Search found 104 matches

Fri Mar 13, 2020 9:58 am
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 2
Views: 67

Final

This might seem like a redundant question, but I would like some clarification of what resources we can use on the final? Thank you.
Wed Mar 11, 2020 11:41 am
Forum: Second Order Reactions
Topic: Zeroth, First, Second Orders
Replies: 4
Views: 126

Zeroth, First, Second Orders

I am confused about what the orders of reactions mean conceptually? I understand how to determine the order mathematically when given the rates and concentrations of reactants. I also understand how the graphs of the orders are derived from. But what does 0, 1st, 2nd order mean?
Wed Mar 11, 2020 11:37 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation A variable
Replies: 2
Views: 59

Arrhenius Equation A variable

Will we be given what the value for A is for the Arrhenius equation? I don't know how else you could solve for k without knowing it.
Wed Mar 11, 2020 11:36 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation A variable
Replies: 3
Views: 57

Arrhenius Equation A variable

Will we be given what the value for A is for the Arrhenius equation? I don't know how else you could solve for k without knowing it.
Wed Mar 11, 2020 11:35 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts vs. Intermediates
Replies: 8
Views: 164

Catalysts vs. Intermediates

What is the difference between a catalyst and an intermediate. Can a catalyst also be an intermediate and vice versa?
Wed Mar 11, 2020 11:30 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: How to determine slow step?
Replies: 9
Views: 141

Re: How to determine slow step?

005162520 wrote:Why does the slow step determine rate law ?

The slow step determines the overall rate law because the overall rate of the reaction can only be as fast as the slowest step. If that makes sense. It's kind of like how a chain is only as strong as its weakest link. Hope that helps? :)
Tue Mar 10, 2020 6:25 pm
Forum: Biological Examples
Topic: COVID-19
Replies: 6
Views: 251

COVID-19

Sorry this post is unrelated to the topic, but I am concerned about what will happen for our final. Also, since classes were cancelled, how will we turn in the last homework assignment?
Mon Mar 09, 2020 11:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: endothermic reaction
Replies: 5
Views: 151

Re: endothermic reaction

If delta H is positive that means that heat is absorbed in the reaction. The heat is on the left with the reactants.
Mon Mar 09, 2020 11:07 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: How to determine slow step?
Replies: 9
Views: 141

Re: How to determine slow step?

Since the slow step determines the overall rate of the reaction, then typically if you are given the overall rate of the reaction that is the slow step.
Mon Mar 09, 2020 11:07 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Approximating X
Replies: 13
Views: 272

Re: Approximating X

If the K value is smaller than 10^-4 then you can approximate the x value. You can double check this by using the 5% rule. If the percent ionization is 5% or less then it is ok to approximate the x value.
Mon Mar 09, 2020 11:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: exothermic reaction
Replies: 4
Views: 121

Re: exothermic reaction

If delta H is negative that means that there is a release of energy so the reaction is exothermic.
Tue Mar 03, 2020 5:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrolysis (6.O.1)
Replies: 3
Views: 75

Re: Electrolysis (6.O.1)

So apparently, H20 is what is getting oxidized in the anode instead of SO4? Is this because SO4 is a spectator ion?
Mon Mar 02, 2020 12:45 am
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 5
Views: 139

Re: Cell Diagrams

The left side of the cell diagram should be the anode reaction (oxidation). The right side of the cell diagram should be the cathode reaction (reduction). They are separated by the salt bridge or double line. Don't put reactants on the left and products on the right. The cell diagram is depicting th...
Mon Mar 02, 2020 12:42 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: what's happening in galvanic cells
Replies: 2
Views: 53

Re: what's happening in galvanic cells

Electrons move from the anode to the cathode. The anode side is getting oxidized, so there is a loss of electrons. The cathode sign has a reduction reaction so there is a gain of electrons. The electrons flow throw the galvanic cell which generates a current of electrons and therefore a voltage.
Mon Mar 02, 2020 12:35 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Voltage Signs for Oxidation Reactions
Replies: 2
Views: 44

