## Search found 53 matches

Sat Mar 17, 2018 9:01 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre equilibrium
Replies: 5
Views: 461

### Pre equilibrium

For pre equilibrium problems, is it okay to leave K1 as k1/k1' in the overall reaction rate?
Sat Mar 17, 2018 9:00 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: internal energy
Replies: 2
Views: 313

### internal energy

If a system is said to go back to its original internal energy do we flip the sign of the internal energy?
Sat Mar 17, 2018 8:49 pm
Forum: Calculating Work of Expansion
Topic: Pressure [ENDORSED]
Replies: 1
Views: 233

### Pressure[ENDORSED]

If a problem states that a system is undergoing an expansion against an external pressure of x atm does that mean we use the w= - P(delta)V equation?
Sun Mar 11, 2018 10:13 pm
Forum: Zero Order Reactions
Topic: Chart problems [ENDORSED]
Replies: 3
Views: 383

### Chart problems[ENDORSED]

If we figure out that a reactant is of zero order, can we ignore it when comparing concentrations to figure out the orders of the other reactants?
Sun Mar 11, 2018 10:12 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Given information
Replies: 5
Views: 319

### Given information

Will we be told which rxn is the slow and which is the fast? Also will we be given the intermediate molecule?
Sun Mar 11, 2018 10:11 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K and K'
Replies: 4
Views: 292

### K and K'

Is the relationship between k and k': k=1/k' ?
Sun Mar 04, 2018 11:15 pm
Forum: General Rate Laws
Topic: zero order in rate laws
Replies: 8
Views: 545

### zero order in rate laws

If a reactant is zero order do we include it in the rate law or write it without it? For example: rate=k[A][B]^2[C]^0 or rate=k[A][B]^2?
Sun Mar 04, 2018 11:10 pm
Forum: First Order Reactions
Topic: 15.23 c
Replies: 2
Views: 227

### 15.23 c

If given the molarity of how much product was formed, how would you use dimensional analysis to figure out [A]?
Sun Mar 04, 2018 11:08 pm
Forum: First Order Reactions
Topic: First order
Replies: 4
Views: 345

### First order

When given a chart, would we identify a reactant as being first order if when its molarity is doubled the rate is doubled?
Thu Feb 22, 2018 3:13 pm
Forum: Balancing Redox Reactions
Topic: Oxidation
Replies: 3
Views: 270

### Oxidation

How do we figure out the oxidation state of a product in a redox reaction?
Thu Feb 22, 2018 3:05 pm
Forum: General Rate Laws
Topic: 15.17
Replies: 1
Views: 180

### 15.17

Is the overall order of a reaction the addition of the orders of each reactant?
Thu Feb 22, 2018 3:04 pm
Forum: First Order Reactions
Topic: 15.15
Replies: 4
Views: 291

### 15.15

Is the concentration of CH3Br raised to the power of 1.2 in the rate law for the reaction? What does 1.2 imply?
Sun Feb 18, 2018 9:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cell
Replies: 3
Views: 236

### Galvanic Cell

For a Galvanic cell, is putting salt bridge as a label enough or do we have to indicate where the NaCl is going?
Sun Feb 18, 2018 9:18 pm
Forum: Balancing Redox Reactions
Topic: Basic v Acidic
Replies: 2
Views: 170

### Basic v Acidic

Unless told so, how are we supposed to know whether to add OH- or H2O? How do we tell if the reaction is acidic or basic?
Sat Feb 17, 2018 11:19 am
Forum: Balancing Redox Reactions
Topic: 9.3b
Replies: 1
Views: 114

### 9.3b

After balancing the half reactions I had 5 electrons for the reduction and 2 for the oxidation. Is the only way to balance these by multiplying by their LCM??
Sun Feb 11, 2018 11:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Monoatomic Ideal Gases
Replies: 1
Views: 129

### Re: Monoatomic Ideal Gases

Cv corresponds to constant volume so you would use (3/2)
Sun Feb 11, 2018 3:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.53
Replies: 2
Views: 152

### 8.53

Why is m dropped in the equation q=mc(delta)T and why is q negative in this calculation?
Sun Feb 11, 2018 2:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.49
Replies: 3
Views: 246

### 8.49

In the solution manual, why are delta H and q shown to be the same when solving for internal energy?
Fri Feb 02, 2018 10:24 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.75
Replies: 1
Views: 124

### 9.75

Would a trans isomer have the same entropy as its corresponding cis octahedral crystal because they are composed of the same molecules? Or when calculating W can its position only be changed with the limitations of staying in a trans or cis formation?
Fri Feb 02, 2018 10:22 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.73
Replies: 1
Views: 106

### 9.73

Do the signs of delta S, G, H signal the spontaneity of a reaction only under standard conditions?
Fri Feb 02, 2018 10:17 am
Forum: Balancing Redox Reactions
Topic: Solids [ENDORSED]
Replies: 2
Views: 262

