Search found 61 matches

Sun Mar 17, 2019 7:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: bomb calorimeter
Replies: 8
Views: 741

Re: bomb calorimeter

So, if volume does not change, then work is equal to zero in a bomb calorimeter, right?
Thu Mar 14, 2019 3:31 am
Forum: General Rate Laws
Topic: Half-life formulas
Replies: 1
Views: 91

Half-life formulas

Could someone briefly list the different half-life formulas for each order of reactions?
Tue Mar 12, 2019 4:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: order of a cell diagram
Replies: 4
Views: 174

Re: order of a cell diagram

The order of a cell diagram would have a structure of: anode|gas, liquid| aq. molecule || aq. molecule|gas, liquid|cathode. Everything to the left of the || is the oxidation reaction while everything to the right of the || is the reduction reaction. H+ if it is in aqueous state would be in the sect...
Tue Mar 12, 2019 4:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: order of a cell diagram
Replies: 4
Views: 174

order of a cell diagram

Can someone please reiterate the order of a cell diagram and where H+ goes?
Mon Mar 11, 2019 6:50 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: PH of a Cell
Replies: 1
Views: 84

PH of a Cell

How do you calculate the pH of a cell, using the Nernst equation? Or can we use the standard potential?
Mon Mar 11, 2019 6:47 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 3
Views: 150

Re: Cell Diagram

Cole Doolittle 2K wrote:H+ is included in the cell diagram, but H2O (l) and electrons are not.

Also, is the H+ state aqueous?
Sat Mar 09, 2019 1:33 pm
Forum: General Rate Laws
Topic: Positive/negative sign for rates
Replies: 1
Views: 92

Positive/negative sign for rates

Is the sign for rate of formation of products and rate of consumption of reactants always positive, if so why?
Sun Mar 03, 2019 8:47 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Melting of ice
Replies: 9
Views: 391

Re: Melting of ice

MichaelMoreno2G wrote:As mentioned above, Delta G would be less than zero because the reaction is spontaneous.

But how do you determine whether the reaction is spontaneous or not?
Sun Mar 03, 2019 8:34 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Rate Determining Step
Replies: 9
Views: 483

Re: Rate Determining Step

The rate-determining step is the slowest step in a reaction mechanism. Because it is the slowest, it determines the rate of the overall reaction. In a reaction with a slow initial step, the rate law will simply be determined by the stoichiometry of the reactants. How do you determine whether a step...
Sun Mar 03, 2019 8:15 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Cell diagram
Replies: 4
Views: 174

Re: Cell diagram

Also, how do you know when to add a conducting solid to the cell diagram?
Sun Feb 24, 2019 11:34 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 3
Views: 144

Re: Cell diagram

So when it is reversed, does the standard reduction potential become negative?
Sun Feb 24, 2019 11:20 am
Forum: Balancing Redox Reactions
Topic: How do you balance a redox reaction
Replies: 4
Views: 142

Re: How do you balance a redox reaction

I think that you also have to make sure that the charges on both sides of the reaction is balanced. So even if the amount of atoms on both sides is balanced, you still need to balance the charge.
Sun Feb 24, 2019 10:26 am
Forum: Van't Hoff Equation
Topic: Van't Hoff equation
Replies: 2
Views: 345

Re: Van't Hoff equation

I’m assuming it is when you want to find the change in gibb’s free energy, and you are given the change in enthalpy and change in entropy of the reaction. But I could be wrong.
Sun Feb 17, 2019 11:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 4
Views: 162

Re: Spontaneity

A reaction is spontaneous when the delta G value is negative. This indicates that the given reaction is favorable in that direction and will lead to a release in free energy, meaning that reactants have more free energy to do work than the products. Why does a negative value for delta g indicate th...
Sun Feb 17, 2019 11:44 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Extensive Property
Replies: 3
Views: 372

Re: Extensive Property

Also, is there a correlation between state functions and extensive Properties?
Sun Feb 17, 2019 11:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 5
Views: 187

Re: Gibbs Free Energy

I am also confused, I recall the professor saying something about Gibbs Free Energy being leftover energy, but I just don’t remember from what.
Sun Feb 10, 2019 11:11 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Using R
Replies: 10
Views: 355

Re: Using R

Are we required to memorize all the different values of r?
Sun Feb 10, 2019 11:08 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 10
Views: 372

Re: Reversible vs Irreversible

Which of the reactions requires you to take the integral of the change in volume when calculating work?
Sun Feb 10, 2019 11:03 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Degeneracy
Replies: 3
Views: 296

Re: Degeneracy

Also, it’s kind of confusing why work and degeneracy have the same constant. Are they somehow related?
Sun Feb 03, 2019 11:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Constant P
Replies: 4
Views: 155

Re: Constant P

Celeste 1I wrote:If it is not otherwise stated, yes you assume the pressure is equal to 1 atm.

