Search found 31 matches

by Jaira_Murphy_2D
Sun Mar 17, 2019 7:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Approximations
Replies: 1
Views: 116

Approximations

Will we be told to make/ not make approximations? Or will we have to decide on our own?
by Jaira_Murphy_2D
Sat Mar 16, 2019 8:54 pm
Forum: *Enzyme Kinetics
Topic: Collision theory
Replies: 2
Views: 131

Collision theory

How can you tell if a reaction would be least likely to occur?
by Jaira_Murphy_2D
Sat Mar 16, 2019 12:58 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.85 6th Edition
Replies: 1
Views: 45

Re: 15.85 6th Edition

This was posted earlier this week: "An activated complex is the the structure that occurs when the molecule is at the highest energy along the reaction path (ie the transition state at the top of that curve at Ea). You will not be asked to draw the structure on the exam."
by Jaira_Murphy_2D
Sat Mar 16, 2019 12:04 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: HW problem 15.73
Replies: 1
Views: 28

HW problem 15.73

Part b) a catalyst is not consumed in the course of a reaction
True of False

The answer is True

I don't understand why the answer is true because when we are looking for a catalyst in a reaction mechanism aren't we supposed to look for a catalyst that is being consumed and then formed?
by Jaira_Murphy_2D
Sat Mar 16, 2019 11:24 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: HW problem 15.67
Replies: 1
Views: 33

HW problem 15.67

The presence of a catalyst provides a reaction pathway in which the activation energy of a certain reaction is reduced from 125 kJ/mol to 75 kJ/mol. (a) By what factor does the rate of the reaction increase at 298 K, all other factors being equal? (b) By what factor would the rate change if the reac...
by Jaira_Murphy_2D
Fri Mar 15, 2019 11:58 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exothermic vs Endothermic
Replies: 6
Views: 74

Re: Exothermic vs Endothermic

I love chemistry community because everyone replies so fast!
by Jaira_Murphy_2D
Fri Mar 15, 2019 11:51 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exothermic vs Endothermic
Replies: 6
Views: 74

Exothermic vs Endothermic

How can you tell if a reaction is endothermic or exothermic based off Arrhenius equation, or given Ea and k?
by Jaira_Murphy_2D
Fri Mar 15, 2019 10:33 am
Forum: General Rate Laws
Topic: Overall Rate Law
Replies: 1
Views: 26

Overall Rate Law

If I'm given a reaction mechanism with 2 steps I can just combine products on one side and reactants on the other side and cancel out like terms to get the overall reaction? And for a reaction mechanism with 3 or more steps, I have to use the pre-equilibrium approach? Or, how do I know when to use t...
by Jaira_Murphy_2D
Thu Mar 14, 2019 12:16 pm
Forum: Second Order Reactions
Topic: solving for time elapsed
Replies: 1
Views: 29

solving for time elapsed

15.35 The half-life for the second-order reaction of a substance A is 50.5 s when [A]0 0.84 molL. Calculate the time needed for the concentration of A to decrease to (a) one-sixteenth; (b) one-fourth; (c) one-fifth of its original value. Can someone please explain how to solve part (a)? I'm pretty s...
by Jaira_Murphy_2D
Tue Mar 12, 2019 6:39 pm
Forum: First Order Reactions
Topic: 15.23 c) Determining rate constant
Replies: 2
Views: 58

Re: 15.23 A) Determining rate constant

Determine the rate constant for each of the following first-order reactions, in each case expressed for the rate of loss of A: (a) A --->B, given that the concentration of A decreases to one-half its initial value in 1000. s

How do you solve part a) for this question?
by Jaira_Murphy_2D
Tue Mar 12, 2019 3:20 pm
Forum: Zero Order Reactions
Topic: Reaction Rate
Replies: 10
Views: 176

Reaction Rate

Given a table of rates and concentrations, when you find the rate constant k, is it the same k for all of the other concentrations?
by Jaira_Murphy_2D
Tue Mar 12, 2019 2:07 pm
Forum: First Order Reactions
Topic: Rate law with 2 reactants
Replies: 3
Views: 38

Rate law with 2 reactants

What is the rate law if the reaction is in 1st order, but there are 2 reactants?
by Jaira_Murphy_2D
Sun Feb 24, 2019 11:53 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Spontaneous cell reaction
Replies: 2
Views: 37

Spontaneous cell reaction

After writing the corresponding cell reaction using the cell diagram how can you tell if the cell reaction is spontaneous as written?
(If the problem only tells you that the cell potential is positive)
by Jaira_Murphy_2D
Sat Feb 23, 2019 9:17 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding n in Delta G = -nFE
Replies: 3
Views: 69

Finding n in Delta G = -nFE

Can someone explain how to find n in Delta G = -nFE ?
by Jaira_Murphy_2D
Fri Feb 22, 2019 7:46 pm
Forum: Balancing Redox Reactions
Topic: Acidic Vs. Basic Redox Rxn
Replies: 3
Views: 62

