Search found 76 matches

by Hanniel U 2B
Sat Mar 16, 2019 11:22 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: A in the arrhenius equation
Replies: 2
Views: 327

Re: A in the arrhenius equation

I believe A is the collision frequency in the correct orientation.
by Hanniel U 2B
Sat Mar 16, 2019 11:12 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius equation
Replies: 2
Views: 199

Arrhenius equation

How is Enthalpy or delta H related to Activation energy, Ea in the Arrhenius equation?
by Hanniel U 2B
Sat Mar 16, 2019 11:10 pm
Forum: First Order Reactions
Topic: Graphs/Plots
Replies: 2
Views: 182

Re: Graphs/Plots

You should be familiar with the graphs of the rate orders just in case and also Arrhenius equation and just be familiar with labeling them too.
by Hanniel U 2B
Sat Mar 16, 2019 8:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Slow and Fast step
Replies: 4
Views: 272

Slow and Fast step

Are we going to have to identify the slow and fast step or will it be shown on the problems in the final?
by Hanniel U 2B
Fri Mar 15, 2019 11:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U
Replies: 4
Views: 221

Re: delta U

Maria Solis Disc 4C wrote:Internal Energy should always be q+w

Thanks. I see q- w sometimes and that confuses me.
by Hanniel U 2B
Fri Mar 15, 2019 10:51 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U
Replies: 4
Views: 221

delta U

What is the difference btw delta U= q + w and delta U= q - w?
by Hanniel U 2B
Wed Mar 13, 2019 9:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Temperature
Replies: 2
Views: 207

Re: Temperatutre

I always convert to Kelvin to be safe... There are many instances, such as when you calculate for entropy when you divide two temperatures, and using Celcius here will mess up your ratio and give you an incorrect answer. You also know what to use based on the units and what you need to cancel out.....
by Hanniel U 2B
Wed Mar 13, 2019 9:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Temperature
Replies: 2
Views: 207

Temperature

When do you know to convert Celcius to Kelvin?
by Hanniel U 2B
Wed Mar 13, 2019 8:51 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Calculating Temperature
Replies: 1
Views: 53

Calculating Temperature

Can someone please explain part (c)?
by Hanniel U 2B
Mon Mar 11, 2019 10:11 pm
Forum: Second Order Reactions
Topic: half-life for second order
Replies: 3
Views: 74

half-life for second order

In the 7th edition textbook, it states "not used" for the equation of half-life of the second order reaction But there are problems, for example, 7b.13 that ask us to calculate the half-life of a second order reaction. I am confused, can someone please clarify this?
by Hanniel U 2B
Mon Mar 11, 2019 1:28 am
Forum: Administrative Questions and Class Announcements
Topic: Homework week 9
Replies: 3
Views: 88

Homework week 9

Do we turn in two homework this wee? That is, do we turn in 14 problems this week ?
by Hanniel U 2B
Sun Mar 03, 2019 4:08 pm
Forum: First Order Reactions
Topic: First Oder
Replies: 1
Views: 80

First Oder

Can someone help me understand 7A.13, 7th edition? Why is the rate first order?
by Hanniel U 2B
Sun Mar 03, 2019 3:27 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Large K value
Replies: 5
Views: 104

Re: Large K value

If the Ecell° is positive, the reaction is favorable forward which means has K>1
by Hanniel U 2B
Mon Feb 25, 2019 6:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 1
Views: 135

Test 2

Would we be given the standard reduction potential values for the test?
by Hanniel U 2B
Sun Feb 24, 2019 2:12 pm
Forum: Balancing Redox Reactions
Topic: Which Equation to Flip?
Replies: 9
Views: 168

Re: Which Equation to Flip?

