Jan 14, 2018 5:23 pm
Forum: Phase Changes & Related Calculations
Topic: phase changes
Replies: 1
Views: 109

### phase changes

When doing problems that involve phase changes, for example changing ice to steam, how do you solve them if given two temperatures one for ice and one for steam and multiple molar heat capacities rather than one temperature?
Tue Jan 09, 2018 10:27 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: systems [ENDORSED]
Replies: 5
Views: 351

### systems[ENDORSED]

regarding homework problem 8.1, why is mercury in a thermometer a closed system rather than isolated?
Sat Dec 09, 2017 1:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentrations increasing, decreasing or remaining constant
Replies: 2
Views: 293

### equilibrium concentrations increasing, decreasing or remaining constant

All of my questions about this are coming from the week 9 review sheet number 8. With that being said, I am particularly confused about why the stoichiometric coefficients doubling would cause an increase or a decrease and I am also confused about what happens when the concentrations of A and B are ...
Sat Dec 09, 2017 12:42 pm
Forum: Administrative Questions and Class Announcements
Topic: week 9 chem review sheet
Replies: 1
Views: 218

### week 9 chem review sheet

For number 1 on the week nine sheet, I am confused because the problem says that the equilibrium concentration for SO2 is X, but it has a coefficient of 2 so it should be adding 2X. Also, the solutions key shows the addition of 2x for both so2 and o2 even though o2 does not have a coefficient. At fi...
Sat Dec 09, 2017 12:03 am
Forum: Determining Molecular Shape (VSEPR)
Topic: exception to nitrogen
Replies: 2
Views: 242

### exception to nitrogen

why would C have a radical on it rather than an N, in a c-n bond?
Wed Dec 06, 2017 8:31 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Percent ionization
Replies: 3
Views: 296

### Re: Percent ionization

yes I believe it is the same. I think he used deprotonization to emphasize the facte that bronzed acids and bases involve the donation and acceptance of protons.
Wed Dec 06, 2017 8:27 am
Forum: Lewis Acids & Bases
Topic: Memorizing Acids and Bases
Replies: 7
Views: 534

### Re: Memorizing Acids and Bases

Even if we don't "have" to memorize strong acids and bases, I'm sure it will help with comfortability on final problems.
Wed Dec 06, 2017 8:25 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Using The Equilibrium Arrow
Replies: 5
Views: 1290

### Re: Using The Equilibrium Arrow

Equilibrium arrows are used for weak acids and weak bases because they do not dissociate completely. Likewise, only weak acids and weak bases have conjugate acids and conjugate bases because they do not dissociate completely.
Tue Dec 05, 2017 12:28 pm
Forum: Conjugate Acids & Bases
Topic: strong and weak acids and bases
Replies: 2
Views: 202

### strong and weak acids and bases

Are weak acids and bases the only acids and bases that have conjugates because they do not ionize completely? Or do strong acids and bases have conjugates as well?
Sun Dec 03, 2017 9:41 pm
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 8
Views: 461

### Re: Naming Coordination Compounds

The "ate" ending is added if the overall compound is an anion(a negatively charged ion)
Sun Dec 03, 2017 9:36 pm
Forum: Sigma & Pi Bonds
Topic: What is a localized and delocalized Bond?
Replies: 5
Views: 21069

### Re: What is a localized and delocalized Bond?

Delocalized bonds are not constricted to one nucleus as localized bonds are. Resonance structures are a good example of delocalized bonding because as we learned, resonance structures exhibit single/double or single/triple etc character throughout the molecule even though each lewis structure shows ...
Sun Dec 03, 2017 8:06 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ph, Poh, and kw
Replies: 2
Views: 415

### Ph, Poh, and kw

Do we use the kw value because water is amphoteric and can act as a base or an acid or is there another reason? Also why does water and kw allow us to figure out ph and Poh?
Sun Dec 03, 2017 8:01 pm
Forum: Lewis Acids & Bases
Topic: Bronsted vs Lewis
Replies: 6
Views: 449

