## Search found 46 matches

Sun Mar 17, 2019 10:11 am
Forum: Second Order Reactions
Topic: Plotting second order reactions
Replies: 3
Views: 372

### Re: Plotting second order reactions

In order to get a straight line plot for a second order rxn you must use the integrated rate law and plot 1/[A] vs. time. The slope will be a positive K value
Sun Mar 17, 2019 10:09 am
Forum: Zero Order Reactions
Topic: Zero order reaction
Replies: 8
Views: 488

### Re: Zero order reaction

The graph of a zero order reaction will be [A] vs. time and will have a slope of -K
Sat Mar 16, 2019 6:04 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates in Rate Law
Replies: 4
Views: 187

### Intermediates in Rate Law

Do you include intermediates in the rate laws for elementary steps in reaction mechanisms?
Sat Mar 16, 2019 11:54 am
Forum: Administrative Questions and Class Announcements
Topic: LYNDON'S PORK RAMEN REVIEW
Replies: 37
Views: 5462

### Re: LYNDON'S PORK RAMEN REVIEW

Sat Mar 16, 2019 10:36 am
Forum: General Rate Laws
Topic: Phase of Reactants in Rate Law
Replies: 3
Views: 216

### Phase of Reactants in Rate Law

Are there any phases of reactants that we exclude when writing rate laws? When we write K, for example, we exclude solids. Does this apply for rate laws as well?
Fri Mar 15, 2019 9:57 pm
Forum: Van't Hoff Equation
Topic: Test #2
Replies: 5
Views: 462

### Re: Test #2

for my K2 value I got 2.78*10^-14

On my test I took the negative log of this value but got the answer wrong, is that the wrong approach?
Fri Mar 15, 2019 9:53 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Equation sheet
Replies: 4
Views: 205

### Equation sheet

Will the Nernst equation be on our equation sheet?
Fri Mar 15, 2019 9:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam Practice Problem
Replies: 3
Views: 418

### Re: Final Exam Practice Problem

Are these questions taken from past final exams?
Tue Mar 12, 2019 11:29 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acid/Base Concentration vs. Weak Acid/Base Concentration
Replies: 2
Views: 146

### Strong Acid/Base Concentration vs. Weak Acid/Base Concentration

Can someone explain the difference in calculating concentrations for a strong acid or base vs. calculating concentration for a weak acid or base?
Mon Mar 11, 2019 9:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants and Solubility
Replies: 2
Views: 134

### Equilibrium Constants and Solubility

How do you determine solubility from the equilibrium constant?
Mon Mar 11, 2019 7:23 pm
Forum: Ideal Gases
Topic: Ideal Gas Law as an Approximation
Replies: 1
Views: 96

### Ideal Gas Law as an Approximation

In the outline Dr. Lavelle posted, he says we need to be able to identify reactions where the ideal gas law can be used as an approximation.
What exactly does this mean?
Wed Feb 27, 2019 6:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: #14.13 Part D (Sixth Edition)
Replies: 1
Views: 92

### Re: #14.13 Part D (Sixth Edition)

I'm stuck on the same problem, I think it might have to do with adding the two half reactions together at the end and having the final equation be balanced, but I'm not sure. If someone could explain this that would be great!
Wed Feb 27, 2019 5:53 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt (s) [ENDORSED]
Replies: 8
Views: 398

### Re: Pt (s)[ENDORSED]

In the homework problem 6L5 part b in the 7th edition, one of the cell diagrams is Pt(s)|I^-(aq)|I2(s)||Ce^4+(aq), Ce^3+(aq)|Pt(s)

I don't really understand why the Pt is included here, can someone explain?
Tue Feb 05, 2019 7:16 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Reversible Processes
Replies: 2
Views: 144

### Reversible Processes

Can someone explain what a reversible process is?
Tue Feb 05, 2019 7:10 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Ideal Gas
Replies: 3
Views: 186

### Ideal Gas

What exactly is an ideal gas?
Wed Jan 30, 2019 8:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 7th edition 4C.3
Replies: 1
Views: 115

### 7th edition 4C.3

This question, you have to use the formulas: qp=nCpDeltaT and qv=nCvDeltaT, but in the solution book they substitute Cp for (5/2R) and Cv for (3/2R). Can someone explain these substitutions?
Tue Jan 29, 2019 7:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity vs. enthalpy
Replies: 4
Views: 187

