Search found 32 matches

Wed Mar 13, 2019 9:08 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Calomel Electrode
Replies: 1
Views: 82

Calomel Electrode

I'm reading over the book right now and was wondering if we need to know about the calomel electrode or glass electrode?
Thanks!
Tue Mar 12, 2019 12:10 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Collision Theory
Replies: 5
Views: 405

Re: Collision Theory

I believe that simply knowing that for a reaction to happen molecules must collide in the proper orientation and with enough kinetic energy to overcome the activation energy to synthesize products
Tue Mar 12, 2019 12:06 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Melting of ice
Replies: 9
Views: 449

Re: Melting of ice

This is a spontaneous reaction (dG <0 ) you can look at it as there is no work being done to the system to cause the ice to melt other than an exchange of heat from the sun to the solid ice
Tue Mar 12, 2019 12:04 am
Forum: Balancing Redox Reactions
Topic: k from lnK
Replies: 5
Views: 829

Re: k from lnK

To get k alone you must raise lnK as the exponent for the number e, this essentially negates the ln and leaves k alone for you to solve
Tue Mar 12, 2019 12:03 am
Forum: Balancing Redox Reactions
Topic: Short hand notation
Replies: 8
Views: 327

Re: Short hand notation

The purpose of the salt bridge is to inhibit the reaction from reaching equilibrium too quickly and maintains a neutral charge balance as electrons move from anode to cathode
Mon Mar 11, 2019 11:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Determine if molecule is in most stable form
Replies: 5
Views: 388

Re: Determine if molecule is in most stable form

If it isn't a diatomic molecule, you would probably have to find this out by calculating the dG for the reaction if it is negative the molecule is more stable than its elements and if the value is positive then vice versa
Mon Mar 11, 2019 11:54 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: negative and k
Replies: 3
Views: 171

Re: negative and k

The negative in the equation already accounts for the negative slope however the actual value of the rate constant cannot be negative as seen from its units mol/L/s since time is involved you cannot have negative time
Mon Mar 11, 2019 11:51 pm
Forum: Experimental Details
Topic: Activated Complex vs. Transition State
Replies: 2
Views: 1373

Re: Activated Complex vs. Transition State

The transition state represents only the highest potential energy configuration of atoms while the activated complex is the possible configurations of those atoms that are close to the transition state
Mon Mar 11, 2019 11:46 pm
Forum: Experimental Details
Topic: Fast vs Slow
Replies: 2
Views: 343

Re: Fast vs Slow

The problem will explicitly state it or you could be shown the values
Mon Mar 11, 2019 11:45 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Replies: 73
Views: 4026

Personally, I use the review sessions to solidify my understanding of the material but for the concepts that are more difficult to grasp in lecture, I usually take notes from the book. I like the way the book explains concepts in depth. Although we aren't tested on what the concepts actually are it ...
Mon Mar 11, 2019 11:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Log version vs ln Version
Replies: 7
Views: 311

Re: Log version vs ln Version

It really shouldn't matter the difference is simply their base number (log with base 10 and ln with base e)
Mon Mar 11, 2019 11:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed vs Isolated
Replies: 5
Views: 437

Re: Closed vs Isolated

the closed system simply exchanges energy whereas an isolated system does not exchange energy or matter, the best example for an isolated system that we have seen is a bomb calorimeter
Mon Mar 11, 2019 11:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Equations
Replies: 5
Views: 486

Re: Equations

understanding conceptually what is happening and recognizing what the question is asking is probably a better approach for studying overall, since most of the equations will be on the formula sheet, as long as you understand when and how to use the equations, that will be more beneficial to you
Mon Mar 11, 2019 11:31 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: n and significant figures
Replies: 5
Views: 503

Re: n and significant figures

Abby-Hile-1F wrote:How do you determine what n is?
The value of n is determined by the electrons that are canceled out when balancing the redox reaction
Mon Mar 11, 2019 11:29 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reactions
Replies: 4
Views: 265

Re: Balancing Redox Reactions

The easiest way to balance redox reactions in basic solution is following the same steps as if it were in acidic solution and in the very end at OH- to both sides to cancel the H+ ions and you will either be left with water or OH-
Mon Mar 11, 2019 11:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka2 in Acids
Replies: 2
Views: 131

Re: Ka2 in Acids

Usually problems that will have you consider the value of Ka2 will give you a Ka1 value that is considerably small, and may ask you to find Ka2 either the value or expression or both
Mon Mar 11, 2019 11:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka/b and pKa/b relationship
Replies: 2
Views: 100

