Search found 118 matches
- Fri Mar 05, 2021 7:41 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Intermediate species
- Replies: 8
- Views: 452
Re: Intermediate species
Dr. Lavelle said in lecture that we do not need to know what that species is- it will be given to us. That is way outside the scope of our knowledge at the moment.
- Fri Mar 05, 2021 7:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 10 Review Sessions
- Replies: 10
- Views: 560
Re: Week 10 Review Sessions
Yes the bolded times are the review sessions while the others are the TA's office hours
- Fri Mar 05, 2021 7:38 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: graphs and order
- Replies: 19
- Views: 939
Re: graphs and order
for zero-order rxns (n=0), [A] vs time in a decreasing linear graph
for first-order rxns (n=1), ln[A] vs time in a decreasing linear graph
for second-order rxns (n=2), 1/[A] vs time in an increasing linear graph
for first-order rxns (n=1), ln[A] vs time in a decreasing linear graph
for second-order rxns (n=2), 1/[A] vs time in an increasing linear graph
- Fri Mar 05, 2021 7:34 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling week 7/8 Question 18
- Replies: 5
- Views: 427
Re: Sapling week 7/8 Question 18
Your answer is correct, but you do not need the parentheses around the product.
- Fri Mar 05, 2021 7:31 pm
- Forum: First Order Reactions
- Topic: 0.693 ?
- Replies: 39
- Views: 8353
Re: 0.693 ?
The equation for half life of something in the first order is t1/2 = ln(2) / k, which = 0.693/k
- Sun Feb 28, 2021 11:52 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Balancing equations
- Replies: 5
- Views: 292
Re: Balancing equations
We use H+ to balance redox reactions occurring in acidic conditions and OH- for redox reactions in basic conditions. Dr. Lavelle has two handouts about this that are super helpful on his website towards the bottom. The section is called Redox Reactions.
- Sat Feb 27, 2021 9:57 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling wk 7/8 #5
- Replies: 6
- Views: 392
Re: Sapling wk 7/8 #5
The problem deals with basic solution, therefore you should not have H+ ions in your equation.
- Sat Feb 27, 2021 9:57 pm
- Forum: Balancing Redox Reactions
- Topic: Determining which molecule is the oxidizing agent
- Replies: 49
- Views: 1945
Re: Determining which molecule is the oxidizing agent
The oxidizing agent is reduced and the reducing agent is oxidized.
- Sat Feb 27, 2021 9:56 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling #15
- Replies: 5
- Views: 363
Re: Sapling #15
As we learned in the first unit of 14B, solids are not accounted for in Q nor K. Therefore, it would just be 0.768/0.0150 for Q
- Sat Feb 27, 2021 9:55 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling week 7/8 #18
- Replies: 3
- Views: 269
Re: Sapling week 7/8 #18
You should try deleting the parentheses. I had the same answer except without the parentheses.
- Sat Feb 27, 2021 9:53 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Writing out Cell Diagrams
- Replies: 5
- Views: 364
Re: Writing out Cell Diagrams
If there are no solids, there needs to be an inert conductor, and the most common one used is Pt(s)
- Sun Feb 21, 2021 10:53 pm
- Forum: Calculating Work of Expansion
- Topic: R constant of an Ideal Gas
- Replies: 16
- Views: 832
Re: R constant of an Ideal Gas
You will typically use the gas constant according to what is given in the problem. You want to cancel out units that are not in the final answer.
- Sun Feb 21, 2021 10:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Property
- Replies: 71
- Views: 3223
Re: State Property
A state property means that the path taken does not matter. You can directly calculate the value with the initial and final values without regarding what is going on in between.
- Sun Feb 21, 2021 10:47 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Meaning of K
- Replies: 55
- Views: 3963
Re: Meaning of K
Uppercase K means the equilibrium constant, or it could mean Kelvins. lowercase k would be the boltzmann constant.
- Sun Feb 21, 2021 10:46 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gas Constant R
- Replies: 43
- Views: 4006
Re: Gas Constant R
It depends on what the problem is asking. You typically should look at the units to determine which gas constant R to use.
