Search found 118 matches
- Sat Mar 13, 2021 10:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: When H and G are similar
- Replies: 2
- Views: 209
Re: When H and G are similar
(Assume the deltas are in the following equations...) G= H -TS G=H when TS=0 When is S=0? S is closest to 0 generally when x moles of solid go to x moles of solid. S is usually the most when x moles of solid/liquid go to kx moles of gas (a phase change occurs that increases entropy, k is some posit...
- Sat Mar 13, 2021 9:22 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: When H and G are similar
- Replies: 2
- Views: 209
When H and G are similar
When given a set of reactions to choose from, how would we determine which ones would have the most similar delta H naught and delta G naught?
- Sat Mar 13, 2021 6:26 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Reactions with elements besides O and H
- Replies: 2
- Views: 224
Re: Balancing Reactions with elements besides O and H
Because HNO 3 dissociates completely in solution, they can be written as aqueous ions in the chemical formula. In balancing the oxidation half-reaction, it becomes clear that NO 3 - is not one of the products of the reaction- the question is somewhat misleading when it suggests that Cu(NO 3 ) is be...
- Sat Mar 13, 2021 4:17 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Reactions with elements besides O and H
- Replies: 2
- Views: 224
Balancing Reactions with elements besides O and H
I was confused on how to set up problems that require more than just adding H2O, OH-, or H+. An example is self test 6k.1A. How do you come up with the half reactions? Are you supposed to just ignore the "extra" species and count them as spectator ions?
- Sat Mar 13, 2021 4:14 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Lecture example?
- Replies: 5
- Views: 330
Re: Lecture example?
Thank you for asking this, I was also confused!
- Fri Mar 12, 2021 8:51 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When to use Platinum
- Replies: 14
- Views: 712
Re: When to use Platinum
Thank you all!!
- Fri Mar 12, 2021 3:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When to use Platinum
- Replies: 14
- Views: 712
When to use Platinum
Hi, I was wondering what the general rule of thumb is for including Pt as our electrode. The textbook says we use it if the oxidized and reduced species are in the same solution, but what does this mean exactly? I have seen examples where Pt is used even when one species is a solid and the other is ...
- Thu Mar 11, 2021 11:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.3
- Replies: 1
- Views: 150
Re: Textbook 6L.3
^This is the work for the problem from the solutions manual but I don't understand how they got this.
- Thu Mar 11, 2021 11:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.3
- Replies: 1
- Views: 150
Textbook 6L.3
For 6L.3d, we are asked to find the balanced equation from this cell diagram: Pt(s)|O2(g)|H+(aq)∥OH−(aq)|O2(g)|Pt(s). I don't understand how to set up the half reactions since the left hand side has the species O2 and H+, which don't have the same elements.
- Sun Mar 07, 2021 8:20 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E naught
- Replies: 13
- Views: 713
Re: E naught
E naught is 0 in a concentration cell, where the substances on either side are the same, just in different concentrations.
- Sun Mar 07, 2021 8:18 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Balancing half-reactions to find overall cell potential
- Replies: 6
- Views: 331
Re: Balancing half-reactions to find overall cell potential
Cell potential is an intensive property, so it does not depend on the number of moles, and you wouldn't need to multiply it by the coefficients.
- Sun Mar 07, 2021 8:16 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in ∆G = -nFE
- Replies: 80
- Views: 3615
Re: n in ∆G = -nFE
You need to balance the chemical reaction. Typically this happens with the same process you would use when splitting the reaction into half reactions. n is the number of electrons transferred once the reaction is balanced.
- Sun Mar 07, 2021 8:15 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E naught
- Replies: 8
- Views: 449
Re: E naught
It is always 0 in a concentration cell.
- Sun Mar 07, 2021 8:15 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Maximum Potential
- Replies: 7
- Views: 420
Re: Maximum Potential
They aren't always equal, but when they are, the maximum potential difference has been reached. No energy gets transferred.
- Sun Feb 28, 2021 10:14 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions in Basic Conditions
- Replies: 7
- Views: 479
Re: Balancing Redox Reactions in Basic Conditions
1. Split into 2 half reactions 2. Balance the oxygens by adding H2O to the appropriate side 3. Balance the H by OH- to the appropriate side 4. Balance the charge by adding e- to the appropriate side 5. Multiply the two half reactions by a coefficient so that the e- on either side can be cancelled ou...
