Search found 61 matches
- Sun Mar 10, 2019 11:16 pm
- Forum: General Rate Laws
- Topic: Graphs
- Replies: 2
- Views: 372
Graphs
Can someone explain to me what order(s) correspond to what graphs? Positive slope, negative slope, decreasing sigmoid, zero order, first order, second order.
- Sun Mar 10, 2019 11:14 pm
- Forum: Zero Order Reactions
- Topic: Zero order reactions
- Replies: 4
- Views: 463
Re: Zero order reactions
I don't think the textbook or Lavelle ever talked about its commonality in terms of ranks. I tried doing a Google Search too, but that just came up empty, so I don't think it's a concern we need to really understand.
- Sun Mar 10, 2019 11:08 pm
- Forum: First Order Reactions
- Topic: pseudo vs 2nd order
- Replies: 4
- Views: 651
Re: pseudo vs 2nd order
To add, in discussion, my TA told me it's appropriate to use it when n=1.
- Sun Mar 10, 2019 11:06 pm
- Forum: General Rate Laws
- Topic: Rate Laws
- Replies: 8
- Views: 887
Rate Laws
Is it necessary for us to understand/know the ways how to derive the formulas? He showed us all the derivations in class, but I'm unsure if he would expect us to on a test.
- Sun Mar 10, 2019 10:54 pm
- Forum: First Order Reactions
- Topic: Half-Life
- Replies: 7
- Views: 792
Half-Life
When we talk about half-life, does this imply that there is normal life? I'm confused about what half-life is and when we would want to calculate it?
- Sun Mar 10, 2019 10:45 pm
- Forum: Second Order Reactions
- Topic: Zero, First, Second Reactions
- Replies: 2
- Views: 416
Zero, First, Second Reactions
Can someone explain to me the difference between these three and what quantifies one to be a zero, first, or second reaction?
- Sun Mar 03, 2019 4:16 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Rusting Process
- Replies: 1
- Views: 253
Re: Rusting Process
The rusting process equation is Fe+O2+H2O----> Fe2O3*H20. Refer to 7th edition 6N.21 problem for more clarification of it in practice. Basically, you need Fe (iron) plus H20 (water) plus O2 (oxygen) for the rusting process to be initiated.
- Sun Mar 03, 2019 4:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Pt(s)
- Replies: 10
- Views: 1075
Pt(s)
When is it necessary to write the Pt(s) in the cell diagram?
- Sun Mar 03, 2019 4:10 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Low voltage in concentration cells
- Replies: 2
- Views: 361
Re: Low voltage in concentration cells
In concentration cells, for example Ag(2)|Ag+(aq)||Ag+(aq)|Ag(s), when you take the standard reduction potential for the anode and cathode, the number will be the same. Thus when you subtract the same number by the same number, you will ultimately get E naught=0V.
- Thu Feb 21, 2019 7:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Max Potential
- Replies: 1
- Views: 240
Max Potential
Why does maximum potential occur when "very little current flows"? This is directly from the lecture, but I am confused what is the logic behind this.
- Thu Feb 21, 2019 7:34 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs Free Energy Decreasing
- Replies: 2
- Views: 443
Gibbs Free Energy Decreasing
Why does Gibbs free energy of a substance decrease (become less positive) as T increases at constant pressure?
- Thu Feb 21, 2019 7:33 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs Free Energy
- Replies: 4
- Views: 479
Gibbs Free Energy
Can someone explain to me why deltaG<0 is a forward process, deltaG>0 is a reverse process, and deltaG=0 is at physical equilibrium? What is the logic behind this?
- Mon Feb 11, 2019 10:14 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: deltaS=nCvln(t2/t1) what is Cv?
- Replies: 7
- Views: 2830
Re: deltaS=nCvln(t2/t1) what is Cv?
where does the 3/2 come from? For heat capacities of ideal gases, we use Cv=3/2R for a monoatomic gas and Cv=5/2R for a diatomic gas such as N2 or H2. The constant being multiplied to R is determined by the greater number of degrees of freedom in diatomic as opposed to monoatomic gases, so 5/2 (dia...
