## Search found 59 matches

Tue Mar 13, 2018 12:32 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates
Replies: 2
Views: 213

### Re: Intermediates

If by reaction profile you mean the graph/diagram of the reaction, then the intermediates would be the troughs in between each peak/step.
Tue Mar 13, 2018 12:11 pm
Forum: Zero Order Reactions
Topic: Chart problems [ENDORSED]
Replies: 3
Views: 358

### Re: Chart problems[ENDORSED]

you can ignore it because a zero order reactant means that the rate of the reaction is not dependent on the change in concentration of that particular reactant. Therefore, you can ignore it.
Tue Mar 13, 2018 12:10 pm
Forum: *Enzyme Kinetics
Topic: Catalysts
Replies: 11
Views: 928

### Re: Catalysts

catalysts lower activation energy therefore the forward and reverse rate will both increase.
Mon Mar 05, 2018 9:45 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Overall reaction order
Replies: 3
Views: 263

### Re: Overall reaction order

But, one of the UAs told me that in this class we won't be getting fractional orders. Maybe someone could verify?
Mon Mar 05, 2018 9:43 am
Forum: First Order Reactions
Topic: K constant
Replies: 3
Views: 252

### Re: K constant

So then will we ever see a positive k value?
Mon Mar 05, 2018 9:41 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Quiz 3
Replies: 3
Views: 221

### Quiz 3

Does anyone know what numbers cover the material that is going to be on this week's quiz?
Sun Mar 04, 2018 6:11 pm
Forum: First Order Reactions
Topic: K constant
Replies: 3
Views: 252

### K constant

can someone explain what Lavelle means when he says that a negative k means negative slope, but it is negative because we want a positive k? How do you get a positive k from a negative k?
Tue Feb 27, 2018 6:52 pm
Forum: General Rate Laws
Topic: 15.3 Unique Rate of the Reaction
Replies: 1
Views: 163

### Re: 15.3 Unique Rate of the Reaction

it is. You use the rate of formation you calculated and divide it by 2 because there is a coefficient of 2 in front of the NO
Mon Feb 26, 2018 2:52 pm
Forum: General Rate Laws
Topic: Overall Order
Replies: 2
Views: 187

### Re: Overall Order

the orders of reactions are the individual powers and the overall order is all of the exponents added together.
Tue Feb 20, 2018 4:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt (s)
Replies: 2
Views: 206

### Re: Pt (s)

What if the electrode isn't made of Pt but some homework problems put Pt as an inert solid on top of the electrode? How do you know when to include an inert solid?
Tue Feb 20, 2018 4:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Flipping the Anode
Replies: 1
Views: 150

### Flipping the Anode

I am confused when you would flip the oxidation half reaction? Also, there were some problems in the homework where you're calculating Ecell from the E of both half reactions, and they don't flip the sign? So how do you know when to flip the sign of E?
Tue Feb 20, 2018 4:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.23c
Replies: 2
Views: 199

### Re: Homework 14.23c

I am not sure what you mean by "why is Pu3+(aq), Pu4+(aq) written Red,Ox?" but that half reaction is supposed to be the oxidation half reaction because it is becoming more positive.
Tue Feb 20, 2018 4:19 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: PH meter
Replies: 3
Views: 243

### Re: PH meter

I'm pretty sure your just looking for the pH of the cell. So you would use the concentrations to find [H+] and then use -log[H+] to find the pH.
Sun Feb 18, 2018 1:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams and Cell Potential
Replies: 1
Views: 146

### Re: Cell Diagrams and Cell Potential

I thought we just switch it back because electrons always flow out of the anode.
Sat Feb 17, 2018 11:11 pm
Forum: Balancing Redox Reactions
Topic: 14.1 Part D
Replies: 4
Views: 256

### Re: 14.1 Part D

you have to split it up into its half reactions. but when you add up the equations, you have to make sure to multiply each half reaction to make the number of electrons on each side cancel out.
Sat Feb 17, 2018 9:10 pm
Forum: Balancing Redox Reactions
Topic: Test #2
Replies: 5
Views: 313

### Re: Test #2

I think it is just electrochem. chapter 14
Mon Feb 05, 2018 3:58 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Vibrationally Active
Replies: 1
Views: 249

### Vibrationally Active

What does it mean when they say that diatomic molecules are vibrationally active? Does it have a higher change in entropy than diatomic molecules that are not?
Mon Feb 05, 2018 3:54 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: molar entropy
Replies: 3
Views: 195

