Search found 53 matches
- Mon Feb 18, 2019 4:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Calculating Gibbs Free Energy Equations
- Replies: 2
- Views: 10
Calculating Gibbs Free Energy Equations
For 6th Edition Chapter 9 #55: Write a balanced chemical equation for the formation reaction of (a) NH3 (g); (b) H2O(g); (c)CO(g); (d) NO2(g). For each reaction, determine H,S, and G from data in Appendix 2A. When calculating the Grxn, can we use the equation "deltaG = deltaGformation(products)...
- Sun Feb 17, 2019 8:19 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Calculating G if H and S are gven
- Replies: 3
- Views: 24
Re: Calculating G if H and S are gven
Why can we use the same deltaH and deltaS to calculate deltaG at any temperature? (like in this problem: 9.53 Calculate the change in molar Gibbs free energy for the process NH3(l) --> NH3 (g) at 1atm and (a) 15.0 C; (b) 45. C (see Tables 8.3 and 9.1 for standard enthalpy and entropy of vaporization...
- Sun Feb 17, 2019 8:04 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy
- Replies: 3
- Views: 18
Re: Gibbs Free Energy
The spontaneity of a reaction does not indicate the reaction rate, so not necessarily.
- Mon Feb 11, 2019 6:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 110
- Views: 2502
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Chem_Mod wrote:005199302 wrote:for #6, shouldn't the work be -12.4kJ?
w=-PxdV = (-122atm/L)(101.33J/atmL) = -12.4kJ
Please see above answer to the same question
Why do we need to find a different pressure if pressure is constant?
- Sun Feb 10, 2019 10:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 47
- Views: 1687
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
How do you calculate internal energy for #6 without knowing the temperature?
- Sun Feb 10, 2019 9:28 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: entropy of vaporization of water [ENDORSED]
- Replies: 3
- Views: 139
Re: entropy of vaporization of water [ENDORSED]
Does that mean that water/substances can undergo phase change without input of heat?
- Sun Feb 10, 2019 12:00 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeters
- Replies: 2
- Views: 18
Re: Calorimeters
Also for this question why do we ignore the heat used to raise the temperature of the water? For reference, the question is: A calorimeter was calibrated with an electric heater, which supplied 22.5 kJ of energy as heat to the calorimeter and increased the temperature of the calorimeter and its wate...
- Sun Feb 03, 2019 8:52 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 2
- Views: 20
Re: Bond Enthalpies
If you want to be really extra you can write out all the bonds in the reactants and all the bonds in the products. Then you can tell which bonds changed in the reaction.
- Sun Feb 03, 2019 8:47 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Equipartition Theorem
- Replies: 2
- Views: 19
Re: Equipartition Theorem
Dr. Lavelle will probably go over it in lecture this week if it's on the syllabus.
- Sun Feb 03, 2019 8:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy of Formation
- Replies: 3
- Views: 20
Re: Standard Enthalpy of Formation
We don't need to memorize them.
- Sun Jan 27, 2019 10:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: Standard Enthalpy of Formation in Most Stable Form
- Replies: 1
- Views: 9
Re: Standard Enthalpy of Formation in Most Stable Form
I think it was supposed to be a really redundant obvious point... so I think you're right
- Sun Jan 27, 2019 10:13 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Calculating Enthalpy
- Replies: 2
- Views: 11
Re: Calculating Enthalpy
The enthalpies of the reactants and the enthalpies of the products.
- Mon Jan 21, 2019 1:36 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 110
- Views: 2502
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Can someone explain how to do Worksheet 1 #4d? My friend did it with initial concentration of NH3 as 0 and she got the right answer. Why doesn't the initial concentration of NH3=5.82*10^-3 ?
- Sun Jan 20, 2019 9:36 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: 5I.13
- Replies: 2
- Views: 27
Re: 5I.13
What does the question say?
- Sun Jan 20, 2019 9:33 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert Gases
- Replies: 7
- Views: 39
Re: Inert Gases
What is an inert gas?
