Search found 49 matches
- Sat Mar 17, 2018 1:52 am
- Forum: Phase Changes & Related Calculations
- Topic: Sign for compression vs expansion
- Replies: 4
- Views: 1135
Re: Sign for compression vs expansion
To determine the sign, think about if the work is done to the system or by the system. W is positive if work is done by the system, and negative if work is done on the system
- Sat Mar 17, 2018 1:48 am
- Forum: Administrative Questions and Class Announcements
- Topic: Topics on final-- lattice enthalpy?
- Replies: 1
- Views: 354
Re: Topics on final-- lattice enthalpy?
I'm pretty sure we don't have to know about lattice enthalpy for the final, and if there aren't any homework questions about it, it's safe to assume it will not be covered.
- Sat Mar 17, 2018 12:56 am
- Forum: Administrative Questions and Class Announcements
- Topic: Derivations
- Replies: 2
- Views: 459
Re: Derivations
Under the class website, there is a section with the lecture outlines with all of the concepts we need to know. The outlines include which equations we need to understand how to derive
- Sat Mar 17, 2018 12:45 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Adiabatic Process
- Replies: 4
- Views: 656
Re: Adiabatic Process
When a process is adiabatic, there is no transfer of heat or matter with surroundings, so all of the energy is transferred to surroundings as work. In this process, deltaU equals w.
- Fri Mar 16, 2018 11:56 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Potential sign
- Replies: 4
- Views: 695
Re: Cell Potential sign
When you reverse the direction of a half reaction, you also change the sign of the reaction potential.
- Fri Mar 16, 2018 11:55 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell diagram
- Replies: 4
- Views: 544
Re: cell diagram
Yes, the anode is always on the left of the salt bridge / porous disc, and the cathode on the right.
- Fri Mar 16, 2018 11:48 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Test 2 Question 8 wording
- Replies: 3
- Views: 535
Re: Test 2 Question 8 wording
The electrons in each half-reaction have to be equal before you can create the overall balanced reaction.
- Fri Mar 16, 2018 11:44 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Lyndon Review Test, Question 7a [ENDORSED]
- Replies: 7
- Views: 948
Re: Lyndon Review Test, Question 7a [ENDORSED]
There are no catalysts in this reaction.
- Fri Mar 16, 2018 11:32 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Functional Groups Overlapping
- Replies: 3
- Views: 2754
Re: Functional Groups Overlapping
Will we be expected to make distinctions within functional groups on the test? For example, being able to identify what type of amine group?
- Fri Mar 16, 2018 6:14 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Steady-State Approximation vs. Pre-equilibrium Condition
- Replies: 4
- Views: 783
Steady-State Approximation vs. Pre-equilibrium Condition
How do we know when to use a steady-state approximation or assume pre-equilibrium condition when we calculate the overall rate law from a mechanism?
- Fri Mar 16, 2018 2:28 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Fast or Slow
- Replies: 8
- Views: 1011
Re: Fast or Slow
Also, if you look at a reaction profile, you can see which is the slow step / fast step based on how high the energy barrier is. A smaller barrier would indicate fast step, and a larger one, slow step.
- Fri Mar 16, 2018 2:23 am
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Electrolysis Anode and Cathode
- Replies: 2
- Views: 519
Re: Electrolysis Anode and Cathode
I am confused as to where we would need to apply this. What type of problem would involve this concept?
- Fri Mar 16, 2018 2:18 am
- Forum: Balancing Redox Reactions
- Topic: Balancing in a basic solution
- Replies: 4
- Views: 2850
Re: Balancing in a basic solution
The course outlines show that we must be able to balance both; check the outlines posted on the class website to see all the material / concepts we need to know for each section.
- Fri Mar 16, 2018 2:16 am
- Forum: Balancing Redox Reactions
- Topic: Half-Reactions Sheet
- Replies: 5
- Views: 741
Re: Half-Reactions Sheet
Like previous exams, we will be given the reaction potentials needed to solve the problem; we are not expected to memorize them.
- Wed Mar 14, 2018 4:18 pm
- Forum: *Alcohols
- Topic: Functional Groups on Final? [ENDORSED]
- Replies: 6
- Views: 2095
Re: Functional Groups on Final? [ENDORSED]
Will we also be expected to remember examples of molecules with functional groups?
- Wed Mar 14, 2018 4:16 pm
- Forum: *Alcohols
- Topic: Functional group structures [ENDORSED]
- Replies: 2
- Views: 1134
Re: Functional group structures [ENDORSED]
The line structure can be turned into the full structure and vise versa, they are just different ways to represent the molecule.
