Search found 60 matches

by ClaireHW
Sat Mar 17, 2018 2:28 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Fast or Slow
Replies: 8
Views: 316

Re: Fast or Slow

For the pre-equilibrium approach, there are 2 ways to do it. I'm going to do it Lavelle's way. For: A + B -> C (fast) C -> D (slow) Write out the rate law for the slow step: Rate = k[C] Since C is an intermediate and it cancels out, you don't want it in your final rate. You can replace it using the ...
by ClaireHW
Thu Mar 15, 2018 9:12 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Fast or Slow
Replies: 8
Views: 316

Fast or Slow

Is there a way to tell if a step is slow or fast in a proposed mechanism? What sort of data would need to be given? And will this sort of question be asked?

Claire Woolson Dis 1K
by ClaireHW
Thu Mar 15, 2018 9:09 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.85
Replies: 1
Views: 103

15.85

The following rate laws were each derived from an elementary reaction. In each case, write the chemical equation for the reaction, determine its molecularity, and draw a proposed structure for the activated complex. a. Rate = k[CH3CHO] (products are CH3 and CHO) b. Rate = k[I] 2 [Ar] (products are I...
by ClaireHW
Thu Mar 15, 2018 8:56 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: K and Q
Replies: 1
Views: 95

K and Q

In terms of a redox reactions, what do K and Q equal?
Do they equal [red]/[ox] or [ox]/[red]?

Thanks!

Claire Woolson Dis 1K
by ClaireHW
Wed Mar 07, 2018 8:22 pm
Forum: Second Order Reactions
Topic: 15.35
Replies: 6
Views: 404

15.35

How does one go about setting up the equations used for this question step by step?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Mar 07, 2018 8:20 pm
Forum: First Order Reactions
Topic: Equation variations
Replies: 9
Views: 423

Equation variations

For 1st order reactions the equation is typically ln[A]f = -kt + ln[A]0
I found a variation used in the textbooks: ln([A]0/[A]f) = kt
Can these equations be used interchangeably and produce the same answer?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Mar 07, 2018 8:16 pm
Forum: General Rate Laws
Topic: Units
Replies: 11
Views: 575

Units

When dealing with rate laws, is it always necessary to convert all units into moles, liters, or seconds?
If not, when can we use difference units?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Feb 28, 2018 4:16 pm
Forum: General Rate Laws
Topic: 15.17 and 15.19 [ENDORSED]
Replies: 2
Views: 116

15.17 and 15.19 [ENDORSED]

Is the order of the reactions just the sum of the exponents of the reactants? If not, how is it calculated?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Feb 28, 2018 4:13 pm
Forum: General Rate Laws
Topic: 15.15 Rate Law
Replies: 4
Views: 342

Re: 15.15 Rate Law

For this problem, why aren't the products considered in the rate law?

(Claire Woolson Dis 1K)
by ClaireHW
Wed Feb 28, 2018 4:11 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: 15.3 c
Replies: 2
Views: 101

Re: 15.3 c

The unique rate for the reaction aA + bB -> cC + dD is -(1/a)(delta [A]/delta t) = -(1/b)(delta [B]/delta t) = (1/c)(delta [C]/delta t) = (1/d)(delta [D]/delta t) Dr. Lavelle explained it in the first kinetics lecture, but didn't explicitly call it the unique rate law. Hope that helps! (Claire Wools...
by ClaireHW
Wed Feb 21, 2018 8:09 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: 14.101
Replies: 4
Views: 419

14.101

In a neuron, the concentrations of K+ ions inside the cell is about 20 - 30 times as great as that outside. What potential difference between the inside and the outside of the cell would you expect to measure if the difference is due only to the imbalance of potassium ions? I'm confused about why E=...
by ClaireHW
Wed Feb 21, 2018 8:03 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrode v. electrolyte
Replies: 1
Views: 206

Electrode v. electrolyte

What is the difference between an electrode and an electrolyte?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Feb 21, 2018 7:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.39 [ENDORSED]
Replies: 1
Views: 112

