Search found 29 matches

Sat Mar 17, 2018 6:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.15
Replies: 1
Views: 136

14.15

For 14.15a, when writing a cell diagram for AgBr (s) <-> Ag+(aq) + Br-(aq), is the anode/cathode just assumed to be Ag(s)? And why?
Sat Mar 17, 2018 4:58 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Difference between calculations
Replies: 1
Views: 213

Difference between calculations

What is the difference between calculating delta G through G(products) - G(reactants) using values given and calculating delta G through the equation deltaG = deltaH - TdeltaS?
Sat Mar 17, 2018 1:09 am
Forum: General Rate Laws
Topic: Unique Rate [ENDORSED]
Replies: 5
Views: 567

Re: Unique Rate[ENDORSED]

Is there a way to know when exactly we should be using unique rate?
Fri Feb 02, 2018 12:03 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Ideal Situation vs. Real Situation
Replies: 2
Views: 151

Ideal Situation vs. Real Situation

In real life situations, why is delta S always greater than Q(rev)/T unlike the ideal situation where delta S is equal to Q(rev)/T?
Thu Feb 01, 2018 11:58 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Extensive/Intensive Property [ENDORSED]
Replies: 4
Views: 268

Extensive/Intensive Property[ENDORSED]

What does being an intensive/extensive property mean?
Thu Feb 01, 2018 11:18 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Adiabatic Expansion of an Ideal Gas
Replies: 1
Views: 137

Adiabatic Expansion of an Ideal Gas

In a problem, how do we know to use the equation for calculating entropy of adiabatic expansion of an Ideal Gas, in other words, using delta S = nRln(V(final) - V(Initial))?
Will the problem just state if the system is adiabatic or are there any more key words to be aware of?
Thu Feb 01, 2018 11:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Free Energy and Pressure
Replies: 4
Views: 206

Free Energy and Pressure

What exactly is the relationship between free energy and pressure? In the notes, it says free energy is dependent on pressure, but I'm not quite sure how.
Thu Feb 01, 2018 11:02 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Molar Entropy
Replies: 2
Views: 228

Molar Entropy

How can you tell the molar entropy of a substance and what does it mean?
Thu Feb 01, 2018 10:42 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy vs. Entropy
Replies: 4
Views: 246

Enthalpy vs. Entropy

What is the conceptual difference between calculating the standard enthalpy of a phase change vs. the standard entropy of a phase change?
Fri Jan 19, 2018 6:32 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Change Question
Replies: 3
Views: 210

Phase Change Question

Was there a formula to use when calculating a phase change like vaporization or anything? In the notes it said something like deltaH of vaporization = H vapor - H liquid, but the solutions manual for problem 8.37 seems to use q and moles instead so I wasn't sure
Fri Jan 19, 2018 6:00 pm
Forum: Phase Changes & Related Calculations
Topic: 8.13
Replies: 3
Views: 187

8.13

For problem 8.13, why is the value of q = 947 kJ negative? I had thought it was positive because the question said that heat was absorbed.
Thu Jan 18, 2018 6:36 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 5
Views: 310

Calorimeter

When calorimeter is mentioned in the question, does it give you a hint as to which equation to use? If so, then how?
Wed Jan 17, 2018 9:11 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.61
Replies: 3
Views: 221

8.61

For 8.61, could someone tell me why the second equation N2 (g) + 3H2 (g) --> 2NH3 (g) is supposed to be switched, which would give the value enthalpy of +92.22 kJ? Since the question is asking for the reaction enthalpy value of H2 (g) + Br2 (l) --> 2HBr (g) the H2 in both equations are both on the r...
Tue Jan 16, 2018 2:15 pm
Forum: Phase Changes & Related Calculations
Topic: Gas Law
Replies: 2
Views: 215

Gas Law

How do you know when to use/apply the Ideal Gas Law in a question?
Wed Jan 10, 2018 5:35 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Work? [ENDORSED]
Replies: 1
Views: 201

Work?[ENDORSED]

What's the relation of thermodynamics to the energy available to do work, since heat is a form of energy? When a question refers to work, is it referring to thermodynamics as well?
Sat Dec 09, 2017 7:36 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure and Volume
Replies: 2
Views: 292

