## Search found 42 matches

Sun Mar 18, 2018 10:13 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: arrhenius
Replies: 1
Views: 248

### Re: arrhenius

The Vant Hoff equation comes by setting the two delta G equations as equal.
Sun Mar 18, 2018 10:11 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: metal dissolved
Replies: 2
Views: 284

### Re: metal dissolved

If delta G is negative then the reaction will occur.
Sun Mar 18, 2018 10:10 pm
Forum: Student Social/Study Group
Topic: I wanted to make a good chemistry joke...
Replies: 2
Views: 388

### Re: I wanted to make a good chemistry joke...

Helium. Helium. Helium.
Sun Mar 18, 2018 10:08 pm
Forum: General Science Questions
Replies: 8
Views: 935

As far as I know, the class is not graded.
Sat Mar 17, 2018 2:01 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Calculating Q and K
Replies: 1
Views: 1548

### Calculating Q and K

When calculating Q and K will can molarity and pressure be used interchangeably?
Sat Mar 17, 2018 1:53 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2 Q7
Replies: 3
Views: 341

### Re: Test 2 Q7

I think you have to use deltaG=-nFE to calculate this.
Sat Mar 17, 2018 1:50 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: First Law Thermo
Replies: 4
Views: 357

### Re: First Law Thermo

No because the first law is deltaU = q + w and but equation you have is only related to q.
Sat Mar 17, 2018 11:45 am
Forum: Balancing Redox Reactions
Topic: Lyndon Review session Q3
Replies: 1
Views: 215

### Lyndon Review session Q3

Q3) Mn2+ (aq) + Br2 (l) → MnO4- (aq) + Br- (aq) Balance the redox reaction. Is the correct answer 8(H2O) + 2(Mn2)+ + 5(Br2) --> 16(H+) + 2(MnO4-) + 10(Br-) ?
Wed Mar 14, 2018 11:03 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Calculating Work
Replies: 2
Views: 193

### Calculating Work

Question: A balloon filled with 31.9 mol of Helium has a volume of 876 L at 0oC and 1.00 atm pressure. At constant pressure, the temperature of the balloon is suddenly increased to 38.0oC , causing the balloon to expand to a volume of 998L. (The molar heat capacity of Helium is 20.8 J/ oC mol) How m...
Wed Mar 14, 2018 10:30 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system after time
Replies: 2
Views: 289

### isolated system after time

If an isolated system contained +100 kJ of energy, after 100 years why will the internal energy be 0? (UA workshop week 2 question 3)
Sun Mar 04, 2018 4:14 pm
Forum: First Order Reactions
Topic: Deriving these Equations
Replies: 7
Views: 401

### Re: Deriving these Equations

[A] is concentration (at any time), and [A]0 is concentration at t=0.
Sun Mar 04, 2018 4:12 pm
Forum: General Rate Laws
Topic: Independent of the rate
Replies: 2
Views: 199

### Re: Independent of the rate

Basically, if the reaction will proceed even with a little bit of reactant and will not make more or less product if you increase or decrease the concentration of reactants then it is independent of the rate.
Sun Mar 04, 2018 4:06 pm
Forum: First Order Reactions
Topic: Second Order Half Life Equation
Replies: 2
Views: 180

### Second Order Half Life Equation

How did we get 0.693 in the equation?
Sat Feb 24, 2018 5:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic cell set up
Replies: 8
Views: 449

### Re: Galvanic cell set up

To add on to that, in real life situations the left might not be the anode, it is just standardized like so in textbooks so that it is easier to comprehend.
Sat Feb 24, 2018 5:03 pm
Forum: General Rate Laws
Topic: Units for 15.3 Part B
Replies: 4
Views: 310

### Re: Units for 15.3 Part B

I believe the (mol O2) is just to specify that the answer is for the moles of O2. Usually when we answer questions we don't need to specify that.
Sat Feb 24, 2018 4:57 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: kinetics
Replies: 5
Views: 433

### Re: kinetics

Both are studying reactions, but thermodynamics is only concerned with the initial and final states while kinetics factors in the speed of the reaction--their rates.
Sun Feb 11, 2018 5:49 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy of vaporization
Replies: 1
Views: 152

### Re: entropy of vaporization

You can calculate it through a series of steps.

