## Search found 30 matches

Fri Mar 15, 2019 8:56 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: homework question
Replies: 1
Views: 97

### Re: homework question

Conceptually pH can't be negative. I'm not sure about the problem itself.
Fri Mar 15, 2019 8:55 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate constants at equilibrium
Replies: 5
Views: 209

### Re: Rate constants at equilibrium

Nope forward and backwards are different. K = k1/k2. If k1 = k2 K would always = 1.
Fri Mar 15, 2019 8:55 am
Forum: Second Order Reactions
Topic: integrating equations
Replies: 2
Views: 328

### Re: integrating equations

My TA specified we should know how to integrate at least the first order equation.
Fri Mar 08, 2019 8:53 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Reaction mechanisms
Replies: 3
Views: 149

### Re: Reaction mechanisms

Determining rate is the slowest bc everything else must wait for it to complete before it can proceed. It's basically the bottleneck.
Fri Mar 08, 2019 8:52 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order of the Reaction
Replies: 3
Views: 141

### Re: Order of the Reaction

The order of each individual reactant tells you how changing the concentration of each will affect the overall rate of the reaction. The overall order will tell you how the reaction occurs and what mechanisms are used.
Fri Mar 08, 2019 8:51 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: k & K
Replies: 18
Views: 811

### Re: k & K

k in electro should be Boltzmann's constant while k in kinetics is a number unique to each reaction scaling how quickly the reaction proceeds.
Fri Mar 01, 2019 9:00 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetically Stable
Replies: 3
Views: 217

### Re: Kinetically Stable

Kinetically stable is that there is such a large energy hump that it is unlikely for a reaction to occur by itself. Thermodynamically stable is that the product has a higher energy state than the initial.
Fri Mar 01, 2019 8:52 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Potentials and Likeliness to be reduced/oxidized
Replies: 3
Views: 128

### Re: Potentials and Likeliness to be reduced/oxidized

Positive potentials are reduced and negative are oxidized.
Fri Feb 22, 2019 8:59 am
Forum: Balancing Redox Reactions
Topic: Difference
Replies: 3
Views: 210

### Re: Difference

Balancing redox reactions requires a balance of charges. Since in normal reactions we don't look at charges, there is no need to (charge of 0 will always balance out with 0).
Fri Feb 22, 2019 8:58 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous
Replies: 2
Views: 149

### Re: Spontaneous

Reactions are spontaneous as long as Gibbs free energy is negative. The other values can be any combination of signs as long as the resulting Gibbs free energy value is negative.
Fri Feb 22, 2019 8:57 am
Forum: Balancing Redox Reactions
Topic: Redox and Oxidation
Replies: 3
Views: 169

### Re: Redox and Oxidation

The best way to do it is to look up the rules for oxidation numbers. He essentially looked at each element on each side of the table and found their oxidation number. Then he looked at if the number of the same element went up or down (comparing the left side to the right side). Using this you can f...
Fri Feb 15, 2019 8:50 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Calculating Delta S with a change in temperature
Replies: 5
Views: 222

### Re: Calculating Delta S with a change in temperature

Check the reaction to see if more molecules are produced on the product side vs reactant side. Then check if it's in a container or not. Assuming Cp is usually safer.
Fri Feb 15, 2019 8:49 am
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: n in degeneracy
Replies: 8
Views: 881

### Re: n in degeneracy

Molecules means the whole thing. O2 is one molecule therefore n = 1. You may be thinking of atoms of O in O2 for n = 2 which is incorrect.
Fri Feb 15, 2019 8:47 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Cv vs. Cp
Replies: 6
Views: 493

### Re: Cv vs. Cp

Cv is used when the problem states the volume doesn't change and Cp is for a constant pressure. In some cases, it's really tricky like the multi change one. But think about what value is changing at independent steps.
Fri Feb 08, 2019 9:00 am
Forum: Calculating Work of Expansion
Topic: Hess's Law
Replies: 2
Views: 83

### Re: Hess's Law

The bond enthalpies should be given or else we can't really solve the problem.
Fri Feb 08, 2019 8:59 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible vs. Irreversible processes
Replies: 1
Views: 120

