## Search found 101 matches

Mon Mar 09, 2020 11:10 pm
Forum: General Rate Laws
Topic: Rounding "a"
Replies: 1
Views: 23

### Rounding "a"

Do we round the exponent a to the nearest whole number?
Mon Mar 09, 2020 9:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Final exam content
Replies: 15
Views: 357

### Final exam content

The document that Dr. Lavelle shared with us says that the final exam questions will come from the homework. Does this mean all questions will be taken from the homework, or will the format be more like the midterm?
Sun Mar 08, 2020 11:25 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding k1 when given two temperatues
Replies: 6
Views: 109

### Re: Finding k1 when given two temperatues

The starting temperature is T1 and it is associated with K1; the final temperature is T2 and it is associated with K2.
Sun Mar 08, 2020 11:24 pm
Forum: Second Order Reactions
Topic: Derivation of the Equation
Replies: 2
Views: 25

### Re: Derivation of the Equation

I think it will be given but not labeled, so we need to be able to ID it.
Sun Mar 08, 2020 11:22 pm
Forum: Balancing Redox Reactions
Topic: Redox Table
Replies: 6
Views: 54

### Re: Redox Table

The equation for E(cell) allows you to use the given reduction potentials for each half-reaction: making E(anode) a negative value accounts for the oxidation sign change.
Sun Mar 08, 2020 11:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2
Replies: 7
Views: 84

### Re: Test 2

Since E(cell) is equal to E(red)-E(ox) and must be positive for a spontaneous reaction, E(red) should be greater than E(ox). So, the half reaction with the greater reduction potential is reduced.
Thu Mar 05, 2020 1:21 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.1
Replies: 5
Views: 75

### Re: 6M.1

I'm confused as well. Why isn't the answer a positive value?
Wed Feb 26, 2020 11:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.9(d)
Replies: 1
Views: 31

### 6L.9(d)

Can someone explain why the oxidation reaction is Au(s) to Au3+(aq) instead of Au+(aq) to Au3+(aq)? I thought that it would make sense to have reactant and product on opposite sides of the reaction...
Wed Feb 26, 2020 10:59 pm
Forum: Balancing Redox Reactions
Topic: Oxygen's oxidation #
Replies: 6
Views: 67

### Re: Oxygen's oxidation #

Oxygen should have a 2- charge in ionic aqueous form, as well as in molecules such as H2O. It should have a charge of zero in O2 gas form, where it is most stable.
Wed Feb 26, 2020 4:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7(a)
Replies: 1
Views: 52

### 6L.7(a)

For 6L.7, why is AgBr(s) only used in the reduction half reaction and not in both?
Wed Feb 26, 2020 4:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert electrode
Replies: 1
Views: 18

### Inert electrode

How do you know when to use an inert electrode in a cell diagram?
Tue Feb 25, 2020 11:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3(b)
Replies: 1
Views: 40

### 6L.3(b)

For the reaction of H2(g) with Cl2(g) as shown in the diagram, how do you know which half reaction to reverse?
Tue Feb 25, 2020 10:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Finding n
Replies: 1
Views: 23

### Finding n

How do you determine the value of n for -nFEcell? Is n the number of moles being reduced?
Sun Feb 23, 2020 9:46 pm
Forum: Balancing Redox Reactions
Topic: Reduction?
Replies: 13
Views: 114

### Re: Reduction?

Reduction is gain of electrons, so look for the atom whose charge is reduced.
Sun Feb 23, 2020 9:45 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 13
Views: 111

### Re: Test 2

I think Dr. Lavelle said it will be on the end of thermo (5G) and electrochem.
Sun Feb 23, 2020 9:44 pm
Forum: Balancing Redox Reactions
Topic: Oxidation?
Replies: 10
Views: 134

### Re: Oxidation?

Oxidation is loss of electrons, so the atom whose charge increases is the one that is oxidized.
Sun Feb 23, 2020 1:36 am
Forum: Balancing Redox Reactions
Topic: Oxidation number of H
Replies: 6
Views: 79