- Sun Feb 21, 2021 10:45 pm
- Forum: Van't Hoff Equation
- Topic: Celcius vs Kelvin for T1 and T2
- Replies: 84
- Views: 6981
Re: Celcius vs Kelvin for T1 and T2
It depends on which constant you're using. Typically the constant is R = 8.314 J/ Kxmol, so you would have to use Kelvins in that case.
- Sun Feb 14, 2021 3:14 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: m versus n
- Replies: 11
- Views: 631
Re: m versus n
Yes, m is mass and n is moles. If you're given m, you should use the specific heat capacity and if given n you should use molar heat capacity. You could also convert the mass to moles and moles to mass to use either of the heat capacities.
- Sun Feb 14, 2021 3:12 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q equation
- Replies: 21
- Views: 3647
Re: q equation
They're the same equation, just with different units. So it would depend on what units you get in the question, and then you will have to either use the specific heat capacity or the molar heat capacity.
- Sun Feb 14, 2021 3:07 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: sapling #15
- Replies: 3
- Views: 235
Re: sapling #15
You should use Hess's law since this is a state property. So you would manipulate equation 2 by reversing the reaction (x-1) and multiplying by 2 (x2) to both the delta S and delta H values. Then you would calculate delta G for each value, and then get the delta H of the rxn by adding them together....
- Sun Feb 14, 2021 3:04 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Kelvin conversion
- Replies: 40
- Views: 3375
Re: Kelvin conversion
The most accurate is 273.15K = 0 C which is given on the equation sheet. The textbook and sapling problems do use 298 K as 25 C though.
- Sun Feb 14, 2021 3:02 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling Week 6 Question 9
- Replies: 6
- Views: 474
Re: Sapling Week 6 Question 9
It's much more straightforward to calculate delta S using the riemann sum equation to get delta S reaction.
- Sun Feb 07, 2021 9:18 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Sapling week 3 and 4 #18
- Replies: 5
- Views: 254
Re: Sapling week 3 and 4 #18
delta U would = n Cv delta T, Cv is 4R - R = 3R so the equation would be delta U = (n mol) (3R) (delta T)
- Sun Feb 07, 2021 9:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling #14 Week 3/4
- Replies: 7
- Views: 382
Re: Sapling #14 Week 3/4
w = -P ext x delta V.
- Sun Feb 07, 2021 9:12 pm
- Forum: Ideal Gases
- Topic: Gas Constant Value
- Replies: 43
- Views: 1688
Re: Gas Constant Value
You decide which value to use by looking at the units. You choose which is the most desirable to get the units of the value you want.
- Sun Feb 07, 2021 9:11 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling Question 14
- Replies: 1
- Views: 98
Re: Sapling Question 14
You would use the initial pressure to calculate the number of moles.
- Sun Feb 07, 2021 9:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Sapling #20
- Replies: 9
- Views: 467
Re: Sapling #20
When the volume is constant, there is no work being done. U = q + w, and when U = q + 0, therefore U = q
- Sun Feb 07, 2021 8:51 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling #14: Why do we use two different values of R for Path A?
- Replies: 5
- Views: 211
Re: Sapling #14: Why do we use two different values of R for Path A?
It depends on the units the problem gives you. You should know what units the answer should be in and then use the appropriate R to cancel out the units for the given information.
- Sat Jan 30, 2021 5:54 pm
- Forum: Ideal Gases
- Topic: Exo vs Endothermic
- Replies: 40
- Views: 2507
Re: Exo vs Endothermic
When bonds are formed, energy will be released which would make it exothermic. When bonds are being broken, energy is required to break them, which means it is endothermic.
- Sat Jan 30, 2021 5:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Making X negligible
- Replies: 34
- Views: 1470
Re: Making X negligible
We make X negligible when X is 10^-4 or smaller. There is a guideline that says 10^-3, but if it were something like 9 x 10^-3, that would be closer to -2, which is why using 10^-4 is safer.
- Sat Jan 30, 2021 5:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Changing Concentrations
- Replies: 5
- Views: 249
Re: Changing Concentrations
If you're given the initial concentrations for both reactants and products, you would calculate Q in order to see which way the reaction will proceed towards. If Q > K, reactants will be favored. if Q< K then products will be favored. If you are only given the initial molar concentration for the eit...
- Sat Jan 30, 2021 5:48 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert gas
- Replies: 25
- Views: 1668
Re: Inert gas
Inert gases are not reactive, therefore they would not "shift" the equilibrium.