- Sun Feb 28, 2021 10:11 pm
- Forum: Balancing Redox Reactions
- Topic: Standard Potentials and Reactions
- Replies: 12
- Views: 663
Re: Standard Potentials and Reactions
I think we would be provided the necessary values (like we were on midterm 2, when we had to find enthalpy, entropy, or Gibbs free energy)
- Sun Feb 28, 2021 10:09 pm
- Forum: Balancing Redox Reactions
- Topic: Determining Phases
- Replies: 28
- Views: 927
Re: Determining Phases
They will usually give you the phases in the original reaction, so just stick to those! Any water added is a liquid, ions are usually aqueous.
- Sun Feb 28, 2021 10:07 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Reaction Confusion
- Replies: 4
- Views: 239
Re: Redox Reaction Confusion
1. Determine if it is acidic or basic 2. Split into 2 half reactions 3. Balance the oxygens by adding H2O to the appropriate side 3. Balance the H by adding H+ (for acidic) or OH- (for basic) to the appropriate side 4. Balance the charge by adding e- to the appropriate side 5. Make sure the equation...
- Sun Feb 28, 2021 10:04 pm
- Forum: Balancing Redox Reactions
- Topic: Finding Reagents From Provided Table
- Replies: 9
- Views: 367
Re: Finding Reagents From Provided Table
Yes, you would use it to fine the reduction potential for the elements involved in the reaction
- Sun Feb 21, 2021 9:05 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: R gas constant and kPa or Pa
- Replies: 9
- Views: 2939
Re: R gas constant and kPa or Pa
Just convert kPa to atm before proceeding with the problem, using 1 atm = 101.325 kPa.
- Sun Feb 21, 2021 9:03 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Q Question
- Replies: 7
- Views: 471
Re: Q Question
C∆T is generally used when calibrating calorimeters. q = nC∆T is used when substances are placed inside the calorimeter.
- Sun Feb 21, 2021 9:01 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Thermo Equation Sheet
- Replies: 4
- Views: 628
Re: Thermo Equation Sheet
only the equation sheet and periodic table that Dr. Lavelle provides is allowed.
- Sun Feb 21, 2021 9:00 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Which R value to choose
- Replies: 13
- Views: 1363
Re: Which R value to choose
If you are trying to find the mols of gas using PV = nRT, use R= 0.08206 L (atm)/ (mol (K)). The units will cancel out and you will be able to find the number of mols.
- Sun Feb 21, 2021 8:57 pm
- Forum: Van't Hoff Equation
- Topic: Celcius vs Kelvin for T1 and T2
- Replies: 84
- Views: 6269
Re: Celcius vs Kelvin for T1 and T2
You should use Kelvin for most calculations, including this one!
- Sun Feb 14, 2021 11:54 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Tips for what gas constant to use
- Replies: 10
- Views: 564
Re: Tips for what gas constant to use
Look at the units in the problem you are working on. If Joules are involved, use 8.314 J/(K x mol); if atm is involved use 0.08206 (L x atm)/(mol x K)
- Sun Feb 14, 2021 11:51 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 10
- Views: 616
Re: Heat Capacity
Sometimes we are not provided the mass of the substance so we cannot use specific heat capacity
- Sun Feb 14, 2021 11:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: m versus n
- Replies: 11
- Views: 546
Re: m versus n
Yeah! m stands for mass while n stands for moles
- Sun Feb 14, 2021 11:38 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific heat and heat capacity
- Replies: 3
- Views: 166
Re: Specific heat and heat capacity
C is the specific heat capacity, not the heat capacity
- Sun Feb 14, 2021 11:37 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: ΔH and q
- Replies: 6
- Views: 286
Re: ΔH and q
they're interchangeable if you have constant pressure!
- Mon Feb 08, 2021 12:23 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Combustion = Exothermic
- Replies: 23
- Views: 738
Re: Combustion = Exothermic
Combustion is exothermic because a water molecule is being formed. Formation of bonds releases energy, so it is exothermic.