- Sun Jan 20, 2019 9:25 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pressure and volume
- Replies: 5
- Views: 30
Re: pressure and volume
As pressure increases, volume decreases, which causes the concentration of reactants and products to change. This change makes the system not in equilibrium, and therefore causes movement towards equilibrium.
- Sun Jan 20, 2019 9:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Kc (Section 5H.3 7th Edition)
- Replies: 2
- Views: 18
Re: K and Kc (Section 5H.3 7th Edition)
I think one of the TAs said that we won't need to know it. I think if it's on the test we'll probably be given the equation and the important values?
- Sun Jan 20, 2019 9:03 pm
- Forum: Ideal Gases
- Topic: pH and pOH
- Replies: 17
- Views: 89
Re: pH and pOH
What does the problem say? I think generally it tells you which to solve for.
- Thu Jan 17, 2019 10:05 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constants
- Replies: 5
- Views: 29
Re: Equilibrium Constants
Also, Kp=Kc*RT^[(moles of products)-(moles of reactants)]
- Sat Dec 08, 2018 5:37 pm
- Forum: Lewis Acids & Bases
- Topic: 6th edition 12.17
- Replies: 5
- Views: 39
Re: 6th edition 12.17
I think BaO is basic because the O will have 3 lone pairs which will allow it to donate an electron pair?
- Sat Dec 08, 2018 5:36 pm
- Forum: Lewis Acids & Bases
- Topic: 6th edition 12.17
- Replies: 5
- Views: 39
Re: 6th edition 12.17
Can someone also explain why SO3 is acidic?
- Fri Dec 07, 2018 3:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 23785
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
For Week 9 worksheet #5, why cant H3O+ and H2O neutralize an added base? And why cant H2O neutralize an acid and be potentially amphoteric?
- Wed Dec 05, 2018 5:48 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric compounds
- Replies: 1
- Views: 23
Re: Amphoteric compounds
An amphoteric compound can act as both an acid and a base, so it can donate and accept protons.
- Wed Dec 05, 2018 5:45 pm
- Forum: Naming
- Topic: 9C3 7th Edition
- Replies: 1
- Views: 13
Re: 9C3 7th Edition
There are 3 Br because one bromide ion has a charge of -1, and since the compound is neutral, you need to balance out the +3 charge on the Cobalt. Therefore you need 3 Bromide ions 3*(-1)=-3 to balance out the +3 charge of the Cobalt.
- Wed Dec 05, 2018 5:40 pm
- Forum: Naming
- Topic: Naming Coordination Compounds
- Replies: 4
- Views: 35
Re: Naming Coordination Compounds
I think we're supposed to memorize the ligand names.
- Wed Nov 28, 2018 12:04 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: London forces vs. Dipole-Dipole Importance
- Replies: 1
- Views: 36
London forces vs. Dipole-Dipole Importance
On Hannah Chew's Week 6 Worksheet #4a [Rank the following from weakest intermolecular forces to strongest a) H2S, H2Te, H2Se] why is the strength of london dispersion forces more important than the dipole-dipole forces? Doesn't H2S have the strongest dipole-dipole forces of the three molecules?
- Tue Nov 27, 2018 10:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Step Up Session Worksheet (Monday + Friday, Hannah) [ENDORSED]
- Replies: 37
- Views: 1356
Re: Step Up Session Worksheet (Monday + Friday, Hannah) [ENDORSED]
On the Week 6 Worksheet #4a [Rank the following from weakest intermolecular forces to strongest a) H2S, H2Te, H2Se] why is the strength of london dispersion forces more important than the dipole-dipole forces? Doesn't H2S have the strongest dipole-dipole forces of the three molecules?
- Mon Nov 26, 2018 9:58 pm
- Forum: Octet Exceptions
- Topic: Tin with only 6 electrons
- Replies: 4
- Views: 60
Re: Tin with only 6 electrons
I thought that completing the octet was more important than minimizing formal charges?
