## Search found 104 matches

Fri Mar 15, 2019 11:25 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: justified approximation
Replies: 1
Views: 282

### justified approximation

when can you justify that it is okay to ignore the second ionization? what will be the indication that we dont have to do the second ionization?
Fri Mar 15, 2019 4:30 pm
Forum: First Order Reactions
Topic: pseudo first order
Replies: 2
Views: 154

### pseudo first order

what is the cut off for something to be considered "very large" for pseudo first order? how will we know to do this? i dont have a full understanding fo the process.
Fri Mar 15, 2019 4:27 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: coefficient in rate law
Replies: 1
Views: 128

### coefficient in rate law

in the book, they give us this formula
NO2 + NO2 --> O2 + N2O2
and tell us the rate law for NO2 is
rate law of formation of NO2 = 2k[N2O2][O2]
ive never seen a coefficient in a rate law and was wondering why this is important.
Fri Mar 15, 2019 11:32 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: reduction is more positive Ecell
Replies: 1
Views: 118

### reduction is more positive Ecell

when given couples like (U3+/U and La3+/La), is the only way to tell which is the reduction and which is the oxidation to compare the Ecell values? and see which is more positive?
Wed Mar 13, 2019 11:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: modeling enthalpy
Replies: 1
Views: 139

### modeling enthalpy

if you were given enthalpy values for each of your elementary steps and had three steps, would the highest enthalpy value have the lesser "dip" (or amount of space between products and reactants) and lowest enthalpy value would have the greater "dip"? I just want to be clear on h...
Wed Mar 13, 2019 10:37 pm
Forum: General Rate Laws
Topic: k1 vs k2?
Replies: 4
Views: 345

### k1 vs k2?

if not specified, do we assume that k is a constant?
i was doing the fast equilibrium method and my answer was rate=k2K[NOCl]^2/[NO], but the correct answer was rate=k[NOCl]^2/[NO].
from this, i can assume k was a constant in the mechanism, correct?
Wed Mar 13, 2019 9:30 pm
Forum: *Enzyme Kinetics
Topic: true statement?
Replies: 4
Views: 408

### true statement?

"the lower the temperature, the higher the rate enhancement will be when a catalyst is added"

is this a correct statement? this question relates to question 7E.3 in the 7th edition- the whole process of it is very confusing to me but id like to understand the conceptual part first.
Wed Mar 13, 2019 9:13 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: subtracting .59? 7D.5 7th ed
Replies: 1
Views: 114

### subtracting .59? 7D.5 7th ed

in the sol'n manual, why is 0.59 subtracted from the end of the Arrhenius calculation? I cant seem to find a good reason for it.
thank you!
Tue Mar 12, 2019 7:31 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: organic chem stuff
Replies: 1
Views: 135

### organic chem stuff

do we need to know how to identify all of the organic chemistry concepts in question 7.29? none of the topics are listed on the outline
Tue Mar 12, 2019 7:26 pm
Forum: Reaction Mechanisms, Reaction Profiles
Replies: 1
Views: 104

how do you identify radicals in a reaction mechanism?
Tue Mar 12, 2019 7:17 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: fast equilibrium approach v steady state equilibrium
Replies: 1
Views: 99

### fast equilibrium approach v steady state equilibrium

I have tried to understand thins concept and how it is different from steady state equilibrium, but it is very difficult for me to conceptualize. Can someone try to describe the difference and importance of each?
Tue Mar 12, 2019 6:51 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: intermediates
Replies: 1
Views: 104

### intermediates

are two intermediates always required to form when there are three steps in a mechanism? and is one intermediate always required to form when there are two steps?
Tue Mar 12, 2019 6:48 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: reaction profile question
Replies: 2
Views: 113

### reaction profile question

concerning the attached picture of a reaction profile which is related to question 7.11 in 7th ed textbook, are the second two bumps higher because a catalyst was introduced after the first step?
Tue Mar 12, 2019 6:42 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: writing elementary steps
Replies: 1
Views: 84

### writing elementary steps

the rate law of the reaction 2NO + 2H2 --> N2 + 2H2O is rate= k[NO]^2[H2] these are the written steps: step 1: NO + NO--> N2O2 step 2: N2O2 + H2 --> N2O + H2O step 3: N2O + H2 --> N2 + H2O why is the NO in the rate law squared but not the H2 when there are 2 of both molecules in the chemical equatio...
Tue Mar 12, 2019 6:40 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: rate determining
Replies: 1
Views: 104