Voltage Signs for Oxidation Reactions

Since the appendix only gives all oxidation reactions in terms of reduction reactions, do we have to change the sign of the voltage?
Mon Mar 02, 2020 12:35 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Voltage Signs for Oxidation Reactions
Replies: 2
Views: 28

Voltage Signs for Oxidation Reactions

Since the appendix only gives all oxidation reactions in terms of reduction reactions, do we have to change the sign of the voltage?
Mon Mar 02, 2020 12:33 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.1.b)
Replies: 4
Views: 94

6N.1.b)

I solved for K for part b) In3+ + U3+ --> In2+ + U4+ and I didn't get the same answer as the solution guide? I used the Nernst equation and got around K=100 but the solutions in the back says 1x10^4. Can someone explain how to solve this problem?
Mon Mar 02, 2020 12:29 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrolysis (6.O.1)
Replies: 3
Views: 75

Electrolysis (6.O.1)

How are we supposed to find the cathode and anode reactions for the electrolysis of NiSO4? I found the cathode reaction for Ni+2 + 2e- --> Ni. I can't find the anode reaction in the appendix?
Sun Feb 23, 2020 10:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 9
Views: 168

Cell Diagrams

What are the different separations in the cell diagrams? Why do you sometimes use commas, bars, and double bars?
Sun Feb 23, 2020 10:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagrams Pt
Replies: 2
Views: 41

cell diagrams Pt

Why do we include Pt when there is no solid? What would the cell diagram look like if there was a solid that could act as the electrode?
Sun Feb 23, 2020 10:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 9
Views: 173

Re: salt bridge

The anions and cations in the salt bridge dissolve in the solutions to maintain a charge balance so that the redox reaction can continue. The video on galvanic cells that Lavelle posted on his website actually really helped me understand this.
Sun Feb 23, 2020 3:57 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.J.11b)
Replies: 1
Views: 126

5.J.11b)

In this problem we have to predict whether the reaction will shift toward products or reactants when the temperature is increased. " X_{2}\leftrightharpoons 2X where X is a halogen." How would we know how the reaction shifts without knowing the enthalpy of the reaction? What does X being a...
Wed Feb 19, 2020 9:05 pm
Forum: Balancing Redox Reactions
Topic: Homework 6K.5 Part B
Replies: 1
Views: 29

Homework 6K.5 Part B

How do I solve this problem?
Br2(l) -----> BrO3- +Br-

I don't understand how to balance the redox reaction when the Br is in both products.
Tue Feb 18, 2020 2:52 pm
Forum: Van't Hoff Equation
Topic: ∆H and ∆S not temperature dependent
Replies: 2
Views: 84

Re: ∆H and ∆S not temperature dependent

Heat and entropy are temperature dependent but because it is the CHANGE in heat and entropy it is not temperature dependent. The change remains the same.
Tue Feb 18, 2020 2:40 pm
Forum: Balancing Redox Reactions
Topic: Reduction vs. oxidation
Replies: 29
Views: 379

Re: Reduction vs. oxidation

Oxidation is when a compound loses electrons in the reaction. Reduction is when a compound gains electrons . You can memorize this with the acronym LEO the lion says GER. LEO=loss of electrons is oxidation, GER=gain of electrons is reduction.
Tue Feb 18, 2020 2:36 pm
Forum: Balancing Redox Reactions
Topic: Reducing/Oxidizing Agent
Replies: 4
Views: 62

Reducing/Oxidizing Agent

What is the difference between the reducing and oxidizing agent? Which one is being reduced and which one is being oxidized? How can you identify them?
Tue Feb 18, 2020 2:35 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 2
Views: 56

Oxidation Numbers

How do we determine the oxidation numbers and how it changed?
Tue Feb 18, 2020 2:33 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions
Replies: 7
Views: 105

Half Reactions

Why do we have to split the reaction into half reactions? What if there are many reactants and products that it needs more than two half-reactions?
Sun Feb 09, 2020 8:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive vs. Extensive
Replies: 15
Views: 469

Intensive vs. Extensive

What is the difference between intensive and extensive properties?
Sun Feb 09, 2020 8:39 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: difference between molar entropies?
Replies: 6
Views: 100

Re: difference between molar entropies?