- Mon Nov 26, 2018 9:27 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Most Favorable Placement of Formal Charges
- Replies: 2
- Views: 41
Most Favorable Placement of Formal Charges
is it more favorable to have formal charges spread out or to have them concentrated? For example, for N3- is it more favorable for one of the formal charges to be [2-, 1+, 0] or [1-, 1+, 1-]? or are neither of them the best one?
- Sun Nov 25, 2018 2:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma and Pi bonds
- Replies: 6
- Views: 35
Re: Sigma and Pi bonds
If there is a double bond will there always be 1 sigma and 1 pi bond?
- Sun Nov 25, 2018 2:46 pm
- Forum: Hybridization
- Topic: SeF3+
- Replies: 2
- Views: 23
Re: SeF3+
The shape is trigonal pyramidal and the lewis structure is
'''''''''''F
'''''''''''|
F — Se — F
'''''''''''. .
'''''''''''F
'''''''''''|
F — Se — F
'''''''''''. .
- Thu Nov 15, 2018 11:14 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion Strength
- Replies: 2
- Views: 31
Re: Repulsion Strength
A lone pair is also more delocalized than a bonding pair, so it will have greater ability to move around and repel other electrons.
- Thu Nov 15, 2018 11:12 am
- Forum: SI Units, Unit Conversions
- Topic: VSEPR model
- Replies: 5
- Views: 92
Re: VSEPR model
The VSEPR model is the Valence-Shell Electron-Pair Repulsion model, which explains experimentally observed shapes of molecules.
- Thu Nov 15, 2018 11:11 am
- Forum: SI Units, Unit Conversions
- Topic: lewis structure shape
- Replies: 6
- Views: 98
Re: lewis structure shape
I think there are 11 we need to know:
linear, trigonal planar, angular, tetrahedral, trigonal pyramidal, trigonal bipyramidal, see-saw, t-shaped, octahedral, square pyramidal, square planar
linear, trigonal planar, angular, tetrahedral, trigonal pyramidal, trigonal bipyramidal, see-saw, t-shaped, octahedral, square pyramidal, square planar
- Sun Nov 04, 2018 11:31 pm
- Forum: Lewis Structures
- Topic: ClO4- 7 bonds
- Replies: 1
- Views: 34
ClO4- 7 bonds
Why can the Cl in ClO4- have 7 bonds? I thought that 6 was the limit for Cl? Can it access more than the 4s and 3d orbitals?
- Fri Nov 02, 2018 1:32 pm
- Forum: Resonance Structures
- Topic: 6th edition 3.57 which resonance structures do we draw?
- Replies: 1
- Views: 28
Re: 6th edition 3.57 which resonance structures do we draw?
Also, in 3.57b) the solutions show a perchlorate ion where Chlorine has 7 bonds. How/why can Chlorine have 7 bonds?
- Fri Nov 02, 2018 1:30 pm
- Forum: Resonance Structures
- Topic: 6th edition 3.57 which resonance structures do we draw?
- Replies: 1
- Views: 28
6th edition 3.57 which resonance structures do we draw?
The question asks: 3.57 Write the Lewis structure, including typical contributions to the resonance structure (where appropriate, allow for the possibility of octet expansion, including double bonds in different positions)... and the solutions include the Lewis structure that obeys the octet rule, b...
- Fri Nov 02, 2018 1:14 pm
- Forum: Lewis Structures
- Topic: 6th edition 3.35b Lewis Structure of BrO-
- Replies: 1
- Views: 24
6th edition 3.35b Lewis Structure of BrO-
For the Lewis Structure of BrO-, does O carry the formal charge because it's more electronegative?
- Thu Nov 01, 2018 1:44 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 14
- Views: 202
Re: Drawing Lewis Structures
How do we know how many resonance structures to draw?
- Thu Nov 01, 2018 1:42 pm
- Forum: Trends in The Periodic Table
- Topic: Trends in first ionization energies
- Replies: 3
- Views: 40
Re: Trends in first ionization energies
Across a period (from left to right), first ionization energy increases. This makes sense since across a period, the number of protons are increasing while the valence electrons are being added to the same energy shell (so they aren't further from the nucleus). This means the nucleus can hold onto t...