### rate determining

in deciding which of three steps is the rate determining step given the rate law, do you just match the given rate law to the reactants of one of the steps? for example step 1: NO + NO--> N2O2 step 2: N2O2 + H2 --> N2O + H2O step 3: N2O + H2 --> N2 + H2O rate= k[NO]^2[H2] is step two the slow step j...
Tue Mar 12, 2019 6:37 pm
Forum: Zero Order Reactions
Topic: conceptual textbook question
Replies: 1
Views: 318

### conceptual textbook question

can someone explain the highlighted part of the attached picture concerning zeroth order reactions?
Tue Mar 12, 2019 6:35 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: correct statement? concerning rate laws
Replies: 1
Views: 77

### correct statement? concerning rate laws

Elementary rate laws can be determined from the chemical formula, but reaction rate laws must be experimentally determined and cannot be determined from the rate law.

is this statement correct? if not, why?
Tue Mar 12, 2019 2:48 pm
Forum: General Rate Laws
Topic: second and zeroth order half life "not used"
Replies: 2
Views: 129

### second and zeroth order half life "not used"

the book states: "the half life increases as the reaction proceeds and reactant concentration decreases. Because of this variation, the half-life is not very useful for describing reactions with second-order kinetics" can someone explain this in a different way? why is the second order hal...
Mon Mar 11, 2019 7:27 pm
Forum: General Rate Laws
Topic: 7A15 how to find order of reactant (no similar C values)
Replies: 2
Views: 130

### 7A15 how to find order of reactant (no similar C values)

in 7A15 in the 7th edition, how can we determine the order of each reactant when all of the values for reactant C are the same? I thought we were supposed to compare the reactants when they were at the same value in two different experiments, but this is not possible for reactant C. 2A+2B+C--> produ...
Mon Mar 11, 2019 7:21 pm
Forum: General Rate Laws
Topic: what if
Replies: 3
Views: 170

### what if

what would the overall rate for the reaction H2 + I2 --> 2HI look like if it was first order?

i know that the second order formula is rate = k[H2][I2], but dont know what to give if it asked for first order.
Mon Mar 11, 2019 6:42 pm
Forum: General Rate Laws
Topic: initial vs overall units
Replies: 1
Views: 99

### initial vs overall units

are units for initial concentration mol/L*s vs units for overall rate constant L/mol*s?
how do we know when to use one or the other?
Mon Mar 11, 2019 6:19 pm
Forum: General Rate Laws
Topic: units
Replies: 2
Views: 144

### units

are the common units for k values (mol/L*s) and the units for overall reactions (L/mol*s)? why are these different in textbook problems?
Wed Mar 06, 2019 7:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L7 and 9
Replies: 2
Views: 125

### Re: 6L7 and 9

I was confused about whether or not we would get a reduction potential index on the test. Thanks!
Wed Mar 06, 2019 7:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: identifying cathode anode
Replies: 4
Views: 159

### Re: identifying cathode anode

It is true that we want the cathode to have a greater positive reduction potential so that the galvanic cell will be able to do useful work (positive cell potential). However, the question never specified that the cell had to have a positive cell potential. It merely asks you to calculate the stand...
Wed Mar 06, 2019 7:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5 part c 7th edition
Replies: 2
Views: 112

### Re: 6M.5 part c 7th edition

This makes so much more sense now, thank you!
Wed Feb 27, 2019 9:50 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: identifying cathode anode
Replies: 4
Views: 159

### identifying cathode anode

in this equation MnO4- + 8H+ + 5Ce^3+ --> 5Ce^4+ + Mn^2+ + 4H2O how would you identify the cathode and anode? i read in the book that the half rxn with the more positive reduction potential is where reduction occurs. however, permanganate potential is more positive, but it is the anode in the equati...
Wed Feb 27, 2019 8:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5 part c 7th edition
Replies: 2
Views: 112

### 6M.5 part c 7th edition

How do you determine which is the cathode and which is the anode in this question? Im confused because it looks to me that both half reactions are losing electrons.
thank u!
Tue Feb 26, 2019 11:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: chapter 6O??
Replies: 2
Views: 100