Lead is a more complex molecule so it has more electrons, neutrons, and protons in one mole. Since there are more particles in lead, there is more degeneracy and therefore more entropy.
Sun Feb 09, 2020 8:37 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal and Reversible
Replies: 6
Views: 46

Re: Isothermal and Reversible

Yes. Isothermal is another way to say reversible.
Sun Feb 09, 2020 7:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating q
Replies: 4
Views: 70

Re: Calculating q

Kennedi2J wrote:How do you know when to use q=mCAT/nCAT vs. q=CAT?

q=mCAT is used when you have the specific heat capacity. q=nCAT is used when you know the molar heat capacity.
Sun Feb 09, 2020 7:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.9 Help
Replies: 3
Views: 45

Re: 4A.9 Help

I was working on the following homework problem 4A.9: A piece of metal of mass 18.0 g at 100.0 C is placed in a vessel of negligible heat capacity but containing 50.2 g of water at 22.0 C. Calculate the final temperature of the water. Assume that no energy is lost to the surroundings. I ran into tr...
Sun Feb 02, 2020 7:27 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: U
Replies: 4
Views: 49

U

What is internal energy? How would you solve for it if you know delta H?
Sun Feb 02, 2020 7:25 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: Boltzmann Equation
Replies: 4
Views: 64

Boltzmann Equation

Can someone explain the Boltzmann equation and what it is used to solve for? What is W (degeneracy)? How do you solve for W.
Sun Feb 02, 2020 7:22 pm
Forum: Calculating Work of Expansion
Topic: Work Formula
Replies: 2
Views: 26

Work Formula

Can someone explain how the work formula w=-PdeltaV is an integral? Would we need to know that for the midterm and would we have to do calculus?
Sun Feb 02, 2020 7:19 pm
Forum: Calculating Work of Expansion
Topic: Expansion
Replies: 4
Views: 56

Expansion

What is the difference between work of expansion and work of compression?
Sun Feb 02, 2020 7:18 pm
Forum: Calculating Work of Expansion
Topic: Work
Replies: 4
Views: 36

Work

Can someone explain what work is? I honestly don't know. Thank you.
Sat Jan 25, 2020 4:34 pm
Forum: Phase Changes & Related Calculations
Topic: Bond Enthalpies
Replies: 5
Views: 47

Bond Enthalpies

Why is using bond enthalpy the least accurate way of calculating the change in enthalpy?
Sat Jan 25, 2020 4:29 pm
Forum: Phase Changes & Related Calculations
Topic: Calculating Bond Enthalpies
Replies: 4
Views: 35

Calculating Bond Enthalpies

How do you calculate bond enthalpies? I did not quite understand it when Professor Lavelle explained in class. Do you have to draw the lewis structures first? Does it matter how many of each type of bond there are? For example, if there are 4 C-H bonds in CH4, does that affect your calculation?
Sat Jan 25, 2020 4:26 pm
Forum: Phase Changes & Related Calculations
Topic: Standard Enthalpy of Formation
Replies: 2
Views: 22

Standard Enthalpy of Formation

Why is the standard enthalpy of formation for an element in its most stable form equal to 0? Are all elements included in this?
Sat Jan 25, 2020 4:23 pm
Forum: Phase Changes & Related Calculations
Topic: Standard State
Replies: 3
Views: 27

Standard State

Why is the standard state for a gas 1ATM, while the standard state for a solution 1M?
Sat Jan 25, 2020 4:21 pm
Forum: Phase Changes & Related Calculations
Topic: State Property
Replies: 6
Views: 129

State Property

Why is enthalpy (H) a state property but heat (q) is not a state property?
Sat Jan 18, 2020 4:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Percent Ionization
Replies: 11
Views: 148

Re: Percent Ionization

If the Ka or Kb is less than 10^-3 then you can approximate x and you don't have to use the quadratic equation.
If the percent ionization is less than 5% then your approximation is correct.
Sat Jan 18, 2020 4:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between K and Q?
Replies: 11
Views: 113

Re: Difference between K and Q?

