Search found 65 matches

by Ruiting Jia 4D
Sat Mar 16, 2019 10:55 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell potential
Replies: 2
Views: 181

cell potential

When choosing which half reaction to flip, do we choose the one in which plugging in Ecathode - Eanode will produce the greatest positive number? If so, how does one do that when we want to keep the sign of E values for each half reaction the same? I'm just kinda confused on which reaction we revers...
by Ruiting Jia 4D
Sat Mar 16, 2019 9:15 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isometric/Isochoric
Replies: 10
Views: 294

Re: Isometric/Isochoric

What does isometric mean? The same as isochoric?
by Ruiting Jia 4D
Sat Mar 16, 2019 9:11 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Frequency factor units
Replies: 2
Views: 170

Re: Frequency factor units

I've found that it's sometimes M^-2 * s^-1 because it uses the same units as the rate constant.
by Ruiting Jia 4D
Sat Mar 16, 2019 9:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell potential
Replies: 3
Views: 182

cell potential

For getting an E(total) from two reactions, how do we know when to add and when to subtract? I always thought we needed to do Ecathode - Eanode ...
by Ruiting Jia 4D
Sat Mar 16, 2019 12:38 am
Forum: Second Order Reactions
Topic: 7E.3 in 7th edition
Replies: 3
Views: 225

Re: 7E.3 in 7th edition

the problem says "the presence of a catalyst provides a reaction pathway in which the activation energy of a certain reaction is reduced from 125 kj to 75 kj, by what factor does the rate increase at 298, all other factors equal?" I tried to do this using the Kr2/Kr1= e^-(Ea2-Ea1)/RT but ...
by Ruiting Jia 4D
Sun Mar 10, 2019 4:56 pm
Forum: Second Order Reactions
Topic: pseudo first order rxns
Replies: 3
Views: 65

Re: pseudo first order rxns

You use pseudo rate laws are used when all reactant concentrations change. When all reactant concentrations are changing it is difficult to study the rate of the reaction. So in order to study it we assume one reactant concentration is small and the others are so much larger that the concentration ...
by Ruiting Jia 4D
Sun Mar 10, 2019 4:41 pm
Forum: General Rate Laws
Topic: writing rate laws
Replies: 4
Views: 65

writing rate laws

Is there a difference between rate law and the "rate of consumption of __"?
by Ruiting Jia 4D
Sun Mar 10, 2019 4:40 pm
Forum: First Order Reactions
Topic: graph
Replies: 3
Views: 54

graph

Why is it that when graphing first order reactions, it is either exponentially decaying or linear?
by Ruiting Jia 4D
Sun Mar 10, 2019 4:39 pm
Forum: Second Order Reactions
Topic: pseudo first order rxns
Replies: 3
Views: 65

pseudo first order rxns

Hello! I am confused about the concept of pseudo-first-order reactions. When would we need to use them, and why is it that some reactants would be insignificant to the rate law?
by Ruiting Jia 4D
Sun Mar 03, 2019 7:37 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff use
Replies: 13
Views: 432

Re: Van't Hoff use

I have found that we use Vant Hoff when we are either given 2 temperatures and a K or two Ks and a temperature.
by Ruiting Jia 4D
Sun Mar 03, 2019 7:35 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q and K with the Nernst Equation
Replies: 3
Views: 72

Q and K with the Nernst Equation

In order to find out which way the reaction is proceeding, would we have to find both Q and K? Or is there another way where we are able to determine this?
by Ruiting Jia 4D
Mon Feb 25, 2019 3:15 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox equations in acidic/basic solutions [ENDORSED]
Replies: 3
Views: 82

Re: Balancing redox equations in acidic/basic solutions [ENDORSED]

How do we recognize whether we are dealing with an acidic or basic solution?
by Ruiting Jia 4D
Sun Feb 24, 2019 1:27 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell potential
Replies: 2
Views: 62

cell potential

What do we need to know about cell potential besides its relation with Gibbs free energy?
by Ruiting Jia 4D
Sun Feb 24, 2019 1:25 pm
Forum: Balancing Redox Reactions
Topic: platinum
Replies: 7
Views: 92

platinum

When Platinum is added to the cell diagram, should it also be added to the overall chemical equation?
by Ruiting Jia 4D
Sun Feb 24, 2019 1:17 pm
Forum: Balancing Redox Reactions
Topic: Test 2 Material
Replies: 13
Views: 230