### chapter 6O??

is chapter 6O (the products of electrolysis) expected for the test this week? it comes after talk about the Nernst equation, but is in a separate chapter, so i am unsure. thanks!
Tue Feb 26, 2019 11:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L7 and 9
Replies: 2
Views: 125

### 6L7 and 9

How are we supposed to be able to come up for the half rxns for these without an appendix?
Especially for 6L7, if anyone could explain how to get the half reactions for this, that would be great. thank u!
Tue Feb 26, 2019 10:53 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 (d) half reactions
Replies: 3
Views: 166

### Re: 6L.5 (d) half reactions

204929947 wrote:how do you tell the difference between a cathode and an anode?????

A cathode is what is being reduced, or gaining electrons. An anode is what is being oxidized, or losing electrons.
Tue Feb 26, 2019 7:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3 part d
Replies: 2
Views: 157

### Re: 6L.3 part d

I just dont understand why the solution manual writes the anode half rxn as O2 +4H+ + 4e- --> 2H2O when the two things listed in the left of the cell diagram are O2(g) and H+(aq). I tried to find the half rxn beginning with

O2 --> H+

but that apparently isnt right.
Tue Feb 26, 2019 7:24 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 (d) half reactions
Replies: 3
Views: 166

### 6L.5 (d) half reactions

can someone help me understand how to write the half reactions for part (d) of 6L.5? the equation is as follows:

Au+(aq)-->Au(s) + Au3+(aq)

The sol'n manual says that the half reactions are :
Au+ + e- --> Au(s)
Au3+ + 3e- -->Au(s)

but i dont understand how to get there. thank u!
Tue Feb 26, 2019 6:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3 part d
Replies: 1
Views: 124

### 6L.3 part d

Write the half reactions and the balanced equation for the cell reaction for the following galvanic cells: (d) Pt(s)|O2(g)|H+(aq)||OH-(aq)|O2(g)|Pt(s) I don't understand how to get the answer that is in the solutions manual or how to set up a half reaction with the cathode. Can someone explain what ...
Tue Feb 26, 2019 6:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3 part d
Replies: 2
Views: 157

### 6L.3 part d

Write the half reactions and the balanced equation for the cell reaction for the following galvanic cells: (d) Pt(s)|O2(g)|H+(aq)||OH-(aq)|O2(g)|Pt(s) I don't understand how to get the answer that is in the solutions manual or how to set up a half reaction with the cathode. Can someone explain what ...
Sat Feb 23, 2019 5:16 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: enthalpy of formation vs standard reaction enthalpy
Replies: 1
Views: 74

### enthalpy of formation vs standard reaction enthalpy

when comparing 4J5 and 4J7, why can you use the enthalpy of formation value for 4J5, but are required to calculate the enthalpy of the reaction for 4J7?
is it because there are 2H2O2 in 4J7? how can both be plugged into the formula for delta G?
Sat Feb 23, 2019 4:57 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: writing reaction for CO(g)
Replies: 1
Views: 101

### writing reaction for CO(g)

when writing the reaction for CO(g), how are we supposed to know that it the carbon is in graphite form and not in gas form? is it because carbon is most commonly found in graphite form? I wrote the eq for 4.J.5 at first as C(g)+.5O(g)--> CO(g) but go the wrong answer for G bc the S value for C was ...
Sat Feb 23, 2019 3:13 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 3
Replies: 14
Views: 540

### Test 3

Will we need to be able to apply Gibbs Free Energy to equilibrium concepts on the test? there are questions surrounding that on the outlines
Tue Feb 19, 2019 11:14 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: system v surroundings entropy
Replies: 4
Views: 445

### Re: system v surroundings entropy

I now understand that the book wrote it like this to help us understand that the energy released from the surroundings is absorbed by the system. It was hard for me to grasp this concept, but I thinking about it in relation to the first law of thermodynamics was helpful.
Tue Feb 19, 2019 11:12 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 11
Views: 699

### Re: Phase Changes

Its important to understand it when solving problems that involve phase changes, as it allows you to visualize the steps.
Tue Feb 19, 2019 11:10 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter - Type of System
Replies: 5
Views: 554

### Re: Calorimeter - Type of System

What are some other systems that will always be isolated?
Tue Feb 12, 2019 2:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4.15 7th ed
Replies: 1
Views: 111