- Mon Feb 11, 2019 10:10 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Internal Energy and Entropy Relationship
- Replies: 1
- Views: 284
Internal Energy and Entropy Relationship
Is internal energy (delta U) and the entropy in a system directly correlated? Like if internal energy is decreased, does the entropy decrease too? Or is there an inverse correlation between them?
- Mon Feb 11, 2019 10:07 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Ideal Behavior
- Replies: 3
- Views: 421
Ideal Behavior
In some questions, they state to assume ideal behavior. What does this mean? And will there be times where we have to assume it and the problem won't tell us?
- Sat Feb 09, 2019 3:18 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: DeltaS=kBlnW
- Replies: 3
- Views: 642
DeltaS=kBlnW
How is the equation DeltaS=kBlnW used and what do the individual variables represent?
- Sat Feb 09, 2019 3:05 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: How to Calculate Degeneracy
- Replies: 5
- Views: 554
How to Calculate Degeneracy
How do we calculate degeneracy? I'm not sure how to use the formula or its variables.
- Sat Feb 09, 2019 3:02 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 10
- Views: 1011
Reversible vs Irreversible
Is there a way to tell whether to use a reversible, isothermal equation or an irreversible equation to represent work?
- Mon Jan 28, 2019 11:40 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies of Diatomic Molecules
- Replies: 2
- Views: 311
Bond Enthalpies of Diatomic Molecules
Why are bond enthalpies of diatomic molecules accurate but using bond enthalpies is the least accurate method for all others?
- Mon Jan 28, 2019 11:38 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Why Enthalpy Changes Are Additive
- Replies: 2
- Views: 328
Why Enthalpy Changes Are Additive
Can someone explain “enthalpy changes are additive” to me and why this is so?
- Mon Jan 28, 2019 11:35 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Clarification on Calculation Methods
- Replies: 1
- Views: 263
Clarification on Calculation Methods
Can someone explain to me the three methods and when to use which?
- Wed Jan 23, 2019 12:34 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Second deprotonation
- Replies: 3
- Views: 406
Re: Second deprotonation
No, I do not think he will be testing us on this concept even though it was lightly touched upon in our Chapter 12 homework.
- Wed Jan 23, 2019 12:33 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Problem 5G.1) 7th edition of textbook
- Replies: 1
- Views: 247
Re: Problem 5G.1) 7th edition of textbook
The first statement is true because equilibrium reactions take account for both the reactants and products. If there is more products or reactants, the reaction will adjust accordingly according to the Le Chatelier's Principle. The second statement refers to its equilibrium CONSTANT, not reaction. F...
- Wed Jan 23, 2019 12:26 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Knowing When to Approximate
- Replies: 4
- Views: 857
Re: Knowing When to Approximate
The value they are saying you need to approximate is the x (or value you are calculating) over that same number's initial value (given in the problem). The reason why we approximate to see if it's less than 5% is to verify if the approximation (aka the calculation we performed) was legitimate. We on...
- Tue Jan 15, 2019 10:41 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume and Pressure
- Replies: 2
- Views: 242
Re: Volume and Pressure
I understand that volume and pressure are inversely related, I'm still a little confused about how this correlates with favoring the side with more moles? I think it is confusing to you because you have the idea wrong. When pressure is increased, volume decreases, and it favors the side with LESS m...
- Tue Jan 15, 2019 10:35 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: stability
- Replies: 3
- Views: 385
Re: stability
I think it would be based on the equilibrium constant. If products are favored, they are more stable. If reactants are favored, they are more stable. I agree with this. However, I think she meant to say that if products are favored, they are more stable. If reactants are favored, then they are less...
- Tue Jan 15, 2019 10:31 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Predict Solubility
- Replies: 1
- Views: 237
Predict Solubility
How do we use equilibrium constants to predict solubility?
- Tue Jan 08, 2019 11:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Finding Q
- Replies: 1
- Views: 237
Re: Finding Q
To find Q, you would calculate it as if you were calculating K. So you would take the partial pressures of the reactants and products by placing the products/reactants (make sure to raise each product/reactant to its respective number). You would then solve for the answer and that's how you get Q.