- Mon Feb 08, 2021 12:22 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Extensive vs Intensive
- Replies: 10
- Views: 305
Re: Extensive vs Intensive
Extensive properties depend on the amount of matter that's being measured but intensive properties don't. Heat capacity would be an extensive property but molar heat capacity is an intensive property.
- Mon Feb 08, 2021 12:20 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: R Constant
- Replies: 91
- Views: 4972
Re: R Constant
That's correct! Just pay attention to the units you are working with to figure out which to use. They should cancel out with the units of the other numbers.
- Mon Feb 08, 2021 12:19 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: isolated systems and constant energy
- Replies: 6
- Views: 337
Re: isolated systems and constant energy
Energy can't escape isolated systems because there is no interaction with surroundings. So, energy within the system is constant.
- Mon Feb 08, 2021 12:17 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Work on a system
- Replies: 27
- Views: 1011
Re: Work on a system
compression
- Sun Jan 31, 2021 8:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pKa and pH
- Replies: 6
- Views: 203
Re: pKa and pH
A lower pKa corresponds to a stronger acid. Since strong acids have low pHs, lower pKa corresponds to a lower pH.
- Sun Jan 31, 2021 8:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong Ka
- Replies: 8
- Views: 817
Re: Strong Ka
This is a strong polyprotic acid and it deprotonates twice. You would have to use both Ka1 and Ka2. Since it's a strong acid, H2SO4 fully dissociates in the first deprotonation. However, for the second deprotonation you would have to set up an ICE table.
- Sun Jan 31, 2021 8:17 pm
- Forum: Ideal Gases
- Topic: Conditions
- Replies: 20
- Views: 1416
Re: Conditions
It's 273.15 K for temperature, 1 bar (which is 100 kPa) for pressure
- Sun Jan 31, 2021 8:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Pressure
- Replies: 7
- Views: 331
Re: Pressure
Constant pressure doesn't mean no pressure! It just means that there is no change in final and initial pressure. It could be both 0 or a nonnegative number.
- Sun Jan 31, 2021 8:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Sapling Week 3/4 #6
- Replies: 14
- Views: 485
Re: Sapling Week 3/4 #6
For this one, it's good to look over all the answer choices first. Think about what is going on in the reaction. Is it combustion? Is something specific being formed?
- Sat Jan 23, 2021 10:25 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: sapling 2 week 2
- Replies: 7
- Views: 451
Re: sapling 2 week 2
This quadratic equation calculator can also be used to check your work: https://www.mathpapa.com/quadratic-formula/
- Sat Jan 23, 2021 10:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Qudratic Formula
- Replies: 19
- Views: 852
Re: Qudratic Formula
This quadratic formula calculator can also be used to check your work: https://www.mathpapa.com/quadratic-formula/
- Sat Jan 23, 2021 10:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Standard enthalpy of formation
- Replies: 4
- Views: 230
Re: Standard enthalpy of formation
Hess's Law has to be used in the first problem because it involves N2 and O2, and both their standard enthalpies of formation are 0. Hess's Law is the method that works with these elements.
- Sat Jan 23, 2021 10:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: Change in temperature when state remains the same
- Replies: 4
- Views: 118
Re: Change in temperature when state remains the same
That's right! It's only when there is a phase change that added heat does not increase the temperature. In these cases, the heat goes towards breaking the bonds between the molecules.
- Sat Jan 23, 2021 10:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: Problems Covered Week 3
- Replies: 2
- Views: 132
Re: Problems Covered Week 3
From the syllabus: 4D: 1, 3, 5, 7, 9, 11,15, 17, 19, 21, 23; 4E: 5, 7, 9
- Sun Jan 17, 2021 11:01 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4133
Re: PV=nRT
P = pressure
V = volume
n = number of mols
R = gas constant
T = temperature
V = volume
n = number of mols
R = gas constant
T = temperature
- Sun Jan 17, 2021 10:57 pm
- Forum: Ideal Gases
- Topic: Gas for equilibrium equation
- Replies: 8
- Views: 395
Re: Gas for equilibrium equation
The P is just the notation we use, as to not confuse it with the notation used when using concentrations to find k.
