Search found 30 matches

by Laurence Tacderas 1K
Mon Mar 11, 2019 9:58 am
Forum: First Order Reactions
Topic: stoichiometry
Replies: 2
Views: 47

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.
by Laurence Tacderas 1K
Mon Mar 11, 2019 9:56 am
Forum: General Rate Laws
Topic: Solving for the rxn order
Replies: 3
Views: 50

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).
by Laurence Tacderas 1K
Mon Mar 11, 2019 9:53 am
Forum: Zero Order Reactions
Topic: Graphs
Replies: 6
Views: 138

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.
by Laurence Tacderas 1K
Tue Mar 05, 2019 3:52 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Delta G rules
Replies: 8
Views: 114

Re: Delta G rules

Positive means non-spontaneous, Negative means spontaneous, and 0 means at equilibrium
by Laurence Tacderas 1K
Tue Mar 05, 2019 3:49 pm
Forum: Student Social/Study Group
Topic: Final
Replies: 24
Views: 561

Re: Final

There was an announcement that review sessions start this Saturday and continue through week 10
by Laurence Tacderas 1K
Tue Mar 05, 2019 3:48 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: n and k
Replies: 3
Views: 55

Re: n and k

N will help to determine the rate of the reaction, while K will determine the rate at varying concentrations
by Laurence Tacderas 1K
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: 71

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
by Laurence Tacderas 1K
Tue Feb 26, 2019 10:22 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs At Equilibrium
Replies: 3
Views: 66

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
by Laurence Tacderas 1K
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: 111

Re: Test 2

I believe it's up to either section 14.7 or 14.8 (for the sixth edition)
by Laurence Tacderas 1K
Mon Feb 18, 2019 2:39 pm
Forum: Student Social/Study Group
Topic: Best Midterm Review
Replies: 7
Views: 138

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.
by Laurence Tacderas 1K
Mon Feb 18, 2019 2:37 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: HW for W7
Replies: 7
Views: 102

Re: HW for W7

Probably the Gibbs Free Energy portion of chapter 9
by Laurence Tacderas 1K
Mon Feb 18, 2019 2:36 pm
Forum: Student Social/Study Group
Topic: Midterms
Replies: 5
Views: 89

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
by Laurence Tacderas 1K
Tue Feb 12, 2019 6:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka value
Replies: 3
Views: 66

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.
by Laurence Tacderas 1K
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: 275

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
by Laurence Tacderas 1K
Tue Feb 12, 2019 5:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 4
Views: 75

Re: Heat Capacity

Yes just make sure your're using the correct heat capacities and units
by Laurence Tacderas 1K
Thu Feb 07, 2019 3:52 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Cup of Tea
Replies: 17
Views: 293

Re: Cup of Tea

The tea can receive and transfer matter to its surroundings, as well as energy in the form of heat
by Laurence Tacderas 1K
Thu Feb 07, 2019 3:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Quiz 1 Number 3c
Replies: 6
Views: 116

Re: Quiz 1 Number 3c

Moles per liters, or moles/L (or often written as M for molarity)
by Laurence Tacderas 1K
Thu Feb 07, 2019 3:49 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm content
Replies: 2
Views: 41

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.
by Laurence Tacderas 1K
Thu Jan 31, 2019 3:56 pm
Forum: Phase Changes & Related Calculations
Topic: Test #1
Replies: 11
Views: 178

Re: Test #1

They'll be returned in section this week
by Laurence Tacderas 1K
Thu Jan 31, 2019 3:52 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 5
Views: 62

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.
by Laurence Tacderas 1K
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: 124

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.
by Laurence Tacderas 1K
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: 170

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...
by Laurence Tacderas 1K
Mon Jan 21, 2019 11:17 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: buffer questions on test
Replies: 7
Views: 107

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
by Laurence Tacderas 1K
Mon Jan 21, 2019 11:09 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Shortcut method (finding concentration change)
Replies: 5
Views: 80

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.
by Laurence Tacderas 1K
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: 45

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.
by Laurence Tacderas 1K
Mon Jan 14, 2019 9:33 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K and Q [ENDORSED]
Replies: 7
Views: 102

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...
by Laurence Tacderas 1K
Mon Jan 14, 2019 9:28 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant
Replies: 6
Views: 89

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.
by Laurence Tacderas 1K
Tue Jan 08, 2019 10:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th Edition 11.7 part c
Replies: 3
Views: 73

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...
by Laurence Tacderas 1K
Tue Jan 08, 2019 10:02 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Heterogeneous equilibrium
Replies: 3
Views: 52

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...
by Laurence Tacderas 1K
Tue Jan 08, 2019 9:44 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.7C
Replies: 2
Views: 59

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).

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