14.39 [ENDORSED]

Determine the unknown quantity in each of the following cells: a) Pt(s) I Hg2 (1.0 bar) I H+ (pH=?) II Cl- (aq, 1.0 M) I Hg2Cl2(s) I Hg(l), E=0.33V b) C(gr) I Cl2(g, 1 bar) I Cl- (aq, ?) II MnO4- (aq, 0.010 M), H+ (pH=4.0), Mn2+ (aq, 0.10 M) I Pt(s), E=-0.30 I'm specifically confused about part b an...
by ClaireHW
Mon Feb 19, 2018 9:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q
Replies: 7
Views: 270

Re: Q

How exactly is Q or K written in terms a cell diagram?

(Claire Woolson Dis 1K)
by ClaireHW
Mon Feb 19, 2018 7:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams [ENDORSED]
Replies: 4
Views: 4934

Cell Diagrams [ENDORSED]

What are the rules for constructing a cell diagram? Order, inert metals, commas v. lines v. double lines, etc.

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Tue Feb 13, 2018 10:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.91
Replies: 1
Views: 114

9.91

Using values in Appendix 2A, calculate the standard Gibbs free energy for the vaporization of water at 25, 100, and 150 degrees C.
b) what should the value at 100 degrees C be?
c) Why is there a discrepancy?

(Claire Woolson Dis 1K)
by ClaireHW
Tue Feb 13, 2018 10:51 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.73 and delta S tot
Replies: 1
Views: 111

9.73 and delta S tot

How does delta S tot determine spontaneity?
I am confused to the difference between delta S and delta S tot.

(Claire Woolson Dis 1K)
by ClaireHW
Tue Feb 13, 2018 4:33 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: delta U [ENDORSED]
Replies: 10
Views: 392

Re: delta U [ENDORSED]

Can someone also explain under what conditions is delta U equal to zero?

(Claire Woolson Dis 1K)
by ClaireHW
Fri Feb 09, 2018 12:05 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.67
Replies: 2
Views: 371

9.67

Assume that the standard change in enthalpy and entropy are independent of temperature and calculate the change in the standard Gibbs Free Energy for each of the following at 80 C. Over what temperature range will each reaction be spontaneous under standard conditions? a) B2O3 + 6HF -> 2BF3 + 3H2O b...
by ClaireHW
Fri Feb 09, 2018 12:01 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.47 b
Replies: 1
Views: 158

9.47 b

Initially a sample of ideal gas at 323K occupies 1.67L at 4.95 atm. The gas is allowed to expand to 7.33L by two pathways a) isothermal, reversible expansion; b) isothermal irreversible free expansion. Calculate delta S total, delta S, and delta S surroundings for each pathway. I'm confused on not o...
by ClaireHW
Thu Feb 08, 2018 11:58 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.35 Explained
Replies: 2
Views: 107

9.35 Explained

I'm super confused about how the answer is figured out in this question. Container A is filled with 1.0 mol of the atoms of an ideal monatomic gas. Container B has 1.0 mol of atoms bound together as diatomic molecules that are not vibrationally active. Container C has 1.0 mol of atoms bound together...
by ClaireHW
Sun Feb 04, 2018 12:42 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy -/+
Replies: 4
Views: 141

Gibbs Free Energy -/+

Why it is more favorable for Gibbs Free Energy to be negative?
Thanks!
(Claire Woolson Dis 1K)
by ClaireHW
Wed Jan 31, 2018 10:38 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Define Entropy
Replies: 4
Views: 143

Re: Define Entropy

Can someone also do the same for Gibbs Free Energy?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Jan 31, 2018 10:37 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Define Entropy
Replies: 4
Views: 143

Define Entropy

What is entropy? Physically what does an entropy change look like?

(Claire Woolson Dis 1K)
by ClaireHW
Wed Jan 24, 2018 1:07 pm
Forum: Phase Changes & Related Calculations
Topic: Irreversible and Reversible
Replies: 7
Views: 258

Re: Irreversible and Reversible

Just for clarification, can someone explain the key differences between irreversible and reversible reactions?

