## Search found 32 matches

Sat Mar 17, 2018 6:14 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Gas Expansion
Replies: 1
Views: 216

### Re: Gas Expansion

Because maybe there is more volume available to it. If it expanded isothermally, then the kinetic and potential energies of the molecules would still be the same, so the internal energy would remain the same. However, if the temperature changed during expansion, the internal energy would not remain ...
Sat Mar 17, 2018 6:10 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Second Law application
Replies: 3
Views: 382

### Re: Second Law application

When looking at entropy, the reaction is determined to be spontaneous if \Delta S total is greater than zero. (\Delta Stotal= \Delta S system+\Delta Ssurroundings) ) So even if the entropy of the system decreases, the reaction can still be spontaneous if the entropy of the surroundings incre...
Sat Mar 17, 2018 6:04 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction Graphs
Replies: 3
Views: 337

### Re: Reaction Graphs

The greater the activation energy of each step, the slower the rate. So the curves with smaller hills/height (whatever you'd like to call them) have lower activation rates and are therefore faster (have greater rates).
Mon Mar 12, 2018 10:15 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.67
Replies: 3
Views: 295

### 8.67

The problem states: "Use the information in Tables 8.3, 8.6, and 8.7 to estimate the enthalpy of formation of each of the following compounds in the liquid state. The standard enthalpy of sublimation of carbon is 717 kJ/mol. (a) H2O; (b) methanol, CH3OH; (c) benzene, C6H6 (without resonance); (...
Sun Mar 11, 2018 5:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Organic Chem on Final
Replies: 9
Views: 735

### Organic Chem on Final

Will any organic chem be on the final since it was introduced in lecture?
Sun Mar 11, 2018 1:20 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: terms
Replies: 1
Views: 200

### Re: terms

Labile: describes substances that do decompose or react rapidly Nonlabile/inert (same thing): describes substances that are thermodynamically unstable but do survive for long periods These are not as significant in relation to Gibbs Free Energy because these terms are more closely related to kinetic...
Sun Mar 11, 2018 1:08 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: catalyst vs intermediate
Replies: 2
Views: 209

### Re: catalyst vs intermediate

If it is serving as a reactant in the first step and then being produced in the second step then it is a catalyst. On the other hand, an intermediate must first be formed by one of the steps and then used up in later steps.
Tue Mar 06, 2018 11:22 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Effect of catalyst on rate constants
Replies: 1
Views: 487

### Effect of catalyst on rate constants

Can someone explain the effect of a catalyst on rate constants?
Sun Mar 04, 2018 11:58 pm
Forum: Zero Order Reactions
Topic: Identifying zero order
Replies: 6
Views: 392

### Re: Identifying zero order

If all other reactant concentrations remain the same and you change the concentration of the reactant of interest without changing the rate, then that reactant is zero order.
Sun Mar 04, 2018 11:56 pm
Forum: General Rate Laws
Topic: zero order in rate laws
Replies: 8
Views: 486

### Re: zero order in rate laws

If it is zero order the rate law is not dependent on the concentration of that reactant so it technically doesn't need to be included.
Sun Mar 04, 2018 11:55 pm
Forum: Zero Order Reactions
Topic: Slopes
Replies: 3
Views: 295

### Re: Slopes

We have gone over the correlating graph with each order so I think that's important to know.
Sun Feb 25, 2018 8:04 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Chapter 15 related videos
Replies: 6
Views: 402

### Chapter 15 related videos

Does anybody know helpful videos to watch for chapter 15?
Wed Feb 21, 2018 11:19 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.47 a
Replies: 6
Views: 428

### Re: 14.47 a

Ammarah 2H wrote:I was stuck too and I keep getting 2649813.982. Is that what you’re getting as well?

Yeah I'm getting the same answer.
Mon Feb 19, 2018 8:48 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Determining the signs of the electrodes in a Electrolytic Cell
Replies: 1
Views: 252

### Determining the signs of the electrodes in a Electrolytic Cell

I was having trouble understanding why the sign of the anode in an electrolytic cell is positive even though electrons are leaving the cell because reduction is taking place there. Does anyone else understand this concept?
Sun Feb 18, 2018 5:46 pm
Forum: Balancing Redox Reactions
Replies: 4
Views: 304

Does anyone know any helpful videos to watch to better understand chapter 14?
Sun Feb 18, 2018 5:42 pm
Forum: Balancing Redox Reactions
Replies: 2
Views: 185

### Re: Add H+ or OH-

14.1 was in an acidic solution while 14.2 was in a basic solution, so you have to know whether it is an acidic or basic solution when doing the problem.
Tue Feb 13, 2018 2:05 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G vs. standard Gibbs free energy
Replies: 1
Views: 133