Re: Test 2 Material

Will acid/base consideration when balancing redox equations be on the test? It's in the textbook but not covered in lecture.
by Ruiting Jia 4D
Sun Feb 17, 2019 8:52 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: vibrational entropy
Replies: 2
Views: 59

vibrational entropy

Is there a way to measure vibrational entropy? I know that residual/positional is measured through degeneracy.
by Ruiting Jia 4D
Sun Feb 17, 2019 8:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneity
Replies: 3
Views: 73

spontaneity

I'm still unsure on how to visualize spontaneity if it doesn't mean that it happens immediately. Is there a good visual on how to describe spontaneity?
by Ruiting Jia 4D
Sun Feb 17, 2019 8:48 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G
Replies: 3
Views: 56

delta G

Besides the fact that delta G indicates that a reaction is in equilibrium, what else can it tell us?
by Ruiting Jia 4D
Sun Feb 10, 2019 10:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 7th edition 4E.5
Replies: 3
Views: 84

Re: 7th edition 4E.5

Hi all. I am currently working on 4E.5 in the 7th edition textbook. The question asks to estimate the reaction enthalpy using bond enthalpies for the formation of benzene: 3C2H2(g) --> C6H6(g) 3 C-C triple bonds are broken and 6 C-C 1.5 bonds are formed. Why isn't the formation of 6 C-H bonds inclu...
by Ruiting Jia 4D
Sun Feb 10, 2019 5:53 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: Concept of 3rd Law of Thermodynamics
Replies: 3
Views: 82

Re: Concept of 3rd Law of Thermodynamics

Chem_Mod wrote:The concept is that entropy’s theoretical limit is 0 if there is absolute order in a system. We can calculate positional and residual entropy with formulas you learned in class.


What do you mean by absolute order?
by Ruiting Jia 4D
Sun Feb 10, 2019 5:53 pm
Forum: Calculating Work of Expansion
Topic: Derivatives and Integrals
Replies: 5
Views: 102

Re: Derivatives and Integrals

I think we may need to write out the integrals, but no real integrating since we didn't do any of those in class.
by Ruiting Jia 4D
Sun Feb 10, 2019 5:51 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 9
Views: 151

Re: Reversible vs Irreversible

How come infinitesimally small changes affect reversible systems?
by Ruiting Jia 4D
Sat Feb 02, 2019 6:31 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Heat vs. Temp
Replies: 9
Views: 268

Re: Heat vs. Temp

Temperature, essentially, measures heat, since heat is the action/energy (of particles moving) and temperature is a measurement (Kelvin, Celsius, etc.).
by Ruiting Jia 4D
Sat Feb 02, 2019 6:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Open, closed, or isolated systems
Replies: 10
Views: 249

Re: Open, closed, or isolated systems

I believe that the question/problem will usually give enough hints as to whether a system is open, closed, or isolated if it was not explicitly stated.
by Ruiting Jia 4D
Sat Feb 02, 2019 6:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Review
Replies: 14
Views: 302

Re: Midterm Review

I believe that Dr. Lavelle will announce midterm review sessions this upcoming week or next week.
by Ruiting Jia 4D
Sat Feb 02, 2019 4:52 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system
Replies: 5
Views: 102

isolated system

If a problem were to include an isolated system, would we be able to do any calculations on it? Or would we just say that everything stays the same?
by Ruiting Jia 4D
Sat Feb 02, 2019 4:46 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Analogy of Boulder
Replies: 5
Views: 106

