Search found 52 matches

by Nancy Le - 1F
Thu Mar 15, 2018 11:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Half-cell concentrations
Replies: 1
Views: 95

Half-cell concentrations

How do you calculate half-cell concentrations? I remember Dr. Lavelle mentioning it in class but I don't have it in my notes.
by Nancy Le - 1F
Wed Mar 14, 2018 10:16 pm
Forum: Experimental Details
Topic: Relationship between temperature and Le Chatelier's principle
Replies: 1
Views: 324

Relationship between temperature and Le Chatelier's principle

Can someone explain how raising the temperature of a reaction, which increases the rate constant of the forward reaction and ultimately the equilibrium constant, is supported by Le Chatelier's principle?
by Nancy Le - 1F
Wed Mar 14, 2018 10:08 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Calculating activation energy from Arrhenius equation
Replies: 1
Views: 93

Calculating activation energy from Arrhenius equation

If given 2 rate constants and the corresponding temperatures, like in exercise 61, does it matter which one we assign as k1,k2,T1,T2?
by Nancy Le - 1F
Fri Mar 09, 2018 10:12 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pseudo Rate Law [ENDORSED]
Replies: 3
Views: 170

Pseudo Rate Law [ENDORSED]

The pseudo rate law is the rate law in between elementary steps, but under what conditions would we need to use this?
by Nancy Le - 1F
Fri Mar 09, 2018 10:08 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediate and rate law [ENDORSED]
Replies: 3
Views: 152

Re: Intermediate and rate law [ENDORSED]

I see, that makes sense! Does it have anything to do with the reactivity of the intermediate as well?
by Nancy Le - 1F
Fri Mar 09, 2018 9:57 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Kinetic information [ENDORSED]
Replies: 3
Views: 120

Kinetic information [ENDORSED]

If kinetic information can support a proposed mechanism, why can't it prove the mechanism to be correct?
by Nancy Le - 1F
Fri Mar 09, 2018 9:55 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediate and rate law [ENDORSED]
Replies: 3
Views: 152

Intermediate and rate law [ENDORSED]

Why can't an intermediate be included in the rate law?
by Nancy Le - 1F
Mon Mar 05, 2018 12:35 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units of k
Replies: 8
Views: 330

Units of k

How do you calculate the units of k for the order of each reactant?
by Nancy Le - 1F
Mon Mar 05, 2018 12:32 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Overall reaction order
Replies: 3
Views: 167

Overall reaction order

When would the overall reaction order be a fraction and what makes it different from other reactions?
by Nancy Le - 1F
Mon Mar 05, 2018 12:29 am
Forum: First Order Reactions
Topic: Half-life of first order reactions
Replies: 3
Views: 149

Half-life of first order reactions

Is it correct to say that the greater the rate constant, the shorter the half-life is because it doesn't depend on the concentration of reactants?
by Nancy Le - 1F
Mon Mar 05, 2018 12:26 am
Forum: Second Order Reactions
Topic: Half-life of second order reactions
Replies: 2
Views: 122

Half-life of second order reactions

Is the half-life of a second order reaction dependent or independent on reaction concentration?
by Nancy Le - 1F
Wed Feb 21, 2018 12:10 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating standard potential [ENDORSED]
Replies: 1
Views: 87

Calculating standard potential [ENDORSED]

For exercise 33 part A, the solutions manual states that the standard Gibbs free energy should be negative because it's the reverse of the formation reaction, but why would this be so?
by Nancy Le - 1F
Tue Feb 20, 2018 11:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Reduction Potential
Replies: 3
Views: 110

Standard Reduction Potential

In exercise 14.25, do the standard reduction potentials follow a periodic trend?
by Nancy Le - 1F
Sat Feb 17, 2018 8:18 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Dissolving
Replies: 2
Views: 121

Re: Dissolving

Can we assume that any spontaneous reaction will dissolve? Does this apply to only this reaction?
by Nancy Le - 1F
Sat Feb 17, 2018 8:07 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing & Reducing Agents
Replies: 6
Views: 228

Re: Oxidizing & Reducing Agents

Oxidizing agents are the species that is reduced, or gaining electrons, because the oxidation number is being decreased. The reducing agents are the species that is oxidized, or losing electrons, because the oxidation number is being increased.
by Nancy Le - 1F
Tue Feb 13, 2018 12:01 am
Forum: Calculating Work of Expansion
Topic: Reversible vs irreversible
Replies: 4
Views: 171

Re: Reversible vs irreversible

Can you give me an example?
by Nancy Le - 1F
Mon Feb 12, 2018 11:15 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs irreversible
Replies: 4
Views: 171

