Search found 49 matches

by aaron tang 2K
Wed Mar 14, 2018 1:11 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k and Ea
Replies: 4
Views: 210

Re: k and Ea

k is small because if the activation energy is high, it will be harder for the reaction to produce products
by aaron tang 2K
Wed Mar 14, 2018 1:10 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Adsorption
Replies: 4
Views: 180

Re: Adsorption

During lecture, Lavelle talked about how sponges absorb water and catalysts are adsorbing a reactant, meaning the reactant sits on top of the catalyst. There is a slight adhesion when a catalyst adsorbs a reactant. This allows the reactant to detach from the catalyst as the reaction proceeds. Once t...
by aaron tang 2K
Wed Mar 14, 2018 1:02 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst
Replies: 2
Views: 117

Re: Catalyst

Catalysts speed up reactions (k) by lowering activation energy. They also provide a new pathway for reactions, and these new pathways have lower activation energy.
by aaron tang 2K
Mon Mar 05, 2018 2:49 pm
Forum: Second Order Reactions
Topic: Determining order of a reaction
Replies: 2
Views: 402

Re: Determining order of a reaction

You can just use the coefficients only when using the reaction mechanisms. You are looking at the individual steps then the overall equation. The order of each of reaction determines the coefficients
by aaron tang 2K
Mon Mar 05, 2018 2:46 pm
Forum: Second Order Reactions
Topic: Order reactions
Replies: 6
Views: 448

Re: Order reactions

Order reactions are determined by looking how the rate changes in relation to the concentration. Then you can use the proper equation and apply it to the problem.
by aaron tang 2K
Mon Mar 05, 2018 2:44 pm
Forum: Second Order Reactions
Topic: molecularity
Replies: 6
Views: 357

Re: molecularity

Yes you do.
A -> P unimolecular
A+B -> bimolecular
A+A -> bimolecular
by aaron tang 2K
Mon Mar 05, 2018 2:22 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Which Step is Slower?
Replies: 8
Views: 209

Re: Which Step is Slower?

You can determine the slowest step by the determination rate or the part of the graph that requires the most activation energy.
by aaron tang 2K
Mon Mar 05, 2018 2:20 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: slowest step determines rate of overall reaction
Replies: 3
Views: 134

Re: slowest step determines rate of overall reaction

The slowest step determines the rate of the overall reaction because all the other reactions following is going as fast as the slowest step. Which means that the slowest step controls the overall rate of the overall reaction.
by aaron tang 2K
Mon Mar 05, 2018 2:15 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Friday Lecture
Replies: 5
Views: 157

Re: Friday Lecture

Correct, CO2 is a zero order so it doesn't affect the determination rate or the slow step.
by aaron tang 2K
Thu Feb 22, 2018 2:45 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Nernst Equation
Replies: 6
Views: 274

Re: Nernst Equation

nr is the molar coefficient of the Nernst Equation. It is basically the number of moles of electrons transferred.
by aaron tang 2K
Thu Feb 22, 2018 2:42 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: redox
Replies: 7
Views: 254

Re: redox

LEO: loss (of) electrons OXIDIZE
Reduction is gaining electrons.
by aaron tang 2K
Thu Feb 22, 2018 2:39 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Cell Potential
Replies: 9
Views: 2276

Re: Cell Potential

Both of these equations are the same. constants R, T, F = to .05916
by aaron tang 2K
Mon Feb 12, 2018 4:15 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Using Nernst Equation
Replies: 2
Views: 136

Re: Using Nernst Equation

The nernst equation is describing the cell potential, which the direction where the electron goes, and how it depends on concentration under different conditions.
by aaron tang 2K
Mon Feb 12, 2018 4:10 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: system vs surroundings
Replies: 6
Views: 327

Re: system vs surroundings

If the surroundings is everything except the system, then the system is the reaction and the beaker and everything else is the surrounding.
by aaron tang 2K
Mon Feb 12, 2018 4:05 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Delta G= Wmax
Replies: 8
Views: 411