- Tue Mar 13, 2018 11:50 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Homogeneous Catalysts
- Replies: 3
- Views: 534
Re: Homogeneous Catalysts
Are there other examples of things that are generally homogeneous catalysts that we should be aware of?
- Tue Mar 13, 2018 8:13 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Drawing Reaction Profiles
- Replies: 3
- Views: 454
Re: Drawing Reaction Profiles
The energy barrier will be steeper corresponding to a slow step, a smaller barrier would correspond to a fast step.
- Mon Mar 12, 2018 4:01 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Relation between k and activation energy
- Replies: 10
- Views: 5626
Re: Relation between k and activation energy
If a catalyst were added, how would this also affect k or activation energy?
- Mon Mar 12, 2018 3:53 pm
- Forum: Biological Examples
- Topic: Nitric Oxide Catalyses
- Replies: 7
- Views: 1663
Re: Nitric Oxide Catalyses
Is there a way to tell by looking at these equations if the catalyst was heterogeneous or homogeneous?
- Mon Mar 12, 2018 3:49 pm
- Forum: *Calculations Using ΔG° = -RT ln K
- Topic: Vocabulary
- Replies: 13
- Views: 4675
Re: Vocabulary
How do we compare these terms to graphs / visually?
- Sun Mar 11, 2018 5:53 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Negative Order
- Replies: 7
- Views: 15697
Re: Negative Order
Are there ever occurrences of negative orders less than -1? Will these be possible / conceptually what would that mean in relation to rates / changing concentration?
- Thu Mar 08, 2018 12:29 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 15.23 part C
- Replies: 3
- Views: 472
Re: 15.23 part C
Tiffany Dao 1A wrote:you can find [A] at 115 seconds by converting the [B].
[A] = 0.153 molA/L - [0.034 molB/L x (2 molA/1 molB)]
then you can use ln[A] = -kt + ln{A]o
Why do we subtract [0.034 molB/L x (2 molA/1 molB)]? Is there an equation on the formula sheet that we derive this from?
- Wed Mar 07, 2018 11:25 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 15.23 part C
- Replies: 3
- Views: 472
15.23 part C
Determine the rate constant for each of the following first-order reactions:
Part C) 2A-->B+C,given that[A]0 =0.153molxL^-1 and that after 115 s the concentration of B rises to 0.034 molxL^-1.
I am confused as to where to start with this problem?
Part C) 2A-->B+C,given that[A]0 =0.153molxL^-1 and that after 115 s the concentration of B rises to 0.034 molxL^-1.
I am confused as to where to start with this problem?
- Tue Mar 06, 2018 9:47 pm
- Forum: Zero Order Reactions
- Topic: Finding 1/2 or negative orders
- Replies: 2
- Views: 414
Finding 1/2 or negative orders
Is there a way to determine if the order of a reaction is 1/2, 1/4, negative, etc. just by looking at data from trials? Will we need to be able to determine these types of orders for any tests?
- Tue Mar 06, 2018 5:35 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation to find pH
- Replies: 6
- Views: 10192
Re: Nernst Equation to find pH
Since the pH is just a measure of the concentration of H ion concentration, we can use the Nernst equation to find it.
- Tue Mar 06, 2018 5:27 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Q vs. K
- Replies: 8
- Views: 1149
Re: Q vs. K
You must also be sure to make the distinction between capital K and lowercase k when we deal with kinetics (rate constant).
- Tue Mar 06, 2018 5:24 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: test 2 last Q
- Replies: 3
- Views: 557
Re: test 2 last Q
Please post the question? It would help other people also compare answers
- Wed Feb 14, 2018 12:20 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: q==q
- Replies: 2
- Views: 437
q==q
For problems where you need to equate q to negative q (dropping a copper cube into water), does it matter if the negative sign goes on the system side or surrounding side?
- Sat Dec 09, 2017 7:20 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert gases
- Replies: 4
- Views: 618
Re: Inert gases
The addition of the inert gas in itself will not affect the concentration, but since the inert gas is taking up space in the container, it is adding to the pressure of the whole system. When pressure is increased, the reaction will shift to favor the side with less total moles of gas.
- Sat Dec 09, 2017 7:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs
- Replies: 5
- Views: 660
Re: Lone pairs
Since the shape of a molecule is altered by lone pairs (i.e. water), the lone pairs will affect the dipole moment in that it "pushes" around the other atoms.
- Sat Dec 09, 2017 7:12 pm
- Forum: Electronegativity
- Topic: Trends? [ENDORSED]
- Replies: 10
- Views: 1662
Re: Trends? [ENDORSED]
You should also be sure to be aware of the exceptions to the periodic trend rules. (Ex: noble gases not being included in the general electron affinity general trend)
- Sat Dec 09, 2017 7:04 pm
- Forum: Lewis Structures
- Topic: resonance and delocalization
- Replies: 2
- Views: 458
Re: resonance and delocalization
Delocalized electrons are not associated with a single atom or covalent bond, so yes, a resonance structure would include the movements of delocalized electrons.