I usually flip the anode equation. Probably that's why the Cu was flipped. Also, the anode equation is being oxidized.
by Hanniel U 2B
Sun Feb 24, 2019 1:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 1
Views: 38

Re: Platinum

I know platinum is used as an oxidation catalyst.
by Hanniel U 2B
Sun Feb 24, 2019 1:12 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 9
Views: 185

Re: Test 2

Calculating the equilibrium constant from Gibbs free energy, calculating the free energy of reaction from formation and using van't Hoff equation.
by Hanniel U 2B
Sun Feb 24, 2019 12:44 pm
Forum: Balancing Redox Reactions
Topic: Oxidation/Reduction
Replies: 2
Views: 46

Oxidation/Reduction

How can you identify the species that are being oxidized or reduced?
by Hanniel U 2B
Mon Feb 18, 2019 2:59 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: deltaG=0
Replies: 2
Views: 57

Re: deltaG=0

The reaction is at equilibrium.
by Hanniel U 2B
Sun Feb 17, 2019 7:14 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy?
Replies: 2
Views: 44

Re: Gibbs free energy?

One thing that I know Gibbs free determines is the spontaneity of a process.
by Hanniel U 2B
Sun Feb 17, 2019 6:42 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Spontaneous reactions
Replies: 7
Views: 1055

Spontaneous reactions

Are exothermic reactions usually spontaneous because energy is released from the system or is there another way to explain it?
by Hanniel U 2B
Sat Feb 09, 2019 2:06 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: When to use deltaS=q/t versus deltaS=nRlnV2/V1
Replies: 2
Views: 69

Re: When to use deltaS=q/t versus deltaS=nRlnV2/V1

Use deltaS= nRLnV2/V1 when there is a change in entropy of an ideal gas when there is an isothermal expansion from a volume V1 to V2. Use deltaS= q/t when you are trying to find the change in entropy with given heat energy and temp.
by Hanniel U 2B
Sat Feb 09, 2019 1:46 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: entropy midterm
Replies: 2
Views: 74

Re: entropy midterm

Yes, I think so. Everything from 4f to 4i. Gibbs free energy is 4j so I don't think we need to study that for the midterm.
by Hanniel U 2B
Sat Feb 09, 2019 1:44 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: 4G. 3 7th edition
Replies: 1
Views: 61

4G. 3 7th edition

How do I go about this question: Which would have higher molar entropy at T=0, single crystal of BF3 or single crystal of COF2
by Hanniel U 2B
Thu Feb 07, 2019 11:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 2
Views: 136

Midterm

Would we be asked to derive equations and formulas relating to thermodynamics on the midterm? Or should we not worry about that?
by Hanniel U 2B
Sat Feb 02, 2019 11:03 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Internal Energy
Replies: 2
Views: 91

Re: Internal Energy

1. Start with w: w=-P_{ex}\Delta V 2. Calculate \Delta V \Delta V=1.846L-0.345L=1.501L 3. Convert the given P_{ex} from Torr to atm P_{ex}=750 \textup{ torr } \times \frac{1 \textup{ atm}}{760 \textup{ Torr}}=.99\textup{ atm} 4. Plug into equation for w w=-.99 \times 1.5 =-1.49 \textup{L}\cdot \tex...
by Hanniel U 2B
Sat Feb 02, 2019 8:36 pm
Forum: Phase Changes & Related Calculations
Topic: Heat
Replies: 6
Views: 125

Heat

Would q be negative if heat is absorbed?
by Hanniel U 2B
Sat Feb 02, 2019 8:07 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Internal Energy
Replies: 2
Views: 91

Internal Energy

Can someone please help me with 4B.5 7th edition?
by Hanniel U 2B
Sun Jan 27, 2019 2:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Biological Example
Replies: 1
Views: 41

Re: Biological Example

I think the example Prof. Lavelle gave in class about why steam burns severely more than liquid is an example of applying enthalpies.
by Hanniel U 2B
Sun Jan 27, 2019 2:25 pm
Forum: Phase Changes & Related Calculations
Topic: Delta H
Replies: 11
Views: 191

Re: Delta H

Positive delta H means an Endothermic reaction because is greater than 0. Negative delta H is an exothermic reaction because heat is released.
by Hanniel U 2B
Mon Jan 21, 2019 10:09 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Conceptual questions
Replies: 6
Views: 123

Re: Conceptual questions

Jordan Lo 2A wrote:Is test 1 the entire outline 2? I could be wrong but I don't remember going over polyprotic acids (last couple exercises in 6th edition) or examples (last bullet points under concepts)