### Re: Bronsted vs Lewis

while lewis and bronsted acids and bases are reversed in roles- Lewis acids accept while bronzed acids donate- the main difference is that Lewis acids and bases involve the donation and acceptance of electrons while bronzed acids and bases are talking about protons.
Sun Nov 26, 2017 3:50 pm
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 2
Views: 178

### Re: Naming Coordination Compounds

not sure how to post a question, but how do we know when to use cyano or cyanido for cn? Also, how do we know which is attached, the C or the N, for example of Cyanide?
Sun Nov 19, 2017 1:58 pm
Forum: Naming
Topic: Coordination Compounds
Replies: 2
Views: 298

### Re: Coordination Compounds

How do we know if we should use the new IUPAC names or the old ones when naming coordination compounds?
Sun Nov 19, 2017 1:45 pm
Forum: Coordinate Covalent Bonds
Topic: coordination compounds
Replies: 1
Views: 315

### coordination compounds

I am nor familiar with coordination compounds/complexes/bonds. Can someone please differentiate and define these?
Thu Nov 16, 2017 10:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angle
Replies: 4
Views: 454

### Re: bond angle

Why do we say bonds are less than 109 degrees or less than 120 degrees? I don't understand why it is "less than"
Mon Nov 06, 2017 10:28 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: unpaired electrons [ENDORSED]
Replies: 3
Views: 267

### unpaired electrons[ENDORSED]

Can someone explain why for example: [kr]4d105s2 has no unpaired electrons?
Mon Nov 06, 2017 9:56 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm Materials [ENDORSED]
Replies: 7
Views: 487

### effective nuclear charge[ENDORSED]

Could someone please explain effective nuclear charge?
Thu Oct 26, 2017 10:41 am
Forum: Quantum Numbers and The H-Atom
Topic: Homework Question 2.17 part d
Replies: 5
Views: 379

### Re: Homework Question 2.17 part d

Since 0 correlates to the S orbitals, 1- p orbitals, 2-d orbitals, and 3- f orbitals, we know that if l = 3 we are referring to the f block. Since the f block has 14 electrons and 7 different orbitals we know there can be 7 subshells. If you memorize what 0,1,2,and 3 correlate to in regards to angul...
Thu Oct 26, 2017 10:35 am
Forum: Quantum Numbers and The H-Atom
Topic: P-Orbitals (x,y,z) [ENDORSED]
Replies: 3
Views: 2464

### Re: P-Orbitals (x,y,z)[ENDORSED]

The (x,y,and z) of px,py, and pz simply distinguish which axis the electrons lie on. If you took AP chem in high school you likely were taught to write use the notation: 1s^2,2p^6 for example rather than 1s^2,2px^2,2py^2,2pz^2. I was confused and asked Professor Lavelle in class and he said either f...
Sun Oct 15, 2017 10:42 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Why don't we use the Rydberg equation from the book?
Replies: 8
Views: 518

### Re: Why don't we use the Rydberg equation from the book?

No the equation given in the book also is only useful for hydrogen related purposes.
Sun Oct 15, 2017 10:41 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Why don't we use the Rydberg equation from the book?
Replies: 8
Views: 518

### Re: Why don't we use the Rydberg equation from the book?

The Rydberg equation given in the text book is a derivation of the formula given by Dr. Lavelle. He said we can use it if we understand the way it was created.
Sun Oct 15, 2017 6:32 pm
Forum: Photoelectric Effect
Topic: Balmer vs Lyman [ENDORSED]
Replies: 5
Views: 428

### Re: Balmer vs Lyman[ENDORSED]

I believe they said we will get a chart to use on the test. However, I don't think it will say for example that the Balmer Series is visible light.
Thu Oct 05, 2017 4:29 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 198
Views: 140476

### Re: Rusty on High School Chem[ENDORSED]

Take notes on your own first and then use lectures and discussions as clarifications! Also, use youtube for catchy phrases to help remember how to approach questions. For example, for empirical formulas I use.. "% to mass, mass to mole, divide by smole(smallest mole), and multiply to whole."