Re: Ka/b and pKa/b relationship

It's better to remember the relation between Ka and pKa (vice versa with Kb) but the smaller the value of Ka, then the larger the value of pKa and thus the weaker the acid, if a weak acid has a small Ka value it's conjugate base will have a large Kb value
Mon Mar 11, 2019 11:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: equilibruim based on enthalpy
Replies: 3
Views: 180

Re: equilibruim based on enthalpy

Looking at the change in enthalpy alone won't be enough information to determine the equilibrium of a reaction or not but the sign of it does tell you whether heat is a reactant or product and from there you can follow the steps mentioned above.
Mon Mar 11, 2019 11:16 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Pre equilibrium approach
Replies: 2
Views: 128

Re: Pre equilibrium approach

The reason for this substitution was because we needed to derive the rate law to match the observed rate law while also knowing that [N2O2] was a dimer and not included in the overall reaction
Mon Mar 11, 2019 11:09 pm
Forum: Phase Changes & Related Calculations
Topic: Isothermal
Replies: 9
Views: 544

Re: Isothermal

If it is not explicitly stated that temperature changes, you can also assume the reaction is isothermal, this also goes with systems in standard state
Mon Mar 11, 2019 11:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Direction of a Reaction
Replies: 8
Views: 517

Re: Direction of a Reaction

If you aren't directly given K, then usually you would have to calculate it in an earlier part of the question and then compare Q to K.
Mon Mar 11, 2019 11:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Direction of a Reaction
Replies: 8
Views: 517

Re: Direction of a Reaction

If you aren't directly given K, then usually you would have to calculate it in an earlier part of the question and then compare Q to K.
Mon Mar 11, 2019 11:03 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number?
Replies: 12
Views: 2683

Re: Oxidation number?

Once you get the hang of what oxidation numbers belong to certain elements, then you can use those to calculate the unknown oxidation numbers of other elements. To do this you must match the overall charge of the substance with the unknown element
Mon Mar 11, 2019 12:12 pm
Forum: First Order Reactions
Topic: 15.27
Replies: 6
Views: 601

Re: 15.27

Do you neglect k in the equations? and do you have to solve for regular t or can you use t(1/2) in the equation?
Thu Mar 07, 2019 12:33 am
Forum: Phase Changes & Related Calculations
Topic: 6th edition 9.19
Replies: 2
Views: 155

Re: 6th edition 9.19

You use these 3 different steps because we are not given standard entropy of vaporization at 85C, this is essentially making a loop, you heat the substance to 100 and calculate the entropy then while T =100C meaning it remains constant, then you calculate the change in entropy there, and finally you...
Thu Mar 07, 2019 12:26 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: system v surroundings entropy
Replies: 4
Views: 429

Re: system v surroundings entropy

Generally, when we consider a reaction and the system it occurs in the surroundings are the immediate surroundings so when calculating entropy for them we usually keep the system positive because the reaction is what we observe the exchange of entropy to the surroundings are negative because it is t...
Thu Mar 07, 2019 12:21 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: R constants
Replies: 21
Views: 795

Re: R constants

One of the good things about the final is we are given the constants sheet with all the gas constants given to us, but like previously stated, the best way to approach a problem where you have to use an R constant is to look at the values and units given and use the constant with most (if not all) t...
Thu Mar 07, 2019 12:16 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: strong and weak acids
Replies: 5
Views: 447

Re: strong and weak acids

Weak acids tend to have higher pH because they do not tend to fully dissociate into hydronium ions and their respective anions. When you calculate the pH of a solution, you take the -log of the concentration of Hydronium ions, for weak acids this concentration will be relatively low compared to stro...
Thu Mar 07, 2019 12:10 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temp affecting K
Replies: 4
Views: 220

Re: Temp affecting K

K is not affected by changes in concentrations of a system; however Q is since it is a measure of where the reaction is at any point in time relative to equilibrium (at K) but the only thing that can change the actual value of K is temperature
Thu Mar 07, 2019 12:07 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Practice problem help
Replies: 2
Views: 250

Re: Practice problem help

All your answers are correct, specifically for a) if the volume of the container was halved, the inverse relationship between pressure and volume states that the pressure of the system should then increase by the inverse of 1/2 which is 2; for c) since CCl4 is a product (and the reaction is at equil...
Thu Mar 07, 2019 12:02 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE
Replies: 19
Views: 668

Re: ICE

E is the concentration of Reactants and Products at Equilibrium, after the Change
Thu Mar 07, 2019 12:02 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE
Replies: 19
Views: 668

Re: ICE

E is the concentration of Reactants and Products at Equilibrium, after the Change