(Claire Woolson Dis 1K)
by ClaireHW
Tue Jan 23, 2018 10:47 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Assuming Temperature
Replies: 3
Views: 123

Assuming Temperature

I noticed that in certain problems the tempurature wasn't given, but was required to solve the problem. The Solutions Manual used the temperature 298K. If the temperature isn't given but is necessary to solve, do we just assume its at 298K?

(Claire Woolson Dis 1k)
by ClaireHW
Tue Jan 23, 2018 10:43 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73 part C
Replies: 3
Views: 139

8.73 part C

Use bond enthalpies in Table 8.6 and 8.7 to estimate the reaction enthalpy for

CH4 + CCl4 -> CHCl3 + CH3Cl

I was confused by the method shown in the Solutions Manuel. Could someone explain step by step how this is done?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Jan 17, 2018 6:42 pm
Forum: Phase Changes & Related Calculations
Topic: 8.31
Replies: 2
Views: 131

8.31

In the solution manual, the values of Cp,m and Cv,m are somehow found. Could someone explain how these equations were derived?

Thanks!

(Claire Woolson Dis 1K)
by ClaireHW
Wed Jan 17, 2018 6:38 pm
Forum: Phase Changes & Related Calculations
Topic: question 8.41
Replies: 5
Views: 260

Re: question 8.41

I'd also like to ask if someone could tell us how many steps will have to be calculated and how they come together to get the final temperature.

(Claire Woolson Dis 1K)
by ClaireHW
Wed Jan 17, 2018 6:34 pm
Forum: Phase Changes & Related Calculations
Topic: 8.15
Replies: 2
Views: 157

8.15

Can someone explain why the given answers are correct? In an diabetic process, no energy is transferred as hear. Indicate whether each of the following statements about an diabetic process in a closed system is always true, always false, or true in certain conditions (specify condition): a) delta U ...
by ClaireHW
Fri Jan 12, 2018 2:06 pm
Forum: Phase Changes & Related Calculations
Topic: Standard Reaction Enthalpy
Replies: 8
Views: 287

Re: Standard Reaction Enthalpy

Also what is the difference between Standard reaction enthalpy and standard enthalpy of formation?

(Claire Woolson Dis 1K)
by ClaireHW
Fri Jan 12, 2018 2:05 pm
Forum: Phase Changes & Related Calculations
Topic: Standard Reaction Enthalpy
Replies: 8
Views: 287

Standard Reaction Enthalpy

HI!
I'm super confused about what a standard reaction enthalpy is. Could someone expand on what Dr. Lavelle defined it as and give another example?
Thanks!

(Claire Woolson Dis. 1K)
by ClaireHW
Tue Jan 09, 2018 4:40 pm
Forum: Phase Changes & Related Calculations
Topic: Endo and Exothermic Ways to Remember
Replies: 28
Views: 2967

Endo and Exothermic Ways to Remember

Hi!
I always forget the difference between endothermic and exothermic reactions. Does anyway have an easy way to remember them?
Thanks!

(Claire Woolson Dis. 1K)
by ClaireHW
Mon Dec 04, 2017 9:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 11.73 d
Replies: 2
Views: 145

11.73 d

State whether reactants or products will be favored by an increase in the total pressure (resulting from compression). If there is no change, explain why that is so.

Cl2(g) <-> 2Cl(g)

Thanks!

(Claire Woolson Dis. 3J)
by ClaireHW
Mon Dec 04, 2017 9:35 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endothermic v. Exothermic Reactions
Replies: 9
Views: 890

Endothermic v. Exothermic Reactions

Hi, could someone explain the difference between endothermic and exothermic reactions and give an example of each?

Thanks!

(Claire Woolson Dis. 3J)
by ClaireHW
Tue Nov 28, 2017 9:23 pm
Forum: Naming
Topic: Special Names for Compounds
Replies: 2
Views: 132

Special Names for Compounds

Are there other special names for compounds (such as aqua for H2O or ammine for NH3) that we should know?