I'm not sure. It would be safe to just go over it and know some information about it.
by Hanniel U 2B
Sun Jan 20, 2019 9:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: amphoteric
Replies: 2
Views: 66

amphoteric

Is NH3 amphoteric? I keep getting confused
by Hanniel U 2B
Sun Jan 20, 2019 9:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Conceptual questions
Replies: 6
Views: 123

Conceptual questions

What sort of conceptual questions would be asked on test 1? What concepts do we need to know to explain?
by Hanniel U 2B
Fri Jan 18, 2019 12:29 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Weak Acids and Bases
Replies: 7
Views: 138

Weak Acids and Bases

If there a way we can easily identify weak acids and bases or should we just memorize the most common ones?
by Hanniel U 2B
Fri Jan 18, 2019 10:13 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 3
Views: 47

Le Chatelier's Principle

Can some please explain how to apply Le Chatelier's Principle?
by Hanniel U 2B
Tue Jan 15, 2019 12:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 2
Views: 41

Test 1

Does anyone know what would be covered on test 1 next week?
by Hanniel U 2B
Tue Jan 08, 2019 10:10 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q
Replies: 6
Views: 81

Q

Can someone please help me with 5G.11 7th edition?
by Hanniel U 2B
Tue Jan 08, 2019 9:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.7
Replies: 5
Views: 119

Re: 11.7

If you are asking about the percentage of X2 molecules that has decomposed at equilibrium, It is the difference between the diatomics at the start and when it reaches equilibrium which is 11-5=6. Divide that by the diatomics at the start = (6/11)*100= 54.5%. I'm not sure but that's how I answered it.
by Hanniel U 2B
Sat Dec 08, 2018 9:52 pm
Forum: Bronsted Acids & Bases
Topic: Strong base
Replies: 5
Views: 272

Re: Strong base

Albert_Luu3K wrote:NaOH is a strong base because it fully dissociates in water. That means there are more OH- ions floating in solution making it more basic.

Does that mean strong acids also fully dissociate in water?
by Hanniel U 2B
Sat Dec 08, 2018 9:51 pm
Forum: Amphoteric Compounds
Topic: amphoteric
Replies: 2
Views: 198

Re: amphoteric

"Not all amphoteric substances are amphiprotic. Although an amphiprotic species must be amphoteric, the converse is not true. For example, the metal oxide ZnO contains no hydrogen and cannot donate a proton. Instead, it is a Lewis acid whose Zn atom accepts an electron pair from the base OH−.&q...
by Hanniel U 2B
Mon Nov 26, 2018 10:48 pm
Forum: Lewis Structures
Topic: Question 3.45
Replies: 4
Views: 94

Re: Question 3.45

Does that mean atoms after row three can? Does this relate to the atomic number?
by Hanniel U 2B
Mon Nov 26, 2018 10:42 pm
Forum: Hybridization
Topic: Question from textbook
Replies: 4
Views: 86

Re: Question from textbook

Because it is T-shaped and T-shaped molecules have sp^3d hybridization.
by Hanniel U 2B
Mon Nov 26, 2018 6:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2F3 part B (7th edition)
Replies: 1
Views: 28

Re: 2F3 part B (7th edition)

I think we have to give both answers during the test. But make sure to clearly differentiate and state your answers when including resonance structures.
by Hanniel U 2B
Mon Nov 26, 2018 11:48 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 1
Views: 69

VSEPR

I found this online. I hope it helps!
by Hanniel U 2B
Sun Nov 25, 2018 8:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of CH2 (2-)
Replies: 2
Views: 53

Re: Shape of CH2 (2-)

Because the electron domain of the central atom is 4 and not 2. Someone correct me if I'm wrong.
by Hanniel U 2B
Sun Nov 25, 2018 4:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 6
Views: 188

Test 3

On test 3, would we be asked to name molecular shapes like seesaw, t-shaped, and square planar?
by Hanniel U 2B
Sat Nov 24, 2018 10:35 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: van der waals forces
Replies: 3
Views: 62