### 4.15 7th ed

Why can you not use mc(delta)T=-mc(delta)T to solve this?? I keep getting 298 (if i use kelvin) and 25 (if i use celsius) as my answer.
Tue Feb 12, 2019 1:40 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: free expansion
Replies: 2
Views: 149

### free expansion

can someone describe the characteristics of free expansion? Is it just that w=0, and therefore q and deltaU are zero? Thank you!
Tue Feb 12, 2019 1:39 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: expansion of ideal gas
Replies: 1
Views: 81

### expansion of ideal gas

When calculating the total entropy change for the expansion of an ideal gas, why can we assume that deltaU=0 and therefore q=-w? I don't understand the logic behind this and may be missing something.
Tue Feb 12, 2019 1:37 am
Forum: Calculating Work of Expansion
Topic: 0 work vs no work
Replies: 4
Views: 215

### 0 work vs no work

Is there a difference between specifying that there is no work versus 0 work? I was confused why the solutions manual put those as two separate answers when regarding situations in question 4.13.9 (a) and (b).
Tue Feb 12, 2019 1:36 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: system v surroundings entropy
Replies: 4
Views: 445

### system v surroundings entropy

I know we use deltaH/T to calculate the delta S of both system and surroundings. I also know that Ssys=-Ssurr. Does it matter whether the system or surroundings side is negative? It seems to me like it shouldn't make a difference if the system is reversible, but the book always make Ssurr negative o...
Tue Feb 12, 2019 1:32 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: entropy change
Replies: 2
Views: 118

### entropy change

Why is entropy change smaller at higher temperatures? Does this only occur in special circumstances?
Tue Feb 12, 2019 1:28 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: hess law equations
Replies: 3
Views: 162

### hess law equations

On the midterm, will we be expected to know how to write out the equations that we will use to utilize Hess's law? Like in book problem 4D15? If so, can someone explain going about that?
Tue Feb 12, 2019 1:23 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: assuming no work
Replies: 2
Views: 72

### assuming no work

When can you assume that no work is done on a system so that deltaU=heat?
Sat Feb 09, 2019 11:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard reaction enthalpy vs reaction enthalpy
Replies: 1
Views: 94

### standard reaction enthalpy vs reaction enthalpy

is there a difference between standard reaction enthalpy and reaction enthalpy? I don't understand why you have to use Hess's Law for 4D15 but not for 4D17, and they use the different wording. thank you!
Thu Feb 07, 2019 12:23 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Enthropy
Replies: 2
Views: 276

### Re: Enthropy

In some problems, it will also specify whether or not these values are constant.
Thu Feb 07, 2019 12:23 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Determining Spontaneity of a Reaction
Replies: 4
Views: 244

### Re: Determining Spontaneity of a Reaction

The LA in a review session I went to today also said that Gibbs free energy, or delta G, is a concept that helps us determine spontaneity. We haven't learned about it yet in lecture, but I think this would be a good reference point for your question.
Thu Feb 07, 2019 12:21 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Negative q
Replies: 7
Views: 936

### Re: Negative q

A negative q value stands for negative heat. This corresponds to vaporization and melting.
Tue Jan 29, 2019 4:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 5H1
Replies: 2
Views: 152

### Re: Question 5H1

Thank you for this reply! After looking back and comparing your answer to some high school notes, this would have been a lifesaver.
Tue Jan 29, 2019 4:07 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE
Replies: 19
Views: 682

### Re: ICE

The E is the final step in an ice chart. It adds up the I and C steps and it is what you will put into an equation to get your x value when given K.
Tue Jan 29, 2019 4:02 pm
Forum: Ideal Gases
Topic: Q and K
Replies: 13
Views: 604

### Re: Q and K

Q is calculated with values that are at any point in the reaction. We can use our answer from Q and compare to to the constant K value to determine whether the reaction will proceed forward or reverse.
Wed Jan 23, 2019 10:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: buffers
Replies: 1
Views: 110

### buffers

Can someone define what a buffer is and the significance of it in calculations?
Wed Jan 23, 2019 9:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: predict solubility
Replies: 2
Views: 151

### predict solubility

How can we use equilibrium constants to predict solubility?
Mon Jan 21, 2019 11:02 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 7th ed 5I19
Replies: 1
Views: 91