### Solids[ENDORSED]

When a solid cathode and anode aren't present we are allowed to put Pt(s) or Carbon (gr). Do we have to choose one element for both the oxidation and reduction or can the cathode be Pt and anode be C??
Sun Jan 28, 2018 10:13 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13
Replies: 3
Views: 224

### 9.13

Where did 1 mol come from? It is not stated in the question, when it is said to assume ideal behavior and we are not given moles does that mean we assume it is 1 mol??
Sun Jan 28, 2018 10:12 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13 [ENDORSED]
Replies: 1
Views: 151

### 9.13[ENDORSED]

Why is the equation change in S= nRln(T2/T1) used instead of S= nCln(T2/T1)? Shouldn't R be multiplied by either 5/2 or 3/2?
Sun Jan 28, 2018 10:03 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.3
Replies: 5
Views: 366

### 9.3

Why is energy negative in the first calculation of entropy (-40000J/800K) and positive in the second (40000J/200K)?
Sun Jan 21, 2018 6:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.41
Replies: 1
Views: 98

### 8.41

Why can't you set (400g)(4.184 J/Cg)(T-45) equal to (50g)(4.184 J/Cg)(T-0)? Why do we set it equal to the change in state instead?
Sun Jan 21, 2018 6:02 pm
Forum: Phase Changes & Related Calculations
Topic: 8.39
Replies: 1
Views: 115

### 8.39

For this problem, because the ice starts at 0 degrees Celsius the step accounting for the solid approaching its melting point isn't necessary correct? You can just start with the phase change calculation?
Sun Jan 21, 2018 4:26 pm
Forum: Phase Changes & Related Calculations
Topic: 8.9
Replies: 2
Views: 214

### 8.9

When calculating w, I understand how to calculate -1.48 L atm but how do we convert that to Joules to use in the equation to calculate the change in internal energy?
Mon Jan 15, 2018 10:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Determining sign of q
Replies: 2
Views: 127

### Re: Determining sign of q

It depends on whether the system releases or absorbs the J of heat
Mon Jan 15, 2018 10:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.45
Replies: 2
Views: 166

### 8.45

For part a, why are we allowed to ignore the 4 moles of C when calculating the heat absorbed in the reaction of 1.25 moles of S8?
Mon Jan 15, 2018 10:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.77
Replies: 2
Views: 145

### 8.77

I understand the calculations behind the two options (resonance vs. 3 single and 3 double bonds) but I am unsure why the resonance bond is more stable?
Mon Jan 15, 2018 10:06 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess Law
Replies: 4
Views: 293

### Hess Law

When manipulating reactions using Hess's Law I know you can multiply the rxn and deltaH by the coefficient needed to become equivalent to the desired rxn. Can you also divide both to obtain the desired rxn??
Thu Dec 07, 2017 10:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Different Shapes
Replies: 4
Views: 759

### Re: Different Shapes

T-shaped:AX3E2
Seesaw:AX4E1
Square pyramidal:AX5E1
Thu Dec 07, 2017 9:57 pm
Forum: Lewis Acids & Bases
Topic: Knowing products formed [ENDORSED]
Replies: 1
Views: 192

### Knowing products formed[ENDORSED]

Are we expected to know the reaction when only given an acid or base reactant?? If its an acid, I understand that it will form H3O+ and if a base, OH- , but how are we supposed to know the other product formed?? and will water always be the other reactant present?
Fri Dec 01, 2017 12:43 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Theory
Replies: 4
Views: 273

### Molecular Orbital Theory

Are we supposed to know this concept for the final? It wasn't covered in class and was not a homework problem, however I've seen it covered in other resources for this class.
Tue Nov 28, 2017 4:15 pm
Forum: Naming
Topic: Oxidation
Replies: 1
Views: 130

### Oxidation

When asked for the oxidation state of the metal atom do we use the changed name or leave it as is for a negative compound? For example: would we say Iron (II) or Ferrate (II) for [Fe(CN)6]^4-
Tue Nov 21, 2017 12:23 pm
Forum: Hybridization
Topic: 4.73
Replies: 2
Views: 190

### 4.73

Why are the molecules CH2 and CH2 ^ 2+ not radicals? Does the fact that carbon has an incomplete octet not qualify it to be a radical??
Tue Nov 21, 2017 12:20 pm
Forum: Hybridization
Topic: 4.31
Replies: 2
Views: 167

### 4.31

How exactly are we supposed to figure out the relative orientations of the hybrid orbitals?? Is it based off the central atom? If its tetrahedral then the atom is connected to 4 things and therefore is sp3??
Thu Nov 16, 2017 10:50 pm
Forum: Hybridization
Topic: Hybridization in Carbon
Replies: 3
Views: 192

### Hybridization in Carbon

Why is the hybridization of a Carbon atom with two single bonds and one double bond sp^2?? I would've expected it to be sp^3 because isn't it still making 4 bonds?? Or since the double bond is one area of electron density it counts as one bond??
Thu Nov 16, 2017 10:47 pm
Forum: Determining Molecular Shape (VSEPR)
Replies: 2
Views: 236