K is the equilibrium constant and can only be solved for when the concentrations of reactants and products at equilibrium are known. Q is the reaction quotient and can be solved at any point in the reaction, regardless if it is in equilibrium. If Q<K then the reaction moves forward and favors the pr...
Sat Jan 18, 2020 4:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids and Bases Ice Box
Replies: 5
Views: 70

Acids and Bases Ice Box

When we make the ice box for acids and base problems, how do we know if we need to use Ka or Kb to solve for x?
Sat Jan 18, 2020 4:13 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Test 1
Replies: 6
Views: 86

Test 1

What topics are being covered in test 1? Just chemical equilibrium and acids and bases?
Sat Jan 18, 2020 4:11 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure
Replies: 3
Views: 31

Pressure

Does increasing the pressure/decreasing the volume change equilibrium according to Le Chatelier's Principle?
Sun Jan 12, 2020 10:37 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using the "ICE" box
Replies: 8
Views: 109

Re: Using the "ICE" box

Solids and liquids are not included in the equilibrium reaction and therefore shouldn't be used in the ICE box.
Sun Jan 12, 2020 10:32 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle
Replies: 5
Views: 61

Le Chatelier's Principle

Will adding/removing solids and liquids change the equilibrium at all according to Le Chatelier's principle?
Sun Jan 12, 2020 10:29 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Meaning of K [ENDORSED]
Replies: 4
Views: 65

Re: Meaning of K[ENDORSED]

I understand that at equilibrium the rates at which the reactions occur are equal, but is the equilibrium constant K the rate at which these reaction occur? In addition, how can you speed up the rate at which a reaction occurs? K does not measure the rate at which these reactions occur. K is just a...
Sun Jan 12, 2020 10:23 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between K and Q
Replies: 6
Views: 77

Re: Difference between K and Q

K is the equilibrium constant for a reaction, a known, experimentally determined value. Q is the reaction quotient which determines the ratio between products and reactants in a reaction. Q can be solved for when the reaction is not in equilibrium. K can only be solved when the reaction is in equili...
Sun Jan 12, 2020 10:21 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs Kp
Replies: 10
Views: 84

Kc vs Kp

Kc is the equilibrium constant using concentration and Kp is the equilibrium constant using pressure. If you solved for Kc and Kp for the same reaction would they be the same value?
Sun Dec 08, 2019 12:03 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Explanation on a Part of the Notes
Replies: 2
Views: 63

Re: Explanation on a Part of the Notes

Can someone explain to me a section of the notes? It was when he asked "Q2: A biological acid, HA, has pKa = 4.22. What's the Ka value of the acid?" I don't understand the part after that says "Is the acid neutral or negatively charged at pH 6?" and the little section under it. ...
Sat Dec 07, 2019 11:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Double bond oxygen
Replies: 1
Views: 105

Re: Double bond oxygen

I believe it has to do with formal charge. An oxygen with a double bond will have a formal charge of 0.
FC=6-(4+(4/2))
FC=6-(6)
FC=0
If the oxygen had a negative formal charge, it would be able to act as a ligand.
Sat Dec 07, 2019 11:53 pm
Forum: Amphoteric Compounds
Topic: amphiprotic vs amphoteric
Replies: 1
Views: 143

Re: amphiprotic vs amphoteric

what are some molecules that are amphoteric but not amphiprotic? do we need to know molecules that fall into one category but not the other? Amphiprotic molecules are all amphoteric, but not all amphoteric molecules are amphiprotic if that makes sense. Amphiprotic means that it can either donate or ...
Sat Dec 07, 2019 11:44 pm
Forum: Student Social/Study Group
Topic: Equilibrium
Replies: 3
Views: 85

Re: Equilibrium

I don't think we need to know anything about equilibrium for the final because it is a Chem 14B topic. I am pretty sure but to be safe you should ask a TA or Lavelle.
Sat Dec 07, 2019 11:42 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: strengths
Replies: 4
Views: 148

