Search found 124 matches
- Tue Mar 10, 2020 7:57 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Class Cancellation
- Replies: 3
- Views: 416
Re: Class Cancellation
My TA said homework is still due, you just send a photo through email.
- Mon Mar 09, 2020 3:08 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: k'
- Replies: 6
- Views: 439
Re: k'
k' is the rate constant for the reverse reaction.
- Mon Mar 09, 2020 3:07 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: HW 7D.5
- Replies: 2
- Views: 227
Re: HW 7D.5
In the textbook and solution, it says L.mol-1.s-1.
- Mon Mar 09, 2020 3:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6K.3
- Replies: 1
- Views: 185
Re: 6K.3
Cl2-->HOCl + Cl- Cl2--> Cl- - balance the Cl and the charge (Cl2 + 2e--> 2Cl-) Cl2-->HOCl - balance the Cl (Cl2-->2HOCl) - balance the O ( 2H2O + Cl2--> 2HOCl) - balance the H and charge (2H2O + Cl2--> 2HOCl + 2H+ +2e-) Combine the two by canceling the electrons (no need to multiply either because t...
- Mon Mar 09, 2020 2:54 pm
- Forum: *Enzyme Kinetics
- Topic: Lecture 3/6
- Replies: 3
- Views: 371
Re: Lecture 3/6
We covered how rates related to the equilibrium constant, the Arrhenius equation, and ways to approach reaction mechanisms (direct computation, determine rate limiting step, steady-state, or pre-equilibrium).
- Mon Mar 02, 2020 8:28 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 6M.11
- Replies: 3
- Views: 387
Re: 6M.11
Which part of the question are you referring to?
- Mon Mar 02, 2020 8:26 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell diagrams
- Replies: 1
- Views: 169
Re: cell diagrams
When there are two aqueous ions or two of the same phase. For example, Cu(s)|Cu 2+ (aq)|| Ce4+ (aq), Ce3+ (aq)| Pt (s)
- Mon Mar 02, 2020 8:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6.43
- Replies: 3
- Views: 281
Re: 6.43
I think it is Ecell.
- Mon Mar 02, 2020 8:16 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 6N.3 c.
- Replies: 1
- Views: 329
Re: 6N.3 c.
It should be a negative value in the end based off the cell diagram.
- Mon Mar 02, 2020 8:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6N.3 a)
- Replies: 1
- Views: 335
Re: 6N.3 a)
The hydrogen is the only element you need to worry about in this case, so the two half reactions are the same thing just flipped: H2 -> 2H+ + 2e-. The left side of the cell diagram is the anode, so that means the electrons should be on the right side of the reaction, and its the opposite for the cat...
- Tue Feb 25, 2020 4:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.1
- Replies: 4
- Views: 415
Re: 6M.1
I am not sure if it is a typo, but I was wondering what answer would you get if the Cu2+/Cu is the cathode so that I can check mine.
- Mon Feb 24, 2020 9:57 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: homework question 6L.1
- Replies: 3
- Views: 381
Re: homework question 6L.1
For this question, you use the equation standard delta G of the reaction= -nFE. All you do is plug in all the variables. E is given, F is a constant, and n is the number of moles of the reaction.
- Mon Feb 24, 2020 9:20 pm
- Forum: Balancing Redox Reactions
- Topic: 6K.3 d
- Replies: 2
- Views: 247
Re: 6K.3 d
I think it is a typo. it should be Cl- like it is in the solutions.
- Mon Feb 24, 2020 3:06 pm
- Forum: Balancing Redox Reactions
- Topic: Homework Question 6K.5 (part b)
- Replies: 1
- Views: 523
Re: Homework Question 6K.5 (part b)
If you are balancing out the half run from Br2->BrO3-, you have to first balance the Br, so now its Br2->2BrO3-. Then you have to balance the O, so you add 6H2O to the left side. Now you have to balance the H, so you add 12H+ + 12 OH-= 12 H20 to the right side. Since you added 12 OH- to the right, y...
- Mon Feb 24, 2020 3:00 pm
- Forum: Student Social/Study Group
- Topic: 2/24 lecture
- Replies: 5
- Views: 437
Re: 2/24 lecture
we discussed the nernst equation further and applications of electron transfer reactions like in electrolysis and ion-selective electrodes. We also discussed concentration cells where there is a transfer of electrons but the voltage is very low and E knot is zero.
- Mon Feb 24, 2020 2:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.5 D.