- Tue Jan 08, 2019 11:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Gibbs Free Energy
- Replies: 4
- Views: 438
Gibbs Free Energy
What is Gibbs free energy and what do we need to know about its concept?
- Tue Jan 08, 2019 11:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q and K
- Replies: 1
- Views: 145
Q and K
What is the difference between Q and K? What are their meanings?
- Sat Dec 08, 2018 12:15 pm
- Forum: Dipole Moments
- Topic: How do you find the "largest dipole moment"?
- Replies: 6
- Views: 91956
Re: How do you find the "largest dipole moment"?
HBr would have a larger dipole moment than HI since as Jamlah said, there's a greater electronegativity difference between H and Br than between H and I. In other words HBr is more polar and Bromine will attract electrons to itself more. I'm not understanding why HBr has a larger dipole moment than...
- Mon Dec 03, 2018 10:31 am
- Forum: Lewis Acids & Bases
- Topic: Acid/Super Acid & Base/Super Base
- Replies: 2
- Views: 592
Acid/Super Acid & Base/Super Base
What is the difference between an acid and a SUPER acid? Same thing for a base and a SUPER base?
- Mon Dec 03, 2018 10:30 am
- Forum: Bronsted Acids & Bases
- Topic: Ka Formula
- Replies: 6
- Views: 941
Re: Ka Formula
Ka is the acid ionization constant or equilibrium constant for chemical equations in weak acids with aqueous solutions. You would use the formula to determine the Ka based on the given information given for the molecule. It will not always be H and A, for there are other cases too.
- Mon Dec 03, 2018 10:21 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: chelates
- Replies: 5
- Views: 541
Re: chelates
Chelates do need to have a specific shape, cyclic or ring structure. For example, in an ethylenediamine-cadmium complex, a chelate ring occurs.
- Mon Nov 26, 2018 3:00 pm
- Forum: Hybridization
- Topic: Hybridization with Lone Pairs
- Replies: 4
- Views: 489
Re: Hybridization with Lone Pairs
Are we going to be dealing with resonance structure and delocalized atoms on this Friday’s test? I do not believe we are going to have those questions because for my discussion, my TA said that the test will focus on VSEPR structures, bond angles, lone pair effect, and physical forces (Van Der Waal...
- Mon Nov 26, 2018 2:54 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis acid and base
- Replies: 5
- Views: 480
Lewis acid and base
Hello, I was wondering to what extent we need to know about Lewis acids and bases. I know the basic information (eg. one shares and one donates), but I don’t know if that’s enough for the test. Can someone give me more information about their differences and similarities?
- Mon Nov 26, 2018 2:47 pm
- Forum: Biological Examples
- Topic: Cisplatin Example
- Replies: 5
- Views: 653
Cisplatin Example
Can someone explain to me the cisplatin example we discussed in class again? I didn’t understand how the coordination compound structure contributed to stopping cell division.
- Sun Nov 25, 2018 9:36 pm
- Forum: Bond Lengths & Energies
- Topic: Why Are Double Bonds Shorter
- Replies: 16
- Views: 6202
Re: Why Are Double Bonds Shorter
The textbook in section 2.16 page 83 says, "Multiple bonds are shorter than single bonds between the same two elements because the additional bonding electrons attract the nuclei more strongly and pull the atoms closer together.” This should help clarify your question!
- Sun Nov 25, 2018 9:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma and pi bonds
- Replies: 4
- Views: 497
Sigma and pi bonds
What is the reason why sigma bonds are stronger than pi bonds?
- Sun Nov 25, 2018 9:30 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs Nonpolar
- Replies: 5
- Views: 490
Polar vs Nonpolar
How can we determine if a compound is polar or nonpolar?
- Mon Nov 12, 2018 2:40 am
- Forum: Bond Lengths & Energies
- Topic: bond length such as the midterm question
- Replies: 5
- Views: 627
Re: bond length such as the midterm question
Hello, my TA told me that because the question was asking the bond length average, it would have been best to write the hybrid "average" of the bond lengths, which in that case 120+140/2=130. However, a range would have also been accepted because we are unable to pinpoint an exact number o...