- Thu Nov 01, 2018 1:35 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation Numbers
- Replies: 3
- Views: 66
Re: Oxidation Numbers
When and why does hydrogen exist as hydride?
- Tue Oct 23, 2018 11:38 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: How do I identify excited state through the electronic configuration
- Replies: 5
- Views: 58
Re: How do I identify excited state through the electronic configuration
Is there a specific way that the electron configuration will change when the electron is excited?
- Tue Oct 23, 2018 6:36 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 23785
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
For question 7 on worksheet 2, why is it not possible to use the eqn in the book that says v= R(1/ni ^2 - 1/nf^2). I tried this just to see if I got the same answer and I didn't. Why doesn't this work as well, because we are using frequency to get n initial? I think that it works as long as you add...
- Tue Oct 23, 2018 1:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 23785
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Can someone explain what the statement in #9 of worksheet 3 means? "It is impossible to determine both the speed and position of an electron with absolute uncertainty." Why is it absolute uncertainty and not absolute certainty?
- Sun Oct 21, 2018 11:15 am
- Forum: SI Units, Unit Conversions
- Topic: Remembering Unit Conversions
- Replies: 5
- Views: 180
Re: Remembering Unit Conversions
I think we do need to memorize the prefixes and be able to convert between them.
- Thu Oct 18, 2018 10:41 pm
- Forum: Photoelectric Effect
- Topic: units
- Replies: 12
- Views: 103
Re: units
do we need to memorize the conversion factor between Joules and eV?
- Wed Oct 17, 2018 4:43 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 6
- Views: 156
- Mon Oct 15, 2018 12:18 am
- Forum: General Science Questions
- Topic: Uncertainty Principle Problem
- Replies: 1
- Views: 111
Uncertainty Principle Problem
Here is the problem (6th edition Example 1.7): Estimate the minimum uncertainty in (a) the position of a marble of mass 1.0 g given that its speed is known to within ±1.0 mm s^-1
In the solution, the speed is multiplied by 2. Is it because of the ±? Can someone please explain this!!!
In the solution, the speed is multiplied by 2. Is it because of the ±? Can someone please explain this!!!
- Mon Oct 15, 2018 12:03 am
- Forum: General Science Questions
- Topic: Workshops
- Replies: 3
- Views: 127
Re: Workshops
I would recommend going to the workshops! They help you a lot with foundational skills and are very helpful if you are totally lost on a particular concept. I think that they are just as helpful as TA office hours and that I feel more comfortable asking really basic clarifying questions during the w...
- Tue Oct 09, 2018 10:19 pm
- Forum: General Science Questions
- Topic: Rydberg Equation n
- Replies: 1
- Views: 149
Rydberg Equation n
When doing problems using the Rydberg Equation, how do you know which energy level is n1 and which is n2?
Sample question -- 6th Edition Chapter 1 #13: Use the Rydberg formula for atomic hydrogen to calculate the wavelength of radiation generated by the transition from n=4 to n=2.
Sample question -- 6th Edition Chapter 1 #13: Use the Rydberg formula for atomic hydrogen to calculate the wavelength of radiation generated by the transition from n=4 to n=2.
- Sun Oct 07, 2018 12:24 pm
- Forum: General Science Questions
- Topic: Problem solving, intermediate steps
- Replies: 2
- Views: 114
Problem solving, intermediate steps
For the test, do we only have to show the amount of intermediate steps shown in the solutions manual?
- Sun Oct 07, 2018 12:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 23785
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Where is the workshop going to be?
- Wed Oct 03, 2018 2:47 pm
- Forum: General Science Questions
- Topic: Finding Molecular Formula, Mass Percentage
- Replies: 2
- Views: 75
Finding Molecular Formula, Mass Percentage
For 6th Edition Chapter F #21, why don't you begin the problem by finding mass percentage? When are you supposed to calculate the mass percentage? This is the problem: "In 1978, scientists extracted a compound with antitumor and antiviral properties from marine animals in the Caribbean Sea. A s...