Search found 49 matches

by Laura Riccardelli
Wed Mar 14, 2018 8:50 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm Question 6A
Replies: 2
Views: 198

Re: Midterm Question 6A

They gave the point to both A and B and A was correct because the C8H18 is such a massive molecule that it will have a higher entropy.
by Laura Riccardelli
Wed Mar 14, 2018 8:48 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Positive or Negative Entropy
Replies: 2
Views: 210

Re: Positive or Negative Entropy

Because the disorder of the container went up as is shown by the increase in the number of moles and the change in phase from solid to liquid and gas.
by Laura Riccardelli
Wed Mar 14, 2018 8:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidation Power
Replies: 3
Views: 124

Re: Oxidation Power

The higher the standard standard reduction potential the better oxidizing agent and the more likely the reaction is to be reduced and the more negative the stanbdard potential the better a reducing agent and the more likely to be oxidized.
by Laura Riccardelli
Tue Mar 06, 2018 4:06 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Units for reaction rates
Replies: 2
Views: 127

Re: Units for reaction rates

And you can get these fom the equations for 0, 1st, and 2nd odrder reactions that are on the equations sheet.
by Laura Riccardelli
Tue Mar 06, 2018 4:03 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.55c
Replies: 1
Views: 78

Re: 15.55c

I think your reasoning is correct. Maybe the questions should have been more specific.
by Laura Riccardelli
Tue Mar 06, 2018 4:00 pm
Forum: First Order Reactions
Topic: 15.37
Replies: 3
Views: 128

Re: 15.37

I think you can use mass because you would be dividing by the same number of L on both sides so they would cancel anyways.
by Laura Riccardelli
Fri Mar 02, 2018 12:23 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Average rate [ENDORSED]
Replies: 6
Views: 438

Re: Average rate [ENDORSED]

Would we need to know if the reaction is proceeding in the forward direction based on the k value?
by Laura Riccardelli
Fri Mar 02, 2018 12:19 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: 15.3 [ENDORSED]
Replies: 7
Views: 240

Re: 15.3 [ENDORSED]

In part c of this peoblem it asks what is unique about it. Could someone explain this to me.
by Laura Riccardelli
Fri Mar 02, 2018 12:16 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.97
Replies: 1
Views: 125

14.97

In problem 14.97 they want you to calculate the ka value. How is this differnt from regular k?
by Laura Riccardelli
Thu Feb 22, 2018 1:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Self Test 14.5B part a
Replies: 1
Views: 113

Re: Self Test 14.5B part a

This is a really good question!
by Laura Riccardelli
Thu Feb 22, 2018 1:01 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 14.33
Replies: 2
Views: 145

Re: 14.33

I think that it means that the ion beocme more neutral.
by Laura Riccardelli
Thu Feb 22, 2018 1:00 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.33
Replies: 1
Views: 113

Re: 14.33

That means that it will become less charged or closer to a neutral charge.
by Laura Riccardelli
Thu Feb 15, 2018 7:08 pm
Forum: Balancing Redox Reactions
Topic: Splitting Redox Reactions
Replies: 3
Views: 170

Re: Splitting Redox Reactions

This is an exccelent question. I was wondering the same thing.
by Laura Riccardelli
Thu Feb 15, 2018 7:05 pm
Forum: Balancing Redox Reactions
Topic: 14.5 c
Replies: 2
Views: 103

14.5 c

I am confused on how cr 3+ is the reducing agent and MnO is the oxidizing agent for this reaction. It seems like it should be opposite.
by Laura Riccardelli
Thu Feb 15, 2018 7:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.9
Replies: 2
Views: 96

Re: 14.9

The n value is found by the diffeence in the number of moles on the product and reactant side.
by Laura Riccardelli
Tue Feb 06, 2018 2:45 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: System vs Surrounding
Replies: 4
Views: 181

Re: System vs Surrounding

I think that they would tell us if it was not obvious what the system and surroundings are.
by Laura Riccardelli
Tue Feb 06, 2018 2:37 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.11
Replies: 2
Views: 118

Re: 9.11

I used the equation delta S=nRTln(P1/P2) since the pressure is changing and these is a constant temperature. You can substitute (T2/T1) for (P1/P2) using the ideal gas law.
by Laura Riccardelli
Tue Feb 06, 2018 2:32 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity and the Direction of a Reaction
Replies: 2
Views: 120