Acidic Vs. Basic Redox Rxn

How will I know if I am balancing an acidic or basic redox reaction? Or will the problem specify which one it is?
by Jaira_Murphy_2D
Thu Feb 21, 2019 5:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Meaning
Replies: 6
Views: 115

Re: Gibbs Free Energy Meaning

Can someone explain this from the learning outcomes: Understand why reaction free energy depends on pressure and the equilibrium constant
by Jaira_Murphy_2D
Tue Feb 19, 2019 3:19 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: irreversible v reversible
Replies: 4
Views: 158

Re: irreversible v reversible

yes, I think S tot for a reversible process is = to 0
by Jaira_Murphy_2D
Sun Feb 17, 2019 8:02 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Non-spontaneous and spontaneous processes
Replies: 2
Views: 45

Non-spontaneous and spontaneous processes

What does a non-spontaneous process need to become spontaneous?
by Jaira_Murphy_2D
Sun Feb 17, 2019 7:45 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 4
Views: 90

Re: Spontaneity

Can someone explain this from the textbook? "At constant temperature and pressure, the direction of spontaneous change is the direction of decreasing Gibbs free energy."
by Jaira_Murphy_2D
Tue Feb 12, 2019 10:44 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids in K expression
Replies: 2
Views: 70

Solids and Liquids in K expression

When writing the K expression and there's a solid or liquid in the reaction, should I balance the whole equation first and then not include the solid or liquid in my K expression? Or ignore the solid or liquid from the beginning and balance my the equation without them?
by Jaira_Murphy_2D
Wed Feb 06, 2019 5:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Dr. Lavelle's In-class Review Sessions
Replies: 2
Views: 61

Dr. Lavelle's In-class Review Sessions

Since Professor has review sessions during his lectures next week, will he be presenting the same past exam questions in each lecture, or different ones?
by Jaira_Murphy_2D
Tue Feb 05, 2019 7:03 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta H and q
Replies: 3
Views: 73

Delta H and q

Can someone please explain the concept behind why Delta H is equal to q at constant pressure?
by Jaira_Murphy_2D
Sun Jan 27, 2019 1:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess' Law Confirmation
Replies: 3
Views: 68

Re: Hess' Law Confirmation

Can someone explain how I know which equation to start with for Hess' Law?
by Jaira_Murphy_2D
Sun Jan 27, 2019 1:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Biological Example
Replies: 1
Views: 38

Biological Example

Can anyone explain and apply the concept of reaction enthalpies to a biological or organic example? I'm not really sure what the outline means by being able to do that.
by Jaira_Murphy_2D
Sun Jan 27, 2019 1:42 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: heat capacity
Replies: 7
Views: 90

Re: heat capacity

Heat Capacity is measurement of heat absorbed or released. Since temperature change is directly proportional to the heat added, with the heat capacity as the proportionality constant, we can use the heat capacity to convert the temperature change into energy.
by Jaira_Murphy_2D
Sun Jan 27, 2019 1:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q(cal)= -q
Replies: 2
Views: 70

Re: q(cal)= -q

I'm not exactly sure how it was derived but I know that it means the Heat lost in a reaction is gained by the calorimeter -q= qcal (- heat required is = + calorimeter constant) I think it applies to when you are Calibrating the calorimeter: the heat capacity is measured by supplying a quantity of he...
by Jaira_Murphy_2D
Sun Jan 27, 2019 1:18 pm
Forum: Phase Changes & Related Calculations
Topic: closed vs isolated system
Replies: 3
Views: 55

Re: closed vs isolated system

Open system: Opened to both heat and matter (Ex. a test tube with liquid inside without a lid) Closed system: Closed to matter, but open to heat (Ex. a test tube with a closed lid, sitting in hot water; the liquid inside the test tube cannot escape but it can get warmer.) Isolated system: Closed to ...
by Jaira_Murphy_2D
Sun Jan 27, 2019 1:12 pm
Forum: Phase Changes & Related Calculations
Topic: State Property
Replies: 3
Views: 51

Re: State Property

A State Property being independent of its path just means that how the system attained that state doesn't matter. For example how fast or slow the change happened doesn't matter, only its actual initial and final state matter. The value only depends on its current state not how it got there.
by Jaira_Murphy_2D
Sun Jan 13, 2019 8:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant
Replies: 6
Views: 94

Re: Equilibrium constant

Kc is just referring to calculating the eq of given concentrations and Kp refers to calculating the eq of given pressures.
by Jaira_Murphy_2D
Sun Jan 13, 2019 5:42 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: reaction quotient [ENDORSED]
Replies: 4
Views: 65

Re: reaction quotient [ENDORSED]

Is the reaction quotient unit-less as well?
by Jaira_Murphy_2D
Fri Jan 11, 2019 11:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kc
Replies: 4
Views: 73

Calculating Kc

Can someone please explain to me why it’s necessary to balance a reaction equation when calculating Kc? I don’t understand why it mattters if concentration changes dont affect Kc.

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