Re: van der waals forces

Van der Waals forces are also known as Dispersion/ induced dipole-induced dipole/ and London interactions. All of these terms describe intermolecular attractions that are always present and attractive. They arise due to fluctuating electron distributions, which results in fluctuating dipoles. These...
by Hanniel U 2B
Sat Nov 24, 2018 8:46 pm
Forum: Hybridization
Topic: Sigma/Pi Bonds
Replies: 5
Views: 80

Re: Sigma/Pi Bonds

Sigma and pi bonds are chemical covalent bonds. Sigma bond has been referred to as the strongest type of covalent bond.
by Hanniel U 2B
Sat Nov 24, 2018 8:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW Question 2E.19B
Replies: 1
Views: 57

Re: HW Question 2E.19B

I was also confused about that. At first, I even thought the molecule would be linear as a whole. But it makes sense that it is Tetrahedral. It is still confusing though.
by Hanniel U 2B
Sat Nov 24, 2018 8:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape vs molecular geometry
Replies: 3
Views: 50

Re: molecular shape vs molecular geometry

Molecular geometry usually includes the lone pair on the central atom. I call this the parent shape. While Molecular shape just describes the shape excluding the lone pair on the central atom. Make sure to differentiate both if or when asked to name shape. An example I like to use is SO2. The molecu...
by Hanniel U 2B
Sat Nov 24, 2018 3:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs determining shape?
Replies: 5
Views: 119

Re: Lone pairs determining shape?

Just to be on the safe side, I identify each shape as the parent shape and molecular shape. For example, S02 has a parent shape that is trigonal planar because of its lone pair on S but the molecular shape for S02 is bent or angular.
by Hanniel U 2B
Sat Nov 24, 2018 3:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.25 6th edition: Polarity of SF4
Replies: 4
Views: 89

Re: 4.25 6th edition: Polarity of SF4

The electronegativity difference between S and F is greater than 0.5, that's why it is Polar.
by Hanniel U 2B
Mon Nov 19, 2018 12:22 pm
Forum: Hybridization
Topic: Hybridization
Replies: 1
Views: 30

Hybridization

During lecture today, C2H4 had a sp^2 hybridization. But when it was expanded, it was 2sp^2 and 2p. I am confused about that.
by Hanniel U 2B
Mon Nov 19, 2018 12:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion
Replies: 6
Views: 189

Discussion

I was wondering; would Tuesday discussion sessions still take place or not?
by Hanniel U 2B
Wed Nov 14, 2018 11:34 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 3
Views: 77

VSEPR

Is the VSEPR group the names of the shapes of the Lewis structure? I'm so confused.
by Hanniel U 2B
Wed Nov 14, 2018 11:32 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 3
Views: 127

Bond Angles

I know Professor Lavelle mentioned this but do we have to know the bond angles or we just have to guess what it is less than? Also, I'm guessing we have to memorize all the names of shapes right?
by Hanniel U 2B
Fri Nov 09, 2018 11:10 am
Forum: Bond Lengths & Energies
Topic: Grading
Replies: 3
Views: 118

Re: Grading

I don't think there is a grading scale. The total number of points you could get is 500. So just add up all your points at the end of the quarter.
by Hanniel U 2B
Fri Nov 09, 2018 11:03 am
Forum: Lewis Structures
Topic: Electrons on Least EN Atom
Replies: 3
Views: 94

Re: Electrons on Least EN Atom

This is a good video:
https://youtu.be/dNPs-cr_6Bk
by Hanniel U 2B
Fri Nov 09, 2018 11:00 am
Forum: Octet Exceptions
Topic: octet exceptions
Replies: 4
Views: 122

Re: octet exceptions

The first four elements on the periodic table are elements with octet exceptions.
by Hanniel U 2B
Wed Oct 31, 2018 12:30 pm
Forum: Octet Exceptions
Topic: Octet rule
Replies: 2
Views: 68

Re: Octet rule

The octet rule is basically a guideline for bonding which says that elements (with atomic number below 20) should have 4 bonding pairs of electrons (8 e- total - the noble gas configuration). The first 4 elements do not follow this guideline as they do not need 8 e- to reach a noble gas configurati...
by Hanniel U 2B
Wed Oct 31, 2018 12:21 pm
Forum: Lewis Structures
Topic: D orbital
Replies: 4
Views: 116