Re: Delta G= Wmax

DeltaG is the maximum amount of work a system can do at a given temperature and pressure, while WMAX is the maximum amount of work a system can do. Therefore, you can set them equal to each other.
by aaron tang 2K
Thu Feb 08, 2018 4:16 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: deltaS question
Replies: 7
Views: 241

Re: deltaS question

5/2 and 3/2 are used for specific heat capacities of ideal gases. For the problems in the book, you should only use Cp when dealing with ideal gases, if not, then use R for non-ideal gases
by aaron tang 2K
Thu Feb 08, 2018 4:10 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: formula for standard entropy
Replies: 5
Views: 212

Re: formula for standard entropy

Yes, the formula for standard entropy is the same as the other standard formations we did last chapter.
by aaron tang 2K
Thu Feb 08, 2018 4:08 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Kelvin
Replies: 4
Views: 166

Re: Kelvin

Look at the signs throughout the problems, but in most cases, you should write in kelvins just to keep it constant throughout the problem.
by aaron tang 2K
Thu Feb 08, 2018 4:05 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G
Replies: 3
Views: 117

Re: Delta G

DeltaG: is the change in free energy under a different temperatures and pressure conditions.
DeltaGnaut: is standardized conditions for pressure (1 ATM) and temperture (25 degree celcius/298 Kelvins)
by aaron tang 2K
Thu Feb 08, 2018 4:03 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy Concept
Replies: 2
Views: 92

Re: Entropy Concept

Endothermic reactions/processes are spontaneous because this kind of process absorbs heat which increases the total entropy of a system.
by aaron tang 2K
Thu Feb 01, 2018 12:01 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy vs. Standard Entropy
Replies: 4
Views: 170

Re: Entropy vs. Standard Entropy

the word standard used in this sense represents that every reactants and products are in their purest forms. Only one mole is produced.
by aaron tang 2K
Wed Jan 31, 2018 11:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: what exactly is free energy?
Replies: 5
Views: 189

Re: what exactly is free energy?

Gibbs free energy is basically the free energy in a process available to do work. An important relationship to consider is ΔG = ΔH - TΔS, which, if you know the signs of the unknowns, you can determine the sign of ΔG and hence predict if a reaction is favorable or not.
by aaron tang 2K
Wed Jan 31, 2018 11:51 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy in a Vacuum [ENDORSED]
Replies: 5
Views: 224

Re: Internal Energy in a Vacuum [ENDORSED]

since work is defined as w = -P DELTA V, and because it is in a vacuum there is no opposing force that is occurring which results in no work.
by aaron tang 2K
Fri Jan 19, 2018 11:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Work Equation
Replies: 4
Views: 211

Re: Work Equation

energy is being released which means there's a negative sign
by aaron tang 2K
Fri Jan 19, 2018 11:10 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 8.1 part c [ENDORSED]
Replies: 8
Views: 408

Re: 8.1 part c [ENDORSED]

it is an isolated system which means that there's no interactions with the environment and heat is not given off.
by aaron tang 2K
Fri Jan 19, 2018 10:47 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter
Replies: 10
Views: 405

Re: Calorimeter

calorimeter is used to measure specific heat capacity. In the example of the coffee cup calorimeter, heat is measured under conditions of constant pressure and in the bomb calorimeter, heat is measured under conditions of constant pressure. Use Q=m x C x Delta T
by aaron tang 2K
Sun Jan 14, 2018 5:34 pm
Forum: Phase Changes & Related Calculations
Topic: qv vs qp
Replies: 4
Views: 568

Re: qv vs qp

Qv is constant volume, Qp is constant pressure. Lavelle used Qv in the example of the bomb calorimeter and Qp in the coffee cup calorimeter.
Qv: heat absorbed or released at constant volume. Qp: heat absorbed or released at constant pressure and gives enthalpy values.
by aaron tang 2K
Sun Jan 14, 2018 5:30 pm
Forum: Phase Changes & Related Calculations
Topic: Methods of Enthalpy
Replies: 8
Views: 274