Re: strengths

Are you talking about intermolecular forces, because you just have to remember them. In order from strongest to weakest, it goes: ion-ion hydrogen bonding ion-dipole dipole-dipole dipole-induced dipole induced dipole-induced dipole You can also tell if the intermolecular forces are stronger if the m...
Sat Nov 30, 2019 2:08 pm
Forum: Naming
Topic: -ate
Replies: 1
Views: 43

Re: -ate

Yes you're correct. If it's a positive charge we do not add anything. For example if the TM was chromium and the coordination complex was neutral or positive, we would write it as chromium. If the complex has a negative charge we would write it as chromate.
Sat Nov 30, 2019 2:05 pm
Forum: Naming
Topic: TM in complexes
Replies: 1
Views: 31

Re: TM in complexes

Typically transition metals are always cations, meaning that they have positive charges. The -ate suffix at the end of ferrate only means that the entire coordination complex has a negative charge. The iron ion itself has a positive charge.
Sat Nov 30, 2019 2:03 pm
Forum: Naming
Topic: 9C.3
Replies: 1
Views: 40

Re: 9C.3

Yes. So you already determined that hexacyanidochromate is [(CN)6Cr]-3. We know that this complex is an anion because of the suffix -ate after chromate. The one Cr has a +3 charge and CN has a -1 charge and there are six of them so it has a -6 charge. If you add +3 and -6, you find that the entire [...
Sat Nov 30, 2019 1:56 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Ka constant
Replies: 5
Views: 117

Re: Ka constant

Ka is an equilibrium constant for acids. It is equal to Ka=[A-][H+]/[AH] (concentration of the products divided by the concentration of the reactants). Lavelle mentioned that only weak acids would have an equilibrium constant. This is because if it were a strong acid, it would dissociate completely ...
Sat Nov 30, 2019 1:51 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Do strong acids dissociate completely in water?
Replies: 7
Views: 110

Re: Do strong acids dissociate completely in water?

Strong acids more easily lose the H+ protons to water. For example, H-I is a strong acid because the bond length between I and H are long and therefore weak; the H+ proton is easily lost. Because of this, the H-I acid dissociates completely in water. Compare this with H-F which is a weak acid. The H...
Sat Nov 23, 2019 12:35 am
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted
Replies: 2
Views: 69

Lewis vs Bronsted

What is the difference between these two definitions? Is one more correct or more accepted as the definition for a base and acid?
Sat Nov 23, 2019 12:32 am
Forum: Naming
Topic: Prefixes
Replies: 4
Views: 102

Re: Prefixes

Can anyone provide an example of the naming with these prefixes? I would like to see how it's used.
Sat Nov 23, 2019 12:31 am
Forum: Naming
Topic: Naming/Coord Comp
Replies: 4
Views: 360

Re: Naming/Coord Comp

The metal ends in -ate if the whole coordination complex has a net negative charge. The example that Lavelle gave in class was [Ni(CN)4]-2.
Sat Nov 23, 2019 12:27 am
Forum: Naming
Topic: Oxidation Number
Replies: 4
Views: 369

Re: Oxidation Number

An atom's oxidation number is its charge. Since transition metals are normally cations, they would have a positive oxidation number.
Sat Nov 23, 2019 12:24 am
Forum: Naming
Topic: Naming Chlorine
Replies: 2
Views: 64

Re: Naming Chlorine

Did you mean anion? We know chlorine is an anion because it has 7 valence electrons and therefore has a -1 charge.
Sat Nov 16, 2019 4:36 pm
Forum: Dipole Moments
Topic: Shape of Molecule/Strength of Interactions
Replies: 4
Views: 104

Shape of Molecule/Strength of Interactions

Why do rod shaped molecules attract each other stronger than spherical molecules?
Sat Nov 16, 2019 4:35 pm
Forum: Dipole Moments
Topic: Interaction Potential Energy
Replies: 2
Views: 56

Interaction Potential Energy

Will we have to know the equation Lavelle gave us for interaction potential energy?
Sat Nov 16, 2019 4:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Inter-molecular Electron Repulsion
Replies: 6
Views: 52