1) Increase temperature from 25 C to 100 C
2) Find the enthalpy of vaporization of water (l -->g)
3) Lower the temperature of the water vapor from 100 C to 25C

Hope that helped!
Sun Feb 11, 2018 2:59 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.13
Replies: 3
Views: 209

### Re: 9.13

Page 281 of the textbook gives a good summary of the Cp and Cv for atoms, linear molecules, and nonlinear molecules.
Sun Feb 11, 2018 2:56 pm
Forum: Balancing Redox Reactions
Topic: nernst eq'n
Replies: 2
Views: 147

### Re: nernst eq'n

Yes, it is the number of moles of electrons.
Sun Feb 04, 2018 9:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G°
Replies: 5
Views: 235

### Re: Delta G°

Looking at the equation deltaG°=-RTlnK, if K=1, that means the products and reactants are of the same concentration, and thus lnK=0, and deltaG° will equal 0.
Sun Feb 04, 2018 9:05 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: thermodynamically favored
Replies: 6
Views: 881

### Re: thermodynamically favored

Thermodynamically favored means the reaction will proceed spontaneously, and it refers to deltaG, the free energy.
Sun Jan 28, 2018 1:46 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Internal Energy and Spontaneity
Replies: 3
Views: 180

### Re: Internal Energy and Spontaneity

To add on to that, the system is at equilibrium when entropy is at a maximum.
Sun Jan 28, 2018 1:40 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13
Replies: 3
Views: 211

### Re: 9.13

Because pressure is increased so we can't use the second equation (Cv is at constant pressure!)
Sun Jan 28, 2018 1:35 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Spontaneous Processes for Entropy
Replies: 2
Views: 251

### Re: Spontaneous Processes for Entropy

Yes, when the value of entropy is positive the process is spontaneous. The equation just spells this out in math. It it true that when V2 is larger than V1, there are more possible positions, so entropy is positive. (spontaneous reaction) But V2 can also be smaller than V1 in which case the equation...
Sat Jan 20, 2018 10:04 pm
Forum: Phase Changes & Related Calculations
Topic: HW #3
Replies: 3
Views: 219

### Re: HW #3

I think there still might be concept questions relating to the topic, but just not calculations.
Sat Jan 20, 2018 10:01 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Perfect Isolated System
Replies: 3
Views: 209

### Re: Perfect Isolated System

It could be argued that the universe is a "perfectly" isolated system!
Sat Jan 20, 2018 9:06 pm
Forum: Calculating Work of Expansion
Topic: Work done on / work done by system
Replies: 5
Views: 313

### Work done on / work done by system

Could anyone explain to me they difference between work done on the system and work done by the system? I have trouble grasping the concept of work and the system.
Sat Jan 13, 2018 7:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Possible Error in Question 8.55 (Hess' Law)
Replies: 4
Views: 292

### Re: Possible Error in Question 8.55 (Hess' Law)

This is a good observation, I do not have a solution manual, but when I solved this question I did this: (-1107)(-3/2)+(-1676)=15.5kJ which rounds to 16kJ. This is the correct answer in the answer manual. But in fact, the oxygen will not be canceled out. The product side will have 3/2 O2 and the rea...
Sat Jan 13, 2018 6:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Question 8.63 (c)
Replies: 2
Views: 170

### Homework Question 8.63 (c)

I checked my equations many times, but my value always comes to -38.72kJ while the answer is 15.28kJ. The previous two questions, (a) and (b) are similar to (c) and I used the same method: enthalpy of products - enthalpy of reactants. Does anyone know how to solve this?
Sat Jan 13, 2018 4:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sig Figs for Question 8.45 (a)
Replies: 5
Views: 299