Re: Methods of Enthalpy

It honestly depends on the question because there are 3 methods of enthalpy. 1. Hess' Method 2. Bond Enthalpies 3. Standard Enthalpies of Formation
by aaron tang 2K
Sun Jan 14, 2018 5:25 pm
Forum: Phase Changes & Related Calculations
Topic: Endo and Exothermic Ways to Remember
Replies: 28
Views: 2444

Re: Endo and Exothermic Ways to Remember

The prefixes of the words determine what the meaning of them. "En"dothermic sounds like "In"dothermic, which means that heat is being absorbed and "Ex"othermic means exit, so heat is being released.
by aaron tang 2K
Sat Dec 09, 2017 5:21 pm
Forum: Bronsted Acids & Bases
Topic: % dissociation
Replies: 3
Views: 229

Re: % dissociation

%dissociation is calculated by taking the conjugate base/acid and dividing it by the initial condition then multiplying it by 100.
by aaron tang 2K
Fri Dec 08, 2017 2:16 am
Forum: Bronsted Acids & Bases
Topic: identifying based on structure
Replies: 4
Views: 210

Re: identifying based on structure

For this question, it was asking about lewis acids and lewis bases. Lewis acids accept electrons and lewis bases donate electrons. Ag+ can accept electrons which makes it an acid, while F- can donate an electron which makes it a base.
by aaron tang 2K
Fri Dec 08, 2017 2:08 am
Forum: Identifying Acidic & Basic Salts
Topic: Final: Strong/ Weak Acids/Bases
Replies: 4
Views: 548

Re: Final: Strong/ Weak Acids/Bases

Salts are not on the final test, but you should look over them in the course reader!
by aaron tang 2K
Thu Nov 30, 2017 11:57 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Quotient
Replies: 3
Views: 284

Re: Quotient

Q is the quotient which is the for when the reaction is given with whatever initial values are given. K is the equilibrium quotient which is the ratio of the concentration and partial pressure of the reactants and products
by aaron tang 2K
Thu Nov 30, 2017 11:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.43
Replies: 1
Views: 141

Re: 11.43

Yes, the problem involves the ICE box. 2NO(g) <>N2(g) + O2(g)
(N2)(O2)/(NO^2) = (x)(x)/(1)^2 = x^2/(1-2x)^2
The answer is C.
2NO N2 O2
I 1.0 0 0
C -2x x x
E 1-2x x x
by aaron tang 2K
Fri Nov 24, 2017 5:56 pm
Forum: Biological Examples
Topic: Coordination Compound
Replies: 2
Views: 240

Re: Coordination Compound

A coordination compound is a neutrally charged compound and it usually consists of a transition metal connected by sets of ligands. You can determine the coordination number because of how many bonds there are on the compound. These do not relate to hybridization.
by aaron tang 2K
Fri Nov 24, 2017 5:35 pm
Forum: Naming
Topic: HW 17.31 b
Replies: 4
Views: 193

Re: HW 17.31 b

The answer that is provided through solutions manual is correct because Cobalt has an oxidation number of 3+ and Sulfate has an oxidation number of 2-, which means the overall oxidation number is 1. So it is [Co(NH3)5(SO4)]Cl
by aaron tang 2K
Fri Nov 17, 2017 11:19 pm
Forum: Hybridization
Topic: sigma/pi bond
Replies: 4
Views: 232

Re: sigma/pi bond

Yes that is correct, as you said with a double bond, the first bond is a sigma bond and the second one is pi bond. For a triple bond, the first bond is a sigma bond and the second and the third bonds are pi bonds
by aaron tang 2K
Fri Nov 17, 2017 11:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Cis- vs. Trans-
Replies: 4
Views: 251

Re: Cis- vs. Trans-

Cis and Trans represents the geometric isomerism. If 2 groups are on the same side, then it is a cis and if the other groups are on opposite side then it is a trans
by aaron tang 2K
Tue Nov 14, 2017 5:49 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating Formal Charge
Replies: 4
Views: 241

Re: Calculating Formal Charge

Subtract the valence electrons of an elements by the bonds and electrons that are around it. Bonds are represented as 1 electron.
by aaron tang 2K
Sun Nov 05, 2017 5:40 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 3
Views: 263