Why do we assume that pressure is equal to 1 ATM when the pressure is constant?
Sun Feb 03, 2019 11:21 pm
Forum: Phase Changes & Related Calculations
Topic: Heat
Replies: 6
Views: 210

Re: Heat

Mukil_Pari_2I wrote:For the reaction, q would be negative if that helps.

I do not think this is correct because if a reaction releases heat then q will be negative-the reaction is losing the energy. On the other hand, if a reaction requires heat then q will be positive because the reaction is gaining the energy.
Sun Feb 03, 2019 11:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: isolated vs closed system
Replies: 7
Views: 327

Re: isolated vs closed system

An example of a closed system is a beaker that can allow energy to exchange with the surroundings but matter doesn't exchange with the surroundings. An example of a closed system would be a really well-insulated coffee mug that doesn't allow energy or matter to exchange with surroundings. Would the...
Sun Jan 27, 2019 10:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating Enthalpy
Replies: 2
Views: 84

Re: Calculating Enthalpy

In the example professor did in class, he added the reactants and products of the two reactions for the formation of nitrogen oxide and its reaction with oxygen, along with their enthalpies.
Sun Jan 27, 2019 10:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard reaction enthalpy
Replies: 2
Views: 109

Re: Standard reaction enthalpy

You can calculate the standard reaction enthalpy by using the standard enthalpy of formation of all products and subtract the standard enthalpy of formation of all reactants. Can you briefly explain what the standard enthrall of formation of an element is? I know that the element has to be in its m...
Wed Jan 23, 2019 11:34 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating pH of a weak acid and its salt
Replies: 4
Views: 372

Re: Calculating pH of a weak acid and its salt

Yes, the steps are exactly the same as calculating without a salt (though the calculations might be a bit more difficult). In these types of problems, the thing to note is that the initial concentration for the salt (or product of the salt) will not be zero. Therefore, the equilibrium concentration...
Sun Jan 20, 2019 11:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Shortcut method (finding concentration change)
Replies: 5
Views: 169

Re: Shortcut method (finding concentration change)

It's also important to remember that we are not saying that X=0, but that it is a small enough number so that when subtracted from a larger number, that larger number remains relatively the same amount.
Sun Jan 20, 2019 11:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ice table mols/molarity
Replies: 3
Views: 111

Re: ice table mols/molarity

It does not matter, as you will get the same answer either way. However, I am confused on how to determine which reaction will be favored when calculating the positive and negative changes in molarity when constructing the ICE table. Does anyone happen to know?
Sun Jan 20, 2019 11:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Is it an acid or a base?
Replies: 8
Views: 313

Re: Is it an acid or a base?

I am also confused on not just determining if something is an acid or base, but determining whether or not something is a WEAK acid or base. Can any of you clarify please?
Sun Jan 13, 2019 9:03 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Determining Which side is favored
Replies: 5
Views: 207

Re: Determining Which side is favored

Yes, that is true and when q>k, the reverse reaction is favored and there are more products, resulting in the production of reactants. However, I am having a hard time understanding why the value of Q matters when determining which direction a reaction will proceed.
Sun Jan 13, 2019 2:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant Eq.
Replies: 4
Views: 158

Re: Equilibrium Constant Eq.

Also, regarding the equilibrium constant equation, donthe concentrations of the reactants and products not change at equilibrium, or do only their ratios not change, or is it both?
Sun Jan 13, 2019 2:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: True or False regarding reaction mixture [ENDORSED]
Replies: 10
Views: 264

True or False regarding reaction mixture[ENDORSED]

When the chemical equilibrium is reached, does the composition of the reaction mixture remain constant because the forward and reverse reactions are occurring at equal rates?
Sat Dec 08, 2018 10:00 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Final Exam
Replies: 8
Views: 1274

Re: Final Exam

Liset Rivera 3A wrote:calculating equilibrium shouldn't be on the final. However, you should know the conceptually know and understand it.