### delta G vs. standard Gibbs free energy

I am confused on the use of $\Delta G$ and $\Delta G^{\circ}$. I know that when $\Delta G$ is negative the reaction is spontaneous, but does this also apply to $\Delta G^{\circ}$? What is $\Delta G^{\circ}$ used for?
Sun Feb 11, 2018 9:24 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.31
Replies: 1
Views: 164

### 8.31

The question is: "Calculate the heat released by 5.025 g of Kr(g) at 0.400 atm as it cools from 97.6 C to 25.0 C at (a) constant pressure and (b) constant volume. Assume that krypton behaves as an ideal gas." The answer for constant pressure is -90.6 J and the answer for constant volume is...
Sun Feb 11, 2018 9:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 2
Views: 208

### Test 2

I know this is jumping ahead, but I was just wondering what chapters Test 2 would be on so I don't fall behind?
Sat Feb 10, 2018 2:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Dr. Lavelle's Review Sessions
Replies: 1
Views: 200

### Dr. Lavelle's Review Sessions

Will Dr. Lavelle's Review Sessions on February 12th cover the same material in the 11 am session and the 1 pm session or are different questions covered in each review session?
Wed Feb 07, 2018 5:29 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.83
Replies: 1
Views: 149

### 11.83

The problem states to calculate the equilibrium constant at 25 C and at 150 C. The solutions manual states that because the equilibrium constant is at 2 different temperatures we need to find the standard enthalpy of the reaction and the standard entropy of the reaction so the standard Gibbs free en...
Tue Feb 06, 2018 5:46 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.33
Replies: 1
Views: 161

### 9.33

The question asks if the entropy of the process increases or decreases: SO 2 (g) + Br 2 (g) + 2 H 2 O(l) --> H 2 SO 4 (aq) + 2 HBr(aq). The solutions manual states that entropy should decrease as the total number of moles decreases. Do they mean the moles of gas or is it a rule that if the total mol...
Tue Feb 06, 2018 3:52 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.1
Replies: 4
Views: 314

### 9.1

The problem states that the human body generated heat at the rate of about 100. W (1 W= 1 J/s). And the question asks at what rate does your body heat generate entropy in your surroundings, taken to be at 20. degrees Celsius? So would the entropy be that of the system or of the surroundings? The sol...
Sun Jan 28, 2018 5:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Chapter 9 help
Replies: 3
Views: 260

### Chapter 9 help

Does anyone know any videos explaining the conceptual ideas of chapter 9? I'm having a harder time understanding this chapter than the last.
Sun Jan 28, 2018 5:00 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy vs. Degeneracy [ENDORSED]
Replies: 5
Views: 338

### Re: Entropy vs. Degeneracy[ENDORSED]

Degeneracy is the number of ways of achieving a given energy state, while entropy is the probability that the system will be in a particular state.
Mon Jan 22, 2018 2:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework Turn In for Week 3
Replies: 2
Views: 166

### Homework Turn In for Week 3

For our discussions this week, should we be turning in homework for chapter 8 or chapter 9? And if it's chapter 8, can we turn in problems from any part of the chapter since we have covered it all?
Sun Jan 21, 2018 4:56 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Standard Enthalpies of Formation
Replies: 3
Views: 209

### Re: Standard Enthalpies of Formation

Multiply the standard enthalpies of formation times the number of moles for the products and add them all together. Do the same for the reactants. Then, subtract the total of the products by the total of the reactants.
Wed Jan 17, 2018 4:38 pm
Forum: Phase Changes & Related Calculations
Topic: Hw 8.87
Replies: 1
Views: 178

### Hw 8.87

Does anyone know how to do this problem using the enthalpy of sublimation instead of separately doing the enthalpy of fusion and enthalpy of vaporization?
The problem is: How much heat is required to convert a 42.30-g block of ice at 5.042 degrees C into water vapor at 150.35 degrees C?
Wed Jan 17, 2018 3:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hw 8.67 part b
Replies: 2
Views: 161

### Hw 8.67 part b

This question states to find the enthalpy of formation of CH 3 OH. I understand where the values for the bond enthalpies came from but in the solutions manual it states that the energy needed to "atomize 1 mol C(gr)" is 717 kJ/mol. Is this something we are meant to know? If so, how is that...
Sun Jan 14, 2018 5:48 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: living plant
Replies: 4
Views: 243

### Re: living plant

A living plant is an open system because it needs to exchange mass and energy with its surroundings to stay alive.
Sun Jan 14, 2018 5:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Reaction Enthalpy Definition
Replies: 7
Views: 302

### Re: Standard Reaction Enthalpy Definition

No the definition of standard states doesn't include temperature so a standard state can exist at any temperature.
Tue Jan 09, 2018 5:18 pm
Forum: Administrative Questions and Class Announcements
Replies: 2
Views: 250

Dr. Lavelle mentioned that students find it easier to read a certain part of chapter 8 first during Monday's lecture. Does anyone know the page numbers for that section?