Search found 30 matches

by Jessica Tsui 1H
Wed Mar 13, 2019 9:02 pm
Forum: Second Order Reactions
Topic: 6th edition 15.39
Replies: 2
Views: 209

Re: 6th edition 15.39

For part a, the coefficient does not affect the rate law equation.
by Jessica Tsui 1H
Wed Mar 13, 2019 6:53 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 6th edition, 15.63
Replies: 2
Views: 49

6th edition, 15.63

In the solutions manual for this problem, the answer subtracts 0.59 from the equation for ln k2 - ln k1. Why do they do this?
by Jessica Tsui 1H
Wed Mar 13, 2019 6:51 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Frequency Factor, A
Replies: 1
Views: 42

Frequency Factor, A

Is there a way to calculate A?
by Jessica Tsui 1H
Wed Mar 06, 2019 7:23 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: fast and slow elementary reactions
Replies: 3
Views: 65

Re: fast and slow elementary reactions

The rate law of multi-step reactions can't be predicted from the net reaction, so the slow step determines the rate law.
by Jessica Tsui 1H
Wed Mar 06, 2019 7:20 pm
Forum: Zero Order Reactions
Topic: General Meaning of "Zero Order" Reactions
Replies: 7
Views: 141

Re: General Meaning of "Zero Order" Reactions

Zero-order reactions can also occur when there is a catalyst, so the reaction would depend on the catalyst instead of the concentration of reactant.
by Jessica Tsui 1H
Wed Mar 06, 2019 7:11 pm
Forum: First Order Reactions
Topic: Half-Life
Replies: 2
Views: 68

Half-Life

Why is the half-life for first order reaction the only one that is independent of initial [A]?
by Jessica Tsui 1H
Wed Feb 27, 2019 11:29 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetics vs. Thermodynamics
Replies: 3
Views: 67

Kinetics vs. Thermodynamics

In class, Lavelle said when the activation energy is high, the reaction happens very slowly because kinetics, not thermodynamics, controls the reaction. What did he mean by kinetics rather than thermodynamics controlling the reaction?
by Jessica Tsui 1H
Wed Feb 27, 2019 11:25 pm
Forum: Balancing Redox Reactions
Topic: oxidizing agent and reducing agent
Replies: 15
Views: 220

Re: oxidizing agent and reducing agent

The chemical that is reduced takes electrons from the other chemical, which is then oxidized, so is the oxidizing agent. Vice versa for the other chemical.
by Jessica Tsui 1H
Wed Feb 27, 2019 11:20 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: E cell
Replies: 4
Views: 84

Re: E cell

n is the transfer of electrons for the chemicals being reduced and oxidized. In this case, n is equal to 6 because Fe loses 6 electrons when oxidized and Cr gains 6 electrons when reduced after the reaction occurs.
by Jessica Tsui 1H
Thu Feb 21, 2019 12:03 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Maximum potential
Replies: 1
Views: 36

Maximum potential

I don't understand how maximum potential is calculated when there is very little current flow. How does that work?
by Jessica Tsui 1H
Wed Feb 20, 2019 11:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge/Porous Disk
Replies: 5
Views: 95

Re: Salt Bridge/Porous Disk

The salt bridge or porous disk between the anode and the cathode allow cation/anion diffusion. This keeps both solutions neutral so that the reaction is able to continue.
by Jessica Tsui 1H
Wed Feb 20, 2019 11:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic/Voltaic Cells
Replies: 4
Views: 96

Galvanic/Voltaic Cells

Is there a difference between the terms "galvanic" and "voltaic"? Or are they interchangeable?
by Jessica Tsui 1H
Tue Feb 19, 2019 1:22 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium
Replies: 3
Views: 71

Equilibrium

Why is a reaction at equilibrium have G = 0?
by Jessica Tsui 1H
Tue Feb 19, 2019 1:20 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 4
Views: 85

Re: Van't Hoff Equation

R is referring to the gas constant.
by Jessica Tsui 1H
Tue Feb 19, 2019 1:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterms
Replies: 4
Views: 112