- Sun Jan 17, 2021 10:54 pm
- Forum: Ideal Gases
- Topic: Equilibrium Constant (Q and K)
- Replies: 13
- Views: 581
Re: Equilibrium Constant (Q and K)
They're not the same. K is constant at all times except when there is a change in temperature. Q is the momentary ratio of products to reactants right after there is a change in pressure, volume, or concentration.
- Sun Jan 17, 2021 10:50 pm
- Forum: Ideal Gases
- Topic: Gas constant
- Replies: 9
- Views: 291
Re: Gas constant
The different constants are used depending on which units the problem uses (ie J vs L)
- Sun Jan 17, 2021 10:47 pm
- Forum: Ideal Gases
- Topic: R Value
- Replies: 17
- Views: 590
Re: R Value
On the formula sheet, is it 8.206 x 10^-2 (L x atm/ (K x mol)
- Mon Jan 11, 2021 11:05 am
- Forum: Ideal Gases
- Topic: Ideal gas law and reverse reactions
- Replies: 5
- Views: 158
Re: Ideal gas law and reverse reactions
I believe it does follow the rule!
- Mon Jan 11, 2021 11:05 am
- Forum: Ideal Gases
- Topic: Does temperature matter?
- Replies: 19
- Views: 485
Re: Does temperature matter?
Temperature is really important, especially if doing questions with PV=nRT!
- Mon Jan 11, 2021 11:03 am
- Forum: Ideal Gases
- Topic: Kp to Kc
- Replies: 6
- Views: 231
Re: Kp to Kc
You can use PV=nRT
- Mon Jan 11, 2021 11:02 am
- Forum: Ideal Gases
- Topic: Ice method
- Replies: 14
- Views: 669
- Mon Jan 11, 2021 11:02 am
- Forum: Ideal Gases
- Topic: Ice method
- Replies: 14
- Views: 669
Re: Ice method
Here is a helpful worked example!
- Sat Dec 12, 2020 10:41 am
- Forum: Lewis Structures
- Topic: Exception to Octet rule (Cl)
- Replies: 6
- Views: 316
Re: Exception to Octet rule (Cl)
claire ikemiya_2I wrote:Yes! All elements below row 3 can expand their octet.
Thank you!
- Sat Dec 12, 2020 10:41 am
- Forum: Lewis Structures
- Topic: Exception to Octet rule (Cl)
- Replies: 6
- Views: 316
Re: Exception to Octet rule (Cl)
Jiwon_Chae_3J wrote:Cl can have an expanded octet but I think that Cl is the central atom here because it is the least numerous element in the compound, though I am not sure why this takes precedence over the electronegativity rule.
Thank you!
- Sat Dec 12, 2020 10:40 am
- Forum: Lewis Structures
- Topic: Exception to Octet rule (Cl)
- Replies: 6
- Views: 316
Re: Exception to Octet rule (Cl)
Cl can have an expanded octet because its in the 3rd period on the periodic table, and the 3p elements and lower can have an expanded octet. I believe for this problem Cl would be the central atom for the sake of symmetry where it could have two O on either side that are double bonded, and a lone p...
- Fri Dec 11, 2020 11:42 pm
- Forum: Lewis Structures
- Topic: Exception to Octet rule (Cl)
- Replies: 6
- Views: 316
Exception to Octet rule (Cl)
When drawing the Lewis Structure for ClO2+, I initially put O as the central atom because it is less electronegative than Cl and I thought that Cl only has one available bond (since it has 7 valence electrons). Does Cl have an expanded octet? Why it is the central atom if it is more electronegative?
- Fri Dec 11, 2020 11:38 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Relative Acidity
- Replies: 7
- Views: 286
Re: Relative Acidity
Steph Du 2B wrote:If the bond being broken for the compounds you are comparing is different, you compare bond length (ex. HCl and HBr). If the bond being broken is the same, then you compare electronegativity (ex. CCl3COOH and CH3COOH).
Thank you!
- Fri Dec 11, 2020 11:37 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Relative Acidity
- Replies: 7
- Views: 286
Re: Relative Acidity
Rose_Malki_3L wrote:First compare bond length. If bonds are the same in the compounds you are comparing then compare stability of the anions (so compare electronegativity)
Thank you!