Could you explain the conceptual meanings of Ka and Kp?
Sat Dec 08, 2018 1:20 pm
Forum: Lewis Structures
Topic: Acid Lewis Structures
Replies: 1
Views: 327

Acid Lewis Structures

How do I determine whether the hydrogen will be attached to the central atom or not in acid Lewis bases? Is there a specific rule?
Sat Dec 08, 2018 1:15 pm
Forum: Bronsted Acids & Bases
Topic: Stronger Acid
Replies: 1
Views: 95

Stronger Acid

Why is hIO weaker than hclo, even though Iodine has a larger atomic radius than chlorine?
Sun Dec 02, 2018 11:37 am
Forum: Lewis Acids & Bases
Topic: lewis acid and bases
Replies: 3
Views: 132

Re: lewis acid and bases

Are conjugate acids the same thing as Lewis acids? If not, what is the difference?
Sun Dec 02, 2018 5:04 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate ligands
Replies: 3
Views: 111

Re: Polydentate ligands

I think you also have to consider whether there are single bonds, double bonds, or triple bonds because if the atom in the ligand contains a pi bond then it won’t be able to bend and bind to the same central atom simutaneously.
Sat Dec 01, 2018 3:22 am
Forum: Naming
Topic: Neutral ligand
Replies: 2
Views: 153

Neutral ligand

If the ligand is neutral, meaning it has no charge, how do we find the oxidation number of the metal?
Sun Nov 25, 2018 11:29 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: Polarity and Boiling Point
Replies: 3
Views: 874

Re: Polarity and Boiling Point

Following up with this question, why does high covalent character mean high boiling point?
Sun Nov 25, 2018 10:52 pm
Forum: Bond Lengths & Energies
Topic: Question 3.85 b
Replies: 3
Views: 464

Re: Question 3.85 b

Can someone explain why so32- has a greater bond length than so2-?
Sun Nov 25, 2018 10:14 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Lengths
Replies: 10
Views: 539

Re: Bond Lengths

So resonance creates a more stable bond, but how do lone pairs affect the strength of the bonds within a molecule?
Sun Nov 18, 2018 9:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar molecules
Replies: 5
Views: 206

Polar molecules

Can someone explain to me why NF3 is a polar molecule? Is it because the lone pair on the central atom distorts the shape of what would have been a tetrahedral, making the molecule asymmetrical?
Sun Nov 18, 2018 9:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity in Molecule
Replies: 3
Views: 159

Re: Polarity in Molecule

Basically, the dipole moment occurs whenever there is a more electronegative molecule within a covalent bond. For example, h2o is a polar molecule because oxygen is way more electronegative then hydrogen; thus the dipole moment occurs as the hydrogen shares its electrons with oxygen and gets a sligh...
Sun Nov 18, 2018 5:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular geometry vs Electron geometry
Replies: 6
Views: 280

Re: Molecular geometry vs Electron geometry

Do you guys know if on the test, when they ask for us to find shape of a molecule, should we assume they are referring to the geometry?
Sun Nov 11, 2018 10:55 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Question 3.81 (Sixth Edition)
Replies: 1
Views: 89

Re: Question 3.81 (Sixth Edition)

I’m also confused, I don’t quite understand why Sr 2+ has a greater polarizing than Rb+, even though they both become krypton when their electrons as removed.
Sun Nov 11, 2018 10:32 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic character
Replies: 1
Views: 68

Ionic character

Can someone please confirm that ionic character is the difference in electronegativity between two atoms? Also can ionic character and polarity be used interchangeably?
Sun Nov 11, 2018 10:28 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds with Covalent Character
Replies: 3
Views: 175

Re: Ionic Bonds with Covalent Character

Going off defining covalent character, why are compounds that have a bond with high covalent character less soluble in water?
Sun Nov 04, 2018 8:14 pm
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 6860

Re: MIDTERM PRACTICE - Garlic Bread Review Session[ENDORSED]

For number 5, I keep getting .127 M after setting the problem up like (.211 M)(.150 L) = M2(.250 L). But in my notes, I believe Lyndon got 1.69 x 10^-2. I was wondering if anyone knows what I am doing wrong. Thanks! Hi! Since the problem stated that only 20ml was removed to the 2nd flask, you put 0...
Sun Nov 04, 2018 5:38 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 9
Views: 577

Re: Bond Length

So, is the number of bond lengths determined by the number of different bonds (single bond, double bond, triple bond) there are?
Fri Nov 02, 2018 11:30 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 1
Views: 130