### Re: Heat capacity vs. enthalpy

If I understand correctly, I believe that heat capacity is sort of a sub-category of enthalpy. Enthalpy is the study of heat released or absorbed in chemical reactions and physical changes, where heat capacity is simply the amount of heat required to raise the temperature of an object by 1 degree C.
Mon Jan 28, 2019 1:33 pm
Forum: Phase Changes & Related Calculations
Topic: SI Unit
Replies: 2
Views: 144

### Re: SI Unit

kilojoules
Mon Jan 28, 2019 1:31 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy and state property
Replies: 2
Views: 159

### Re: Enthalpy and state property

Enthalpy is a state property because the value of enthalpy is determined by its current state, not on the pathway taken to obtain that value. To use Dr. Lavelle's example from class, if someone went on a hike, the distance they travelled would not be a state property, however, their altitude change ...
Mon Jan 28, 2019 1:27 pm
Forum: Phase Changes & Related Calculations
Topic: Delta Hº versus delta H
Replies: 7
Views: 863

### Re: Delta Hº versus delta H

deltaH^0 refers to the standard reaction enthalpy (the rxn enthalpy when all R and P are in their standard state). DeltaH is the general symbol for the amount of heat absorbed or released. There is also deltaHf^0 which refers to the Standard Enthalpy of Formation (the standard rxn enthalpy for the f...
Mon Jan 28, 2019 1:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law (Method 1)
Replies: 4
Views: 231

### Hess's Law (Method 1)

In Method 1, why is it necessary to add the rxns to get the net rxn? Why would you not simply just add together the two deltaHs?
Mon Jan 28, 2019 1:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy Formation of an element
Replies: 4
Views: 202

### Standard Enthalpy Formation of an element

Why is it that the standard enthalpy formation of an element in its most standard form is zero?
Mon Jan 28, 2019 1:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Rxn Enthalpies for liquids and solids
Replies: 2
Views: 106

### Standard Rxn Enthalpies for liquids and solids

In the notes, Dr. Lavelle wrote "for a pure liquid or solid it [the standard rxn enthalpy] is the pure L or S"
Can someone explain what this means?
Mon Jan 28, 2019 12:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy vs. Heat as a state property
Replies: 1
Views: 89

### Enthalpy vs. Heat as a state property

If q=deltaH, then why is it that enthalpy is a state property but heat is pathway dependent?
Mon Jan 28, 2019 12:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Energy vs. Enthalpy
Replies: 2
Views: 94

### Energy vs. Enthalpy

Is there a difference between the enthalpy of a reaction and the energy required for the same reaction to take place?
Wed Jan 16, 2019 10:31 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure, 5J.5
Replies: 1
Views: 103

### Change in Pressure, 5J.5

Can anyone explain the reasoning behind the textbook problem 5J. 5 (7th edition)? I understand why in part d there would be no change, but for a,b,c, and e I'm confused as to how you would know reactants would be favored with an overall increase in pressure.
Mon Dec 03, 2018 12:33 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: what is a ligand?
Replies: 8
Views: 410

### Re: what is a ligand?

Just for clarification, a ligand must be able to donate electrons in order to form a coordinate covalent bond with the central atom, correct?
Mon Dec 03, 2018 12:30 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand names
Replies: 3
Views: 242

### Re: Ligand names

Dr. Lavelle mentioned in class that knowing the ligand names is useful, and that we should go to the textbook for common ligand names--however, I'm not sure if this is a requirement for the final.
Mon Dec 03, 2018 12:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelates
Replies: 4
Views: 170

### Re: Chelates

How are you able to tell if a molecule is a chelating molecule?
Mon Dec 03, 2018 12:24 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: cis and trans
Replies: 1
Views: 104

### cis and trans

If we are only given the formula for a molecule, how are we supposed to distinguish whether it is a cis or trans molecule?
Mon Dec 03, 2018 12:18 pm
Forum: Naming
Topic: Knowing oxidation states
Replies: 11
Views: 437

### Re: Knowing oxidation states

Ruiting Jia 4D wrote:
Becky Belisle 1F wrote:I think it's useful to memorize the oxidation states of the common ligands.

Which are the common ligands that we would need to memorize for?