Thanks!

(Claire Woolson Dis 3J)
by ClaireHW
Tue Nov 28, 2017 9:17 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.33 (whole)
Replies: 3
Views: 250

Re: 17.33 (whole)

Thanks guys! Impressive and super helpful responses.

(Claire Woolson Dis 3J)
by ClaireHW
Tue Nov 28, 2017 9:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.37
Replies: 2
Views: 232

11.37

For the reaction N2(g) + 3H2(g) <-> 2NH3(g) at 400K, K= 41. Find the value of K for each of the following reactions at the same temperature.
a) SO2(g) + 1/2O2(g) <-> SO3(g)
b) SO3 <-> SO2(g) +1/2O2(g)
c) 3SO2(g) + 3/2O2 <-> 3SO3(g)

Thanks!

(Claire Woolson Dis 3J)
by ClaireHW
Wed Nov 22, 2017 11:11 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.81
Replies: 1
Views: 122

4.81

Borazine, B3N3H3, a compound that has been called "inorganic benzene" because of its similar hexagonal structure (but with alternating B and N atoms in place of C atoms), is the basis of a large class of boron-nitrogen compounds. Write its Lewis structure and predict the composition of the...
by ClaireHW
Wed Nov 22, 2017 11:07 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.33 (whole)
Replies: 3
Views: 250

17.33 (whole)

Hi, can someone explain how to do this problem? Which of the following ligands can be polydentate? If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center. a) HN(CH2CH2NH2)2 b) Co3 2- c) H2O d) oxalate Thanks! (Claire Wo...
by ClaireHW
Fri Nov 17, 2017 3:46 pm
Forum: Hybridization
Topic: Double sigma v. pi bonds
Replies: 4
Views: 180

Re: Double sigma v. pi bonds

So when a there are a sigma and a pi bond, does this mean there are two sigma bonds over lapping?

(Claire Woolson Dis 3J)
by ClaireHW
Thu Nov 16, 2017 10:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.19 b
Replies: 3
Views: 160

4.19 b

Hi could someone go over 4.19 b?
The question is:
Predict the bond angles at the central atom of (CH3)2Be

Thanks

(Claire Woolson Dis. 3J)
by ClaireHW
Thu Nov 16, 2017 10:17 pm
Forum: Hybridization
Topic: Double sigma v. pi bonds
Replies: 4
Views: 180

Double sigma v. pi bonds

I'm confused about the distinction between a double sigma and a pi bond. Are they the same thing or is there a slight variation?

Thanks!

(Claire Woolson Dis. 3J)
by ClaireHW
Wed Nov 08, 2017 8:28 pm
Forum: Balancing Chemical Reactions
Topic: Net Moles of Gas
Replies: 5
Views: 269

Re: Net Moles of Gas

The answer given was 6.
I'm wondering how we get to 6 from that amount of moles.
by ClaireHW
Wed Nov 08, 2017 7:05 pm
Forum: Balancing Chemical Reactions
Topic: Net Moles of Gas
Replies: 5
Views: 269

Net Moles of Gas

Given the balanced equations: 2C4H10 + 13O2 -> 8CO2 + 10H2O
What is the net number of moles of gas produced if 4 moles of C4H10 are used?

(Claire Woolson Dis 3J)
by ClaireHW
Tue Nov 07, 2017 11:15 pm
Forum: Octet Exceptions
Topic: Radical Rules
Replies: 1
Views: 159

Radical Rules

Are there any rules for determining when a molecule will have a radical? If so what are they? Also, on the midterm, will we be required to determine if a molecule has a radical?

Thanks.