Re: Resonance Structures

The most important idea here is draw out all the possible lewis structures to determine the resonance. A lot of the times, the double bond or triple bond can occur almost anywhere, but in some specific elements a double bond can only occur in a specific spot. So beware and be careful when drawing ou...
by aaron tang 2K
Sun Nov 05, 2017 5:37 pm
Forum: Lewis Structures
Topic: electron configuration
Replies: 6
Views: 304

Re: electron configuration

The electron configuration is written [Ar]3d104s2 because the it goes in order increasing energy and it is the way that Dr. Lavelle wants it to be written.
by aaron tang 2K
Thu Oct 26, 2017 10:49 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Px, Py, Pz
Replies: 10
Views: 508

Re: Px, Py, Pz

On Wednesday, during the lecture, Lavelle said that you can write it both ways. He prefers that you write in the notation Px, Py, Pz because it is much more specific and it clears up all kinds of confusion when determining paired/parallel electrons.
by aaron tang 2K
Fri Oct 20, 2017 12:05 am
Forum: Photoelectric Effect
Topic: Energy of Photon [ENDORSED]
Replies: 9
Views: 499

Re: Energy of Photon [ENDORSED]

When the energy is equal to each other, the energy is still enough to emit a photon, but the kinetic energy would be zero.
by aaron tang 2K
Fri Oct 20, 2017 12:01 am
Forum: Properties of Electrons
Topic: Rydberg's formula
Replies: 6
Views: 517

Re: Rydberg's formula

Rydberg's formula is used for finding the wavelength, energy, or frequency of an electron that is moving from one level to the next. Usually you the initial and final levels will be given, but in some other cases, the question will ask for the initial and the final. So that's when you used the formu...
by aaron tang 2K
Thu Oct 19, 2017 11:57 pm
Forum: DeBroglie Equation
Topic: λ=c/v VS. λ=h/mv
Replies: 9
Views: 1037

Re: λ=c/v VS. λ=h/mv

λ=c/v : this equation means λ (wavelength) is equal to c (speed of light) divided by v (frequency). c will always be 3.00 x 10^8 m/s. λ=h/mv : this equations means that λ (wavelength) is equal to h (Plank's constant) divided by m (momentum) * v (velocity). The biggest difference between the that λ=c...
by aaron tang 2K
Sat Oct 14, 2017 7:16 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Question about Balmer Series [ENDORSED]
Replies: 2
Views: 853

Re: Question about Balmer Series [ENDORSED]

The Balmer series begins at n=2, if the electron is going down from n=2 to n=1, it would be considered the Lyman series.
by aaron tang 2K
Sat Oct 14, 2017 7:11 pm
Forum: Properties of Light
Topic: Balmer vs Lyman Series [ENDORSED]
Replies: 3
Views: 236

Re: Balmer vs Lyman Series [ENDORSED]

Balmer Series (656.3 nm, 486.1 nm, 434.8 nm, 410.2 nm) is connected to visible light section of the spectrum, while Lyman Series (121.6 nm, 102.6 nm, 97.3 nm) is connected to the ultraviolet section of the spectrum. The Lyman series is indicated by when the electron is excited from the ground state ...
by aaron tang 2K
Fri Oct 06, 2017 4:56 pm
Forum: Empirical & Molecular Formulas
Topic: F.13
Replies: 6
Views: 1403

Re: F.13

you are on the right track by subtracting 27.8 grams by 4.14 grams of P. That will give you 23.66 grams of Cl, so all you have to do is divide each of the element by it's mass. P: 4.14/30.974 = .1336604894 Cl: 23.16/75.45 = .6533145275 Next, you would divide the smallest amount into each of them, so...
by aaron tang 2K
Fri Oct 06, 2017 4:36 pm
Forum: Significant Figures
Topic: 3 Sig Figs 1795.507? [ENDORSED]
Replies: 5
Views: 366

Re: 3 Sig Figs 1795.507? [ENDORSED]

You should round up to 1800, then convert it into scientific notation. For 3 sig figs, the answer should be 1.80 x 10^3

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