Reversible vs irreversible

Given an equation, how can you tell if it's reversible or irreversible?
by Nancy Le - 1F
Fri Feb 09, 2018 12:53 am
Forum: Balancing Redox Reactions
Topic: Anode vs cathode
Replies: 6
Views: 141

Anode vs cathode

Is the anode always the side of the oxidation half-reaction and the cathode, the side with the reduction half reaction?
by Nancy Le - 1F
Fri Feb 09, 2018 12:50 am
Forum: Balancing Redox Reactions
Topic: Standard Reduction Potential
Replies: 3
Views: 138

Standard Reduction Potential

Can someone explain how to balance half reactions when calculating the standard reduction potential? Do we treat the equations like how we would normally balance chemical reactions?
by Nancy Le - 1F
Fri Feb 09, 2018 12:44 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.17
Replies: 1
Views: 110

9.17

Can someone please explain the relationship between enthalpy and entropy according to Trouton's rule?
by Nancy Le - 1F
Sun Feb 04, 2018 1:16 am
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: Standard molar entropy
Replies: 1
Views: 89

Standard molar entropy

Can someone explain the graphs of Figure 9.11 in section 9.7 of the textbook?
by Nancy Le - 1F
Sun Feb 04, 2018 1:06 am
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: Residual Entropy
Replies: 4
Views: 180

Residual Entropy

What is residual entropy and how is it different from regular entropy?
by Nancy Le - 1F
Sun Feb 04, 2018 12:54 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy -/+
Replies: 4
Views: 146

Re: Gibbs Free Energy -/+

A negative Gibbs Free Energy means that the energy of the products is less than the energy of the reactants. If it were the reverse, an input of energy would be needed, which is not favorable. Therefore, a negative Gibbs free energy is favored because it drives the reaction forward spontaneously.
by Nancy Le - 1F
Fri Jan 26, 2018 7:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Relation of degeneracy and entropy
Replies: 2
Views: 128

Relation of degeneracy and entropy

Can someone explain what increasing/decreasing degeneracy does to entropy?
by Nancy Le - 1F
Fri Jan 26, 2018 7:37 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy of gas vs liquid vs solid
Replies: 7
Views: 1552

Entropy of gas vs liquid vs solid

Why is the entropy of a gas much greater than that of a liquid or solid?
by Nancy Le - 1F
Sat Jan 20, 2018 11:44 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity Properties
Replies: 3
Views: 117

Heat Capacity Properties

Why is heat capacity an intensive property while specific heat capacity and molar heat capacity are extensive properties?
by Nancy Le - 1F
Sat Jan 20, 2018 11:35 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.37
Replies: 1
Views: 74

Re: 8.37

You divide the number of joules by the number of moles because you want to find how much heat(q) is required to raise 1 mol of the substance to a certain temperature.
by Nancy Le - 1F
Sat Jan 20, 2018 11:32 am
Forum: Calculating Work of Expansion
Topic: 8.13 - Understanding the Solution
Replies: 2
Views: 137

Re: 8.13 - Understanding the Solution

947kJ should be positive because the system is absorbing the heat in order to cool down, which means it's an endothermic process. Work done by the system produces a negative work value.
by Nancy Le - 1F
Tue Jan 09, 2018 10:08 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molar Heat Capacity [ENDORSED]
Replies: 1
Views: 117

Molar Heat Capacity [ENDORSED]

How does having additional vibrational modes increase a molecule's molar heat capacity?
by Nancy Le - 1F
Tue Jan 09, 2018 9:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equipartition Theorem
Replies: 1
Views: 126

Equipartition Theorem

What is the equipartition theorem used to calculate?
by Nancy Le - 1F
Tue Jan 09, 2018 9:43 pm
Forum: Calculating Work of Expansion
Topic: Work for reversible vs irreversible process
Replies: 3
Views: 174

Work for reversible vs irreversible process

Why is it that more work is done for a reversible process than for a irreversible process?
by Nancy Le - 1F
Sat Dec 09, 2017 3:31 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: What is MO theory for? [ENDORSED]
Replies: 20
Views: 6766

Re: What is MO theory for? [ENDORSED]

How does the number of paired or unpaired electrons relate to the magnetism of a molecule?
by Nancy Le - 1F
Sat Dec 09, 2017 3:19 pm
Forum: Bond Lengths & Energies
Topic: Bond Order
Replies: 6
Views: 470

Re: Bond Order

Would the bond order of a CN radical be 1.5 then? Since there is a triple bond,3, and 2 atoms, would it be 3/2=1.5?
by Nancy Le - 1F
Sat Dec 02, 2017 5:39 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Problem 55 Part D
Replies: 1
Views: 126

Problem 55 Part D

How do you explain the differences in pH based on molecular structure?
by Nancy Le - 1F
Sat Dec 02, 2017 5:02 pm
Forum: Calculating the pH of Salt Solutions
Topic: Calculating pH
Replies: 3
Views: 263