Midterms

Hi I was just wondering when our midterms will be passed back to us. Thank you.
by Jessica Tsui 1H
Thu Feb 07, 2019 1:16 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy
Replies: 2
Views: 62

Degeneracy

Can some explain how the number of energy states/arrangements relates to the calculation for degeneracy?
by Jessica Tsui 1H
Thu Feb 07, 2019 1:12 am
Forum: Phase Changes & Related Calculations
Topic: Solids and Liquids
Replies: 5
Views: 86

Solids and Liquids

In reactions with solids and liquids, why is PV insignificant?
by Jessica Tsui 1H
Thu Feb 07, 2019 12:50 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 1
Views: 40

Enthalpy

What is the difference between the H values used for Hess's Law and the H values used in standard enthalpy in formation?
by Jessica Tsui 1H
Thu Jan 31, 2019 9:45 pm
Forum: Calculating Work of Expansion
Topic: Equations for w
Replies: 5
Views: 99

Equations for w

I'm a little confused. What was the point of showing the integral for the work equation to arrive at the same work of expansion equation (w = -PV)?
by Jessica Tsui 1H
Thu Jan 31, 2019 9:41 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work
Replies: 3
Views: 83

Re: Work

When work is done on a system, w is positive. When work is done by a system, w is negative.
by Jessica Tsui 1H
Thu Jan 31, 2019 9:39 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Piston and value of W
Replies: 3
Views: 65

Re: Piston and value of W

Work done by the system is energy lost, so w is negative. Work done on the system is energy gained, so w is positive.
by Jessica Tsui 1H
Thu Jan 24, 2019 10:00 pm
Forum: Phase Changes & Related Calculations
Topic: Heat and path taken
Replies: 1
Views: 50

Heat and path taken

How does heat depend on the "path taken"?
by Jessica Tsui 1H
Thu Jan 24, 2019 9:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: H and Q
Replies: 4
Views: 63

Re: H and Q

H, enthalpy, is the measure of potential energy change of a chemical reaction in kJ/mol, while q measures heat in joules. H and q are related, in that -H = +q.

Please correct me if I am wrong.
by Jessica Tsui 1H
Thu Jan 24, 2019 9:28 pm
Forum: Phase Changes & Related Calculations
Topic: Thermochemistry Video Modules
Replies: 1
Views: 43

Thermochemistry Video Modules

Are there going to be video modules for the thermochemistry unit?
by Jessica Tsui 1H
Wed Jan 16, 2019 6:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Using a Eq. table for questions
Replies: 1
Views: 35

Re: Using a Eq. table for questions

When two reactions are combined, their K values are multiplied to find the K value of the new reaction.
by Jessica Tsui 1H
Wed Jan 16, 2019 6:00 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Approximation of x
Replies: 3
Views: 210

Approximation of x

Can we only assume x is negligible (after ICE table) if the reaction is with a weak acid?
by Jessica Tsui 1H
Wed Jan 16, 2019 5:53 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Catalysts
Replies: 7
Views: 139

Re: Catalysts

Catalysts simply speed up the rates of both the forward and reverse reactions, and equilibrium will be reached more quickly. The concentrations of reactants and products at equilibrium will be unchanged.
by Jessica Tsui 1H
Sat Jan 12, 2019 3:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Values of K
Replies: 2
Views: 56

Re: Values of K

When K>10 3 products are favored, meaning there is largely more product than reactant at equilibrium. The opposite is true for when K<10 -3 . For the intermediate values, neither reactants nor products are "strongly favored", meaning there is a relatively equal amount of reactant and produ...
by Jessica Tsui 1H
Sat Jan 12, 2019 3:31 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Example in Class
Replies: 7
Views: 155

Re: Example in Class

Decreasing the amount of NH3 increases the yield of NH3 because the system would react in order to get back to chemical equilibrium. Taking away product in the system allows more reactants to react to form more product.
by Jessica Tsui 1H
Sat Jan 12, 2019 3:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Liquids and Solids
Replies: 3
Views: 37

Re: Liquids and Solids

I think Professor Lavelle said it's because solids and liquids aren't changed in concentration during the reaction.

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