Search found 101 matches
- Mon Mar 09, 2020 11:10 pm
- Forum: General Rate Laws
- Topic: Rounding "a"
- Replies: 1
- Views: 144
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: 1098
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: 438
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: 224
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: 384
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: 505
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: 393
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: 148
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: 412
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: 196
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: 169
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: 184
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: 142
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: 589
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: 604
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: 650
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: 420
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: 163
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: 398
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: 641
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: 367
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: 211
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: 265
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: 622
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: 296
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: 99
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: 276
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: 185
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: 487
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: 87
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: 192
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: 228
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: 456
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: 97
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: 109
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: 133
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: 91
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: 81
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: 265
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: 211
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: 97
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: 445
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: 107
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: 162
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: 51
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: 198
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: 226
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: 908
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: 195
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: 4
- Views: 232
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: 160
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: 173
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: 132
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: 137
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: 154
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: 264
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: 358
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: 386
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: 391
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: 252
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: 258
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: 52
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: 110
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: 110
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: 94
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: 164
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: 333
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: 207
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: 176
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: 707
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: 73
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: 647
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: 331
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: 141
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
- Topic: Chemistry Youtube Channels
- Replies: 8
- Views: 417
Re: Chemistry Youtube Channels
For broad understanding, I like Crash Course!
- Sun Nov 03, 2019 11:13 am
- Forum: Resonance Structures
- Topic: Drawing Resonance Structures
- Replies: 4
- Views: 264
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: 207
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: 8
- Views: 445
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: 140
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: 285
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: 338
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: 88
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: 110
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: 184
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: 8386
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: 103
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: 104
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: 156
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: 278
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: 266
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: 132
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: 204
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: 163
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: 261
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: 48
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: 105
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
- Topic: Study Strategies/Youtube Videos
- Replies: 14
- Views: 514
Re: Study Strategies/Youtube Videos
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: 298
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: 930
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: 124
Re: Net Ionic Units
Not all polyatomic ions dissolve. If the ion is insoluble, you don't distribute the stoichiometric coefficient.