Pressure and Volume

How do pressure and volume affect a reaction?
Sat Dec 09, 2017 4:09 pm
Forum: DeBroglie Equation
Topic: Difference between DeBrogile and Light
Replies: 3
Views: 255

Difference between DeBrogile and Light

How do we know to differentiate between using the DeBrogile equation and the equation of c = (wavelength) (frequency)? For example, when we are given the frequency and asked to find wavelength, how do we know whether or not to use one equation rather than the other since both variables are present i...
Sat Dec 09, 2017 3:40 pm
Forum: Naming
Topic: Ligand Suffix
Replies: 2
Views: 363

Ligand Suffix

Is there a difference between naming with the suffix -o and-ido? For example, hydroxo and hydroxido
Sat Dec 09, 2017 10:45 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Lobes [ENDORSED]
Replies: 4
Views: 316

Lobes[ENDORSED]

When is it necessary to take the lobes of an orbital into account? For example, using px, py, and pz.
Thu Dec 07, 2017 12:33 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.29C
Replies: 1
Views: 199

12.29C

For problems such as 12.29C, why do we multiply Ba(OH)2 by 2 to get the concentration of OH? Is it because of the 2 outside the parentheses?
Wed Dec 06, 2017 11:13 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 12.21
Replies: 1
Views: 187

12.21

In 12.21, how does Kw = [H3O+][OH-] manage to turn into [OH-] = Kw/[H3O+]?
Also, are we expected to memorize that Kw = [H3O+][OH-] = 1.0 x 10^-14?
Wed Nov 29, 2017 12:08 pm
Forum: Naming
Topic: 17.29 a and c
Replies: 2
Views: 204

17.29 a and c

In 17.27 a and c, why is it that cyanido (CN-) is changed to cyano when naming the compound?
Thu Nov 09, 2017 3:39 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 2
Views: 277

Could someone explain what the difference is between a radial node and a radial plane and how to figure them out in a problem?
Wed Nov 01, 2017 9:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Unpaired Electrons [ENDORSED]
Replies: 3
Views: 360

Unpaired Electrons[ENDORSED]

When trying to figure out how many unpaired electrons an atom has, what would you need to know to draw the configuration?
Wed Oct 25, 2017 3:52 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Difference between subshell and orbital [ENDORSED]
Replies: 9
Views: 1573

Difference between subshell and orbital[ENDORSED]

Could someone explain the difference between a subshell and an orbital? I've heard both of the terms be referred to in the same problem, but I wasn't quite sure how they differed.
Thu Oct 19, 2017 12:59 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wavelength Units
Replies: 5
Views: 388

Wavelength Units

I was confused about whether wavelength had to be in nanometers or simply meters, because in the module, the answer to 39. was 486 nm, so I answered the next question number 40. with 746 nm, which was wrong. I'm assuming the correct answer was 7.46 x 10^-6 m, but I wasn't sure how to differentiate w...
Fri Oct 13, 2017 9:35 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Post-Module Assessment 32B, 33 [ENDORSED]
Replies: 2
Views: 442

Photoelectric Effect Post-Module Assessment 32B, 33[ENDORSED]

32. B. In a second experiment a shorter wavelength light source is used resulting in ejected electrons with a kinetic energy of 4.200 x 10-19 J. What is the energy of this incident light? What is the wavelength of this incident light? I used the Energy of a photon = (threshold)(kinetic energy) and g...
Fri Oct 13, 2017 3:11 pm
Forum: Photoelectric Effect
Topic: Photoelectric Post Assessment Module 30C
Replies: 4
Views: 410

Photoelectric Post Assessment Module 30C

For 30C, to find the frequency, do we have to use the equation where Energy of the photon = (Threshold energy)(kinetic energy)?
Wed Oct 04, 2017 10:34 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Scientific Notation [ENDORSED]
Replies: 3
Views: 368

Scientific Notation[ENDORSED]

Hi, not sure if I'm posting in the right forum or not, but in the test, is it necessary for us to convert our answer into scientific notation?