- Fri Dec 11, 2020 11:37 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Relative Acidity
- Replies: 7
- Views: 286
Re: Relative Acidity
Bond length is mainly considered when comparing binary acids, such as HF, HCl, and HI. In this case, the acids with longer bonds will be stronger acids, as they have weaker bonds and can deprotonate easier. Electronegativity and how well the conjugate base anion dilutes the negative charge is used ...
- Fri Dec 11, 2020 3:13 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Relative Acidity
- Replies: 7
- Views: 286
Relative Acidity
When determining relative acidity, do we consider bond length first or electronegativity? Which one is more important?
- Sun Dec 06, 2020 4:09 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligands we should be familiar with?
- Replies: 3
- Views: 128
Re: Ligands we should be familiar with?
It would also be helpful to note the ligands Dr. Lavelle mentions in lectures. Hope this helps!
- Sun Dec 06, 2020 4:07 pm
- Forum: Lewis Acids & Bases
- Topic: Acids and Bases
- Replies: 5
- Views: 258
Re: Acids and Bases
In his lecture, Dr. Lavelle said that stronger acids are ones that lose protons easily. This happens when the resulting anion is stabilized by resonance or electronegative atoms that stabilize the - charge by withdrawing electron density. For example, if two different atoms are bonded to an oxygen, ...
- Sun Dec 06, 2020 4:01 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number With Atoms outside of Coordination Compound
- Replies: 8
- Views: 306
Re: Coordination Number With Atoms outside of Coordination Compound
Coordination numbers concern the atoms inside the coordination sphere (inside the brackets []).
- Sun Dec 06, 2020 3:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Delocalized Bonds
- Replies: 5
- Views: 324
Re: Delocalized Bonds
Delocalized bonds occur in resonance structures, where the electrons are equally shared between all the bonds.
- Sun Dec 06, 2020 3:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Chart
- Replies: 4
- Views: 343
- Sun Nov 29, 2020 11:57 pm
- Forum: Hybridization
- Topic: PBr5
- Replies: 6
- Views: 524
Re: PBr5
remember that the number of hybrid orbitals = the regions of electron density
- Sun Nov 29, 2020 11:44 pm
- Forum: Sigma & Pi Bonds
- Topic: Strength of bonds
- Replies: 5
- Views: 332
Re: Strength of bonds
I agree, I think pi bonds should be stronger since they are present in double and triple bonds (which are stronger than single bonds) while sigma bonds are only in single bonds.
- Sun Nov 29, 2020 11:42 pm
- Forum: Sigma & Pi Bonds
- Topic: sapling no 18
- Replies: 5
- Views: 449
Re: sapling no 18
here is a helpful image of the possible structures: https://haygot.s3.amazonaws.com/questio ... ff183f.png
- Sun Nov 29, 2020 11:41 pm
- Forum: Sigma & Pi Bonds
- Topic: sapling no 18
- Replies: 5
- Views: 449
Re: sapling no 18
The third one is cyclic
- Sun Nov 29, 2020 11:40 pm
- Forum: Sigma & Pi Bonds
- Topic: Delocalized pi bonds
- Replies: 2
- Views: 189
Re: Delocalized pi bonds
I believe these occur in resonance structures, where the electrons are delocalized.
- Sun Nov 29, 2020 11:39 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma Bond Rotation
- Replies: 1
- Views: 56
Re: Sigma Bond Rotation
Since atoms bound by a sigma bond are free to rotate about their axis, I believe they can rotate both clockwise and counterclockwise.
- Sun Nov 22, 2020 9:28 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: Hydrogen Bond
- Replies: 6
- Views: 385
Re: Hydrogen Bond
The hydrogen in one molecule is partially positive, and would form a hydrogen bond with an oxygen in another molecule, which is partially negative.
- Sun Nov 22, 2020 9:27 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-bonding
- Replies: 5
- Views: 221
Re: H-bonding
I think you're right, but it has 3 hydrogen bonds when pairing with cytosine.
- Tue Nov 17, 2020 10:11 am
- Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Topic: Boiling and Melting point
- Replies: 24
- Views: 2606
Boiling and Melting point
Are boiling point and melting point directly related? Do molecules with higher melting points have stronger intermolecular forces?