### molar entropy

How do you know which molecule has higher molar entropy? And is molar entropy the same as the entropy we have been talking about?
Mon Feb 05, 2018 3:52 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Evaluation 9.2B
Replies: 1
Views: 138

### Re: Evaluation 9.2B

I'm pretty sure you have to convert the temperature to kelvin. Multiply the specific heat by the grams of steel they give you and plug into the equation.
Tue Jan 30, 2018 6:46 pm
Forum: Phase Changes & Related Calculations
Topic: hw problem #109
Replies: 1
Views: 131

### Re: hw problem #109

density is used to calculate the mass of the water. If they give you a certain volume of water (i.e 1L), you would use the density of water (1.00g/ml) to convert the 1L to grams.
Tue Jan 30, 2018 6:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpies
Replies: 3
Views: 235

### Re: bond enthalpies

I'm not entirely sure what you mean by "when they give you bond enthalpies of only the products", but the enthalpy of a reaction can be calculated by subtracting the sum of the bonds broken (reactants) - the sum of the bonds formed (products) the bond enthalpies are the enthalpies for each...
Mon Jan 29, 2018 10:24 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy in Relation to Temp [ENDORSED]
Replies: 1
Views: 140

### Entropy in Relation to Temp[ENDORSED]

I would think that entropy would increase when temperature increases but according to the equation S=q/t, there is an indirect relationship between the two. Can someone explain why?
Wed Jan 24, 2018 1:44 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: qp=deltaH
Replies: 2
Views: 3165

### qp=deltaH

Can someone explain why qp=deltaH at constant pressure?
Tue Jan 23, 2018 6:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Isothermal expansion
Replies: 3
Views: 197

### Re: Isothermal expansion

I think it is because in and irreversible isothermal expansion, no work or heat is being lost so the internal energy stays constant. The book says that when an ideal gas expands isothermally, its molecules continue to move at the same average speed, so their total KE remains the same, and because th...
Tue Jan 23, 2018 3:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: How to use Hess’s Law
Replies: 1
Views: 91

### Re: How to use Hess’s Law

You always add whatever is on the same side of the equations and subtract the ones opposite. That's why the CO2's cancel off.
Tue Jan 23, 2018 11:50 am
Forum: Calculating Work of Expansion
Topic: expansion vs non expansion
Replies: 1
Views: 123

### expansion vs non expansion

is non expansion work and expansion work the same as reversible and irreversible work, respectively?
Fri Jan 19, 2018 10:51 am
Forum: Phase Changes & Related Calculations
Topic: Phase Change and Energy Absorbed
Replies: 1
Views: 111

### Re: Phase Change and Energy Absorbed

Because it requires a certain amount of energy to get through the phase change itself, you have to use m(Delta)H. Then after the substance has changed phases you have to use mC(delta)T to find the q. You add them together because that is the total q for the substance to get through the phase change ...
Thu Jan 18, 2018 9:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.67
Replies: 3
Views: 155

### Re: 8.67

For part a, that's what I thought, but the solutions manual said that water is in gas form so you have to use the enthalpy of vaporization equation to find the enthalpy of the liquid state. So are we supposed to know that H2 gas and O2 gas make H2O gas. And for the rest of the parts, are we assuming...
Thu Jan 18, 2018 9:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.67
Replies: 3
Views: 155

### 8.67

8.67: Estimate the enthalpy of formation of each of the following compounds in the liquid state. (a) H2O (b) methanol (c) benzene (d) benzene (without resonance)

how do you know what phase each is in when it is produced?
Tue Jan 16, 2018 3:38 pm
Forum: Calculating Work of Expansion
Topic: Expansion/Contraction
Replies: 2
Views: 164

### Expansion/Contraction

when the book says that internal energy equals q when no expansion or contraction take place, does that mean volume stays the same? In other words, are expansion/contraction referring to whether the volume increases/decreases, respectively?
Tue Jan 16, 2018 12:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 2
Views: 213

### Re: Bond Enthalpies

You only include the bonds that change at the reaction goes, so yes exclude those that stay the same in reactants and products.
Mon Jan 15, 2018 12:31 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 3 Methods
Replies: 4
Views: 250

