## Search found 53 matches

Sat Mar 17, 2018 9:20 pm
Forum: General Rate Laws
Topic: how to find the rate constant given instantaneous
Replies: 2
Views: 368

### Re: how to find the rate constant given instantaneous

Depending on the order of the reaction which should be given, you would use the integral of the rate law equation.
Sat Mar 17, 2018 9:18 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: when exactly do you use the Arrhenius equation?
Replies: 3
Views: 407

### Re: when exactly do you use the Arrhenius equation?

When you want to find k, A, Ea, or sometimes T, when you have other parameters. But since there are many forms of the equation it can be hard to tell
Sat Mar 17, 2018 9:15 pm
Forum: Phase Changes & Related Calculations
Topic: carbon
Replies: 4
Views: 359

### Re: carbon

I think that you only have to sublimize when you have only two molecules in different states and nothing else
Sat Mar 03, 2018 11:05 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Rate Constant Units
Replies: 9
Views: 679

### Re: Rate Constant Units

Or you could think of it like this units of k=M^(1-n).s-1 where n is the order.
Sat Mar 03, 2018 10:57 pm
Forum: General Rate Laws
Topic: 15.39a
Replies: 3
Views: 245

### Re: 15.39a

I'm not quite sure why they don't use that specifically but I am pretty sure that coefficients don't really affect anything
Sat Mar 03, 2018 10:54 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: reaction mechanisms reaction rate
Replies: 2
Views: 160

### Re: reaction mechanisms reaction rate

We are given the rate law and all we are doing is proving that it is correct and logical and no the second order has nothing to do with the coefficient 2
Wed Feb 28, 2018 9:18 pm
Forum: Zero Order Reactions
Topic: Units of k [ENDORSED]
Replies: 13
Views: 667

### Re: Units of k[ENDORSED]

Basically you take the rate law (rate=k[a] for first order) and the units of rate are always mol.L-1.s-1 and then the units of concentration are always mol.L-1 and then you plug those in to find units of k, which would be s-1.
Wed Feb 28, 2018 9:16 pm
Forum: General Rate Laws
Topic: 15.85
Replies: 3
Views: 414

### Re: 15.85

Can you clarify what you mean by how the answers are constructed?
Wed Feb 28, 2018 9:11 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.107
Replies: 2
Views: 199

### Re: 14.107

E naught is standard reduction potential and E is the potential of a reaction
Thu Feb 22, 2018 9:57 am
Forum: Balancing Redox Reactions
Topic: 14.15
Replies: 2
Views: 209

### Re: 14.15

You just look in the back of the book in Appendix 2B and then find the best half reaction with Mno4- and the best half reaction for Fe2+
Thu Feb 22, 2018 9:56 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 14.33 (b) Half-reactions
Replies: 2
Views: 242

### Re: 14.33 (b) Half-reactions

I think it is because Tl+ is more stable than Tl3+
Thu Feb 22, 2018 9:55 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13 c
Replies: 1
Views: 152

### Re: 14.13 c

I think its just based off whats in Appendix 2B
Thu Feb 22, 2018 9:54 am
Forum: Balancing Redox Reactions
Topic: 14.1 (b)
Replies: 2
Views: 194

### Re: 14.1 (b)

You have to look at the other molecules and their typical oxidation states like in this one you would look at the oxidation states of H and O, Usually +1 and -2 respectively and then look at the total charge of both molecules, I think in this case its 0 for both and then you just do algebra. Like fo...
Tue Feb 20, 2018 7:58 pm
Forum: Balancing Redox Reactions
Topic: Oxidation States
Replies: 2
Views: 187

### Re: Oxidation States

I think just the ones for group 1(+1), group 2(+2), group 6(-2), group 7(-1), etc.
Tue Feb 20, 2018 7:54 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q & K?
Replies: 4
Views: 286

### Re: Q & K?

I think that was just for Chem 14A
Tue Feb 20, 2018 7:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2
Replies: 1
Views: 147

### Re: Test 2

I think we should be getting it
Wed Feb 07, 2018 8:52 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.15
Replies: 4
Views: 296

### Re: 9.15

Why is the deltaH fusion negative though? I don't understand
Wed Feb 07, 2018 8:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: formula
Replies: 3
Views: 189

### Re: formula

Is this formula ever negative?
Wed Jan 31, 2018 8:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Total Enthalpy
Replies: 2
Views: 182

### Re: Total Enthalpy

This is because reversible reactions basically means it is at equilibrium so that means that Stotal would be 0.
Wed Jan 31, 2018 8:31 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.57
Replies: 1
Views: 133

