Search found 49 matches
- Sun Mar 18, 2018 4:14 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Work when pressure is constant
- Replies: 6
- Views: 1014
Re: Work when pressure is constant
Yes. If pressure is not constant, then we would use w=-nrt ln (v2/v1)
- Sun Mar 18, 2018 4:13 am
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: complex molecules
- Replies: 8
- Views: 1720
Re: complex molecules
A larger molecule has greater entropy than smaller molecules
- Sun Mar 18, 2018 4:10 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G at equilibrium
- Replies: 1
- Views: 442
Delta G at equilibrium
Is delta G always equal to zero at equilibrium/ during a phase change?
- Sun Mar 18, 2018 4:07 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: First Law
- Replies: 5
- Views: 996
Re: First Law
If no heat is transferred, then q will be equal to zero. This also means that delta U will now be equal to work.
- Sun Mar 18, 2018 4:05 am
- Forum: Calculating Work of Expansion
- Topic: Conversion of R
- Replies: 7
- Views: 1048
Re: Conversion of R
Check the units behind the constant R to see what needs to cancel out in the problem you are solving.
- Sat Mar 17, 2018 11:07 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic/ basic conditions
- Replies: 4
- Views: 726
Acidic/ basic conditions
Other than using H+ or OH-, is there a main difference in balancing acidic vs basic reactions?
- Sat Mar 17, 2018 11:04 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic/Voltaic Cells
- Replies: 2
- Views: 497
Galvanic/Voltaic Cells
could someone expand on the concepts behind galvanic/voltaic cells?
- Fri Mar 16, 2018 3:31 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: Microstate Determination
- Replies: 2
- Views: 592
Microstate Determination
could someone explain how to calculate microstates?
- Fri Mar 16, 2018 2:18 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond enthalpies to calculate change in enthalpy
- Replies: 3
- Views: 549
Bond enthalpies to calculate change in enthalpy
Could someone explain how to use bond enthalpies to calculate the change in enthalpy of a reaction?
- Fri Mar 16, 2018 1:22 pm
- Forum: General Rate Laws
- Topic: Rate Constant Units
- Replies: 1
- Views: 293
Rate Constant Units
Could someone elaborate on how to find the units for different rate constants in a reaction?
- Wed Mar 14, 2018 3:26 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Elementary reactions
- Replies: 6
- Views: 896
Elementary reactions
could someone elaborate on elementary reactions?
- Wed Mar 14, 2018 3:24 pm
- Forum: *Enzyme Kinetics
- Topic: Catalysts and Intermediates
- Replies: 5
- Views: 1196
Catalysts and Intermediates
could someone further explain the concepts for catalysts and intermediates?
- Wed Mar 14, 2018 3:20 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation and constant
- Replies: 3
- Views: 555
Arrhenius Equation and constant
could someone elaborate more on using the Arrhenius equation and its constant?
- Wed Mar 14, 2018 3:16 pm
- Forum: First Order Reactions
- Topic: Determining Reaction Order
- Replies: 5
- Views: 928
Determining Reaction Order
could someone further explain how to determine reaction orders?
- Wed Mar 14, 2018 3:15 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Finding the slow step
- Replies: 5
- Views: 1201
Finding the slow step
How should we determine which step is the slow step?
- Wed Mar 14, 2018 3:13 pm
- Forum: *Alcohols
- Topic: Functional group structures [ENDORSED]
- Replies: 2
- Views: 1139
Functional group structures [ENDORSED]
For the final do we only need to know the line structures for functional groups or should we also be able to draw the full structure?
- Mon Feb 12, 2018 4:01 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Trouton's Rule
- Replies: 1
- Views: 377
Trouton's Rule
Could someone explain how to apply Trouton's rule when solving for the standard enthalpy of vaporization?
- Mon Feb 05, 2018 2:08 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 2nd law of thermodynamics [ENDORSED]
- Replies: 1
- Views: 283
2nd law of thermodynamics [ENDORSED]
Could someone elaborate more on the 2nd law of thermodynamics?
- Mon Jan 22, 2018 10:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.49
- Replies: 3
- Views: 460
Problem 8.49
For this problem, how do we know to use 298K for the change in temperature in the equation?
