## 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: 368

### 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: 207

### 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: 261

### 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
Replies: 4
Views: 380

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: 338

### 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: 259

### 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: 278

### 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: 480

### 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: 2
Views: 1175

### 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: 394

### 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: 480

### 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: 290

### 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: 2592

### 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: 342

### 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: 5
Views: 912

### 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: 493

### 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: 287

### 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: 240

### 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: 6
Views: 2028

### 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: 733

### 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: 5
Views: 2427

### 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: 4522

### 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: 245

### 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: 245

### 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.

Tue Mar 06, 2018 9:47 pm
Forum: Zero Order Reactions
Topic: Finding 1/2 or negative orders
Replies: 2
Views: 269

### 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: 2825

### 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: 586

### 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: 270

### 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: 205

### 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: 373

### 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: 386

### 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: 844

### 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: 269

### 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: 257

### 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: 665

### 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: 451

### 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: 254

### 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: 281

### 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: 603

### 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: 346

### 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: 174

### 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: 566

### 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: 837

### 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: 441

### 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: 189

### 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
Sun Dec 03, 2017 5:21 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.33
Replies: 4
Views: 569

### 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: 559

### 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: 510

### 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: 241

### 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