### Re: 9.57

Im pretty sure that that is just a typo in the solutions manual and it should have an l because if you look at the value they use it is the value for H20(l) not (aq)
Wed Jan 31, 2018 1:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Homework 9.55
Replies: 2
Views: 157

### Homework 9.55

In this question they ask you to calculate deltaG but they give no temperature and the solutions manual uses 298K so does that mean we are supposed to use room temperature when T is not given?
Wed Jan 24, 2018 10:09 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.41
Replies: 2
Views: 210

### Re: 8.41

This is because you are calculating the two things, the ice that melts into water and the liquid water that you started with, separately.
Wed Jan 24, 2018 10:07 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Changing the energy of a system
Replies: 6
Views: 374

### Re: Changing the energy of a system

I'm pretty sure it increases the amount of energy
Wed Jan 24, 2018 9:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies vs Standard Enthalpies of Formation
Replies: 2
Views: 141

### Bond enthalpies vs Standard Enthalpies of Formation

Why when calculating bond enthalpies are reactants positive and products negative but then when calculating standard enthalpies of formation are reactants negative and products positive?
Thu Jan 18, 2018 7:51 pm
Forum: Phase Changes & Related Calculations
Topic: 8.99
Replies: 1
Views: 152

### 8.99

For question 8.99 can someone tell my why in the last step the solutions manual uses 800g, like where did that come from?
Wed Jan 17, 2018 10:31 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73a
Replies: 2
Views: 97

### 8.73a

In this question why are there no h-c bonds broken or formed? Are they just unimportant?
Wed Jan 17, 2018 9:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.45
Replies: 2
Views: 81

### Re: 8.45

This because the reaction enthalpies are give in simply kJ, but they are meant for one mole of the reaction so for this question you need to acknowledge the units to get kJ in the answer
Thu Jan 11, 2018 7:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Molar Heat Capacity
Replies: 1
Views: 153

### Re: Molar Heat Capacity

This is because there are more atoms which makes it possible to have more possible bond vibrations that can absorb added heat.
Thu Jan 11, 2018 7:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 2
Views: 96

### Bond Enthalpies

What are bond enthalpies and what are they used for?
Thu Jan 11, 2018 7:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.31a on homework
Replies: 1
Views: 107

### Question 8.31a on homework

In the answer for 8.31a, what is the significance of Cp,m=5/2R. Is that supposed to be the molar heat capacity? If so, how would we calculate that using that formula?
Fri Dec 01, 2017 9:18 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Do lone pairs affect polarization?
Replies: 1
Views: 214

### Do lone pairs affect polarization?

Do lone pairs affect polarization? If so which way is the dipole towards the lone pair or towards the bonding atom?
Fri Dec 01, 2017 9:15 am
Forum: Naming
Topic: Order of Ligands
Replies: 8
Views: 500

### Re: Order of Ligands

Ligands are pretty much only put in order in alphabetical order although I am not sure about the prefixes bis, tris, etc.
Fri Dec 01, 2017 9:13 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Theory
Replies: 4
Views: 271

### Re: Molecular Orbital Theory

I'm pretty sure since there weren't a lot if any problems about Molecular Orbital Theory that we don't need to know it for the test.
Fri Dec 01, 2017 9:10 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Dentates
Replies: 6
Views: 419

### Dentates

How can you figure out whether or not a command is bidentate, tridentate, polydentate, etc.? Or do you just have to memorize them?
Mon Nov 27, 2017 8:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Shifts or Lie to the Right or Left
Replies: 1
Views: 154

### Shifts or Lie to the Right or Left

On the first module it asks two different questions on whether it shifts to the right or lies to the right and with left also. Is there a difference between saying shifts or lies to the right/left? If so, which is better?
Mon Nov 20, 2017 9:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: seesaw
Replies: 2
Views: 179

### Re: seesaw

Because the angle is large between the equatorial atoms at 120 degrees while if it were on the axial it would only be 90 degrees between the axial atom and the equatorial atom
Mon Nov 20, 2017 9:25 pm
Forum: Naming
Topic: meaning of bis-, tris-, tetrakis-...
Replies: 1
Views: 225

### Re: meaning of bis-, tris-, tetrakis-...

I believe that it means there are two oxalates
Mon Nov 20, 2017 9:23 pm
Forum: Hybridization
Topic: lone pair effect on hybridization
Replies: 3
Views: 207

### Re: lone pair effect on hybridization

You have to take into account the regions of electron density when hybridizing orbitals which includes the lone pairs so you have to take them into account
Mon Nov 20, 2017 8:54 pm
Forum: Hybridization
Topic: Writing Hybridization
Replies: 3
Views: 301