Is there a certain place in the textbook that is good for studying this?
Mon Nov 26, 2018 7:41 pm
Forum: Resonance Structures
Topic: Bond Lengths
Replies: 3
Views: 370

### Bond Lengths

If you have, for example, SO2, SO3, and SO3^2-, each molecule has a lewis structure with single bonds and one double bond.
If all of them have resonance, how would you determine which bond lengths are longer/shorter in comparison to one another? Are they all the same length?
Sun Nov 25, 2018 4:23 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Energy of Interactions
Replies: 4
Views: 168

### Energy of Interactions

In Dr. Lavelle's lecture notes for interactions between ions and molecules, he wrote:
1. Ion-Ion : Na+Cl- -250 kJ/mol

What does the -250 kJ/mol represent? How do you find this number if it is not given/what use does it have?
Sat Nov 24, 2018 8:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 10
Views: 415

### Re: Test 3

Does anyone remember what the website was that Dr. Lavelle mentioned in class that has learning modules similar to the ones we had for the first units? I could be wrong but I remember him making a comment about more learning modules.
Mon Nov 05, 2018 12:39 pm
Forum: Administrative Questions and Class Announcements
Replies: 135
Views: 31731

On the midterm review worksheet, could someone explain how to draw the lewis structure for XeO2F2?
Mon Nov 05, 2018 11:05 am
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 7277

### Re: MIDTERM PRACTICE - Garlic Bread Review Session[ENDORSED]

Could someone please explain the mathematics behind 13E to me?
Mon Nov 05, 2018 10:46 am
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 7277

### Re: MIDTERM PRACTICE - Garlic Bread Review Session[ENDORSED]

Could someone explain why for 13D (I looked this up on the internet) the atoms have different electron configurations? I know that the electron configurations are: Neutral SC Atom: 1s2 2s2 2p6 3s2 3p6 3d1 4s2 SC2+ Ion: 1s2 2s2 2p6 3s2 3p6 3d1 Neutral K atom: 1s2 2s2 2p6 3s2 3p6 4s1 But could someon...
Mon Nov 05, 2018 10:46 am
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 7277

### Re: MIDTERM PRACTICE - Garlic Bread Review Session[ENDORSED]

Could someone explain why for 13D (I looked this up on the internet) the atoms have different electron configurations? I know that the electron configurations are: Neutral SC Atom: 1s2 2s2 2p6 3s2 3p6 3d1 4s2 SC2+ Ion: 1s2 2s2 2p6 3s2 3p6 3d1 Neutral K atom: 1s2 2s2 2p6 3s2 3p6 4s1 But could someon...
Mon Nov 05, 2018 9:47 am
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 7277

### Re: MIDTERM PRACTICE - Garlic Bread Review Session[ENDORSED]

Can someone please explain 10b to me? I don't understand why they wouldn't all be equal
Sat Nov 03, 2018 6:25 pm
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 7277

### Re: MIDTERM PRACTICE - Garlic Bread Review Session[ENDORSED]

For #6, how are you supposed to convert the molar mass of GarBreadium to kg in order to use the de broglie equation?
Sun Oct 14, 2018 12:32 pm
Forum: Photoelectric Effect
Topic: Threshold Energy and Energy Levels
Replies: 1
Views: 76

### Threshold Energy and Energy Levels

Just a clarification question:
Each metal has their own unique threshold energy, correct?
Also, does this mean that each metal has their own unique energy levels that their electrons can move between?
Sun Oct 14, 2018 12:24 pm
Forum: Properties of Light
Topic: Photons of Light [ENDORSED]
Replies: 1
Views: 103

### Photons of Light[ENDORSED]

I understand that a photon of light is like a "packet" of energy, but is there any sort of numeric value to a photon?
Sun Oct 14, 2018 12:19 pm
Forum: Photoelectric Effect
Topic: Electrons Lost
Replies: 3
Views: 173

### Electrons Lost

In the photoelectric effect, does the electron that is released come from the metal that the EM radiation is shining on?
Sun Oct 07, 2018 4:14 pm
Forum: Limiting Reactant Calculations
Topic: Calculating Molar Mass in Limiting Reactant Problem
Replies: 3
Views: 185

### Calculating Molar Mass in Limiting Reactant Problem

In Prof. Lavelle's lecture notes on how to find limiting reactants, he said in step 3 to calculate the molar mass of each reactant and product. However in the example he gave us he only calculated the molar mass for one of the products and not the other. Why is this?
Sun Oct 07, 2018 3:49 pm
Forum: Administrative Questions and Class Announcements
Replies: 135
Views: 31731