Re: D orbital

d orbitals can hold up to 10 electrons.
by Hanniel U 2B
Wed Oct 31, 2018 12:19 pm
Forum: Octet Exceptions
Topic: Octet rule
Replies: 2
Views: 68

Octet rule

Can someone please explain the octet rule and why the first 4 atoms on the periodic table don't have it. Thanks !
by Hanniel U 2B
Wed Oct 31, 2018 12:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons Counting
Replies: 1
Views: 85

Re: Valence Electrons Counting

Valence electrons are the outer electrons that are involved in bonding and they hold the highest energy. That's why electrons in the s and p orbitals are valance electrons.
by Hanniel U 2B
Sun Oct 21, 2018 3:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Test 2
Replies: 1
Views: 54

Test 2

What kind of questions would be on the test relating to Atomic Spectra?
by Hanniel U 2B
Sun Oct 21, 2018 3:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Test On Tuesday
Replies: 10
Views: 451

Re: Test On Tuesday

From what I know, the test will cover the Photoelectric effect, De Broglie wavelength, Heisenberg uncertainty, Atomic spectra, and Quantum numbers.
by Hanniel U 2B
Thu Oct 18, 2018 10:49 pm
Forum: DeBroglie Equation
Topic: De Broglie
Replies: 12
Views: 511

Re: De Broglie

Also, p=mv. So wavelenght=h/p which is also wavelenght= h/mv.
by Hanniel U 2B
Thu Oct 18, 2018 8:21 pm
Forum: DeBroglie Equation
Topic: units
Replies: 3
Views: 105

Re: units

It depends. Sometimes you would have to use kg*m^2*s^-2 instead of J*s to cancel out and get the right units at the end of your calculations.
by Hanniel U 2B
Wed Oct 17, 2018 12:44 pm
Forum: *Shrodinger Equation
Topic: Schrodinger's equation
Replies: 2
Views: 73

Schrodinger's equation

I just want to clarify. Do we have to know and are we gonna use the schrodinger's equation or not?
by Hanniel U 2B
Wed Oct 17, 2018 12:40 pm
Forum: Properties of Light
Topic: Mnemonic for em spectrum
Replies: 2
Views: 80

Re: Mnemonic for em spectrum

Thanks!
by Hanniel U 2B
Wed Oct 17, 2018 12:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Difference in orbitals
Replies: 3
Views: 75

Re: Difference in orbitals

I don't think you have to worry about the f-orbitals for now. They are more complicated in shape. Just be familiar with s, p and d.
by Hanniel U 2B
Thu Oct 11, 2018 8:26 am
Forum: Properties of Light
Topic: Wave Model of Light
Replies: 1
Views: 73

Re: Wave Model of Light

Electromagnetic radiation is a form of energy that is produced by oscillating electric and magnetic disturbance, or by the movement of electrically charged particles traveling through a vacuum. Electron radiation is released as photons, which are bundles of light energy that travel at the speed of l...
by Hanniel U 2B
Thu Oct 11, 2018 8:16 am
Forum: Properties of Light
Topic: Photoelectric effect
Replies: 4
Views: 50

Photoelectric effect

Does photon have to be greater than work function for photoelectric effect to work?
by Hanniel U 2B
Thu Oct 11, 2018 8:10 am
Forum: Properties of Light
Topic: Do I need to memorize the Light Spectrum? [ENDORSED]
Replies: 13
Views: 173

Re: Do I need to memorize the Light Spectrum? [ENDORSED]

I think we need to. There will be problems were we we need to state the spectrum given the answer we get. There was a similar problem like that on the homework.
by Hanniel U 2B
Fri Oct 05, 2018 9:36 am
Forum: Limiting Reactant Calculations
Topic: Limiting reagents
Replies: 12
Views: 200

Re: Limiting reagents

Okay but during the post assessment, I answered that it cannot have two limiting reactants but the answer was wrong. That's why I'm confused.
by Hanniel U 2B
Mon Oct 01, 2018 11:56 am
Forum: Limiting Reactant Calculations
Topic: Limiting reagents
Replies: 12
Views: 200

Limiting reagents

I watched the video but I'm still not sure. Can a chemical equation have two limiting reagents ?

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