Search found 30 matches
- Mon Mar 11, 2019 9:58 am
- Forum: First Order Reactions
- Topic: stoichiometry
- Replies: 2
- Views: 301
Re: stoichiometry
There may be problems where you need the final concentration of A to solve for the rate constant k or the time, but you are only given the final concentration of B. So then, given a balanced chemical equation, you would convert that final concentration in terms of A using stoichiometry.
- Mon Mar 11, 2019 9:56 am
- Forum: General Rate Laws
- Topic: Solving for the rxn order
- Replies: 3
- Views: 404
Re: Solving for the rxn order
If you're given 2 experiments between two reactants A & B and there is one experiment that has both concentrations changing, solve for the order of reactant A first and then use that to help you find the order of reactant B (in the experiment which has both changing).
- Mon Mar 11, 2019 9:53 am
- Forum: Zero Order Reactions
- Topic: Graphs
- Replies: 6
- Views: 871
Re: Graphs
They're definitely really helpful because they can tell you what order the reaction is simply based on what is being measured vs time. Then you can go from there and calculate the rate constant from the slope of the line.
- Tue Mar 05, 2019 3:52 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Delta G rules
- Replies: 8
- Views: 783
Re: Delta G rules
Positive means non-spontaneous, Negative means spontaneous, and 0 means at equilibrium
- Tue Mar 05, 2019 3:49 pm
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 24
- Views: 2227
Re: Final
There was an announcement that review sessions start this Saturday and continue through week 10
- Tue Mar 05, 2019 3:48 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: n and k
- Replies: 3
- Views: 414
Re: n and k
N will help to determine the rate of the reaction, while K will determine the rate at varying concentrations
- Tue Feb 26, 2019 10:26 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Reducing agent/oxidizing agent
- Replies: 5
- Views: 558
Re: Reducing agent/oxidizing agent
Just remember that what ever reduces/oxidizes (or is the "reducing/oxidizing" agent) is the one getting oxidized/reduced. Then you can tell if it is the cathode (reduction) or anode (oxidation) half reaction
- Tue Feb 26, 2019 10:22 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs At Equilibrium
- Replies: 3
- Views: 535
Re: Gibbs At Equilibrium
The deltaG will be equal to zero, and you'll know because the reaction won't be spontaneous in either direction
- Tue Feb 26, 2019 10:21 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Test 2
- Replies: 4
- Views: 533
Re: Test 2
I believe it's up to either section 14.7 or 14.8 (for the sixth edition)
- Mon Feb 18, 2019 2:39 pm
- Forum: Student Social/Study Group
- Topic: Best Midterm Review
- Replies: 7
- Views: 768
Re: Best Midterm Review
I found certain review sessions to be rather helpful, generally they were the ones that went over specific topics. I would also recommend going to sessions, both TA and UA led, that provide practice questions that mirror the difficulty of the tests.
- Mon Feb 18, 2019 2:37 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: HW for W7
- Replies: 7
- Views: 692
Re: HW for W7
Probably the Gibbs Free Energy portion of chapter 9
- Mon Feb 18, 2019 2:36 pm
- Forum: Student Social/Study Group
- Topic: Midterms
- Replies: 5
- Views: 579
Re: Midterms
I believe as long as you did your work in pen you can have your TA re-check the scoring that gave you
- Tue Feb 12, 2019 6:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka value
- Replies: 3
- Views: 363
Re: Ka value
Since strong acids fully disassociate, just know that they won't even have a Ka value because there's no reactants at the end of the reaction. If Ka=[P]/[R] and there's no R, then you won't have to worry about Ka for strong acids, only weak acids.
- Tue Feb 12, 2019 5:58 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: When does delta U equal zero?
- Replies: 17
- Views: 8322
Re: When does delta U equal zero?