### Re: 3 Methods

You use Hess law when they give you multiple reactions with the enthalpy of reaction values. You add up the bonds formed and broken when your given a table with bond enthalpies. And you use the enthalpy of formations when everything in the reaction is in standard state.
Tue Jan 09, 2018 8:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Constant P vs Constant V [ENDORSED]
Replies: 2
Views: 168

### Constant P vs Constant V[ENDORSED]

I know that when P is constant, q=deltaH for the reaction. What happens when V is constant? Is there a certain relationship between these two?
Tue Jan 09, 2018 8:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat vs Energy
Replies: 2
Views: 175

### Heat vs Energy

When talking about the definition of heat capacity, can heat and energy be used interchangeably? Is that why they both have the same units?
Sat Dec 09, 2017 5:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.79
Replies: 1
Views: 243

### 11.79

If the Kp is greater than 10^-3, but the denominator has an order that is larger than a quadratic, can we still use the 5% rule.
Fri Dec 08, 2017 2:54 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 12.65
Replies: 1
Views: 216

### Re: 12.65

If there are H3O+ ions in the equation, it means the reaction is acidic; therefore, less than 7. If there are OH- ions then the reaction is basic, greater than 7. If the reaction is a neutralization reaction, strong acid nd strong basic, producing water and a salt, the reaction is neutral, pH is 7.
Wed Dec 06, 2017 10:37 am
Forum: Administrative Questions and Class Announcements
Topic: REVIEW WORKSHEET (CH 3 & 4) FALL 2017 [ENDORSED]
Replies: 5
Views: 778

### Re: REVIEW WORKSHEET (CH 3 & 4) FALL 2017[ENDORSED]

Thank You!
Wed Nov 29, 2017 10:02 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K constant
Replies: 1
Views: 133

### K constant

How do you know when to use K and Kc because in the homework, there are some problems where the reactants and the products are all gases, but I get it wrong because I used Kc instead of K and vice versa? Also, is it true that the larger K is, the more stable the reaction?
Mon Nov 27, 2017 9:54 pm
Forum: Naming
Topic: Neutral ligands
Replies: 1
Views: 138

### Re: Neutral ligands

there's also en(ethylenediamine) and dien(diethylenetriamine).
Mon Nov 27, 2017 9:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Assuming x is negligible
Replies: 3
Views: 304

### Re: Assuming x is negligible

I think he addressed this question on one of the modules. If K is less than 10^-3, that's when you can assume x is negligible.
Fri Nov 24, 2017 10:29 pm
Forum: Hybridization
Topic: Nitrogen hybridization
Replies: 2
Views: 239

### Re: Nitrogen hybridization

Nitrogen originally has 5 electrons so three electrons will make the three bonds but the last two will serve as the last place of electron density. nitrogen can make 3 bonds by sharing its electrons, but there is still one lone pair after.
Tue Nov 21, 2017 2:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: CH2CL2 4.25
Replies: 2
Views: 133

### Re: CH2CL2 4.25

There is nothing that says that the Cl's are opposite. Also, drawing it on paper does not accurately depict the actual shape. The different atoms are what makes it polar.
Thu Nov 16, 2017 11:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Figure 4.7
Replies: 1
Views: 130

### Re: Figure 4.7

If I am understanding your question correctly, a molecule's polarity is dependent upon the atoms that are attached to the central atom when there is no lone pairs. For example if you have CCl4, that would nonpolar because the molecule has four attachments on the C and they are all the same; therefor...
Mon Nov 13, 2017 10:21 am
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE [ENDORSED]
Replies: 2
Views: 183

### Re: AXE[ENDORSED]

My bad, I think it was 9 shapes
Mon Nov 13, 2017 10:10 am
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE [ENDORSED]
Replies: 2
Views: 183

### Re: AXE[ENDORSED]

Both. For me, visualizing it is easier, but Lavelle said to know the AXE format so he is probably going to test on that. And we went over 8 so far
Sun Nov 12, 2017 5:18 pm
Forum: Dipole Moments
Topic: Dipole // Molecular Shape and Bond Polarity
Replies: 2
Views: 201

### Re: Dipole // Molecular Shape and Bond Polarity

I'm not sure about shape but bond polarity is dictated by the dipole moment. if the difference in electronegativity is zero, then the bond is nonpolar and if it is greater than zero, the bond is polar. The larger the difference in electronegativity, the larger the dipole moment.
Fri Nov 10, 2017 10:25 pm
Forum: Lewis Structures
Topic: Lewis acids and bases [ENDORSED]
Replies: 3
Views: 327