### Textbook 7th ed 5I19

I don't understand why in this question the solutions manual uses 0.80 as the x value without using the quadratic formula or anything. Can someone explain why it is like this?
Mon Jan 21, 2019 11:01 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE chart
Replies: 3
Views: 138

### ICE chart

Can both molar values and concentrations go into the ice chart? I have seen it used both ways in the homework and it was confusing me.
Mon Jan 21, 2019 11:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 5H1
Replies: 2
Views: 152

### Question 5H1

The concept presented in this question is confusing me. Why is part b considered the square root of the original equation? In part c, how it is the square of the original equation if 3^2 is 9?
Mon Jan 21, 2019 10:56 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Thermodynamically Favorable
Replies: 2
Views: 118

### Thermodynamically Favorable

How do you determine which product or which reactant is more favorable based on the K value? This question is referring to 7th edition 5H13 part C. Thank you!
Wed Jan 16, 2019 11:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 7th edition 6E1
Replies: 1
Views: 48

### Textbook 7th edition 6E1

I have a couple questions about this question that are confusing me. Why do we need to be doing this set up at all if H2So4 is a strong acid? I thought we did the ICE chart for weak acids? Does this relate to why there is a "second ionization in the solutions manual? What is that? Lastly, Where...
Mon Jan 14, 2019 10:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ksp
Replies: 2
Views: 136

### Ksp

I remember discussion a Ksp constant in high school and was wondering if anyone else was familiar with it and if it is something we have already discussed in class. Can anyone explain or define it? Thanks!
Mon Jan 14, 2019 10:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure [ENDORSED]
Replies: 2
Views: 151

### Pressure[ENDORSED]

Can someone explain the significance of pressure when discussing equilibrium constants? For example, how would adding an inert gas to a system at equilibrium change anything?
Mon Jan 14, 2019 10:23 pm
Forum: Ideal Gases
Topic: Water
Replies: 13
Views: 433

### Water

I was wondering in class today- is water always a liquid in equations? Can it ever be aqueous? If not, why not?
Thu Jan 10, 2019 3:45 pm
Forum: Ideal Gases
Topic: Equilibrium Constant
Replies: 3
Views: 149

### Re: Equilibrium Constant

Both gaseous and aqueous reactants and products can be used when calculating K or Q. We cannot use solids or liquids as they do not effect the amount of products or reactants at all, so we keep them at value=1.
Thu Jan 10, 2019 3:43 pm
Forum: Ideal Gases
Topic: Equilibrium Constant and Reaction Quotient
Replies: 3
Views: 250

### Re: Equilibrium Constant and Reaction Quotient

The equilibrium constant is K and Q is the reaction quotient. While they are calculated the same way ([products]/[reactants]), they are different. Q is the quantity of products and reactants that actually changes as the system approaches equilibrium. K is the numerical value of Q at the end of the r...
Wed Jan 09, 2019 9:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: how to write the formula for K
Replies: 6
Views: 208

### how to write the formula for K

I noticed in the solutions manual that when writing the equation for the K value, the concentrations were always written as the reactant or product as a subscript of P. Do we have to write it like that? I don't want to lose credit on my homework for that. Thank you!
Sat Dec 08, 2018 11:03 pm
Forum: Formal Charge and Oxidation Numbers
Topic: #21 on churro Qs
Replies: 1
Views: 388

### #21 on churro Qs

Referring to #21 on churro questions ("The overall molecule as shown is neutral. What is the oxidation state of the iron?") Can someone explain to me why the answer is +2? When I added up all of the formal charges for the surrounding N atoms, I got +6, and I don't understand how a +2 charg...
Sat Dec 08, 2018 9:19 pm
Forum: Quantum Numbers and The H-Atom
Topic: Why is this statement incorrect?
Replies: 3
Views: 389

### Why is this statement incorrect?

A question from the midterm identified the statement "the lowest value that the magnetic quantum number ml can take is -9" as incorrect. Can someone explain WHY it is incorrect?
.'
Sat Dec 08, 2018 9:18 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ranking strong bases
Replies: 2
Views: 88

### ranking strong bases

how would we go about ranking strong bases? what is the first thing we should look for when doing so?
Fri Dec 07, 2018 12:16 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ranking strong acids and bases
Replies: 4
Views: 291