Calculating pH

When calculating the logarithm to find the pH of a solution, why is there a negative sign?
by Nancy Le - 1F
Wed Nov 22, 2017 12:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Gas concentration
Replies: 2
Views: 123

Re: Gas concentration

To convert between partial pressure and concentration of a gas, you would use the Ideal Gas Law: PV=nRT.
Simplifying the equation would give: concentration=P/(RT)
by Nancy Le - 1F
Tue Nov 21, 2017 11:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant
Replies: 4
Views: 155

Re: Equilibrium constant

To find K(p), the ratio would be 1/P(r). Since the molar concentration of a solid or liquid does not change in a reaction, solids and liquids aren't included in K expression. You would only need to find the concentration of the reactants.
by Nancy Le - 1F
Fri Nov 17, 2017 3:25 pm
Forum: Sigma & Pi Bonds
Topic: Pi bonds
Replies: 6
Views: 506

Re: Pi bonds

Since the electrons overlap side-by-side in pi bonds, rotating one atom would break the parallel orientation of the orbitals.
by Nancy Le - 1F
Fri Nov 17, 2017 3:14 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 2
Views: 123

Re: Ligands

In order to clearly show which atom is being bound to the central atom, the ligands are sometimes written backwards.
by Nancy Le - 1F
Mon Nov 13, 2017 8:37 pm
Forum: Hybridization
Topic: Hybrid orbitals
Replies: 2
Views: 97

Re: Hybrid orbitals

You can determine the number of hybrid orbitals by looking at the regions of electron density. Different shapes indicate different hybrids of valence atomic orbitals during bond formation.
by Nancy Le - 1F
Mon Nov 13, 2017 8:27 pm
Forum: Octet Exceptions
Topic: Radicals
Replies: 2
Views: 194

Radicals

Are radicals stable compounds even though they have an unpaired electron?
by Nancy Le - 1F
Sat Nov 04, 2017 3:37 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 9
Views: 375

Ionic and Covalent Bonds

What are the main differences between ionic and covalent bonds?
by Nancy Le - 1F
Sat Nov 04, 2017 3:34 pm
Forum: Resonance Structures
Topic: Resonance and energy
Replies: 2
Views: 146

Re: Resonance and energy

Resonance structures spread multiple bond characters over a molecule, lowering the overall energy of the molecule.
by Nancy Le - 1F
Sun Oct 29, 2017 3:54 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground state and electron configuration
Replies: 2
Views: 150

Re: Ground state and electron configuration

If the electron configuration has the right number, direction, and spacing of the arrows, then the electron is in the ground state.
by Nancy Le - 1F
Sun Oct 29, 2017 3:47 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Gallium
Replies: 3
Views: 879

Electron Configuration of Gallium

According to the periodic table, the electron configuration of Ga is [Ar]4s^2 3d^10 4p^1. However, why did Dr. Lavelle write it as [Ar]3d^10 4s^2 4p^1 in class?
by Nancy Le - 1F
Sun Oct 22, 2017 11:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Wave Functions
Replies: 1
Views: 145

Wave Functions

How are the wave functions of px, py, and pz derived?
by Nancy Le - 1F
Sun Oct 22, 2017 11:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital Orientation
Replies: 1
Views: 123

Orbital Orientation

Does only the p orbital have lobes oriented along the x, y, z axes or do the other orbitals have different orientations as well?
by Nancy Le - 1F
Sat Oct 14, 2017 2:16 pm
Forum: Einstein Equation
Topic: 1.69 [ENDORSED]
Replies: 1
Views: 231

Re: 1.69 [ENDORSED]

a) An electron can only be ejected if a photon has the minimum energy equal to that of the work function for that metal strikes it. 1. E(work) = (2.93 eV)(1.602 18 x10^(19)JeV^(-1)) = 4.69 x 10^(-19)J 2. Calculate the energy for the red and violet laser using the equation E=hcλ ^(-1). 3. The laser w...
by Nancy Le - 1F
Sat Oct 14, 2017 1:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Change in energy of an electron [ENDORSED]
Replies: 3
Views: 198

Re: Change in energy of an electron [ENDORSED]

The positive and negative signs only indicate whether the photon is emitted or absorbed, but the amount of energy that is used is always positive.
Hope this helps!
by Nancy Le - 1F
Fri Oct 06, 2017 12:52 am
Forum: Molarity, Solutions, Dilutions
Topic: G13
Replies: 2
Views: 214

G13

How do you start this problem?
by Nancy Le - 1F
Fri Oct 06, 2017 12:32 am
Forum: Balancing Chemical Reactions
Topic: M9 Part A
Replies: 2
Views: 188

M9 Part A

How do you find the net ionic equation for the reaction?

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