### Oxidation number of H

When is the oxidation number of hydrogen -1? For this course, should we just assume that it is +1?
Sat Feb 22, 2020 4:37 pm
Forum: Balancing Redox Reactions
Topic: Elements with only 1 ionization state
Replies: 1
Views: 29

### Elements with only 1 ionization state

Which elements have only one ionization state? For example, oxygen is always O2-.
Wed Feb 12, 2020 4:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Mnemonic Devices
Replies: 2
Views: 64

### Re: Mnemonic Devices

IN-tensive properties are IN-dependent of quantity.
Wed Feb 12, 2020 3:29 pm
Forum: Phase Changes & Related Calculations
Topic: Heating curve
Replies: 5
Views: 151

### Heating curve

How is the formula for enthalpy with a change in temperature along a heating curve different from the formula for enthalpy at temperature plateaus?
Wed Feb 12, 2020 1:53 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Midterm: Cp,m and Cv,m
Replies: 3
Views: 113

### Midterm: Cp,m and Cv,m

For the midterm, do we need to know the values of Cp,m and Cv,m for monatomic gases only, or for linear and nonlinear molecules as well?
Mon Feb 10, 2020 11:27 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: Online resources for W/Boltzmann EQ
Replies: 1
Views: 28

### Online resources for W/Boltzmann EQ

I'm having a hard time understanding degeneracy and the Boltzmann equation. Can anyone recommend a good Youtube video or link a website that explains it well?
Mon Feb 10, 2020 12:44 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pizza Rolls - State Functions
Replies: 5
Views: 83

### Re: Pizza Rolls - State Functions

When you're under Pressure or Depressed, you'll want to watch TV and get HUGS.
Mon Feb 10, 2020 12:42 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: identifying systems
Replies: 3
Views: 49

### Re: identifying systems

I think it would be good to know. An isolated system does not allow for the transfer of heat or matter, a closed system allows for the transfer of heat and an open system allows for both.
Mon Feb 10, 2020 12:39 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q=CΔT
Replies: 5
Views: 42

### Re: q=CΔT

Not just - it's used primarily to calculate enthalpy when a system's heat changes.
Mon Feb 10, 2020 12:38 am
Forum: Phase Changes & Related Calculations
Topic: equation for phase changes
Replies: 3
Views: 31

### Re: equation for phase changes

Delta H times mass.
Mon Feb 10, 2020 12:38 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy of universe
Replies: 3
Views: 31

### Re: Entropy of universe

The universe favors disorder. The textbook has a good example: it's a lot easier for heat to leave a block of metal than enter it because in order for it to enter the block of metal, it has to be concentrated and directional.
Mon Feb 10, 2020 12:36 am
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: standard entropy meaning
Replies: 3
Views: 18

### Re: standard entropy meaning

Standard entropy is found when a substance is in its pure state at 1 bar.
Tue Feb 04, 2020 9:01 pm
Forum: Calculating Work of Expansion
Topic: Units: J/(k*mol) vs J/K
Replies: 1
Views: 46

### Units: J/(k*mol) vs J/K

In 4F, the textbook says that "the entropy change for or of 1 mol of a substance is reported differently from the entropy change per mole: the units of the former are joules per kelvin (J/K), whereas those of the latter are joules per kelvin per mole (J/K*mol)". Can someone explain why thi...
Mon Feb 03, 2020 12:54 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Standard Reaction Enthalpy
Replies: 4
Views: 25

### Re: Standard Reaction Enthalpy

Enthalpy of formation is the enthalpy of change between products and reactants; enthalpy of reaction is the difference.
Mon Feb 03, 2020 12:50 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy
Replies: 7
Views: 49

### Re: enthalpy

At a constant pressure, enthalpy is equal to change in heat.
Mon Feb 03, 2020 12:42 am
Forum: Calculating Work of Expansion
Topic: Reversible
Replies: 7
Views: 61