- Sat Jan 30, 2021 5:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Taking the Anti-Log
- Replies: 37
- Views: 2650
Re: Taking the Anti-Log
pKa would be -log ([H30+])
Ka would be 10^(-pKa)
Ka would be 10^(-pKa)
- Sat Jan 30, 2021 5:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: is HClO3 weak or strong? [ENDORSED]
- Replies: 49
- Views: 4368
Re: is HClO3 weak or strong? [ENDORSED]
HClO3 is considered to be one of the 7 strong acids.
- Sun Jan 24, 2021 12:45 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 5698
Re: Kelvin or Celsius?
That equation requires the usage of Kelvins.
- Sun Jan 24, 2021 12:45 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HClO3 Strong or Weak Acid
- Replies: 7
- Views: 454
Re: HClO3 Strong or Weak Acid
Sapling included HCLO3 as a strong acid last quarter.
- Sun Jan 24, 2021 12:42 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids in Ice Tables
- Replies: 11
- Views: 1028
Re: Solids in Ice Tables
Solids and Liquids are not included in the equilibrium tables, only aqueous solutions and gases.
- Sun Jan 24, 2021 12:41 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Acids and Bases
- Replies: 8
- Views: 366
Re: Acids and Bases
We are focusing on Bronsted-Lowry acids and bases, because we're dealing with the proton transfer.
- Sun Jan 24, 2021 12:39 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Ice Tables
- Replies: 28
- Views: 1082
Re: Ice Tables
Depends on the reaction. If concentrations of both products and reactants are given, you could calculate the reaction quotient(Q) and see whether it is small, equal to, or bigger than K. This way you could determine which direction the reaction is proceeding. If only one of the two (R&P) concent...
- Sun Jan 24, 2021 12:37 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Tables
- Replies: 36
- Views: 1867
Re: ICE Tables
The x's are determined by the stoichiometric coefficients.
- Sun Jan 24, 2021 12:36 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Do concentrations change at equilibrium?
- Replies: 9
- Views: 228
Re: Do concentrations change at equilibrium?
The concentrations should stay the same because the rate of the forward and reverse rxn's should be equal.
- Sun Jan 17, 2021 5:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pure Liquids (Solutes)
- Replies: 7
- Views: 352
Re: Pure Liquids (Solutes)
Dr. Lavelle tells us to write the chemical reaction with the (l) or (aq), as an easier way to identify if something is a pure liquid. Typically problems will include the chemical reaction, specifying which of the reactants and products are liquids or solids, and which are aqueous and gases.
- Sun Jan 17, 2021 5:42 pm
- Forum: Ideal Gases
- Topic: Inverse Kc [ENDORSED]
- Replies: 41
- Views: 2185
Re: Inverse Kc [ENDORSED]
Kc is the equilibrium constant, so we use it to describe the forward reaction. When we are describing the reverse reaction(when products are making the reactants), we will use 1/Kc to describe the equilibrium constant. Another two to remember are when we multiply the moles of the entire reaction by ...
- Thu Jan 14, 2021 10:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: solids and liquids in K expression
- Replies: 7
- Views: 193
Re: solids and liquids in K expression
We do not use solids or liquids because they do not have concentration. We will include all gases, and aqueous solutions as well because they have concentration (we can calculate their molarity)
- Thu Jan 14, 2021 10:14 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: H2O as a Gas
- Replies: 69
- Views: 6643
Re: H2O as a Gas
We do not exclude any gases. We will only exclude H2O when it is in liquid form. All liquids and solids are excluded because they do not have concentration. All gases and aqueous solutions will be included in the equilibrium constant/expression.
- Thu Jan 14, 2021 10:12 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Getting two positive x values when using quadratic
- Replies: 43
- Views: 4841
Re: Getting two positive x values when using quadratic
From all the examples we have done so far, when there are two positive values, one of the x values will be larger than the initial concentration we need to subtract x from. Since it's not possible to have a negative concentration, the one that is smaller than the initial concentration will be the an...
- Thu Jan 14, 2021 10:08 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Which Acids and Bases to remember
- Replies: 4
- Views: 243
Re: Which Acids and Bases to remember
Since we will probably be dealing with weak acids and bases this quarter, every acid and base that is not part of the strong acids and bases is a weak acid/base. So the strong acids are HCl, HClO4, HClO3, HNO3, HBr, HI, H2SO4. and the strong bases are the groups one and two metal oxides.