Re: Analogy of Boulder

If you literally place a boulder on the side of the mountain/hill, it will roll down on its own due to the pull of gravity. We do not expect it to go up, unless another force was acted upon it (say, a machine) that could pull it up.
by Ruiting Jia 4D
Sat Feb 02, 2019 4:44 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: calorimeters
Replies: 7
Views: 117

calorimeters

Besides knowing that a bomb calorimeter is an isolated system, should we know anything else about the bomb calorimeter or other types of calorimeters?
by Ruiting Jia 4D
Sat Jan 19, 2019 1:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: strong acids and bases
Replies: 2
Views: 75

strong acids and bases

Can someone give a quick refresher on how to identify strong acids and bases vs weak acids and bases, and are there pages in the textbook to also help with this? I understand how the two differ when it comes to dissociating in the chemical equations.
by Ruiting Jia 4D
Sat Jan 19, 2019 1:38 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: exothermic/endothermic
Replies: 3
Views: 160

exothermic/endothermic

Besides the reaction equation, are there any other ways we can identify whether a reaction is endothermic or exothermic? And are there exceptions to being able to identify this from the equation?
by Ruiting Jia 4D
Sat Jan 19, 2019 1:35 pm
Forum: Ideal Gases
Topic: PV=nRT
Replies: 8
Views: 337

Re: PV=nRT

Hi Ryan,
I think we use PV=nRT to support Le Chatelier's principle, but there isn't much else on where you'd use it in class. However, we may have to use the concentration to calculate P, such as in P = (conc) * RT given temperature. R is a constant.
by Ruiting Jia 4D
Sat Jan 12, 2019 9:05 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: doubling pressure
Replies: 2
Views: 59

doubling pressure

When talking about Le Chatelier's implications on changing physicial parameters, such as pressure, why did Dr. Lavelle double pressure to find the new initial concentration of the equation : N2 + 3 H2 <=> 2 NH3 ??
by Ruiting Jia 4D
Sat Jan 12, 2019 9:02 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pressure and temperature
Replies: 4
Views: 31

pressure and temperature

Can the effects of changing pressure and temperature on concentration be summarized? I only understand how to increase yield of products by removing products, but unfortunately I didn't learn anything in high school regarding the effects of pressure or temperature.
by Ruiting Jia 4D
Sat Jan 12, 2019 8:54 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Explaining Q<K and Q>K [ENDORSED]
Replies: 7
Views: 161

Re: Explaining Q<K and Q>K [ENDORSED]

You can think of it like a pendulum. When K means the pendulum is in the middle (at equilibrium), Q lets you know how far it is from equilibrium based on its relation to K. If Q swings left, such as the arrow "<", you can visualize it as being driven to products because it is before reachi...
by Ruiting Jia 4D
Fri Dec 07, 2018 11:50 pm
Forum: Polyprotic Acids & Bases
Topic: polyprotic acids and bases in equations
Replies: 3
Views: 262

polyprotic acids and bases in equations

when writing the proton transfer equilibria equations, do we need to automatically apply polyprotic acids/bases such that for example in H2SO4 it is H2SO4 + H2O -> H3O+ + SO4 2- ? or would it still be HSO4 - ?
by Ruiting Jia 4D
Sun Dec 02, 2018 11:18 pm
Forum: Biological Examples
Topic: Cisplatin Example
Replies: 5
Views: 174

Re: Cisplatin Example

it forms coordination compounds with DNA to stop cell division. I don't think we need to know the details other than that.
by Ruiting Jia 4D
Sun Dec 02, 2018 11:13 pm
Forum: Biological Examples
Topic: Knowledge of Biological Applications for Final
Replies: 5
Views: 92

Re: Knowledge of Biological Applications for Final

I believe it's just cisplatin and hemoglobin.
by Ruiting Jia 4D
Sun Dec 02, 2018 10:59 pm
Forum: Amphoteric Compounds
Topic: Amphoteric compounds besides water
Replies: 6
Views: 123

Re: Amphoteric compounds besides water

Sarah Zhao 4E wrote:So besides water, they get kind of weird.
Hydrogen carbonate, bisulfate, amino acids, BUT MOST IMPORTANTLY (and probably the only one you will need to know) WATER


Can you explain why amino acids would be amphoteric?
by Ruiting Jia 4D
Sun Dec 02, 2018 10:57 pm
Forum: Bronsted Acids & Bases
Topic: Questions
Replies: 2
Views: 66

Questions

Will questions on the exam be asking characteristics of acids and bases or identifying different types of acids and bases?
by Ruiting Jia 4D
Sun Dec 02, 2018 10:53 pm
Forum: Dipole Moments
Topic: dipole
Replies: 6
Views: 177

Re: dipole

Luc Galaif wrote:Do we need to know how to draw dipoles for the test?