### Ranking strong acids and bases

How would you go about ranking which strong acid is stronger or which strong base is stronger? For example, how would you compare HI and HClO4 or Ca(OH)2 and KOH?
Tue Dec 04, 2018 4:03 pm
Forum: Hybridization
Topic: bond angles
Replies: 2
Views: 148

### Re: bond angles

I think concerning bond angles, you are better off memorizing them specific to their shape.
Tue Dec 04, 2018 4:01 pm
Forum: Hybridization
Replies: 3
Views: 176

When you have a radical, how do you know where to place the one extra electron? Is it just in the place that would ensure the most stability about the central atom?
Tue Dec 04, 2018 4:00 pm
Forum: Hybridization
Topic: Hybridization of p orbitals
Replies: 3
Views: 231

### Re: Hybridization of p orbitals

I thought that two p orbitals could hybridize with a pi bond.
Wed Nov 28, 2018 2:14 pm
Forum: Hybridization
Topic: Biological Importance
Replies: 1
Views: 100

### Biological Importance

What is the biological importance of hybridization? When and where is it most likely to occur?
Wed Nov 28, 2018 2:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 3
Views: 95

### Re: Bond Angles

I have found that googling "VSEPR Chart" brings up great charts that you can help use to memorize these bond angles. Some can be inferred, but many, in my opinion, should just be memorized.
Mon Nov 19, 2018 12:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs. Angular
Replies: 3
Views: 175

### Re: Bent vs. Angular

It is important to understand, though, that while the names are interchangeable, there are bent shapes for structures with three and four areas of electro density. Follow the pictured bond angles when recognizing the difference.
Mon Nov 19, 2018 12:44 pm
Forum: Octet Exceptions
Topic: The center atom
Replies: 20
Views: 1163

### Re: The center atom

Here is the correct lewis structure for HClO.
Mon Nov 19, 2018 12:43 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability v. Polarizing Power
Replies: 2
Views: 188

### Re: Polarizability v. Polarizing Power

I find it helpful to separate their definitions. I think that a cation has a plus sign, so it's fitting that polarizing power has one more word than polarizability. Polarizability is therefore associated with anions, and polarizing power with cations.
Tue Nov 13, 2018 3:27 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: polarizing power vs polarizability
Replies: 3
Views: 226

### polarizing power vs polarizability

Can someone explain the difference between polarizing power and polarizability?
Tue Nov 13, 2018 3:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 6
Views: 265

### Re: Molecular Shape

We learned about the wedge and dash model in discussion today. The wedge represents the idea that the atom is coming out at you, and the dashes represent the atom falling behind the structure. This model is just a way to interpret the shape in your head.
Tue Nov 13, 2018 3:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Names and Shapes of molecules
Replies: 2
Views: 62

### Re: Names and Shapes of molecules

My TA told us to be familiar with linear, trigonal planar, angular (bent), tetrahedral, trigonal pyramidal, trigonal bi-pyramidal, seesaw, T-shaped, octahedral, square planar, and square pyramidal. You need to also know bond the different bond angles for each of these and understand the fact that st...
Sat Nov 03, 2018 12:35 am
Forum: Lewis Structures
Replies: 2
Views: 107

I've found that when I draw out structures, even if I have all of the valence electrons represented and correct, I will still get the structure wrong. I know this is because I need to make my structure have a formal charge close to 0. But, how can I be sure that it is the most stable it can be? How ...
Tue Oct 30, 2018 11:41 pm
Forum: Electronegativity
Topic: Electronegativity vs Electron Affinity [ENDORSED]
Replies: 1
Views: 161

### Electronegativity vs Electron Affinity[ENDORSED]

My TA tried to explain to us today about the difference, but it was hard to understand with the given definitions. Can someone explain the difference better and give an example comparing two elements?
Tue Oct 30, 2018 11:39 pm
Forum: Resonance Structures
Topic: How does a resonance structure work?
Replies: 10
Views: 552

### Re: How does a resonance structure work?

An important thing to remember about resonance structures, along with the above definitions, is that all of the bonds in the Lewis Structure have the same length. This displays that drawing resonance is just a way of showing that all of the bonds have the same length no matter where they are placed.
Tue Oct 30, 2018 11:37 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Finding the lowest energy structure
Replies: 5
Views: 286