- Mon Nov 12, 2018 2:34 am
- Forum: Ionic & Covalent Bonds
- Topic: Polarizability vs Polarizing Power
- Replies: 2
- Views: 301
Re: Polarizability vs Polarizing Power
Although polarizability and polarizing power sound similar, they are very different indeed and only share one relation: they are both related to the covalent character of ionic bonds, which means that the electrons slightly shared as opposed to being separated. Polarizing power is used to describe c...
- Mon Nov 12, 2018 2:27 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: How do you utilize the VSEPR model?
- Replies: 4
- Views: 465
Re: How do you utilize the VSEPR model?
I would like to add on that this also works vice-versa, which means that if you know the shape of the molecule or compound, you are able to figure out its bond pairs and lone pairs. Thus, the VSEPR model is ultimately very useful for deciphering both the molecular shape or the properties that the mo...
- Tue Nov 06, 2018 3:06 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: exceptions
- Replies: 6
- Views: 897
Re: exceptions
I'm not sure if everyone helped clarify your question, but something that really helped me grasp the concept of when I should take from the 4s and add to the 3d is when it helps the orbitals become either half-filled (3d^5) or fully filled (3d^10). The reason being is because half-filled and fully f...
- Tue Nov 06, 2018 3:01 am
- Forum: Photoelectric Effect
- Topic: UA practice problem frequency of light
- Replies: 3
- Views: 889
Re: UA practice problem frequency of light
Can someone explain what a work function is? I think i got that wrong on the test because i thought a work function was work as a function of time. Yes I can. Work function is basically the idea of the energy required to eject or emit an electron. In the equation, E(photon) = work function + E(kine...
- Tue Nov 06, 2018 2:51 am
- Forum: Trends in The Periodic Table
- Topic: Electronegativity vs. Electron Affinity?
- Replies: 11
- Views: 1717
Re: Electronegativity vs. Electron Affinity?
If an element has a high electronegativity, does that mean it has higher electron affinity? I believe so because for one of our practice questions, the answer was something along the lines "If an element has a high ionization energy and a higher electron affinity, it is also highly electronega...
- Fri Nov 02, 2018 10:32 am
- Forum: Octet Exceptions
- Topic: Max # of bonds
- Replies: 4
- Views: 465
Re: Max # of bonds
I agree with the previous posts in that theoretically, I believe you could form 9 bonds, but would be extremely unlikely since it deviates so far away from the desired charge of zero. By creating so many bonds, it would make the formal charge insanely high and unstable (since the best and most stabl...
- Fri Nov 02, 2018 10:22 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Stable Condition
- Replies: 8
- Views: 2575
Re: Stable Condition
I believe that it is always desirable to make the formal charge of a compound ultimately zero because it shows that a molecule is neutral, if we can. However, with the example compound you gave [SO4]-2, it is not possible to make the formal charge zero, thus we would have to strive to make the forma...
- Fri Nov 02, 2018 10:09 am
- Forum: Lewis Structures
- Topic: How to determine central atom
- Replies: 8
- Views: 1493
Re: How to determine central atom
To sum up the ideas of this post and contribute to the discussion, to determine the central atom, there are multiple factors you can consider: 1. Which element is least frequently present in the compound? 2. Which one has the lowest ionization energy? 3. Which one is the least electronegative? The a...
- Mon Oct 22, 2018 12:44 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Test Two: Electron Configuration
- Replies: 6
- Views: 659
Re: Test Two: Electron Configuration
does this include knowing the appearances of the orbitals like the d-orbital? To clarify, in my workshop today, my UA said that appearances of the orbitals would be useful to know and he might expect us to know the orbital shapes of s (circle-shaped), p (infinity sign-shaped), and d (four leaf clov...