- Thu Jan 14, 2021 10:03 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: What is the Conjugate Seesaw
- Replies: 11
- Views: 724
Re: What is the Conjugate Seesaw
The conjugate seesaw essentially says
- the stronger the acid, the weaker the conjugate base.
- the stronger the base, the weaker the conjugate acid.
- the weaker the acid, the stronger the conjugate base
- the weaker the base, the stronger the conjugate acid.
- the stronger the acid, the weaker the conjugate base.
- the stronger the base, the weaker the conjugate acid.
- the weaker the acid, the stronger the conjugate base
- the weaker the base, the stronger the conjugate acid.
- Fri Jan 08, 2021 11:53 am
- Forum: Ideal Gases
- Topic: Chemical Equilibrium Part 1A Post-Module Assessment
- Replies: 11
- Views: 1994
Re: Chemical Equilibrium Part 1A Post-Module Assessment
The answer is C, because even during equilibrium, there are chemical reactions happening at a "molecular level." Equilibrium is achieved when the rate of the forward reaction equals the reverse reaction, therefore C is false.
- Tue Jan 05, 2021 10:55 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4881
Re: Kc vs Kp
Depends on what the problem gives you. If it gives you units in bar/atm, it will most likely be Kp. If it gives you units in M or x moles in x L, it will probably be Kc.
- Tue Jan 05, 2021 10:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Molar Ratios and ICE box
- Replies: 3
- Views: 123
Re: Molar Ratios and ICE box
It's easier to use whole numbers because you will usually end up with a quadratic equation already, and it's easier to calculate when you have as many whole numbers as possible. Theoretically though, you could, as long as you don't mind the decimals.
- Tue Jan 05, 2021 10:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc favoring products
- Replies: 10
- Views: 563
Re: Kc favoring products
Yes, if the number is between 10^-3(or 10^-4 in some cases) and 10^3, they are not strongly favoring neither reactants or products.
- Tue Jan 05, 2021 10:07 pm
- Forum: Ideal Gases
- Topic: Units of Temperature
- Replies: 82
- Views: 3819
Re: Units of Temperature
We should be using Kelvins
- Tue Jan 05, 2021 10:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Kc
- Replies: 15
- Views: 555
Re: K vs. Kc
K is the equilibrium constant and can be Kp or Kc. Kc is used for concentrations.
- Sat Dec 12, 2020 4:28 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Why isn't HF a strong acid?
- Replies: 23
- Views: 7440
Re: Why isn't HF a strong acid?
F is very electronegative, so the bond between H and F are stronger than with the other H-halogen acids, which means its a weaker acid!
- Wed Dec 09, 2020 1:51 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: H3O+ versus H+
- Replies: 19
- Views: 5806
Re: H3O+ versus H+
They are basically the same thing. When we say we donate a proton, typically means donating an H+ which will form H3O+, so theyre essentially saying the same thing.
- Wed Dec 09, 2020 1:49 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Titration Diagram
- Replies: 5
- Views: 251
Re: Titration Diagram
ABCDE were just points in the data collection where S is the pH at 7 where the solution is at the stoichiometric point.
- Wed Dec 09, 2020 1:48 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sapling #12
- Replies: 7
- Views: 453
Re: Sapling #12
The more oxygen atoms there are, the stronger the acid.
- Wed Dec 09, 2020 1:47 pm
- Forum: Bronsted Acids & Bases
- Topic: HF
- Replies: 15
- Views: 877
Re: HF
The bond between HF is very strong because F is very electronegative. A strong acid dissociates/ionizes almost completely. It would be hard for the aqueous solution to dissociate HF, therefore it is not a strong acid.
- Wed Dec 09, 2020 1:46 pm
- Forum: Student Social/Study Group
- Topic: lecture bruincast #29 problem
- Replies: 10
- Views: 550
Re: lecture bruincast #29 problem
I also had this problem with today's lecture. I took a break and refreshed it 40 minutes later and it was fine again. It might be due to the amount of people on CCLE since finals are coming up.