### Re: Reversible

By definition, at equilibrium forward and reverse reactions occur at the same rates. So, any reaction that is at equilibrium must be reversible.
Mon Feb 03, 2020 12:41 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 7
Views: 63

### Re: Hess's Law

Hess's law states that the total enthalpy change for a reaction is the sum of the enthalpy changes for each step of the reaction. So, you just balance the equations given and add their delta H's.
Thu Jan 30, 2020 11:44 am
Forum: Phase Changes & Related Calculations
Topic: 4C.15
Replies: 1
Views: 42

### 4C.15

I had a hard time matching the data given to a heating curve because b) and c) look pretty similar to me. Does anyone have tips for interpreting these curves? Will we have problems like this on the test?
Sun Jan 26, 2020 11:25 pm
Forum: Phase Changes & Related Calculations
Topic: 3 Methods
Replies: 4
Views: 46

### Re: 3 Methods

bond enthalpy is the least accurate, but it really depends on what information its given to you. I would definitely know how to use all 3.
Sun Jan 26, 2020 11:15 pm
Forum: Phase Changes & Related Calculations
Topic: Solids, liquids, and gases
Replies: 4
Views: 36

### Re: Solids, liquids, and gases

SOME solids do have a higher heat capacity than water and the same goes for gases. If you mean in terms of the solid and gaseous forms of water, it is because liquid water is polar and has the ability to expand a little when heated.
Sun Jan 26, 2020 10:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating enthalpy change with phase changes
Replies: 3
Views: 26

### Re: Calculating enthalpy change with phase changes

You need to calculate a reaction's enthalpy when all reactants and products are in the gas phase. If there are solids and/or liquids present, you need to add in the enthalpy it takes to convert them to gases.
Thu Jan 23, 2020 9:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sig figs for pH/pOH, constants and concentrations
Replies: 2
Views: 30

### Sig figs for pH/pOH, constants and concentrations

Just to confirm: do we use 2 decimal places for pH/pOH and follow sig fig rules for constants and concentrations?
Mon Jan 20, 2020 1:34 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6C.7
Replies: 1
Views: 88

### 6C.7

How can we find the pKa/relative strength for +NH3OH and (CH3)2NH2+, since they aren't listed in the tables we're asked to refer to?
Mon Jan 20, 2020 10:47 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier Principle
Replies: 4
Views: 62

### Re: Le Chatelier Principle

If you change partial pressure or concentration, the reaction will shift to maintain the original equilibrium constant. A change in temperature changes reaction rates.
Mon Jan 20, 2020 10:42 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.1
Replies: 2
Views: 30

### Re: 5J.1

By Le Chatelier's principle, a change in partial pressure on one side of the equilibrium equation will cause the other side to adjust to maintain equilibrium.
Sun Jan 19, 2020 9:54 pm
Forum: Ideal Gases
Topic: ICE Tables
Replies: 8
Views: 96

### Re: ICE Tables

Since the reaction begins with only reactants and moves towards equilibrium as products form, the amount of reactant decreases and the amount of product increases. So, you use +x for products and -x for reactants
Sun Jan 19, 2020 8:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.11
Replies: 2
Views: 43

### 6B.11

For part b, why is the equation Na2O+H2O -> 2NaOH instead of Na2O +2H2O -> H3O + OH + 2 Na?
Sun Jan 19, 2020 7:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stoichiometric coefficients for pH/pOH
Replies: 3
Views: 34

### Stoichiometric coefficients for pH/pOH

When we calculate the pH or pOH for strong acids and bases, do we need to raise [H3O+] or [OH-] to their stoichiometric coefficients? For example, would the pOH of Ba(OH)2 be -log[OH]^2?
Sun Jan 12, 2020 5:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solvents
Replies: 1
Views: 15

### Re: Solvents

Solvents aren't really part of the reaction, and their concentrations don't change much from one side of the reaction to the other. So, the product concentration will cancel out that of the reactants.
Sun Jan 12, 2020 5:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding K: liquids and aqueous
Replies: 7
Views: 73