Yes, and I believe it will also be on the final.
by Ruiting Jia 4D
Sun Dec 02, 2018 10:52 pm
Forum: Biological Examples
Topic: Biological Importance of Coordination Compounds
Replies: 3
Views: 87

Re: Biological Importance of Coordination Compounds

In the chem review session, we were told that there could be multiple choice questions based on biological examples and that we should memorize the examples in case.
by Ruiting Jia 4D
Sun Dec 02, 2018 10:49 pm
Forum: Naming
Topic: Knowing oxidation states
Replies: 11
Views: 144

Re: Knowing oxidation states

Becky Belisle 1F wrote:I think it's useful to memorize the oxidation states of the common ligands.

Which are the common ligands that we would need to memorize for?
by Ruiting Jia 4D
Sun Dec 02, 2018 10:48 pm
Forum: Naming
Topic: coordination number
Replies: 1
Views: 24

coordination number

Does the coordination number (which equals number of bonds) determine the complex?
by Ruiting Jia 4D
Sat Nov 24, 2018 9:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming the Shape
Replies: 16
Views: 247

Re: Naming the Shape

With the shapes, do we need to memorize the bond angles?
by Ruiting Jia 4D
Fri Nov 23, 2018 10:28 pm
Forum: Dipole Moments
Topic: dipole
Replies: 6
Views: 177

dipole

in my understanding, a dipole is closely related to polarity - are there instances where a dipole would exist where polarity did not?
by Ruiting Jia 4D
Sun Nov 18, 2018 1:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angle
Replies: 4
Views: 98

bond angle

Is there a way to calculate bond angle besides memorizing the shapes that are associated with the bond angles?
by Ruiting Jia 4D
Sun Nov 18, 2018 1:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Shape
Replies: 10
Views: 237

Re: Determining Shape

I think besides just drawing the Lewis structure, what would also help is sketching or imagining the Lewis structure in 3d. The Lewis structure presents you with a very 2d linear version of what the model actually looks like.
by Ruiting Jia 4D
Sun Nov 18, 2018 1:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pairs
Replies: 11
Views: 173

lone pairs

When there is a lone pair in a molecular shape, is it safe to say a general statement for how the other angles are affected? For example, saying that the angles of 90 and 180 degrees are slightly decreased due to the lone pair or to state a specific angle?
by Ruiting Jia 4D
Sun Nov 11, 2018 11:00 pm
Forum: Bond Lengths & Energies
Topic: bond length such as the midterm question
Replies: 5
Views: 128

bond length such as the midterm question

Hi,

When determining bond lengths with two differently valued lengths, should we write it as a range or a specific value? I know that on the midterm, any value between was accepted, but would writing a range be considered wrong?
by Ruiting Jia 4D
Sun Nov 11, 2018 10:57 pm
Forum: Resonance Structures
Topic: Drawing resonance
Replies: 17
Views: 613

Re: Drawing resonance

If the problem itself does not indicate that we have to draw all the different resonance structures, I believe it is not needed.
by Ruiting Jia 4D
Sun Nov 04, 2018 7:51 pm
Forum: Lewis Structures
Topic: Expanded octets? + other octet exceptions
Replies: 3
Views: 58

Expanded octets? + other octet exceptions

Hi! Which elements follow the expanded octet structures, and what are the other octet exceptions that we have to know?
by Ruiting Jia 4D
Sun Nov 04, 2018 7:50 pm
Forum: Lewis Structures
Topic: Lewis Acids and Bases
Replies: 2
Views: 71