- Wed Dec 09, 2020 1:45 pm
- Forum: Bronsted Acids & Bases
- Topic: Ions as Bases/Acids
- Replies: 3
- Views: 259
Re: Ions as Bases/Acids
In terms of looking at salts, you can tell which salts will behave as acids or bases. For example, NH4+ Cl- + H2O -> NH3 + H3O+ Cl-, chlorine does not affect the pH which means it has no effect as an acid or base. However, H3O+ concentration increases, which lowers the pH. You will need to see whic...
- Wed Dec 09, 2020 1:43 pm
- Forum: Polyprotic Acids & Bases
- Topic: CO2 + H2O
- Replies: 7
- Views: 1042
Re: CO2 + H2O
CO2 and H20 mix to make carbonic acid which is H2CO3. H2CO3 can give off protons and become HCO3-, another common acid (bicarbonate).
- Wed Dec 09, 2020 1:40 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 25 degrees celsius [ENDORSED]
- Replies: 6
- Views: 2024
Re: 25 degrees celsius [ENDORSED]
25 degrees is considered the standard, much like we consider room temperature.
- Wed Dec 09, 2020 1:40 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Na2SO4 - Basic or Neutral?
- Replies: 2
- Views: 3267
Re: Na2SO4 - Basic or Neutral?
Na2SO42- would be the neutral salt that occurs when the strong acid and strong base are combined into one solution. The result of the combination of a strong acid and strong base would be the salt and H20 at the stoichiometric point where the pH is neutral
- Sun Dec 06, 2020 8:55 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 4
- Views: 228
Coordination Number
In the textbook problems that Dr. Lavelle has assigned, specifically 9C.9, it asks us to determine the coordination number of the metal ion in the following complexes. For c and d, it gives [PtCl2(en)2]^2+ and [Cr(edta)]^-. Without knowing the structure and formula of ethylenediamine and EDTA, how w...
- Sun Dec 06, 2020 7:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Finding Coordination Number
- Replies: 14
- Views: 651
Re: Finding Coordination Number
You see how many bonds are formed with the Transition metal, by counting the number of atoms/molecules inside the square brackets.
- Thu Dec 03, 2020 12:35 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acid strength and bond length
- Replies: 11
- Views: 2148
Re: Acid strength and bond length
The longer the bond length, the weaker the bond, which means it is more easily dissociated/ionized. In lecture, Dr. Lavelle said that strong acids are almost completely ionized/dissociate in solution, therefore the longer the bond, the stronger the acid. (In most cases)
- Thu Dec 03, 2020 12:32 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Finding Coordination Number
- Replies: 14
- Views: 651
Re: Finding Coordination Number
The coordination number is the number of ligands attached to the central TM atom, which is essentially the stuff inside the square brackets.
- Thu Dec 03, 2020 12:29 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acids Strength
- Replies: 3
- Views: 153
Re: Bronsted Acids Strength
A strong acid(or even base) is almost completely ionized/dissociated in solution. The longer the bond, the more easily the acid dissociates, which is why HBr would be a stronger acid than HCl
- Thu Dec 03, 2020 12:27 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 8
- Views: 464
Re: Coordination Number
coordination number is the number of ligands attached to the transition metal, essentially the atoms inside the square brackets.
- Thu Dec 03, 2020 12:25 pm
- Forum: Biological Examples
- Topic: Hemoglobin vs. Myoglobin
- Replies: 30
- Views: 1355
Re: Hemoglobin vs. Myoglobin
Hemoglobin is in blood, and myoglobin is in tissue ie. muscles etc. essentially myoglobin gets oxygen from hemoglobin, and hemoglobin gets oxygen when it passes through our lungs when we breathe in the oxygen, the local partial pressure of oxygen is the highest in the lungs which is why hemoglobin b...
- Sun Nov 29, 2020 7:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent
- Replies: 9
- Views: 508
Re: Bent
Yes, bent and angular are both terms used for that shape.
- Sun Nov 29, 2020 7:14 pm
- Forum: Ionic & Covalent Bonds
- Topic: Homework due date
- Replies: 49
- Views: 2279
Re: Homework due date
The hw is due on Sunday at 23.59!
- Sun Nov 29, 2020 7:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: #13 Sapling Week 8
- Replies: 18
- Views: 687
Re: #13 Sapling Week 8
Tetrahedral should be correct, maybe check your spelling!