### Re: Finding K: liquids and aqueous

Liquids don't change, so they cancel out.
Sun Jan 12, 2020 5:14 pm
Forum: Ideal Gases
Topic: Kc and Kp
Replies: 8
Views: 64

### Re: Kc and Kp

Kc is used for aqueous solutions and Kp is for gases.
Sun Jan 12, 2020 5:12 pm
Forum: Ideal Gases
Topic: P=(n/v)RT
Replies: 12
Views: 117

### Re: P=(n/v)RT

n/V is the same as (nRT)/V!
Sun Jan 12, 2020 3:05 am
Forum: Administrative Questions and Class Announcements
Topic: Test Dates
Replies: 3
Views: 54

### Test Dates

I saw dates for the midterm and final on CCLE, but does anyone know the dates for Test 1 and Test 2?
Sat Dec 07, 2019 11:58 pm
Forum: Sigma & Pi Bonds
Topic: Hybridization for p
Replies: 2
Views: 115

### Hybridization for p

Why do pi bonds only have p hybridization and not spx?
Fri Dec 06, 2019 2:37 pm
Forum: Conjugate Acids & Bases
Topic: Homework 6.A.1 #3: Polyprotic Acids
Replies: 1
Views: 89

### Homework 6.A.1 #3: Polyprotic Acids

In the textbook answer key, the proton transfer equations for H2SO4 and H2PO4 show only one H+ (not both) being transferred. Why is this? Wouldn't both protons be transferred? Are both answers correct?
Fri Dec 06, 2019 1:29 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: biological importance
Replies: 2
Views: 38

### Re: biological importance

I think we're supposed to know the ones we reviewed in class.
Thu Dec 05, 2019 7:50 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Solubility rules
Replies: 1
Views: 50

### Solubility rules

Should we have solubility rules memorized for the final? Will we see any problems with precipitates?
Thu Dec 05, 2019 7:48 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis Definitions
Replies: 2
Views: 35

### Bronsted vs. Lewis Definitions

I understand what differentiates the Bronsted definition from the Lewis definition, but how will we know which definition to apply? In other words, what kind of situation would you use each definition in?
Tue Dec 03, 2019 5:04 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining binding sites
Replies: 3
Views: 41

### Re: Determining binding sites

The lone pairs on one atom can't get close enough to bind in two locations; only one pair can align with the binding site.
Tue Dec 03, 2019 5:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: week 9 hw problems
Replies: 4
Views: 67

### Re: week 9 hw problems

I think you're supposed to do both and turn in two separate HWs.
Tue Dec 03, 2019 4:59 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Resonance and Formal Charge
Replies: 4
Views: 144

### Re: Resonance and Formal Charge

The major contributor is the most stable, where the central atom's charge is close to 0.
Tue Dec 03, 2019 4:58 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Where to minimize formal charge
Replies: 4
Views: 137

### Re: Where to minimize formal charge

You usually want 0 charge on the central atom.
Tue Dec 03, 2019 4:49 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: deprotonation and protonation
Replies: 3
Views: 53

### Re: deprotonation and protonation

When strong acids and strong bases deprotonate, they separate into aqueous ions; for example, HCl would become H+ (aq) + Cl- (aq). Weak acids and bases, on the other hand, do not separate fully.
Tue Dec 03, 2019 4:43 pm
Forum: Bronsted Acids & Bases
Topic: Self-test J.1A/B
Replies: 3
Views: 51

### Re: Self-test J.1A/B

Bronsted acids are proton donors and Bronsted bases are proton acceptors. Since H+ represents a proton, you're right that it helps to look for an H at the beginning of the compound when you're trying to identify an acid. Likewise, an OH- attached to the end of a compound indicates that the compound ...
Sun Nov 24, 2019 11:28 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Polydentate Ligands
Replies: 5
Views: 47