When tested and asked for the bond angle, are we expected to be very specific? For example, if the shape is trigonal pyramidal and we say the bond angle is 109.5 degrees instead of slightly less than 109.5 degrees, will we loose points??
Wed Nov 08, 2017 10:45 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: delta v
Replies: 4
Views: 387

### delta v

When solving a problem related to the Heisenberg indeterminacy equation and given the velocity as 4.65 x 10^6 +/-1.64 x 10^6 is it correct that I would plug in (2 x (1.64x10^6)) as my delta v?
Wed Nov 08, 2017 9:52 pm
Forum: Ionic & Covalent Bonds
Topic: Polar vs. Non-polar
Replies: 7
Views: 444

### Polar vs. Non-polar

If asked to identify if a bond is polar or non-polar, would we be given the distance between the two atoms in order to calculate the electric dipole moment??
Thu Nov 02, 2017 8:56 pm
Forum: Lewis Structures
Topic: 3.61
Replies: 2
Views: 251

### 3.59

In part a) ClO, I calculated the total valence e-s (13) and used a single bond, but how do we know to put the unpaired electron on chlorine and not oxygen??
Thu Nov 02, 2017 8:40 pm
Forum: Lewis Structures
Topic: 3.59
Replies: 3
Views: 329

### 3.41

For part c) H2C(NH2)COOH, the first step I did was to calculate the total number of valence electrons (30e-s). I understand after looking at the solutions manual that each atom has a full octet (or for hydrogen a full shell), but I don't understand the thought process behind connecting and centering...
Thu Oct 26, 2017 9:55 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.19 Part B
Replies: 5
Views: 427

### 2.43 part e

What is the ground sate electron configuration for (e) tungsten?? I understand that you start with [Xe] but I'm lost on how the 4f^14 5d^4 6s^2 was attained First of all will d-block n value always be one less than that of s block??? Secondly, do we plug in the f-block to the periodic table to get t...
Thu Oct 26, 2017 9:48 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs. Covalent Bonds [ENDORSED]
Replies: 8
Views: 606

### Re: Ionic vs. Covalent Bonds[ENDORSED]

In relation to covalent and ionic bonds are Lewis diagrams only applicable to covalent bonds???
Thu Oct 19, 2017 10:45 pm
Forum: Properties of Electrons
Topic: Atomic Spectra and Energy Levels
Replies: 3
Views: 278

### 1.69

I understand that in order to figure out which laser should be used we must calculate the energies and compare that to the work function of lithium, but I don't understand where the numbers being used to calculate the work function are coming from. Where did (2.93 eV) and (1.60218x10^-19 JeV^-1) com...
Thu Oct 19, 2017 10:40 pm
Forum: *Shrodinger Equation
Topic: Schrodinger Equation
Replies: 3
Views: 219

### Re: Schrodinger Equation

So this is a topic we should understand conceptually but isn't something we will be asked a mathematical question on??
Tue Oct 17, 2017 11:04 pm
Forum: Properties of Light
Topic: Oscillation of Light
Replies: 3
Views: 230

### Modules

Is the module "Chemical Equilibrium Part 1" part of this week's lectures??
Thu Oct 12, 2017 11:03 pm
Forum: Properties of Light
Topic: 1.15
Replies: 4
Views: 332

### Re: 1.15

I also had a question on this problem, in the solutions manual it plugs in 1 for the value of n1. Should we assume that the initial energy level is always 1? Or is this specifically for hydrogen??
Thu Oct 12, 2017 7:32 pm
Forum: Properties of Electrons
Topic: Rydberg's Equation [ENDORSED]
Replies: 3
Views: 293

### Rydberg's Equation[ENDORSED]

In one of the modules the professor writes the equation as v=-hR/n^2 but when I came across the equation expressed as V=R[(1/n^2) + (1/n^2)] the negative sign is gone so I'm just wondering whether or not the equation should or should not have a negative sign??
Thu Oct 12, 2017 7:10 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Memorization of frequencies for test [ENDORSED]
Replies: 2
Views: 239

### Re: Memorization of frequencies for test[ENDORSED]

I went to a UAs office hours today and was told that we will most likely be given the ranges if asked to identify the type of EM wave but should know the spectrum of visible light.
Thu Oct 05, 2017 9:29 pm
Forum: Limiting Reactant Calculations
Topic: M. 15 Fundamentals
Replies: 4
Views: 522

### Limiting Reactant

After figuring out the limiting reactant, how do I calculate how much product is produced and how much excess is produced? Do I multiply the amount of moles available of the limiting reactant by the ratio of moles in the equation???
Wed Oct 04, 2017 9:42 pm
Forum: SI Units, Unit Conversions
Topic: Limiting Reagents [ENDORSED]
Replies: 8
Views: 706

### Re: Limiting Reagents[ENDORSED]

For problem M.9 what's the process to figuring out how to write the net ionic equation for the reaction? Also will we need to know how to do that by the quiz this friday?