- Sun Jan 21, 2018 10:30 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv vs. Cp [ENDORSED]
- Replies: 13
- Views: 11917
Re: Cv vs. Cp [ENDORSED]
Also to solve for the values of Cvm and Cpm you can use the equations Cvm=3/2*R and Cpm=5/2*R for the molar heat capacity.
- Sun Jan 21, 2018 9:38 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.31
- Replies: 3
- Views: 499
Re: 8.31
To solve part b you would start with the equation Cvm=3/2*R to get the heat capacity at constant volume. I got 12.47 J/mol for Cvm. Then you would plug in the value you got for Cvm and your other known variables into the equation q=m*C*delta T to solve for the heat released.
- Sat Jan 20, 2018 7:09 pm
- Forum: Phase Changes & Related Calculations
- Topic: Test 1 topics
- Replies: 2
- Views: 392
Test 1 topics
What homework problems will be covered on test 1?
- Sat Jan 20, 2018 1:13 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Diathermic walls
- Replies: 3
- Views: 970
Re: Diathermic walls
Would adiabatic walls be almost the opposite of diathermic walls?
- Sat Jan 20, 2018 1:09 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: relationship between q and w
- Replies: 2
- Views: 288
Re: relationship between q and w
The relationship between q and w is also affected by the change in energy of the system which can influence the signs.
- Sat Jan 20, 2018 1:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard enthalpies on test 1 [ENDORSED]
- Replies: 7
- Views: 614
Re: Standard enthalpies on test 1 [ENDORSED]
Also, the diatomic elements all have standard states at zero.
- Tue Jan 09, 2018 6:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes [ENDORSED]
- Replies: 3
- Views: 293
Phase Changes [ENDORSED]
What are some important phase changes to know? (such as changes between solids/liquids/gases)
- Tue Jan 09, 2018 6:47 pm
- Forum: Phase Changes & Related Calculations
- Topic: reversible process
- Replies: 3
- Views: 799
Re: reversible process
A reversible process is when the direction can be reversed by an infinitely small change in a variable. An irreversible process is when an infinitely small change in the external pressure does not reverse the direction of travel of the piston. Also the work a system can do is the greatest in a rever...
- Tue Jan 09, 2018 6:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endo and Exothermic Ways to Remember
- Replies: 28
- Views: 11709
Re: Endo and Exothermic Ways to Remember
Another comment on this is when you're solving for the change in enthalpy for example, a negative value for kilojoules means that the reaction was exothermic and a positive value for kilojoules means that the reaction is endothermic.
- Sun Dec 10, 2017 1:18 am
- Forum: Ideal Gases
- Topic: Value of R
- Replies: 3
- Views: 2627
Value of R
Is the value of R in PV=nRT always equal to .082?
- Sun Dec 10, 2017 12:25 am
- Forum: Octet Exceptions
- Topic: Exceptions [ENDORSED]
- Replies: 7
- Views: 1324
Exceptions [ENDORSED]
When do you know that octet exceptions occur?
- Sun Dec 10, 2017 12:24 am
- Forum: Resonance Structures
- Topic: Delocalization in Resonance Structures
- Replies: 2
- Views: 510
Delocalization in Resonance Structures
For delocalization to occur, do you have to always have resonance?
- Sun Dec 10, 2017 12:23 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation Number
- Replies: 1
- Views: 396
Oxidation Number
How do you solve for the oxidation number?
- Sun Dec 10, 2017 12:22 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strong or weak acids/ bases
- Replies: 6
- Views: 2073
Strong or weak acids/ bases
How do you determine if an acid/base is weak or strong?
- Sun Dec 10, 2017 12:19 am
- Forum: Lewis Acids & Bases
- Topic: Determine Lewis Acid
- Replies: 13
- Views: 1679
Determine Lewis Acid
How do you determine if an element is a Lewis acid?