Since deltaU=3/2nRT, if the reaction is at constant temperature, the internal energy will be equal to zero
- Tue Feb 12, 2019 5:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 4
- Views: 428
Re: Heat Capacity
Yes just make sure your're using the correct heat capacities and units
- Thu Feb 07, 2019 3:52 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Cup of Tea
- Replies: 17
- Views: 2550
Re: Cup of Tea
The tea can receive and transfer matter to its surroundings, as well as energy in the form of heat
- Thu Feb 07, 2019 3:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Quiz 1 Number 3c
- Replies: 6
- Views: 670
Re: Quiz 1 Number 3c
Moles per liters, or moles/L (or often written as M for molarity)
- Thu Feb 07, 2019 3:49 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Midterm content
- Replies: 2
- Views: 282
Re: Midterm content
I checked and saw that the midterm will cover problems up to #47 of chapter 9 (6th edition). Everything else seems to involve Gibbs Free Energy which won't be on the midterm.
- Thu Jan 31, 2019 3:56 pm
- Forum: Phase Changes & Related Calculations
- Topic: Test #1
- Replies: 11
- Views: 981
Re: Test #1
They'll be returned in section this week
- Thu Jan 31, 2019 3:52 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 5
- Views: 540
Re: Heat Capacity
As people have said above, the fact that molar heat capacity is intensive, we can apply it to any similar reaction regardless of the number of moles reacted.
- Thu Jan 31, 2019 3:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework
- Replies: 9
- Views: 932
Re: Homework
I saw that too. I think if you start with enthalpies and then go back to the first law it might be more coherent.
- Mon Jan 21, 2019 11:23 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: The Conjugate Seesaw
- Replies: 13
- Views: 997
Re: The Conjugate Seesaw
Since Kw is a constant value, the strengths of acids and their conjugate bases (as well as bases and their conjugate acids) are complimentary. That would make sense if you think about it: the stronger an acid/base, the more likely it will stay disassociated and thus its conjugate base will be weaker...
- Mon Jan 21, 2019 11:17 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: buffer questions on test
- Replies: 7
- Views: 529
Re: buffer questions on test
Yes, buffer questions are mentioned in the outline so there's a chance they'll show up on the test
- Mon Jan 21, 2019 11:09 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Shortcut method (finding concentration change)
- Replies: 5
- Views: 424
Re: Shortcut method (finding concentration change)
If K is less than 10^-3, then the reaction heavily favors product. Thus, x, or the change in molar concentration, is so low that it can be considered negligible. Essentially, the equilibrium concentration of reactant is the same as its initial concentration.
- Mon Jan 14, 2019 9:41 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Change in Pressure
- Replies: 4
- Views: 309
Re: Change in Pressure
When decreasing the volume of the container, the reaction will favor the side which produces less moles. This is due to the fact that reducing volume increases concentration (moles/volume=conc), so, following Le Chatlier's Principle, the reaction will try to minimize changes in concentration.
- Mon Jan 14, 2019 9:33 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: K and Q [ENDORSED]
- Replies: 7
- Views: 697
Re: K and Q [ENDORSED]
Q, the reaction quotient, uses the molar concentrations of the reactants and products at any point during the reaction, while K is the value when the reaction is at equilibrium. If the two values are equal, then the reaction is at equilibrium. If not, then more products or reactant will form so Q ca...
- Mon Jan 14, 2019 9:28 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium constant
- Replies: 6
- Views: 548
Re: Equilibrium constant
Partial pressures of the reactant and products affect Kp, not Kc. Changing the pressure by reducing the volume can affect both Kp and Kc.
- Tue Jan 08, 2019 10:18 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th Edition 11.7 part c
- Replies: 3
- Views: 262
Re: 6th Edition 11.7 part c
The flask shows the reaction at equilibrium - while the number of X 2 molecules and X atoms are different compared to their initial amounts (no X initially), the total number of moles is the same before and after the reaction. By taking the mole fractions (the number of moles X 2 or X / the total nu...
- Tue Jan 08, 2019 10:02 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Heterogeneous equilibrium
- Replies: 3
- Views: 280
Re: Heterogeneous equilibrium
You would have to convert either the partial pressure of the gas to equilibrium molar concentration to determine Kc or convert the equilibrium molar concentration of the aqueous solution to determine Kp. However, molarity and partial pressures cannot be used in the same equilibrium constant expressi...
- Tue Jan 08, 2019 9:44 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.7C
- Replies: 2
- Views: 260
Re: 11.7C
To create a balanced chemical equation, X must have a stoichiometric coefficient of 2 (since the flask shows the diatomic molecule X2 decomposing into X atoms).