Can anyone explain how to calculate the radial and angular nodes and their correlation to quantum numbers? Does L equal the number of angular nodes, and does n-1 equal the number of radial nodes?
Sun Oct 28, 2018 11:48 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Indeterminacy Equation
Replies: 4
Views: 217

Re: Heisenberg Indeterminacy Equation

So delta p also represents the uncertainty of the velocity times the mass. Therefore if we are given the uncertainty of a specific mass and delta x, we can calculate delta v?
Sun Oct 28, 2018 9:35 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Replies: 3
Views: 205

I believe the diameter of the atom is twice of "delta x," it looks like the question wants you to put 1/2 of that diameter into the uncertainty equation in delta x and solve of velocity. So, to confirm that I am solving this problem correctly, whenever the diameter is given, that represen...
Sun Oct 28, 2018 9:13 pm
Forum: DeBroglie Equation
Topic: Exercise 1.39 [ENDORSED]
Replies: 4
Views: 905

Re: Exercise 1.39[ENDORSED]

So, mass is always represented in kilograms and velocity in meters per second?
Sun Oct 21, 2018 7:26 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect original purpose
Replies: 2
Views: 191

Photoelectric Effect original purpose

I know that he photoelectric effect shows that increasing the intensity of light does not increase the amount of ejected electrons if the energy of the light is below threshold, but what was the original purpose of the photoelectric experiment?
Sun Oct 21, 2018 7:18 pm
Forum: Photoelectric Effect
Topic: Kinetic Energy
Replies: 3
Views: 171

Kinetic Energy

Just to be sure, kinetic energy is the same thing as the amount of excess energy left once the electron is released? Also, work function also means the amount of energy required to eject an electron? I’m just wondering because I’ve been seeing them being used interchangeably?
Sun Oct 21, 2018 7:12 pm
Forum: Photoelectric Effect
Topic: Conditions that allow electron to be ejected from metal surface
Replies: 12
Views: 792

Conditions that allow electron to be ejected from metal surface

Just to clarify, an electron can be ejected from a metal surface if the energy of the photon is greater than the energy required to remove the electron or if the energy of the photon is equal to the energy required to remove the electron?
Sat Oct 13, 2018 9:48 pm
Forum: Properties of Light
Topic: HW 1.7A
Replies: 3
Views: 641

Re: HW 1.7A

Nano means one billionth i.e. 10^-9 so 1 nanometer is a billionth of a meter. To convert meters to nanometers, you should multiply by 10^9 instead of divide. Do u mean divide, instead of multiply because I think they originally multiplied and got the wrong answer. I divided, but I’m not sure if I d...
Sat Oct 13, 2018 9:10 pm
Forum: Properties of Light
Topic: Homework 1.5
Replies: 6
Views: 333

Re: Homework 1.5

Because energy and frequency are proportional, if the question asked to arrange the photons in order of increasing frequency, would the answer remain the same?
Sat Oct 13, 2018 8:37 pm
Forum: Properties of Light
Topic: Homework Question 1A.3
Replies: 4
Views: 141

Re: Homework Question 1A.3

So, just to break it down for you... If you look at (a) you’ll notice that this can’t be the answer because speed is constant. The speed of the radiation wouldn’t decrease. For (b) the wavelength of the radiation wouldn’t decrease since frequency and wavelength are inversely proportional. (D) isn’t...
Fri Oct 05, 2018 12:31 am
Forum: Significant Figures
Topic: Using Sig Figs Throughout a Problem?
Replies: 6
Views: 223

Re: Using Sig Figs Throughout a Problem?

And just to confirm, the amount of sig figs in our answer should always be equivalent to the lowest amount of sig figs given in the data of our problem?
Tue Oct 02, 2018 10:35 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding
Replies: 6
Views: 305

Re: Rounding

What happens when you are dividing the given molar mass by the molar mass of the empirical formula in order to find the molecular formula and get a number like 2.18. Do i just round this to 2 and multiply the empirical formula by 2?
Tue Oct 02, 2018 9:16 pm
Forum: Empirical & Molecular Formulas
Topic: Molar Mass
Replies: 2
Views: 126

Molar Mass

I am in need of clarification on how to go about calculating the molar mass of a metal , given its percent composition within a compound formula, but not given the specific element. How do we calculate its molar mass, if we do not know the element. Should we use Avogadro's number?