- Sun Dec 10, 2017 12:16 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Quick Determination of FC [ENDORSED]
- Replies: 6
- Views: 1111
Re: Quick Determination of FC [ENDORSED]
Another quick way that I determine formal charge is:
1- counting the lone pairs around the atom (each equals 2 electrons)
2- counting the bonds around the atom (each counts as 1 electron)
1- counting the lone pairs around the atom (each equals 2 electrons)
2- counting the bonds around the atom (each counts as 1 electron)
- Sun Dec 10, 2017 12:12 am
- Forum: Dipole Moments
- Topic: Dipole Occurence
- Replies: 4
- Views: 732
Dipole Occurence
How do we determine when a dipole moment occurs?
- Sun Dec 10, 2017 12:11 am
- Forum: Sigma & Pi Bonds
- Topic: Delocalization of Pi bonds
- Replies: 1
- Views: 356
Delocalization of Pi bonds
How do you determine when a pi bond is delocalized?
- Sun Dec 10, 2017 12:09 am
- Forum: Amphoteric Compounds
- Topic: Amphoteric compounds
- Replies: 3
- Views: 1036
Amphoteric compounds
How do you determine if a compound is amphoteric?
- Thu Dec 07, 2017 6:21 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Arrhenius acids and bases
- Replies: 2
- Views: 357
Arrhenius acids and bases
Will Arrhenius acids and bases be covered on the final?
- Wed Dec 06, 2017 7:11 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Types and strength of Acids/Bases
- Replies: 3
- Views: 739
Types and strength of Acids/Bases
Could someone elaborate on strong/ weak acids and bases and give examples for them? Also, how do we determine the type of a certain acid/base?
- Sat Nov 25, 2017 8:27 pm
- Forum: Dipole Moments
- Topic: Dipole Moments
- Replies: 3
- Views: 423
Dipole Moments
Could someone elaborate on dipole moments and how to draw them? Also, should we only draw dipole moments when the question specifically asks for them?
- Sun Nov 19, 2017 6:40 pm
- Forum: Sigma & Pi Bonds
- Topic: drawing sigma/pi bonds
- Replies: 6
- Views: 927
drawing sigma/pi bonds
How do you determine when/ where to draw sigma and pi bonds?
- Sun Nov 12, 2017 12:01 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 3.5 Give the ground state configuration expected for each of the following ions:
- Replies: 3
- Views: 2865
Re: 3.5 Give the ground state configuration expected for each of the following ions:
You would subtract electrons from the 4p and then 4s orbitals (the outer orbitals in the configuration) before the 3d orbital.
- Tue Oct 31, 2017 6:11 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 2.53 [ENDORSED]
- Replies: 4
- Views: 681
Re: 2.53 [ENDORSED]
Additionally, why does Se have 2 unpaired electrons instead of 4 unpaired electrons?
- Tue Oct 31, 2017 6:06 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Homework 2.43
- Replies: 4
- Views: 567
Re: Homework 2.43
For your second question, the electron configuration for tungsten is [Xe]4f^14 5d^4 6s^2 instead of [Xe]4f^14 5d^3 6s^2 because tungsten is located in the fourth space over from the start of the d block in period 6. Therefore it's noted as 5d^4 instead of 5d^3. Because the answers for the homework i...
- Thu Oct 26, 2017 12:41 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Units [ENDORSED]
- Replies: 4
- Views: 560
Units [ENDORSED]
When solving for the uncertainty in position, should the units be in picometers for the final answer or is it ok to leave the units in meters?
- Wed Oct 18, 2017 8:02 pm
- Forum: DeBroglie Equation
- Topic: Wave vs Particle Properties of Light
- Replies: 3
- Views: 601
Wave vs Particle Properties of Light
The Photoelectric effect shows light behaving as particles/photons. However, light is also described as having some wave-like properties. Does light behave as a combination of particles and waves or mainly as particles?
- Thu Oct 12, 2017 11:32 am
- Forum: Properties of Light
- Topic: Prefix Conversion
- Replies: 12
- Views: 1367
Prefix Conversion
When converting from a prefix such as nm into meters, should the conversion be before or after we solve the problem?
- Tue Oct 03, 2017 2:40 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 36408
Re: All students read this sig fig post [ENDORSED]
I believe we use a sig fig rule each time we do a calculation. For addition/ subtraction, the number of decimal places in the answer should have the smallest number of decimal places from the number being added/ subtracted. Example: 112.2+60.23= 172.4 . For multiplication/ division, the number with ...