Re: Inter-molecular Electron Repulsion

An example of a lone pair-bonding pair repulsion would be sulfur tetrafluoride, SF4. It has 5 areas of electron density: 4 bonding pairs and 1 lone pair. The lone pair on the central sulfur atom repels the four bonding pairs and reduces the bond angle.
Sat Nov 16, 2019 4:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Symmetry and Polarity
Replies: 13
Views: 200

Re: Symmetry and Polarity

The symmetry of a Lewis Structure can be an indicator of polarity. For example, CCl4 has a carbon atom surrounded by four chlorine atoms of equal electronegativity. Because it is a symmetrical molecule, the dipole moments of the four chlorines cancel and it is a nonpolar molecule. This would not be ...
Sat Nov 16, 2019 4:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar vs nonpolar
Replies: 6
Views: 87

Re: polar vs nonpolar

In lecture, Lavelle spoke about how you can tell if a molecule is polar or non-polar if it has polar or non-polar bonds. Polar bonds have an electronegativity difference between the two atoms and non-polar bonds do not have an electronegativity difference. If there are polar bonds, the molecule can ...
Sun Nov 10, 2019 1:18 am
Forum: Dipole Moments
Topic: Polarizing Power
Replies: 3
Views: 115

Polarizing Power

What is polarizing power and what does it do? Which atoms have a higher polarizing power?
Sun Nov 10, 2019 1:17 am
Forum: Dipole Moments
Topic: Ionic vs Covalent Solubility
Replies: 3
Views: 39

Ionic vs Covalent Solubility

Why are ionic compounds more soluble in water while covalent compounds are not?
Sun Nov 10, 2019 1:15 am
Forum: Dipole Moments
Topic: Hydrogen Bonds, Electronegativity
Replies: 1
Views: 44

Hydrogen Bonds, Electronegativity

Why do hydrogen bonds only work in molecules with N,O,F atoms (i.e. atoms with high electronegativity) when the Chlorine atom is more electronegative than Nitrogen. Why does it not also work with Chlorine?
Sun Nov 10, 2019 1:13 am
Forum: Dipole Moments
Topic: Boiling Point
Replies: 11
Views: 200

Boiling Point

In Professor Lavelle's lecture, why did he use boiling points to indicate which dipole attractions are stronger?
Sun Nov 10, 2019 1:11 am
Forum: Dipole Moments
Topic: Dispersion Forces
Replies: 1
Views: 31

Dispersion Forces

What causes an induced-dipole induced-dipole to occur between two atoms?
Fri Nov 01, 2019 1:27 pm
Forum: Trends in The Periodic Table
Topic: Noble Gases
Replies: 10
Views: 170

Noble Gases

Do the noble gases experience the periodic trends of ionization energy and electron affinity? If they don't, why are they different from other elements?
Fri Nov 01, 2019 1:20 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 8
Views: 77

Re: Electron Affinity

Electron affinity is the energy released when an electron is added to a neutral atom in the gas phase. Electron affinity has the same trend as ionization energy. It increases left to right across a period and up a group.
Fri Nov 01, 2019 1:11 pm
Forum: Ionic & Covalent Bonds
Topic: Transition Metals
Replies: 3
Views: 40

Transition Metals

How would you know the charge for a transition metal in the d-block?
Fri Nov 01, 2019 1:09 pm
Forum: Ionic & Covalent Bonds
Topic: Anions and Cations
Replies: 9
Views: 187

Anions and Cations

Why are anions larger than cations?
Fri Nov 01, 2019 12:37 pm
Forum: Octet Exceptions
Topic: More than 8 e-
Replies: 3
Views: 70

More than 8 e-

Can someone explain why having a d-shell allows an atom to have an expanded octet?
Thu Oct 24, 2019 11:22 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 4
Views: 83

Resonance Structures

Can someone explain what the purpose of resonance structures are? Do we have to draw all the resonance structures for every molecule's Lewis structure?
Thu Oct 24, 2019 11:18 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 7
Views: 264

Ionization Energy

Why is the second ionization energy always much higher than the first ionization energy?
Thu Oct 24, 2019 11:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Affinity
Replies: 1
Views: 48