Re: Spontaneity and the Direction of a Reaction

My understanding is that if the delta G is negative then it is a spontaneous favorable reaction and will proceed toward the products.
by Laura Riccardelli
Tue Jan 30, 2018 4:35 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: isothermal
Replies: 5
Views: 169

Re: isothermal

Also, since delta U is zero then we also know that q=-w.
by Laura Riccardelli
Tue Jan 30, 2018 4:32 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 9.19
Replies: 3
Views: 146

Re: 9.19

I think because it does not specify you don't need to worry about moles.
by Laura Riccardelli
Tue Jan 30, 2018 4:31 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Regarding the equation deltaS=nCln(Tf/Ti)
Replies: 3
Views: 208

Re: Regarding the equation deltaS=nCln(Tf/Ti)

If you look at problem 9.19 they give you the Cp for liquid and vapor water so I am assuming that the equation can be used for nay state as long as they give you the Cv/Cp for the problem.
by Laura Riccardelli
Thu Jan 25, 2018 12:20 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Confusion about entropy formula
Replies: 6
Views: 141

Re: Confusion about entropy formula

Also,most biological systems are irreversible because that needs less work then reversible expansion.
by Laura Riccardelli
Thu Jan 25, 2018 12:16 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: 8.65
Replies: 3
Views: 166

8.65

I am confused in this homework problem where the N2 value goes because it is not in the final equation when using Hess's Law. I know that the delta H of N2 is era but it does not show up in the final equation with the actual molecules.
by Laura Riccardelli
Thu Jan 25, 2018 12:01 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Confusion about entropy formula
Replies: 6
Views: 141

Re: Confusion about entropy formula

I think that the reversible problems occur in heat reservoir so they have a constant temperature all the time.
by Laura Riccardelli
Wed Jan 17, 2018 5:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.99
Replies: 1
Views: 125

8.99

In this problem the you have to use the equation H= sum of n(Hf) of products -sum of n(Hf) of reactants but the solution manual seems to have these the products being subtracted from the reactants. How is this correct? Am I using the wrong formula?
by Laura Riccardelli
Tue Jan 16, 2018 2:43 pm
Forum: Phase Changes & Related Calculations
Topic: 8.15 b
Replies: 3
Views: 149

8.15 b

Why is it that w=0 is always true in an adiabatic system because I thought that work could be done to or by the system as long as no heat was lost or gained from the soundings?
by Laura Riccardelli
Tue Jan 16, 2018 2:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.31
Replies: 4
Views: 149

Re: 8.31

I believe that you should use the equation q=(M)(change in T )(specific heat capacity) the solution maple also has you using the equations Cp,m=(5/2) R to find the specific heat capacity for the ideal gas at an constant pressure and Cv,m= (3/2) R for the molecule at a specific volume. I am confused ...
by Laura Riccardelli
Thu Jan 11, 2018 1:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 8
Views: 327

Re: Hess's Law

I found in question 8.55 that the O2 term was multiplied by 1.5 to cancel out but the rest of the equation remained the same. How is this allowed?
by Laura Riccardelli
Thu Jan 11, 2018 12:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Chapter 8
Replies: 6
Views: 210

Re: Chapter 8

I found that equation 55 starts with the problems that my TA and Lavelle has referenced
by Laura Riccardelli
Thu Jan 11, 2018 12:57 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.55
Replies: 1
Views: 110

Question 8.55

In question 8.55 in the answer manual, in order to get ride of the 1.5 O2 in the first equation to end up with the second equation the O2 molecules in the second equation is made into 1.5 O2 as well but nothing is changed in the rest of the equation. I am wondering how you are able to change the O2 ...
by Laura Riccardelli
Wed Dec 06, 2017 2:20 pm
Forum: Air Pollution & Acid Rain
Topic: compounds for acid rain
Replies: 3
Views: 423

Re: compounds for acid rain

Lavelle said we should complete the acid run homework problem but I did not find it. Do you know which problem he is referring to?
by Laura Riccardelli
Wed Dec 06, 2017 2:18 pm
Forum: Dipole Moments
Topic: Dipole Moments and Polarity
Replies: 9
Views: 367

Re: Dipole Moments and Polarity

If the shape of the molecule is trigonal bi-pyramidal do the dipole moments cancel because their are 5 binding sites?
by Laura Riccardelli
Thu Nov 30, 2017 2:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Denate
Replies: 3
Views: 157