- Replies: 7
- Views: 567
Re: 6L.5 D.
For this specific reaction, Au + acts in both the cathode and anode reaction, so you should see both in each reaction. For cathode, the half reaction is: Au+ + e- -> Au For anode, the half reaction is" Au3+ + 3e- -> Au+ Then, you should multiply the half reaction of cathode by 3 and flip the a...
- Wed Feb 19, 2020 5:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: midterm Q1A
- Replies: 7
- Views: 484
Re: midterm Q1A
Since the reaction is forming a bond, it is exothermic, so if more heat is added, the reaction would favor the formation of the reactants. If the reaction was reversed, it would be breaking a bond, and that would be endothermic.
- Wed Feb 19, 2020 5:11 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal reversible and irreversible
- Replies: 2
- Views: 370
Re: Isothermal reversible and irreversible
I know that for irreversible and reversible there are two different equations for work. For irreversible it is w=PdeltaV, but for a free expansion there is no work, so it would be zero.
- Tue Feb 18, 2020 8:44 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test #2
- Replies: 4
- Views: 451
Re: Test #2
Any material covered after the midterm.
- Tue Feb 18, 2020 8:44 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5G.13
- Replies: 8
- Views: 1732
Re: 5G.13
The equation for delta G of the reaction equals -RTlnK (standard delta G for rxn) + RTlnQ. The problem gives you K and T, and the pressures it gives you can be used to solve for Q, which equals the concentration of products over concentration of reactants at a given time. Plug in all the values you ...
- Tue Feb 18, 2020 8:41 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: converting T to kelvin
- Replies: 46
- Views: 3525
Re: converting T to kelvin
It depends on the units you are solving for and any other units involved in the equation by other constants, etc. Can you give a specific instance that you have a question about?
- Mon Feb 10, 2020 11:42 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: ∆S and ∆H at constant temp and pressure
- Replies: 1
- Views: 217
Re: ∆S and ∆H at constant temp and pressure
A kind of brief summary is that using the Gibbs free energy equation (∆G = ∆H - T∆S) when ∆H is negative and ∆S is positive,the reaction is spontaneous and when ∆H is positive and ∆S is negative, its not.This is because -delta G means spontaneity. I'm not quite sure if thats what the bullet point is...
- Mon Feb 10, 2020 11:37 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: spontaneity
- Replies: 7
- Views: 396
Re: spontaneity
For part 2, it is like the example in class where you set delta G equal to zero and then use the Gibbs equation to solve for T.
- Mon Feb 10, 2020 11:35 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: types of disorder
- Replies: 2
- Views: 272
Re: types of disorder
Positional disorder is when there are more positions for a substance to fill, like if a substance spreads out into a greater volume, it will have greater positional disorder. Thermal disorder occurs when a substance heats up, and there is more disorder because there is an increase in motion in the m...
- Mon Feb 10, 2020 11:31 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Units for entropy, enthalpy, and GFE
- Replies: 1
- Views: 234
Re: Units for entropy, enthalpy, and GFE
Entropy should be J/K, enthalpy is kJ/mol, and I think GFE is kJ/mol but I also did notice that the solutions guide switched around, so I would assume that maybe you can leave it as kJ, but I don't think its wrong to have kJ/mol because the moles don't really cancel out I think it just means thats t...
- Mon Feb 10, 2020 11:23 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U = w
- Replies: 1
- Views: 86
Re: delta U = w
When there is no heat being transferred, so the system is adiabatic.
- Mon Feb 10, 2020 11:15 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: isolated system
- Replies: 16
- Views: 886
Re: isolated system
I think so because it cannot exchange heat or work with the surroudings.
- Wed Feb 05, 2020 3:27 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible Reactions
- Replies: 3
- Views: 204
Re: Reversible Reactions
A reversible reaction is where products and reactants are being formed at the same time, and once the forward and reverse reactions occur at the same rate, they reach equilibrium.
- Mon Feb 03, 2020 7:33 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Expansion Work on a Piston
- Replies: 1
- Views: 81
Re: Expansion Work on a Piston
I think you have to use the conversion from L atm to J. 101.325 J is one L atm.
- Mon Feb 03, 2020 7:32 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: asking for final temp
- Replies: 2
- Views: 138
Re: asking for final temp
You only find enthalpy if the substance is going through a phase change I think.