- Wed Nov 25, 2020 11:34 pm
- Forum: Hybridization
- Topic: UA Workshop Number 6a
- Replies: 4
- Views: 239
Re: UA Workshop Number 6a
It is sp^2 because there are three regions of electron density. The double bond with the other N, the lone pair, and the single bond with C. The double bond still counts as 1 region of electron density, so there are 3 regions which means it is sp^2.
- Wed Nov 25, 2020 3:03 pm
- Forum: Lewis Structures
- Topic: NO2 Polarity
- Replies: 6
- Views: 2885
Re: NO2 Polarity
The dipole moments do not cancel out in NO2 similarly to SO2, but unlike CO2 because CO2 has a linear shape. NO2 and SO2 both have lone pairs, which due to electron repulsion cause the shape to be bent/angular, therefore the dipole vectors do not completely cancel out and you will have a polar molec...
- Wed Nov 25, 2020 2:58 pm
- Forum: Bond Lengths & Energies
- Topic: Tetrahedral Bond Angle
- Replies: 7
- Views: 505
Re: Tetrahedral Bond Angle
We should know the approximate angle, ie. greater than, less than 109.5, etc.
- Wed Nov 25, 2020 2:47 pm
- Forum: Lewis Structures
- Topic: Most Stable Structure
- Replies: 23
- Views: 3609
Re: Most Stable Structure
The most stable lewis structure is the structure with the lowest formal charge. The more electronegative atoms would be more likely to hold the negative formal charge in the molecule.
- Wed Nov 25, 2020 2:46 pm
- Forum: Dipole Moments
- Topic: Negative Pole
- Replies: 7
- Views: 755
Re: Negative Pole
You would look at the electronegativity of the atoms. The most electronegative would be the more negative pole of the dipole moment.
- Sat Nov 21, 2020 5:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shape Names
- Replies: 50
- Views: 2537
Re: Shape Names
This kind of shape can be called angular or bent.
- Sat Nov 21, 2020 5:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle
- Replies: 9
- Views: 487
Re: Bond Angle
Bond angles will depend on what molecule you are examining.
- Sat Nov 21, 2020 5:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polar Bonds [ENDORSED]
- Replies: 26
- Views: 1327
Re: Polar Bonds [ENDORSED]
You would draw the dipole moments on the lewis structure(by determining en) and then using vector addition, you could see which of the dipole moments cancel.
- Sat Nov 21, 2020 5:30 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Non-Polar Bonds
- Replies: 3
- Views: 285
Re: Non-Polar Bonds
Hydrocarbons are typically nonpolar, and molecules that have cancelling dipole moments are also nonpolar. It would be much more efficient to know how to draw the lewis structures and the dipole moments to know which cancel out.
- Sat Nov 21, 2020 5:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair E-
- Replies: 47
- Views: 2042
Re: Lone Pair E-
Lone pairs count as e- density regions as well.
- Fri Nov 13, 2020 9:07 pm
- Forum: Lewis Structures
- Topic: Recognizing lowest formal charge
- Replies: 11
- Views: 418
Re: Recognizing lowest formal charge
calculate the number of electrons, then find the atom with lowest ionization energy to put in the center, then find the number of lone pairs on the central atom and how many bonds the central atom forms, and then you draw the structure out with as much symmetry as possible. Then you can calculate th...
- Fri Nov 13, 2020 9:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook problem 2D. 5
- Replies: 2
- Views: 84
Re: Textbook problem 2D. 5
The electronegativity of H is 2.2, F is 4.0(the most electronegative element), and C is 2.6. The EN difference between C and H is only 0.4 while the EN difference between C and F is 1.4. So CH4 could even be classified as a nonpolar covalent bond, while CF4 would display more ionic character.
- Fri Nov 13, 2020 8:59 pm
- Forum: Dipole Moments
- Topic: Dipole dipole vs LDF
- Replies: 10
- Views: 3445
Re: Dipole dipole vs LDF
These are both intermolecular forces, but LDF and dipole-dipole are different. LDF could be used interchangably with induced dipole-induced dipole/van der waals forces/dispersion.
- Thu Nov 12, 2020 11:54 am
- Forum: Lewis Structures
- Topic: Radicals
- Replies: 12
- Views: 325
Re: Radicals
Radicals have an unpaired electron, you can usually tell when the total number of valence electrons you calculate out before you draw the lewis structure are odd.