### Re: Lewis acids and bases[ENDORSED]

An atom, ion, or molecule with an incomplete octet of electrons can act as an Lewis acid.
Thu Nov 02, 2017 7:36 pm
Forum: Lewis Structures
Topic: Expanded rules
Replies: 4
Views: 194

### Re: Expanded rules

any element that is in period 3 and below because there is a d orbital present
Mon Oct 30, 2017 5:28 pm
Forum: Lewis Structures
Topic: Formal Charge and Lewis Structures
Replies: 2
Views: 183

### Formal Charge and Lewis Structures

If we draw a Lewis structure and the formal charge isn't zero for multiple different formations, do we draw all of the possible arrangements as a resonance? For example, 3.35b has BrO^- but when you calculate the formal charge with a single bond, O has a -1 charge. When there is a double bond betwee...
Thu Oct 26, 2017 7:44 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Electron affinity
Replies: 4
Views: 279

### Electron affinity

does the nuclear charge have an effect on electron affinity or is it only because of the atom having an almost filled valence shell?
Tue Oct 24, 2017 1:09 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Shells, Subshells, and Orbitals
Replies: 4
Views: 429

### Shells, Subshells, and Orbitals

What Is the difference between shells, subshells, and orbitals?
Sun Oct 22, 2017 3:30 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Week 4 [ENDORSED]
Replies: 5
Views: 420

### Week 4[ENDORSED]

So is Week 4 only covering topics in chapter 2 or are we going into chapter 3 as well? If so, then Quiz 3 will be covering 1.6-1.7, all of ch2, and ch3 correct?
Mon Oct 16, 2017 5:23 pm
Forum: DeBroglie Equation
Topic: De Broglie Wavelength
Replies: 23
Views: 1881

### Re: De Broglie Wavelength

Isn't it approx. 420nm?
Mon Oct 16, 2017 5:20 pm
Forum: Properties of Light
Topic: Photoelectric Effect Post-Assessment Question 31A
Replies: 1
Views: 166

### Re: Photoelectric Effect Post-Assessment Question 31A

The work function is 3.607x10^-19 J.

Also, the longest wavelength that could remove the electron would be when Ek=0.

So you use Ek=h(frequency)-(work function)

Frequency=c/wavelength

0=h(c/wavelength) - (work function)
0=(6.626x10^-34)(3.00x10^8/wavelength) - (3.607x10^-19)

Solve for wavelength.
Mon Oct 09, 2017 2:39 pm
Forum: Photoelectric Effect
Topic: Maximum possible kinetic energy of the emitted electrons
Replies: 7
Views: 772

### Re: Maximum possible kinetic energy of the emitted electrons

Oh ok, I understand. Thank you!
Mon Oct 09, 2017 9:43 am
Forum: Photoelectric Effect
Topic: Maximum possible kinetic energy of the emitted electrons
Replies: 7
Views: 772

### Maximum possible kinetic energy of the emitted electrons

If molybdenum is irradiated with 194 nm light, what is the maximum possible kinetic energy of the emitted electrons? The calculated minimum work is 7.22x10^-19J

Sat Oct 07, 2017 4:47 pm
Forum: Properties of Electrons
Topic: Balmer vs Lyman series [ENDORSED]
Replies: 5
Views: 619

### Balmer vs Lyman series[ENDORSED]

I know that the Balmer series categorizes the visible part of the EM spectrum right? And the Lyman categorizes the lines in the UV region. But what role do these play when solving problems with the Rydberg equation, if it plays any? Is it a different constant, R? or does it not really matter much.
Sat Oct 07, 2017 2:18 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Unit [ENDORSED]
Replies: 2
Views: 255

### Re: Formula Unit[ENDORSED]

a mole = 6.0221 x 10^23 formula units = 6.022 x 10^23 molecules

empirical formula of any ionic or covalent network solid compound used as an independent entity
Sat Oct 07, 2017 2:15 pm
Forum: Limiting Reactant Calculations
Topic: Theoretical Yield [ENDORSED]
Replies: 6
Views: 491

### Re: Theoretical Yield[ENDORSED]

We've basically been calculating theoretical yields rather than actual yields this whole time, so we would only know the actual yield if it were given to us in the problem. And then you would take the actual yield that is given and divide that over the theoretical yield calculated times 100 to find...