### Sig Figs for Question 8.45 (a)

My answer was 448.5 which I rounded to 449. But the answer was 448. Does anyone know why?
Thu Dec 07, 2017 2:51 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Formic Acid and Acetic Acid
Replies: 2
Views: 448

### Formic Acid and Acetic Acid

Why is Formic acid a stronger acid than Acetic?
Thu Dec 07, 2017 2:49 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: 12.53 Names of acidic compounds
Replies: 2
Views: 243

### 12.53 Names of acidic compounds

I noticed in 12.53 only the names of the compounds were given. Are we supposed to know the formulas by heart?
Mon Dec 04, 2017 8:01 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: F and Cl in acids
Replies: 2
Views: 257

### F and Cl in acids

Why is HF a weak acid and HCl a strong one, while C2O2HF3 is a stronger acid than C2O2HCl3?
Wed Nov 15, 2017 9:34 pm
Forum: Hybridization
Topic: Polar/nonpolar [ENDORSED]
Replies: 14
Views: 1654

### Re: Polar/nonpolar[ENDORSED]

Nicole, yes, that is true for polar molecules.
Wed Nov 08, 2017 1:41 pm
Forum: Trends in The Periodic Table
Topic: Hydrogen Electronegativity
Replies: 4
Views: 2481

### Hydrogen Electronegativity

Why does hydrogen have a relatively high electronegativity?
Thu Nov 02, 2017 10:21 am
Forum: Electronegativity
Topic: Finding Electronegativity
Replies: 4
Views: 346

### Re: Finding Electronegativity

Also, just to add, the common Electronegativity chart that we use now is based on the Pauling's scale, which I believe uses the disassociation energy of diatomic bonds to calculate the disassociate energy of a molecule if it were a purely covalent bond. Then it measures the difference between the ac...
Mon Oct 30, 2017 2:53 pm
Forum: Trends in The Periodic Table
Topic: Fluorine's Formal Charge
Replies: 1
Views: 274

### Fluorine's Formal Charge

Today in lecture Professor Lavelle said that Fluorine's formal charge cannot be +1 because it is highly unstable. Why is this?
Sun Oct 22, 2017 3:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: nodal planes [ENDORSED]
Replies: 3
Views: 534

### Re: nodal planes[ENDORSED]

Based off of the homework questions in the textbook, believe we need know how many nodal planes there are for the s p d orbitals. (However, if you look at the assigned homework, questions regarding the nodal planes were skipped.)
Sat Oct 21, 2017 5:58 pm
Forum: Properties of Light
Topic: Mathematical Error with 1.55 (a) [ENDORSED]
Replies: 2
Views: 347

### Mathematical Error with 1.55 (a)[ENDORSED]

This is what I did:

v/c=3600cm^-1
v/c=36m^-1
v=36 x c
v=36 x 3x10^8
v=1.1x10^10 (1/s)

Yet the answer is 1.1x10^14 (1.s)

Does anyone know what went wrong with my method?
Wed Oct 11, 2017 10:14 pm
Forum: Properties of Light
Topic: Question 1.15 Rydberg Equation Math Problem
Replies: 1
Views: 153

### Question 1.15 Rydberg Equation Math Problem

1.15 In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. I used \frac{1}{\lambda }=R_{H}(\frac{1}{n1^2}-\frac{1}{n2^2})...
Wed Oct 04, 2017 7:33 pm
Forum: Significant Figures
Topic: E29 (d) Significant Figures
Replies: 3
Views: 399

### E29 (d) Significant Figures

For Question E29, the question only gives a number with 3 significant figures (8.61), yet the answer for (d) on the textbook is 4 sig figs (0.3099). Does anyone know why?
Wed Oct 04, 2017 5:22 pm
Forum: Molarity, Solutions, Dilutions
Topic: L7 Help
Replies: 4
Views: 634

### Re: L7 Help

In my opinion, L7 (b) states "What mass of oxygen is needed to oxidize this amount of tristearin?" Since they're asking for the same amount (454g), you should still continue using 454g as the amount of tristearin to solve the problem.