- Thu Nov 12, 2020 11:52 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: formal charge and stability
- Replies: 8
- Views: 266
Re: formal charge and stability
It is of course best for the whole structure to have a formal charge of 0, but if that doesn't happen, i think the second most stable form is when the central atom has a formal charge of 0.
- Thu Nov 12, 2020 11:47 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Calculating Formal Charge
- Replies: 9
- Views: 421
Re: Calculating Formal Charge
The equation is the most straightforward way to find the formal charge and find the most stable lewis structure.
- Sat Nov 07, 2020 9:08 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Textbook 1D #21
- Replies: 5
- Views: 199
Re: Textbook 1D #21
n gives the energy level, and every orbital can hold up to two electrons. l=0 would correspond to s sublevel, l=1 would be p, l=2 would be d, and l=3 would be f, etc. for instance, n=5 l=2 would be 5d based on the definition we gave for n and l.
- Sat Nov 07, 2020 9:03 pm
- Forum: Electronegativity
- Topic: Electronegativity Table/Chart in Lecture
- Replies: 14
- Views: 536
Re: Electronegativity Table/Chart in Lecture
We will need to know the trends, but it is not expected of us to memorize the specific electronegativity of each element.
- Sat Nov 07, 2020 9:00 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Can you have the same 3 quantem number but not the 4 same quantem numbers
- Replies: 12
- Views: 503
Re: Can you have the same 3 quantem number but not the 4 same quantem numbers
Yes, the first three quantum numbers can be the same, but the fourth must be different as each electron on that orbital would have a different spin.
- Fri Nov 06, 2020 10:24 pm
- Forum: Lewis Structures
- Topic: Lewis Bases and Lone Pair Electrons
- Replies: 3
- Views: 153
Re: Lewis Bases and Lone Pair Electrons
In the example Dr. Lavelle gave during lecture, the lone pair donor(lewis base) was NH3 and it was on the N atom, and the lone pair acceptor(lewis acid) is B from BF3.
- Fri Nov 06, 2020 10:19 pm
- Forum: Electronegativity
- Topic: Shielding Effect
- Replies: 6
- Views: 194
Re: Shielding Effect
Lucy's analogy of people standing around the fire pit is a good example! Since s-orbitals are closer to the nucleus, they are more effective at shielding.
- Fri Nov 06, 2020 10:16 pm
- Forum: Ionic & Covalent Bonds
- Topic: Homework due date
- Replies: 49
- Views: 2279
Re: Homework due date
Sunday at 11.59 pm or 23.59.
- Fri Nov 06, 2020 10:14 pm
- Forum: Resonance Structures
- Topic: Bond lengths
- Replies: 20
- Views: 755
Re: Bond lengths
We don't have to draw them to be longer vs shorter, but we should know double bonds are shorter and single bonds are longer.
- Fri Nov 06, 2020 10:03 pm
- Forum: Student Social/Study Group
- Topic: Making it through Midterm Results
- Replies: 13
- Views: 765
Re: Making it through Midterm Results
Honestly, going to UA sessions and office hours is super helpful. Going through each of Dr. Lavelle's lectures and processing the information, and then APPLYING the actual stuff we learned is also important. Doing all the homework problems in the outlines. Going to as many UA sessions as possible re...
- Fri Oct 30, 2020 1:32 pm
- Forum: Lewis Structures
- Topic: Using Lewis Structures
- Replies: 7
- Views: 236
Re: Using Lewis Structures
Yes, during lecture 12(10/30), Dr. Lavelle used the example of Potassium Chloride to show the lewis structure of an ionic compound.
- Fri Oct 30, 2020 1:25 pm
- Forum: Lewis Structures
- Topic: Line in place of paired dots
- Replies: 8
- Views: 216
Re: Line in place of paired dots
It's probably better to draw the lone pairs as pairs of dots, and to leave the lines to denote bonds.
- Fri Oct 30, 2020 1:22 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configurations
- Replies: 15
- Views: 539
Re: Electron Configurations
Dr. Lavelle has said that he would prefer for us to use the longer notation because it will tell us more about the configuration ie. which orbital the electron is occupying rather than writing 2p3.