### Identifying Polydentate Ligands

How can you tell whether a ligand is polydentate?
Sat Nov 23, 2019 2:55 pm
Forum: Naming
Topic: English name vs Latin stem for transition metals
Replies: 1
Views: 22

### English name vs Latin stem for transition metals

When naming coordination compounds, how can you tell whether you should use the English name for a transition metal (like Iron (II)) or the Latin name (like ferrate (II))?
Mon Nov 18, 2019 2:16 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: H-bonds: 3F.5 (b)
Replies: 2
Views: 40

### Re: H-bonds: 3F.5 (b)

Oh, that makes sense! I didn't look closely at the structures and missed the fact that in diethyl ether, O is bonded to C and not H. Thank you :)
Mon Nov 18, 2019 2:12 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: H-bonds: 3F.5 (b)
Replies: 2
Views: 40

### H-bonds: 3F.5 (b)

Why is H bonding possible for C4H9OH (butanol) but not C2H5OC2H5 (diethyl ether)?
Mon Nov 18, 2019 1:46 pm
Forum: Dipole Moments
Topic: 3F.1 Dipole-dipole vs dipole-induced dipole
Replies: 1
Views: 38

### 3F.1 Dipole-dipole vs dipole-induced dipole

How do you determine whether a molecule exhibits dipole-dipole or dipole- induced dipole interactions? I had believed that H2SeO4 would have dipole-induced dipole interactions, because H2SO4 is polar and O4 is non polar.
Sun Nov 17, 2019 11:04 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonds
Replies: 2
Views: 56

### Re: Hydrogen Bonds

I don't think H bonds have a direct influence on ionic bonds. They are separate, but what makes them distinct is how strong they are.
Sun Nov 17, 2019 11:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone vs. Bonding Pair
Replies: 6
Views: 80

### Re: Lone vs. Bonding Pair

Lone pairs take up more space - they push away other atoms.
Sun Nov 17, 2019 11:00 pm
Forum: Ionic & Covalent Bonds
Topic: Dispersion Forces
Replies: 2
Views: 47

### Re: Dispersion Forces

As you go down a group, the atoms grow larger. This makes them more polarizable, which in turn makes them more prone to Van Der Waals attractive forces. When atoms are pulled together by these forces, they become liquids.
Sun Nov 17, 2019 10:58 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: can someone explain ion-dipole?
Replies: 3
Views: 38

### Re: can someone explain ion-dipole?

Ion dipole describes the permanent dipole moment between a cation and anion; a dipole-dipole interaction is a Van der Waals force that exists in non-ionic molecules, where one atom is permanently negative (distorting e-) and the other Is permanently positive (being distorted).
Sun Nov 17, 2019 10:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Why is SF4 Polar?
Replies: 6
Views: 68

### Re: Why is SF4 Polar?

The shape of the molecule plays a role in determining its polarity. Since the seesaw shape is not symmetrical, the S-F bond energies do not cancel and there is polarity.
Sun Nov 10, 2019 9:21 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: Relationship between size of atom and bond strength
Replies: 2
Views: 20

### Re: Relationship between size of atom and bond strength

Yes! Stronger bonds are harder to disturb, so the atoms stay close together - aka in solid state.
Sun Nov 10, 2019 9:17 pm
Forum: Student Social/Study Group
Topic: chem 14b + cehm14bl
Replies: 9
Views: 154

### Re: chem 14b + cehm14bl

I've heard that it's possible to take both at once and do well, but it can be helpful to take 14B first. 14B lays the groundwork for 14BL.
Sun Nov 10, 2019 7:38 pm
Forum: Ionic & Covalent Bonds
Topic: Both types of bonds
Replies: 6
Views: 67

### Re: Both types of bonds

Yes! No bond is purely one or the other.
Sun Nov 10, 2019 7:37 pm
Forum: Bond Lengths & Energies
Topic: Resonance Bond Lengths
Replies: 3
Views: 39