- Mon Oct 22, 2018 12:38 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Principle Quantum #
- Replies: 5
- Views: 726
Re: Principle Quantum #
To add on, "n" determines the energy and the size of the orbital. It is represented by integers like 1, 2, 3, 4, etc. "n" is important because it can help you determine possible values of l and m(l) because those quantum numbers are dependent on the value of "n".
- Mon Oct 22, 2018 12:30 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Finding an electron at a certain location
- Replies: 2
- Views: 271
Re: Finding an electron at a certain location
We are not expected to calculate the probability of finding the electron at a particular location since we did not learn it in class.
- Thu Oct 18, 2018 9:04 pm
- Forum: Photoelectric Effect
- Topic: Work Function: Increase in Energy
- Replies: 3
- Views: 527
Re: Work Function: Increase in Energy
To add on to the discussion, my UA told me today an analogy that I think would be really helpful! She said that increasing the intensity of a wavelength won't have an effect on the electron if there is not enough energy to eject an electron. Think of it like a hurdle. If the person attempting to jum...
- Thu Oct 18, 2018 8:43 pm
- Forum: Properties of Light
- Topic: Friday 10/5 Lecture
- Replies: 7
- Views: 676
Re: Friday 10/5 Lecture
I would like to add on that v in that case would be velocity because of the units correlation. However, you can also determine if it's velocity or frequency by the way it's written. v is often straight, while curly v represents frequency and often will use Hz or Hertz as units.
- Thu Oct 18, 2018 8:39 pm
- Forum: Einstein Equation
- Topic: The symbol v?
- Replies: 16
- Views: 8871
Re: The symbol v?
Hello! I was confused on this earlier too, but my UA clarified in my session that for this class, when you see v in terms of velocity, it will most likely be paired up with m (mass) in an equation or formula. Velocity is seen in the equations 1/2mv^2 and p=mv. While with the curly v, that would be c...
- Wed Oct 10, 2018 11:41 pm
- Forum: Properties of Light
- Topic: Summary Notes Clarification
- Replies: 3
- Views: 431
Re: Summary Notes Clarification
I was actually very confused about this myself recently, but I believe that the reason why long wavelengths cannot eject e- is because long wavelengths means smaller frequency. Frequency is related to energy and if there is small frequency, the energy is small too, thus meaning insufficient energy t...
- Wed Oct 10, 2018 11:36 pm
- Forum: Properties of Light
- Topic: Telling color by wavelength
- Replies: 3
- Views: 271
Re: Telling color by wavelength
Yes, there are ways to tell what color is presented by memorizing different wavelength ranges or using a chart. However, I feel that he does not expect us to be able to eyeball a wavelength and be able to determine its color.
- Wed Oct 10, 2018 11:32 pm
- Forum: Properties of Light
- Topic: Why Short Wavelengths Can Eject e-
- Replies: 6
- Views: 983
Why Short Wavelengths Can Eject e-
Hello, I know that the notion that short wavelengths can eject e-, while long wavelengths cannot. However, I am unsure of the reasoning behind this and how this idea came about, so I would greatly appreciate it if someone helped explain this to me.
- Thu Oct 04, 2018 6:35 pm
- Forum: Balancing Chemical Reactions
- Topic: Order of balancing an equation
- Replies: 8
- Views: 674
Re: Order of balancing an equation
To add on to the discussion, I usually start the process of balancing the chemical equation by balancing the element that does not repeat or occurs the least. Then I try to balance the elements that are not common first and save the common ones, such as H or O for last.
- Thu Oct 04, 2018 6:27 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: V=n/c
- Replies: 7
- Views: 9202
Re: V=n/c
To answer the above extended question of the difference between m and M, I believe that m represents the molar mass of an element, while M represents the molarity of the element.
- Thu Oct 04, 2018 6:24 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Question Self-Test E.3B
- Replies: 1
- Views: 188
Question Self-Test E.3B
It says to "calculate the molar mass of copper, given that a natural sample typically consists of 69.17% of copper-63, which has a molar mass of 62.94 g*mol^-1, and 30.83% copper-65, which has a molar mass of 64.93 g*mol^-1. (Note that the molar mass of an isotope is proportional to its atomic ...