## Search found 61 matches

Sun Mar 10, 2019 11:16 pm
Forum: General Rate Laws
Topic: Graphs
Replies: 2
Views: 72

### 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: 88

### 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: 103

### 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: 137

### 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: 126

### 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: 64

### 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: 40

### 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: 191

### 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: 67

### 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: 39

### 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: 87

### 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: 85

### 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: 211

### 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: 56

### 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: 103

### 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: 95

### 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: 117

### 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: 223

### 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: 60

### 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: 57

### 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: 68

### 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: 73

### 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: 48

### 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: 126

### 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: 49

### 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: 92

### 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: 57

### 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: 82

### 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: 145

### 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: 59

### 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: 55360

### 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: 60

### 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: 144

### 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: 152

### 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: 102

### 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: 132

### 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: 201

### 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: 172

### 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: 100

### 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: 110

### 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: 143

### 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: 79

### 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: 80

### 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: 434

### 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: 474

### 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: 394

### 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: 161

### 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: 1790

### 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: 187

### 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: 167

### 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: 198

### 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: 100

### 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: 121

### 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: 167

### 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: 743

### 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: 101

### 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: 62

### 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: 143

### 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: 197

### 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: 139

### 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: 66

### 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 ...

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