### Re: Resonance Bond Lengths

Pretty much! The bond lengths are the average of bond lengths across all of the structures, so each bond length is the same.
Sun Nov 10, 2019 7:35 pm
Forum: Student Social/Study Group
Replies: 8
Views: 140

For broad understanding, I like Crash Course!
Sun Nov 03, 2019 11:13 am
Forum: Resonance Structures
Topic: Drawing Resonance Structures
Replies: 4
Views: 58

### Re: Drawing Resonance Structures

I think there is a quicker way, but we haven't learned it yet.
Sun Nov 03, 2019 11:11 am
Forum: Resonance Structures
Topic: All Molecules?
Replies: 4
Views: 56

### Re: All Molecules?

Nope! Some molecules have a symmetrical e- distribution, so no resonance.
Sun Nov 03, 2019 11:10 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: When would 3d orbital be filled before the 4s orbital?
Replies: 6
Views: 68

### Re: When would 3d orbital be filled before the 4s orbital?

I believe that past the 4s2 elements, you start filling the d orbital first. For the f orbital, you start filling it after 6s2 (Ba).
Sun Nov 03, 2019 11:08 am
Forum: Electronegativity
Topic: Relation between Electronegativity and ionization energy
Replies: 3
Views: 45

### Re: Relation between Electronegativity and ionization energy

Ionization energy is the energy required for an atom to lose an electron; electron affinity is the energy released when an atom gains an electron.
Sun Nov 03, 2019 11:05 am
Forum: Electronegativity
Topic: Noble Gases and Electronegativity
Replies: 3
Views: 35

### Re: Noble Gases and Electronegativity

Most noble gases have no electronegativity, with the exception of Kr and Xe. These elements are heavier, so their outermost electrons have more shielding from the nuclear pull and can be ionized by highly electronegative elements.
Sun Oct 27, 2019 10:42 am
Forum: Ionic & Covalent Bonds
Topic: Midterm Topics Covered
Replies: 7
Views: 117

### Re: Midterm Topics Covered

I'd expect it to cover at least the first two weeks of chemical bonds, since we're being given time to study the material.
Fri Oct 25, 2019 10:26 pm
Forum: Lewis Structures
Topic: Denoting charge on ions
Replies: 2
Views: 25

### Denoting charge on ions

Since you adjust the Lewis structures of ions to reflect the number of additional electrons that they have, why do you still need to put brackets around them and write the charge? Isn't this redundant?
Thu Oct 24, 2019 3:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.5: What happens with s and d orbitals?
Replies: 2
Views: 33

### 2A.5: What happens with s and d orbitals?

For Ti 3+, why is the electron configuration [Xe] 4f14 5d10 instead of [Xe] 4f14 5d8 6s2?
Thu Oct 24, 2019 3:08 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2.A.1 (c) - valence electrons for elements in d block
Replies: 1
Views: 60

### HW 2.A.1 (c) - valence electrons for elements in d block

For Mn, which has electron configuration {Ar} 3d5 4s2, the textbook says there are 7 valence electrons. Is this because you need 8 electrons to close an octet, so all of the d-subshell electrons are still unstable in this configuration? If so, how do you know when there is a stable d-subshell? Is it...
Mon Oct 21, 2019 5:17 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 3699

### Re: Rydberg equation[ENDORSED]

Do we need to understand how the Rydberg equation for other 1-electron ions, -[(Z^2)hR]/n^2 is derived, or can we just apply it?
Sun Oct 20, 2019 11:01 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: spin
Replies: 3
Views: 46

### Re: spin

Spins are opposite because electrons repel each other, and you always start up.
Sun Oct 20, 2019 10:57 pm
Forum: Trends in The Periodic Table
Topic: Inert-Pair Effect
Replies: 1
Views: 16

### Re: Inert-Pair Effect

If it's assigned, I think he'll go over it this week.
Sun Oct 20, 2019 10:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ordering for different orbitals
Replies: 3
Views: 31