- Sat Dec 09, 2017 7:02 pm
- Forum: Bronsted Acids & Bases
- Topic: Mg(OH)2
- Replies: 2
- Views: 443
Re: Mg(OH)2
Strong bases include group one and two hydroxides and oxide like KOH, NaOH, etc.
- Sat Dec 09, 2017 6:58 pm
- Forum: Lewis Acids & Bases
- Topic: Strength [ENDORSED]
- Replies: 5
- Views: 1163
Re: Strength [ENDORSED]
Another method is to determine the stability of the conjugate base. If it is a very stable structure, the acid is strong. If the resulting conjugate base has an unstable structure, the acid was weak.
- Sat Dec 09, 2017 6:54 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Formic Acid and Acetic Acid
- Replies: 2
- Views: 752
Re: Formic Acid and Acetic Acid
A method you can use to determine the strength of an acid is to look at it's conjugate base. Drawing the the Lewis structure of the conjugate bases will help you to determine stability.
- Thu Dec 07, 2017 3:27 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Arrhenius, Lewis, and Bronsted Definitions
- Replies: 1
- Views: 381
Arrhenius, Lewis, and Bronsted Definitions
Is there a certain time when an acid or base reaction should be considered a Arrhenius, Lewis, or Bronsted Acid / Base? How do you know when to use each type / definition?
- Wed Dec 06, 2017 4:51 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: J.5
- Replies: 2
- Views: 442
Re: J.5
Perhaps you are expected to balance before solving
- Wed Dec 06, 2017 4:46 pm
- Forum: Octet Exceptions
- Topic: Octet Exceptions
- Replies: 8
- Views: 1029
Re: Octet Exceptions
Should we memorize all of the exceptions for the final?
- Wed Dec 06, 2017 4:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculations using ice box
- Replies: 4
- Views: 622
Re: Calculations using ice box
Is there a time to use the 5% approximation versus using the value of K to determine if x is negligible?
- Wed Dec 06, 2017 4:39 pm
- Forum: Conjugate Acids & Bases
- Topic: Identifying Acid / Base
- Replies: 1
- Views: 233
Identifying Acid / Base
In a review session, an example was brought up of an acid that had a PH of 10. How is it possible for an "acid" to have a PH that is considered basic (above 7)?
- Wed Dec 06, 2017 4:29 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: ICE Chart [ENDORSED]
- Replies: 9
- Views: 1316
Re: ICE Chart [ENDORSED]
Is it possible to use an ICE chart if there are more than 2 reactants / products?
- Tue Dec 05, 2017 1:58 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Why is Kw value typically used at 25 degrees C [ENDORSED]
- Replies: 6
- Views: 2096
Re: Why is Kw value typically used at 25 degrees C [ENDORSED]
Will we be expected to be able to calculate at different temperatures for the final?
- Mon Dec 04, 2017 10:20 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Pi and sigma bonds [ENDORSED]
- Replies: 7
- Views: 780
Re: Pi and sigma bonds [ENDORSED]
Can anyone explain how pi and sigma bonds change with resonance structures?
- Sun Dec 03, 2017 5:23 pm
- Forum: Lewis Acids & Bases
- Topic: Distinguishing Lewis Acid
- Replies: 2
- Views: 317
Re: Distinguishing Lewis Acid
Here is another thread on the forum addressing the same topic, it may be worth the read:
viewtopic.php?t=8812
viewtopic.php?t=8812
- Sun Dec 03, 2017 5:21 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 17.33
- Replies: 4
- Views: 986
Re: 17.33
Does anyone know if we are expected to have the whole chart memorized for the final?
- Sun Dec 03, 2017 5:03 pm
- Forum: Biological Examples
- Topic: Other Biological Examples
- Replies: 5
- Views: 997
Re: Other Biological Examples
Chlorophyll is also another biological example, with a very similar structure to that of hemoglobin.
- Sat Oct 28, 2017 3:27 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation Applications [ENDORSED]
- Replies: 7
- Views: 803
Re: Shrodinger Equation Applications [ENDORSED]
I'm also curious as to what the equation can be applied to in real life situations. Can anyone elaborate on that?
- Sun Oct 15, 2017 11:48 pm
- Forum: Properties of Light
- Topic: Homework Week 3
- Replies: 3
- Views: 396
Re: Homework Week 3
I'm pretty sure if you have a discussion that is before your lecture, you should complete homework that is up to date with that. Otherwise, do homework corresponding to how far he got in your lecture