(Claire Woolson DIs. 3J)
by ClaireHW
Tue Nov 07, 2017 11:13 pm
Forum: Electronegativity
Topic: 3.79
Replies: 3
Views: 331

3.79

Compounds having bonds with a high covalent character tend to be less soluble in water than similar compounds that have low covalent character. Use electronegativities to predict which of the following compounds is more soluble in water; a) AlCl3 or KCl b) MgO or BaO Could you just briefly explain t...
by ClaireHW
Tue Nov 07, 2017 11:04 pm
Forum: Resonance Structures
Topic: 3.71
Replies: 1
Views: 152

3.71

Select from each of the following pairs of Lewis structures the one that is likely to make the dominant contribution to a resonance hybrid. Explain your selection. Unfortunately, I can't include the structures, but I'm confused about the answers given in the book. Can you explain the resonance hybri...
by ClaireHW
Wed Nov 01, 2017 6:07 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2.29
Replies: 2
Views: 129

2.29

How many electrons can have to following electrons in an atom:
a) n=2, l=1
b) n=4, l=2, m=-2
c) n=2
d) n=3, l=2, m=+1

I'm confused about the logic behind solving these problems.

(Claire Woolson Dis. 3J)
by ClaireHW
Wed Nov 01, 2017 6:03 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Quantum Number m
Replies: 1
Views: 117

Quantum Number m

I'm confused about m and its relationship to electron configurations in general.
Does m influence electron configurations when we write them out? For instance how does m affect Carbon or [He]2s22p2? Where does m become relevant doing orbital problems?

(Claire Woolson Dis. 3J)
by ClaireHW
Tue Oct 24, 2017 9:27 pm
Forum: Photoelectric Effect
Topic: Work function v. Ionization Energy
Replies: 2
Views: 650

Work function v. Ionization Energy

What's the difference between the work function and the ionization energy?

(Claire Woolson Dis 3J)
by ClaireHW
Tue Oct 24, 2017 9:23 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Actual Electron Configuration
Replies: 1
Views: 202

Actual Electron Configuration

I'm confused about the relationship between electron configuration, the wave function, orbitals, and the actual pattern of electron movement. Can anyone explain these concepts?

(Claire Woolson Dis 3J)
by ClaireHW
Wed Oct 18, 2017 4:39 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework
Replies: 3
Views: 176

Homework

Does anyone know what homework is due this week, if any?

(Claire Woolson Dis. 3J)
by ClaireHW
Mon Oct 16, 2017 8:42 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Module Q 29
Replies: 2
Views: 267

Atomic Spectra Module Q 29

In 1.0 s, a 60 W bulb emits 11J of energy in the form of infrared radiation (heat) of wavelength 1850 nm. a) What is the energy per photon of light emitted? b) How many photons are emitted in one second?

I am particularly confused by part b.

(Claire Woolson Dis. 3J)
by ClaireHW
Wed Oct 11, 2017 4:02 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Negative Energy
Replies: 1
Views: 137

Negative Energy

When using the equations v=-R(1/n2 - 1/n2) or E= -hR/n2, the final answer for energy is negative if the electron is descending in energy levels. If negative energy is energy lost, where does it go?

(Claire Woolson, Dis 3J)
by ClaireHW
Wed Oct 11, 2017 3:54 pm
Forum: Properties of Light
Topic: 1.11
Replies: 1
Views: 155

1.11

Question: In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series, Lyman series, Paschen series), as shown in Figs. 1.10 and 2.1. What is common to the lines within a series that makes grouping them together logical? I ...
by ClaireHW
Sat Oct 07, 2017 2:55 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.17 [ENDORSED]
Replies: 6
Views: 666

Re: G.17 [ENDORSED]

Does the CuSO4 bond with the H2O to form the new compound or do they become more connected due to being in an aqueous solution?
(Claire Woolson 3J)
by ClaireHW
Sat Oct 07, 2017 2:50 pm
Forum: Properties of Light
Topic: Transparency [ENDORSED]
Replies: 2
Views: 303

Transparency [ENDORSED]

Does anyone know what makes certain substances see through or transparent? What about certain molecular structures makes substances that way?
Thanks
(Claire Woolson 3J)
by ClaireHW
Tue Oct 03, 2017 3:37 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.17 [ENDORSED]
Replies: 6
Views: 666

Re: G.17 [ENDORSED]

Why is the molar mass of CuSO4 5H20 used in part b?

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