### Re: Ordering for different orbitals

I think it has to go to 2px first.
Sun Oct 20, 2019 10:48 pm
Forum: Student Social/Study Group
Topic: Week 4 HW Problems
Replies: 7
Views: 135

### Re: Week 4 HW Problems

It's from Quantum World!
Sun Oct 20, 2019 10:47 pm
Forum: Properties of Light
Topic: homework 1A.3
Replies: 8
Views: 99

### Re: homework 1A.3

Speed will remain constant- only wavelength and frequency are inversely proportional.
Sun Oct 13, 2019 5:12 pm
Forum: General Science Questions
Topic: Audio-Visual focus topics
Replies: 4
Views: 43

### Re: Audio-Visual focus topics

I think they're just a resource that you can use whenever you want to review his lectures! No deadline :)
Sun Oct 13, 2019 4:30 am
Forum: Properties of Light
Topic: Question on 1A 11
Replies: 4
Views: 43

### Re: Question on 1A 11

Lines within a series share a principal quantum number, n.
Sun Oct 13, 2019 4:26 am
Forum: Properties of Electrons
Topic: Electron Quantum Energies
Replies: 3
Views: 44

### Re: Electron Quantum Energies

Electrons absorb and emit energy in photons, which are basically discrete packets of light. I think of photons like tide pods, and electrons like laundry: I can do a smaller load of laundry with one tide pod, or a larger load of laundry with two. One tide pod is sufficient for a lower range of laund...
Sun Oct 13, 2019 4:15 am
Forum: Properties of Light
Topic: Light's Behavior
Replies: 3
Views: 51

### Re: Light's Behavior

I found Dr. Lavelle's watering can analogy helpful for understanding this concept. In large quantities, water moves as a wave (continuously). However, we can also think of water jumping out of the (now shrunken to microscopic proportions) mouth of the water can in single molecules, or particles.
Sun Oct 13, 2019 4:07 am
Forum: Photoelectric Effect
Topic: Representation of electrons
Replies: 2
Views: 19

### Re: Representation of electrons

I think that the term "circular standing wave" just refers to the oscillatory behavior of electromagnetic radiation. It's a standing wave because the wave's amplitude doesn't move, and it's circular because it's continuous. Do you remember Dr. Lavelle's diagram for this concept, where the ...
Mon Oct 07, 2019 2:26 pm
Forum: Limiting Reactant Calculations
Topic: M11: Grams vs. Moles in Intermediate Calculations
Replies: 1
Views: 58

### M11: Grams vs. Moles in Intermediate Calculations

For problem M11, which gives the following information: A reaction vessel contains 5.77 g of white phosphorus and 5.77 g of oxygen. The first reaction to take place is the formation of phosphorus(III) oxide, P4O6: P4(s) + 3 O2(g) --> P4O6(s). If enough oxygen is present, the oxygen can react further...
Thu Oct 03, 2019 8:53 pm
Forum: Limiting Reactant Calculations
Replies: 14
Views: 266

Crash Course is fun but less specific than Khan Academy. A lot of people also like the OChem tutor!
Thu Oct 03, 2019 8:52 pm
Forum: SI Units, Unit Conversions
Topic: unit conersations
Replies: 7
Views: 142

### Re: unit conersations

For the problem you're referencing, Dr. Lavelle said either unit is fine. I think you don't need to convert unless explicitly asked.
Thu Oct 03, 2019 8:19 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E15
Replies: 3
Views: 113

### Re: E15

You probably read the second half of E16, which asks for chloride. E15 asks: "The molar mass of the metal hydroxide M(OH)2 is 74.10 g/mol. What is the molar mass of the sulfide of this metal?"
Thu Oct 03, 2019 8:17 pm
Forum: Balancing Chemical Reactions
Topic: Net Ionic Units
Replies: 2
Views: 68

### Re: Net Ionic Units

Not all polyatomic ions dissolve. If the ion is insoluble, you don't distribute the stoichiometric coefficient.