## Search found 29 matches

Mon Mar 11, 2019 12:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 3
Views: 149

### Re: Cell Diagram

Michelle Nwufo 2G wrote:
Cole Doolittle 2K wrote:H+ is included in the cell diagram, but H2O (l) and electrons are not.

Also, is the H+ state aqueous?

Because H+ is in it's ionic state it must be aqueous
Mon Mar 11, 2019 1:25 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Unique rate?
Replies: 7
Views: 220

### Re: Unique rate?

No, the unique rate is the rate of disappearance of a reactant/formation of a product divide by its stoichiometric coefficient. This rate should be the same for all species in the reaction.
Mon Mar 11, 2019 1:18 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Pneumonic for remembering units
Replies: 1
Views: 81

### Re: Pneumonic for remembering units

I don't have a pneumonic but you can solve for units of k pretty easily. Rate = k [A]^x and since the units of rate will always be M/s you just have to make sure the units are equal. For example a 0 order reaction will be Rate = k [A]^0, and since Rate = M/s and [A]^0, then the units for k must be M...
Mon Mar 11, 2019 12:35 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous Reaction
Replies: 5
Views: 403

### Re: Spontaneous Reaction

I was confused by the same question. How do we interpret delta G without knowing the magnitude of delta H and T delta? Is there a way to use pressure to help solve?
Mon Mar 11, 2019 12:26 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential
Replies: 2
Views: 98

### Re: Cell Potential

And just to clarify above, you would want to choose the cathode with the highest E cell value and subtract the anode with the lowest E cell value
Mon Mar 04, 2019 3:08 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 4
Views: 142

### Re: Nernst Equation

Often times the book won't explicitly say to use the appendix, but that may be used, or like stated above you can usually solve given the majority of the equation being constants.
Mon Mar 04, 2019 3:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Edition 6 14.25
Replies: 3
Views: 176

### Re: Edition 6 14.25

Like stated above, you have to remember the appendix lists reduction potentials which is the ability to be reduced, so a substance that has a lower reduction potential is more likely to be oxidized, thus reducing another substance.
Tue Feb 26, 2019 6:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Writing Cell Diagrams
Replies: 3
Views: 99

### Writing Cell Diagrams

When do we know to include an inert metal (i.e. Pt) in our cell diagrams?
Sat Feb 23, 2019 11:20 am
Forum: Balancing Redox Reactions
Topic: distinguishing between acidic and basic solutions
Replies: 3
Views: 127

### Re: distinguishing between acidic and basic solutions

I think that would have to be given in the question
Sat Feb 23, 2019 11:16 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating E naught of the cell
Replies: 3
Views: 157

### Re: Calculating E naught of the cell

The second method just allows for more clear identification of the cathode and anode in order to avoid switching the order and confusing the two. Both accomplish the same thing.
Sat Feb 23, 2019 10:59 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: clarification on equations for delta G
Replies: 2
Views: 99

### Re: clarification on equations for delta G

Delta G naught just indicates the reaction occurs at standard conditions. My understanding is that either equation can be used with either delta G, except everything has to be at standard conditions or not at all.
Sun Feb 17, 2019 4:51 pm
Forum: Van't Hoff Equation
Topic: Concept behind Van't Hoff Equation
Replies: 5
Views: 225

### Re: Concept behind Van't Hoff Equation

The Van't Hoff Equation relates temperature change and K so you're able to calculate it if T of the system is changed.This temperature change can affect the equilibrium of the system so this can be used to examine that.
Sun Feb 17, 2019 4:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Positive Gibbs Free Energy
Replies: 3
Views: 133

### Re: Positive Gibbs Free Energy

Like stated above, reactions with positive delta G usually involve coupling with ATP hydrolysis in order to carry out an anabolic reaction where the reactants form a higher energy product. These reactions are called endergonic. Another example of a reaction like this is photosynthesis which utilizes...
Sun Feb 17, 2019 4:39 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: reversible and irreversible processes
Replies: 9
Views: 472

### Re: reversible and irreversible processes

Reversible processes are always in equilibrium with their surroundings and are ideal whereas irreversible processes can occur naturally and involve a definite change in entropy.
Wed Feb 06, 2019 12:13 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW Problem 8.9 6th edition
Replies: 2
Views: 133

### Re: HW Problem 8.9 6th edition

You take the steps above except you have to make sure your pressure units work out to yield Joules.It may be helpful to convert the torr to atm and then convert the answer using 101.325 J = 1 L atm.
Wed Feb 06, 2019 12:06 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units
Replies: 2
Views: 117