### Re: Finding the lowest energy structure

I think that this is the most efficient way and only way to be completely sure of stability.
Wed Oct 24, 2018 11:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ordering of electrons in d-shell
Replies: 2
Views: 121

### Ordering of electrons in d-shell

How important is it to put, for example, 3d10 before 4s1? Does order matter even though you are conveying the same information? Are there any exceptions? Thanks!
Wed Oct 24, 2018 11:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground vs Excited State
Replies: 3
Views: 198

### Re: Ground vs Excited State

Hund's Rule is important to remember in answering this: every orbital must be filled in order for any of them to be doubly occupied. If you ever see two electrons in one orbital, two in the second and none in the third, or a diagram where one arrow is pointing up, one down, and then one up (in case ...
Wed Oct 24, 2018 11:01 pm
Forum: Properties of Light
Topic: Using a rounded speed of light in EM problems
Replies: 4
Views: 298

### Re: Using a rounded speed of light in EM problems

I always have literally typed 3E8 in my calculator and have never had a problem with it. Also, if you have a TI 36 calculator, there is a constants section that has the full number in there, so I use that a lot too.
Mon Oct 15, 2018 11:46 am
Forum: Properties of Electrons
Topic: Constructive vs Destructive
Replies: 3
Views: 131

### Constructive vs Destructive

Can someone explain the difference between constructive and destructive waves and why they are important in determining the properties of an electron? How are they unique?
Thank you!
Mon Oct 15, 2018 11:45 am
Forum: Properties of Light
Topic: List Of Equations
Replies: 2
Views: 78

### List Of Equations

Does anyone have a helpful list of equations that pertain to this unit? I've been trying to compile one, but lose track of units and constants. If anyone could post a complete list (with labeled constants), that would be very helpful!
Thank you!
Mon Oct 15, 2018 11:44 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Incorrect Atomic Model
Replies: 6
Views: 296

### Incorrect Atomic Model

Today in class we discussed an "incorrect atomic model" situation worded like this: AN electron is located inside the nucleus of an atom. For H-atoms, the electron is confined to its nuclear diameter, 1.7*10^-15 m. The process to get to the answer, which was 3.4*10^10 m/s, was very confusi...
Mon Oct 15, 2018 11:41 am
Forum: Molarity, Solutions, Dilutions
Topic: Units?
Replies: 8
Views: 501

### Re: Units?

I've found that it depends on both the question and the units that were given in the question. Whether your answer is in liters or mL doesn't matter as long as it isn't specified in the question. I like to stick to liters, as the units for molarity are mol/L.
Sat Oct 13, 2018 2:09 pm
Forum: Properties of Light
Topic: frequencies and wavelength
Replies: 5
Views: 234

### Re: frequencies and wavelength

Anjali_Kumar3E wrote:In the formula E=hv what does the letter v respresent? I know E is energy and h is a given number which is the constant but what is v.

V represents velocity of the particle.
Sat Oct 13, 2018 2:09 pm
Forum: Properties of Light
Topic: frequencies and wavelength
Replies: 5
Views: 234

### Re: frequencies and wavelength

V represents the velocity of the object.
Sat Oct 13, 2018 2:07 pm
Forum: Photoelectric Effect
Topic: Work function
Replies: 3
Views: 101

### Re: Work function

I think workforce may be a term he used in class in reference to physics as part of an example? I could be wrong.
Sat Oct 13, 2018 2:06 pm
Forum: DeBroglie Equation
Topic: Wavelike Properties
Replies: 2
Views: 84

### Wavelike Properties

How do you tell if an object has wavelike properties? Is it solely based on the answer?
Sun Oct 07, 2018 7:55 pm
Forum: Balancing Chemical Reactions
Topic: Where to start [ENDORSED]
Replies: 10
Views: 862

### Where to start[ENDORSED]

When balancing, where does everyone start? Does everyone always balance the one that occurs the least first? I was wondering if there are any other methods that people use because I have had trouble with balancing equations for a while. Thanks!
Sun Oct 07, 2018 7:53 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: diatomic elements
Replies: 12
Views: 2084

### Re: diatomic elements

In high school, we learned to remember them with a phrase pronounced "Br-inkl-hoff," which is Br(bromine), I(iodine), N (nitrogen), Cl(chlorine), H(hydrogen), O(oxygen), and F(fluorine). Helped me a lot back then and now.