### Re: Reversible vs. Irreversible processes

In a reversible reaction, we assume that the process occurs in minute increments back in forth but tending to one side. An increase in volume can be thought of as the volume increasing a little bit and then decreasing a bit and then increasing a bit. This allows for temperature to "balance out&...
Fri Feb 08, 2019 8:53 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 2
Views: 140

### Re: Systems

Open system allows both matter and energy to be exchanged with the environment. A closed system allows only energy to do so. Isolated systems allow nothing to exchange with the env.
Fri Feb 01, 2019 8:57 am
Forum: Phase Changes & Related Calculations
Topic: Steam
Replies: 11
Views: 390

### Re: Steam

Steam is worse bc it can carry more energy for the same temperature compared to liquid water.
Fri Feb 01, 2019 8:55 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed System
Replies: 6
Views: 250

### Re: Closed System

The sealed beaker can still exchange energy. By definition an isolated system must not exchange energy and matter. If you touch a beaker full of boiling hot water, you can feel how hot the beaker is getting. That's a closed system.
Fri Feb 01, 2019 8:50 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy vs Internal energy
Replies: 5
Views: 174

### Re: Enthalpy vs Internal energy

Enthalpy includes internal energy. Internal energy includes both kinetic and potential energy but enthalpy measure the total thermo potential so it adds on the pressure times volume part.
Fri Jan 25, 2019 9:07 am
Forum: Phase Changes & Related Calculations
Topic: Irreversible and Reversible process
Replies: 2
Views: 92

### Re: Irreversible and Reversible process

A reversible reaction has an equilibrium and will tend to that state naturally. Irreversible processes do not tend towards and equilibrium.
Fri Jan 25, 2019 8:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units When Calculating Equilibrium Constant
Replies: 4
Views: 167

### Re: Units When Calculating Equilibrium Constant

The units will cancel out when solving for equilibrium constants since the same units are in the numerator and denominator.
Fri Jan 25, 2019 8:54 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle question
Replies: 4
Views: 224

### Re: Le Chatelier's Principle question

The reason pressure affects the reaction is the probability of one molecule colliding into another. The collision is what results in a change. If you increase the pressure by adding an inert gas, the molecule in question for the reaction crashing into the inert gas won't result in a reaction. The mo...
Thu Jan 17, 2019 3:26 pm
Forum: Student Social/Study Group
Topic: ICE Table
Replies: 5
Views: 208

### Re: ICE Table

You can ignore it when the value of x you calculated is less than 5% of the initial concentration. If the x value is anywhere near or greater than 5% you have to do the quadratic by hand.
Wed Jan 16, 2019 10:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th edition 6A.23
Replies: 1
Views: 74

### Re: 7th edition 6A.23

If your calculations are correct, then the solution is neutral. The [H30+]<10^-7 so therefore the amount of change in [H3O+] is negligible and the pH will not change dramatically from neutral.
Wed Jan 16, 2019 10:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.89 Part B 6th Edition
Replies: 3
Views: 104

### Re: 11.89 Part B 6th Edition

It doesn't always have to be in atm. You use whatever units are convenient or given to you. If the problem gives the gas constant in atm you have to use atm for your calculations.
Wed Jan 09, 2019 8:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE chart
Replies: 1
Views: 71

### Re: ICE chart

The point of an ice chart is it gives you a way to organize and see how a reaction affects the concentration of reactants and product. It is used when we cannot assume a reaction goes to "100% completion". If you have the final resulting value of the reaction, you can find C by doing initi...
Wed Jan 09, 2019 8:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.1 part B
Replies: 2
Views: 64

### Re: 5H.1 part B

For part b the equation is what would happen if you took the original and divide it by two. Part c is when you take the original and multiply by two. I don't think we have yet to go over how to manipulate k when you do a scalar multiplication to the reaction.
Tue Jan 08, 2019 8:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.43
Replies: 2
Views: 139

### Re: 11.43

Yeah you have to use a RICE table. If it's any help the book covers them starting page 441 in the 6th edition.
Mon Jan 07, 2019 8:02 pm
Forum: General Rate Laws
Topic: Visualizing Equilibrium
Replies: 1
Views: 140

### Visualizing Equilibrium

For question 7 in chapter 11 6th edition how do we visualize the equilibrium of a reaction? From what I can tell there is not a very compelling reason to say flask 3 is a better representation of equilibrium than flask 4 or vice versa. Both flasks have molecules that are kinda spread out and the rat...