### Re: Units

I think when the problem is only concerned with the enthalpy of the reaction it can be either J or J/mol, however when it specifically asks for energy per mol that is when you'd have to take it into account. It's helpful to make sure to keep track of all units and cancel them out accordingly when so...
Wed Feb 06, 2019 10:32 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Irreversible/Reversible Processes
Replies: 2
Views: 100

### Re: Irreversible/Reversible Processes

Isothermal reversible processes assume total efficiency, so they're idealized processes. Because no energy is lost in this process maximum work is completed, as opposed to an irreversible process where some energy would be lost in the form of heat.
Sun Feb 03, 2019 8:07 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Reversible v irreversible
Replies: 4
Views: 168

### Re: Reversible v irreversible

Free expansion occurs when no work is done on a system
Sun Feb 03, 2019 8:05 pm
Forum: Calculating Work of Expansion
Topic: Free expansion
Replies: 3
Views: 153

### Re: Free expansion

Free expansion occurs when no work is done to the system. Like Aidan said if a divider is removed and the gas can move freely that is free expansion; however, if the gas had to move against a weighted piston that would not be free expansion because work is being done.
Sun Feb 03, 2019 7:59 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: What is pKa and Ka exactly?
Replies: 11
Views: 8988

### Re: What is pKa and Ka exactly?

pKa is basically a simplified way to view Ka (-logKa), just as pH is a simpler scale to interpret concentrations of H30+.
Sun Jan 27, 2019 12:03 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Molar Entropy
Replies: 3
Views: 99

### Re: Molar Entropy

Molar entropy is the amount of disorder in a system. You can imagine gas particles have more disorder than solid particles because of the distance between them so as stated in a previous response entropy would increase as a substance transitions from solid to liquid to gas.
Sat Jan 26, 2019 11:59 pm
Forum: Ideal Gases
Topic: units for partial pressure of gases
Replies: 6
Views: 353

### Re: units for partial pressure of gases

1 atm = 1.01325 bar so you could just use dimensional analysis and this conversion factor.
Sat Jan 26, 2019 11:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Method 2 Example
Replies: 3
Views: 86

### Re: Method 2 Example

When using bond enthalpies Dr. Lavelle said to only account for the bonds that change in the reaction so that less calculation is involved. In this case the double bond was broken and then a single bond was formed, in addition to the H-Br bond breaking and forming a C-Br bond. All the other hydrogen...
Sat Jan 19, 2019 8:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K - small verses big
Replies: 4
Views: 164

### Re: K - small verses big

^ Yes, especially when dealing with salts a larger Ka would indicate an acidic salt
Sat Jan 19, 2019 12:22 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strong vs Weak Acids
Replies: 2
Views: 86

### Re: Strong vs Weak Acids

You can determine the strength based on the Ka and Kb. If the Ka or Kb is smaller than 10^-3 then it is weak.
Sat Jan 19, 2019 12:02 pm
Forum: Identifying Acidic & Basic Salts
Topic: Salts
Replies: 1
Views: 201

### Re: Salts

A salt is a product of a neutralization reaction. It contains a cation and an anion and in order to determine the acidity/basicity you have to compare the Ka and Kb of the anion. If Ka>Kb the anion is acidic and will yield an acidic solution. If Kb>Ka then the anion is basic and will yield a basic s...
Fri Jan 11, 2019 1:05 am
Forum: Ideal Gases
Topic: Equilibrium Favoring
Replies: 4
Views: 92

### Re: Equilibrium Favoring

It can be helpful to visualize the concept of K in terms of the cube diagram Dr. Lavelle showed in class. K is a ratio and for the ratio to show any significant favor there would have to be a majority of the cubes in either color. And thinking of a 10x10x10 cube 10^3 would be the majority of the cub...
Fri Jan 11, 2019 12:58 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to use Kp or Kc
Replies: 3
Views: 108

### Re: When to use Kp or Kc

In terms of the textbook I believe they use K and Kp interchangeably, but I'm not sure if this applies to everything. I think further clarification would be helpful.
Fri Jan 11, 2019 12:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Gas unit conversions
Replies: 1
Views: 40

### Re: Gas unit conversions

I'm not exactly sure for all problems, but in terms of the homework units should be consistent. For example, 6th edition problem 25 only requires the use of the regular Kp equation and solving for the missing partial pressure after plugging in known pressures.