- Mon Nov 16, 2020 11:43 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: electron spin
- Replies: 4
- Views: 202
electron spin
When a question asks for the electron spin, do we always say that it can either be +½ or -½? Or if we know that the electron in question is an unpaired electron, we can say that it has an electron spin of +½?
- Mon Nov 16, 2020 5:14 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Homework 1D #5
- Replies: 2
- Views: 143
Re: Homework 1D #5
Jagveer 2L wrote:We are not expected to know that. The questions on the midterm are going to be modeled after the problems given in the syllabus and 1D#5 was not on the syllabus, so I do not think that we will be quizzed on it.
Okay, thank you!
- Mon Nov 16, 2020 4:10 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Homework 1D #5
- Replies: 2
- Views: 143
Homework 1D #5
Question:
Show that the electron distribution is spherically symetrical for an atom in which an electron occupies each of the three p-orbitals of a given shell.
The solution to this involves lots of equations with sin and cos. Are we expected to know how to do this for the midterm?
Show that the electron distribution is spherically symetrical for an atom in which an electron occupies each of the three p-orbitals of a given shell.
The solution to this involves lots of equations with sin and cos. Are we expected to know how to do this for the midterm?
- Sun Nov 15, 2020 9:44 pm
- Forum: Electronegativity
- Topic: General Idea of Electronegativity [ENDORSED]
- Replies: 3
- Views: 257
Re: General Idea of Electronegativity [ENDORSED]
You should know that electronegativity increases going from left to right across a period and decreases going down a group.
- Sun Nov 15, 2020 9:42 pm
- Forum: Electronegativity
- Topic: Tips on remembering trend
- Replies: 5
- Views: 286
Re: Tips on remembering trend
I would draw out perodic tables and draw arrows describing each trend (i.e. for electronegativity, draw an arrow starting in the bottom left hand corner and going to the top right corner, where electronegativity is the highest). This is the most straightforward way to represent each trend.
- Sun Nov 15, 2020 9:38 pm
- Forum: Dipole Moments
- Topic: Dipole moment
- Replies: 2
- Views: 70
Re: Dipole moment
Dipole moments occur when there is a difference in electronegativity between two atoms. The larger the difference in electronegativity, the larger the dipole moment. Electrons are more drawn to the more electronegative atom, distorting the electron cloud around the molecule. Dipole moments occur whe...
- Sun Nov 15, 2020 9:34 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bonding Lone pairs
- Replies: 3
- Views: 195
Re: Hydrogen Bonding Lone pairs
A hydrogen bond is a bond between an partially positive hydrogen atom of one molecule and a partially negative N, O, or F atom of a neighboring molecule. The lone pair in that N, O, or F atom is what interacts in the hydrogen bond. It is what gets drawn to the partially positive H atom.
- Sun Nov 15, 2020 9:31 pm
- Forum: Bond Lengths & Energies
- Topic: Electron Relationship in Bonding
- Replies: 6
- Views: 397
Re: Electron Relationship in Bonding
The more bonds there are, the less lone pairs the atoms will have (i.e. two atoms joined with a triple bond have less lone pairs than two atoms joined in a single bond because more electrons are involved in the bond). Thus, molecules with single bonds have more free electrons, which repel each other...
- Sun Nov 08, 2020 2:35 pm
- Forum: Lewis Structures
- Topic: Oxidation Numbers
- Replies: 7
- Views: 169
Re: Oxidation Numbers
It will probably be covered soon; in the meantime here is a helpful chart in case you want to take a look: https://www.google.com/url?sa=i&url=https%3A%2F%2Fchemistryonline.guru%2Foxidation-number%2F&psig=AOvVaw0JmA1MDHorFL6buG72dNmb&ust=1604961159100000&source=images&cd=vfe&...
- Sun Nov 08, 2020 2:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Oxidation number
- Replies: 7
- Views: 178
Re: Oxidation number
Here is a helpful chart: https://www.google.com/url?sa=i&url=htt ... AdAAAAABAD
- Sun Nov 08, 2020 2:31 pm
- Forum: Student Social/Study Group
- Topic: Midterm 2 Study Group
- Replies: 25
- Views: 964
Re: Midterm 2 Study Group
This sounds great! Thanks for organizing it
- Sun Nov 08, 2020 2:30 pm
- Forum: Ionic & Covalent Bonds
- Topic: Question about bond Length
- Replies: 6
- Views: 226
Re: Question about bond Length
Specific bond lengths are usually determined experimentally. You should just know that the more bonds there are, the shorter the bond length is (i.e. a triple bond is shorter and stronger than a single bond).