Lewis Acids and Bases

How much of Lewis acids and bases do we have to know for the midterm?
by Ruiting Jia 4D
Sat Nov 03, 2018 3:59 pm
Forum: *Shrodinger Equation
Topic: radial distribution function
Replies: 1
Views: 218

radial distribution function

Hi! Do we need to know how to find the radial distribution function or probability density for the midterm? Thanks!
by Ruiting Jia 4D
Sun Oct 28, 2018 1:14 pm
Forum: Ionic & Covalent Bonds
Topic: ionization energy
Replies: 7
Views: 149

ionization energy

Why is the 2nd ionization energy of an element always higher?
by Ruiting Jia 4D
Sun Oct 28, 2018 1:12 pm
Forum: Octet Exceptions
Topic: Octet Exceptions
Replies: 3
Views: 106

Octet Exceptions

How come H, He, Li, Be are the octet exceptions?
by Ruiting Jia 4D
Sun Oct 28, 2018 1:02 pm
Forum: Lewis Structures
Topic: Dot's in the Lewis Structure
Replies: 10
Views: 187

Re: Dot's in the Lewis Structure

It doesn't matter where you place the dots, but you should make sure to fill up all the sides first before adding more than 4. For example, it's not right to have 3 dots on one side and no dots on the other sides.
by Ruiting Jia 4D
Sun Oct 21, 2018 3:12 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Delta x
Replies: 1
Views: 80

Delta x

If the uncertainty equation is delta p * delta x is greater than or equal to 1/2 h/2pi, then can we combine m*delta x (delta p) with delta x so that it's m*delta x^2?
by Ruiting Jia 4D
Sun Oct 21, 2018 3:10 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Equal sign?
Replies: 1
Views: 45

Equal sign?

In the book, I saw an example where the final answer used an equal sign instead of a greater than or equal to sign. How important is this sign, and what is its significance?
by Ruiting Jia 4D
Sun Oct 14, 2018 2:32 pm
Forum: Properties of Light
Topic: Geiger and Marsden experiment
Replies: 3
Views: 46

Geiger and Marsden experiment

Can someone explain the significance of this experiment? I understand that most of the particles passed through but I don't understand why they called the atoms "blobs of positively charged jelly" or why some bounced back.
by Ruiting Jia 4D
Sun Oct 14, 2018 2:25 pm
Forum: Properties of Light
Topic: Colors and Frequency
Replies: 14
Views: 518

Colors and Frequency

Do we need to memorize which colors corresponds with which frequency/wavelength/energy of photons? For example, if given a wavelength in nm, do we need to automatically know which color it corresponds to?
by Ruiting Jia 4D
Sun Oct 14, 2018 2:22 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 41
Views: 731

Re: Speed of Light

AustinGrove3B wrote:more specifically 2.99792 x 108. I think in the book they use this (more sig figs) than 3.0 x 108


Would it be advisable to calculate using 2.99792 x 10^8 on the exams? I'm not sure when to apply significant figures - either throughout the problem or just for the final answer.
by Ruiting Jia 4D
Thu Oct 04, 2018 11:59 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: atoms vs molecules vs formula units?
Replies: 3
Views: 63

atoms vs molecules vs formula units?

Hello! I would like some clarification on when to use these three units. How would we calculate finding an atom or molecule differently than calculating formula units? Or is it the same process but with different units?

Thanks!
by Ruiting Jia 4D
Thu Oct 04, 2018 11:55 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molecule vs Formula Unit
Replies: 4
Views: 124

Re: Molecule vs Formula Unit

Adding on to the original post, how would you know to label an answer with "formula units" or "molecules"?
by Ruiting Jia 4D
Thu Oct 04, 2018 11:53 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: writing the formula of a molecule
Replies: 5
Views: 346

Re: writing the formula of a molecule

A magnesium ion is Mg2+ Sulfate is SO4 2- Together that makes MgSO4 The heptahydrate basically just adds H2O at the end. Hepta- is a prefix for 7. So the official formula is MgSO4 . 7H2O In chemistry, it's standard to add a little dot between the compound and the hydrate For quizzes/tests, would we...

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