Electron Affinity

Can someone explain what electron affinity is? Lavelle defined it as the energy released when an electron is added to a gas-phase atom. If the energy released is greater, does this mean that the electron affinity is greater?
Thu Oct 24, 2019 11:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 5
Views: 80

Electron Configurations

Do we have to write 4s after 3d in electron configurations? And why is the energy of the 3d orbital less than the 4s orbital only if it is partially filled?
Thu Oct 24, 2019 11:09 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron Configurations (p-orbital)
Replies: 5
Views: 68

Electron Configurations (p-orbital)

When writing electron configurations for the p-orbital, do we have to write px, py, pz?
Wed Oct 16, 2019 9:30 pm
Forum: Quantum Numbers and The H-Atom
Topic: Schrodinger's Wave Equation
Replies: 2
Views: 43

Schrodinger's Wave Equation

In lecture today, why did Prof. Lavelle say that Schrodinger's wave equation can be solved for 1 electron atoms? Can it not be used for other atoms?
Wed Oct 16, 2019 9:26 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers question, ml
Replies: 2
Views: 72

Quantum Numbers question, ml

Why is it that ml can be -1, 0, or 1 when l is 1, but ml can only by 0 when l is 0?
Wed Oct 16, 2019 9:22 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 2
Views: 54

Quantum Numbers

Does anyone know how the quantum numbers are derived? I know that l is n-1 and ml is l-1, but why is this?
Wed Oct 16, 2019 9:17 pm
Forum: *Shrodinger Equation
Topic: Hamiltonian
Replies: 1
Views: 43

Hamiltonian

I understand that the Hamiltonian in Schrodinger's equation is a double derivative. But what is it taking the derivative of? Is it a wave function?
Wed Oct 16, 2019 9:14 pm
Forum: *Shrodinger Equation
Topic: Electron Spin
Replies: 2
Views: 67

Electron Spin

Can someone explain what the electron spin is? And what determines how/in what direction the electron spins?
Sat Oct 12, 2019 4:52 pm
Forum: DeBroglie Equation
Topic: Applying the DeBroglie Equation
Replies: 6
Views: 59

Re: Applying the DeBroglie Equation

The DeBroglie equation is used to find the wavelength of anything that has momentum (mass in motion). With the DeBroglie equation, we can tell if an object displays wave-like properties, depending on its mass.
Sat Oct 12, 2019 4:48 pm
Forum: Photoelectric Effect
Topic: Wave-like Properties
Replies: 4
Views: 74

Wave-like Properties

Can someone explain why all matter has wavelike properties, but only matter with a small mass can have noticeable wavelike properties?
Sat Oct 12, 2019 4:25 pm
Forum: Properties of Light
Topic: Intensity of Light
Replies: 4
Views: 96

Re: Intensity of Light

I think that increasing the intensity of light results in more photons being emitted. However, in the photoelectric experiment, the frequency is what determines whether an electron is ejected. This is because the frequency of the wave determines the energy of each individual photon.
Sat Oct 12, 2019 4:19 pm
Forum: Photoelectric Effect
Topic: What is high light frequency?
Replies: 3
Views: 43

Re: What is high light frequency?

It is based on the parameters of the individual question. In the photoelectric experiment, the energy of a photon (E=hv) must be greater than or equal to the work function, the energy required to remove an electron from a metal surface. The work function will not be the same in every problem, so the...
Fri Oct 11, 2019 10:20 am
Forum: Quantum Numbers and The H-Atom
Topic: Rydberg Equation
Replies: 2
Views: 49

Rydberg Equation

In lecture, why did Professor Lavelle tell us not to use the Rydberg equation and instead use E=-hR/n^2 ?
Fri Oct 04, 2019 11:16 pm
Forum: Properties of Light
Topic: "n" variable
Replies: 3
Views: 63

"n" variable

Hi guys! In today's lecture, what did Professor Lavelle mean by the variable "n" and how does it affect the energy of an electron?
Fri Oct 04, 2019 11:13 pm
Forum: Properties of Light
Topic: Quantum Mechanics
Replies: 9
Views: 164