### Writing Hybridization

When writing the hybridization in what order does it go in? I've seen it as both sp2d and as dsp2. Which is best or which is correct?
Mon Nov 20, 2017 8:46 pm
Forum: Hybridization
Topic: Question 4.81
Replies: 2
Views: 211

### Question 4.81

For question 4.81 which asks to predict the composition of the hybrid orbitals used by each B and N atom for the compound borazine, will we have to know this for the test? I don't think Lavelle went over this in class so I want to make sure it's not super important.
Sun Nov 05, 2017 7:45 pm
Forum: Lewis Structures
Topic: 11/5 ch3 review SNF3
Replies: 1
Views: 231

### Re: 11/5 ch3 review SNF3

This is because sulfur has a lower ionization energy than nitrogen and fluorine
Sun Nov 05, 2017 7:40 pm
Forum: Lewis Structures
Topic: Review Session ClO4-
Replies: 2
Views: 196

### Review Session ClO4-

In the review session today why does the Lewis Structure have three double bonds for three of the O atoms instead of just one bond for each O atom?
Sun Nov 05, 2017 7:33 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent Bonds
Replies: 4
Views: 327

### Re: Ionic vs Covalent Bonds

Covalent bonds are stronger in terms of intermolecular bonds, but in terms of intramolecular bonds ionic bonds are stronger. This is because in terms of intermolecular bonds, there is only electrostatic energy holding the atoms together but with covalent bonds the atoms are sharing electrons which m...
Mon Oct 30, 2017 12:02 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8046
Views: 1412462

### Re: Post All Chemistry Jokes Here

Q: I heard oxygen And magnesium were going out
A: And I was like OMg
Sun Oct 29, 2017 11:59 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8046
Views: 1412462

### Re: Post All Chemistry Jokes Here

Q: Why do chemists like nitrates so much?
A: They're cheaper than day rates.
Sun Oct 29, 2017 11:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Chapter 2, #43 [ENDORSED]
Replies: 3
Views: 359

### Re: Chapter 2, #43[ENDORSED]

This is because like copper right above it, the half full or full d subshells (4d5 or 4d10) are more stable than 4d4 or 4d9 so the electron is in the 4d subshell rather than the 5s subshell
Sun Oct 29, 2017 11:50 pm
Forum: *Shrodinger Equation
Topic: Shrodinger Equation [ENDORSED]
Replies: 2
Views: 420

### Shrodinger Equation[ENDORSED]

For the upcoming test 3, what exactly do we need to know about Shrodinger's Equation? Is it just concepts or is there calculations we need to know?
Fri Oct 20, 2017 12:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Configuration Notation [ENDORSED]
Replies: 5
Views: 381

### Re: Configuration Notation[ENDORSED]

Yes because in the example he gave in class he specified what type of p orbitals. So I think we will need to do that for the test.
Fri Oct 20, 2017 12:15 pm
Forum: Properties of Electrons
Topic: Energy Levels
Replies: 3
Views: 362

### Re: Energy Levels

Yes, for example if the energy of the incoming photon matches the energy difference between n=3 and n=1 then the electron will move to n=1, but if the energy of the incoming photon matches the energy difference between n=3 and n=2 then the electron will only move to n=2.
Sun Oct 15, 2017 7:52 pm
Forum: DeBroglie Equation
Topic: When to use DeBroglie equation? [ENDORSED]
Replies: 4
Views: 374

### When to use DeBroglie equation?[ENDORSED]

I am just a little bit confused on when to use DeBroglie's equation. I'm not quite sure when to use it, so can someone please explain it to me?
Sun Oct 15, 2017 7:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Why don't we use the Rydberg equation from the book?
Replies: 8
Views: 518

### Why don't we use the Rydberg equation from the book?

I was curious as to why we don't use the Rydberg equation from the book and why it is better to use -hR/n^2? Doesn't it kind of do the same thing?
Thu Oct 05, 2017 7:37 pm
Forum: Limiting Reactant Calculations
Topic: Problem M11 part a
Replies: 5
Views: 487

### Re: Problem M11 part a

The way I solved this problem was finding the limiting reactant in the first reaction (P4) and then using the leftover O2 and the amount of P406 as the amounts given for the second reactant and then I was able to find the limiting reactant for the formation of P4O10. I did this because the question ...
Thu Oct 05, 2017 7:03 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamentals F21
Replies: 3
Views: 296

### Re: Fundamentals F21

Hi I also had a question about this problem too. In the answer after they divided each substance by 0.0113 mmol, they then multiplied by 6. I understand that you have to multiply by a whole number to get whole number ratios, but I am very confused why they used 6 and not another number like 5. If so...