Denate

How do you know if a molecule is mono, bi, tri, tetra, or hexadenate simply by looking at the molecular name?
by Laura Riccardelli
Mon Nov 27, 2017 4:08 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: problem 11.89
Replies: 1
Views: 133

problem 11.89

The problem has a graph and asks you to write a balanced chemical equation for it but gives no coefficients. How do you write the balanced equation?
by Laura Riccardelli
Tue Nov 21, 2017 3:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 11.39
Replies: 3
Views: 229

Re: Question 11.39

Look at the base equations H2 + Cl2= 2HCl and 2BrCl=Br2 = Cl2 which have corresponding K values and multiply those K values together.
by Laura Riccardelli
Tue Nov 21, 2017 2:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.13
Replies: 2
Views: 163

11.13

Can someone explain the difference between Q and K?
by Laura Riccardelli
Wed Nov 15, 2017 1:41 pm
Forum: Hybridization
Topic: Unhybridized Orbitals
Replies: 2
Views: 135

Re: Unhybridized Orbitals

The orbitals that are not a part of the hybridized orbital as will form pi bonds.
by Laura Riccardelli
Fri Nov 10, 2017 11:46 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polar vs nonpolar vs ionic
Replies: 11
Views: 1220

Re: Polar vs nonpolar vs ionic

Is a N2 molecule covalent?
by Laura Riccardelli
Fri Nov 10, 2017 11:43 am
Forum: Lewis Acids & Bases
Topic: Lone Pairs in Bases?
Replies: 2
Views: 204

Re: Lone Pairs in Bases?

And likewise, a molecule that needs a lone pair to be stable would be a Lewis acid. You can think about OH- and H+ as examples. H+ is the acid because it needs another election to be stable while OH- is a base because it can donate an electron in order to be stable.
by Laura Riccardelli
Thu Nov 02, 2017 5:26 pm
Forum: Lewis Structures
Topic: 3.61
Replies: 2
Views: 195

3.61

In problem 3.61 b, how do we know that "I" has to have 12 electrons and does not follow the octet rule?
by Laura Riccardelli
Thu Nov 02, 2017 5:24 pm
Forum: Lewis Structures
Topic: 3.59
Replies: 3
Views: 202

3.59

In problem 3.39, how do we know that some of the Lewis structures should have double bonds such as in c and some should only have single bonds such as in a and b? Does this have to do with the Formal Charge?
by Laura Riccardelli
Tue Oct 24, 2017 1:24 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Ground State naming of elements
Replies: 1
Views: 117

Ground State naming of elements

Which elements are we expected to be able to name in the ground state?
by Laura Riccardelli
Tue Oct 24, 2017 12:05 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question 51
Replies: 1
Views: 133

Question 51

hen you are writing the electron configuration for elements in order to find the unpaired electrons, how do you know which quantum number (ex: 4f, 3p, 2s) to continue counting up with after the core element is used form the Nobel gases? Do you simply have to count all the quantum numbers out and the...
by Laura Riccardelli
Thu Oct 19, 2017 11:56 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.19 Part B
Replies: 5
Views: 265

Re: 2.19 Part B

I was also a little confused by this question but I believe that because it is talking about "d" orbitals which can have 5 different lobes each lobe can have a different sub-shell value so their would be 5 possible ml or sub-shell values.
by Laura Riccardelli
Thu Oct 19, 2017 11:25 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: ch1 question 43
Replies: 8
Views: 556

Re: ch1 question 43

Will Lavelle ever use the "h" that stands for another value other then Planks constant that the solution manual uses in the equation?
by Laura Riccardelli
Tue Oct 10, 2017 9:53 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Chapter 1 question 15
Replies: 4
Views: 555

Re: Chapter 1 question 15

How often will be asked to apply Rydberg's equation in this class?
by Laura Riccardelli
Tue Oct 10, 2017 9:38 pm
Forum: Einstein Equation
Topic: HW 1.23
Replies: 4
Views: 470

Re: HW 1.23

In the answer to question 1.23 how did you get the equation lambda=(hc)/E from the two equations E=hv and c=lambda?
by Laura Riccardelli
Tue Oct 03, 2017 5:11 pm
Forum: SI Units, Unit Conversions
Topic: Formula Units [ENDORSED]
Replies: 9
Views: 536

Re: Formula Units [ENDORSED]

When you write the answer to question 9 do you follow the number answer with "formula units" or do you leave it blank?
by Laura Riccardelli
Tue Oct 03, 2017 5:05 pm
Forum: SI Units, Unit Conversions
Topic: Test 1 [ENDORSED]
Replies: 3
Views: 474

Re: Test 1 [ENDORSED]

The problems that can be found in the first three modules on the class website are also a great way to study for the test.

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