- Sun Nov 08, 2020 2:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bonds
- Replies: 3
- Views: 149
Re: Hydrogen Bonds
The number of bonds that can be formed in general depend on the number of valence electrons an atom has. For example, carbon has 4 valence electrons and can therefore form 4 bonds with hydrogen (4 C-H bonds) to reach an octet. Oxygen has 6 valence electrons, so it needs 2 more electrons to reach an ...
- Sun Nov 01, 2020 10:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Finding Workshop Answers
- Replies: 4
- Views: 122
Re: Finding Workshop Answers
If you missed the workshop, I'd advise asking someone who did attend for the key. I think they provide answer keys at the session.
- Sun Nov 01, 2020 10:06 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Offline Lecture Content
- Replies: 4
- Views: 332
Re: Offline Lecture Content
I don't know if you can watch lectures offline, but the video modules on his website can be downloaded.
- Sun Nov 01, 2020 10:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Textbook
- Replies: 4
- Views: 104
Re: Textbook
The code should have been emailed to you soon after you bought the textbook. My email got lost in between all my other ones so I would suggest searching up "ASUCLA" or "UCLA Store" in your email to make sure that you see it. After you get the code, you will have access to both sa...
- Sun Nov 01, 2020 10:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Curve on Midterm
- Replies: 9
- Views: 376
Re: Curve on Midterm
I believe we can see scores at the end of Week 5!
- Sun Nov 01, 2020 10:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Participation Points [ENDORSED]
- Replies: 62
- Views: 3267
Re: Participation Points [ENDORSED]
You can click on Quick Links on the upper left hand corner, which will take you to "Your Posts". You can see all the posts you made and make sure you posted 5 times this week.
- Sun Oct 25, 2020 10:10 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Measuring Uncertainty- Homework 1B.27
- Replies: 4
- Views: 191
Re: Measuring Uncertainty- Homework 1B.27
Wouldn't the uncertainty be 10 m/s, since it is (5 m/s + 5 m/s) - (5 m/s - 5 m/s)?
- Sun Oct 25, 2020 9:33 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Measuring Uncertainty- Homework 1B.27
- Replies: 4
- Views: 191
Re: Measuring Uncertainty- Homework 1B.27
Do we disregard the +/- 5.0 m/s^-1 because the problem calls for the minimum uncertainty?
- Sun Oct 25, 2020 9:32 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Measuring Uncertainty- Homework 1B.27
- Replies: 4
- Views: 191
Measuring Uncertainty- Homework 1B.27
A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00 ± 5.0 m⋅s^−1. What is the minimum uncertainty in its position? The textbook says the uncertainty in velocity is 5.00 m/s, but why? When given a number +/- another number, do we just disregard the second number (in this case t...
- Fri Oct 23, 2020 9:22 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Module Question #23
- Replies: 4
- Views: 202
Re: Module Question #23
The uncertainty in position should be 10m, not 5m. So you should use the following equation to solve for the uncertainty in momentum first: delta p >= h/(4pi)(delta x) when you plug everything in, you'd get delta p >= (6.626x10^-34 Js)/(4pi)(10m) and then delta p >= 5.2728 x 10^-36kgms^-1 After, yo...
- Fri Oct 23, 2020 9:03 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Module Question #23
- Replies: 4
- Views: 202
Module Question #23
You are caught in a radar trap and hope to show that the speed measured by the radar gun is in error due to the Heisenberg uncertainty principle. If you assume that the uncertainty in your position was +/- 5 m when your speed was measured, and that the car has a mass of 2150 kg, what is your calcula...
- Wed Oct 21, 2020 9:56 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect Module #29
- Replies: 9
- Views: 344
Re: Photoelectric Effect Module #29
Before you divide h by v, I think you need to add together the kinetic energy of the ejected electron (E excess ) with the kinetic energy needed to remove that electron (E threshold ) to get the energy of the incident light, then find its frequency Adalia is right; energy must be conserved . Theref...