- Mon Feb 03, 2020 7:31 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: asking for final temp
- Replies: 2
- Views: 138
Re: asking for final temp
You have to use q=mCdeltaT for the substances they are asking you to find the final temperature for. For example, if they ask you to find the final temperatures for an ice cube in water, once you calculate the delta H for the ice cube, then you find the q for the ice and q for the water, set them eq...
- Mon Feb 03, 2020 2:25 pm
- Forum: Calculating Work of Expansion
- Topic: 4.7 answer
- Replies: 1
- Views: 100
Re: 4.7 answer
you have to balance the equation of the combustion of the C6H6 then find how many moles of gas you have (it should be -1.50 mil). Plug it into the equation w=-nRT.
- Mon Feb 03, 2020 2:22 pm
- Forum: Calculating Work of Expansion
- Topic: internal energy
- Replies: 4
- Views: 138
Re: internal energy
it only depends on the current state of the system not how that state was prepared.
- Mon Feb 03, 2020 2:13 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Textbook question 4D.23
- Replies: 1
- Views: 112
Re: Textbook question 4D.23
The chemical equation you want is N2+5/2O2->N2O5, so you have to cancel out the NO and the NO2.
- Tue Jan 28, 2020 3:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 2
- Views: 223
- Mon Jan 27, 2020 7:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid
- Replies: 2
- Views: 179
Re: Acid
Use the equation M=n/v (molarity=moles/liter) in order to solve for number of moles.
- Mon Jan 27, 2020 7:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid
- Replies: 2
- Views: 179
Re: Acid
The buffering capacity is dependent on the number of moles of buffer in the solution. Since both have the same number of moles of HCN, they have the same buffering capacity.
- Mon Jan 27, 2020 7:23 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy Intensive or Extensive
- Replies: 4
- Views: 2910
Re: Enthalpy Intensive or Extensive
Enthalpy is an extensive property because it depends on the amount of matter that is involved. If you double the amount of matter, then you are doubling the enthalpy.
- Mon Jan 27, 2020 7:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equilibria
- Replies: 4
- Views: 296
Re: Chemical Equilibria
To answer part of this post, at equilibrium, the forward and reverse reactions are occurring at equal rates.
- Mon Jan 27, 2020 7:18 pm
- Forum: Ideal Gases
- Topic: Chemical Equilibrium
- Replies: 4
- Views: 220
Re: Chemical Equilibrium
Catalysts can affect the rate of a chemical reaction, but I do not think that they affect the equilibrium constant.
- Fri Jan 24, 2020 4:30 pm
- Forum: Calculating Work of Expansion
- Topic: Same Initial and Final States
- Replies: 1
- Views: 199
Re: Same Initial and Final States
https://www.usna.edu/Users/chemistry/mo ... onal18.doc This document might help your question.
- Fri Jan 24, 2020 3:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4A.1
- Replies: 1
- Views: 120
4A.1
The question states, "Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump is 3.0 cm, and the pump is depressed 20. cm with pressure of 2.00 atm. a) How much work is done to the compression?" So, work equals the -external pressure times the change in...
- Fri Jan 24, 2020 2:58 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Steam
- Replies: 5
- Views: 154
Re: Steam
More energy is required to turn water into steam, so when it comes into contact with skin, it transfers a greater amount of heat energy.
- Fri Jan 24, 2020 2:55 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpy Accuracy
- Replies: 6
- Views: 142
Re: Bond Enthalpy Accuracy
I think it is because the bond enthalpies are calculated as averages from many different molecules, so they are not the most accurate.
- Thu Jan 23, 2020 2:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6B.9
- Replies: 5
- Views: 171
Re: 6B.9
I think they multiplied the [OH-] over and then divided by Kw.
- Thu Jan 23, 2020 2:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6B.9
- Replies: 5
- Views: 171
Re: 6B.9
Just reverse the fraction and you should get 1.5x10^-14.
- Wed Jan 22, 2020 5:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6B.9
- Replies: 5
- Views: 171
Re: 6B.9
Can you post a picture of the problem or your work for reference?
- Wed Jan 15, 2020 8:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5J.11
- Replies: 4
- Views: 149
Re: 5J.11
In the solutions, it says that it takes energy to break an X-X bond, so processes with halogens will be endothermic and increased temperatures favors the formation of products.
- Wed Jan 15, 2020 7:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: concentration of H3O+
- Replies: 2
- Views: 82
concentration of H3O+
I am confused about what Dr.Lavelle was discussing at the end of lecture. He said that if [H3O+]< 10^-7 then the solution is considered neutral because we know autoprotolysis generates 10^-7 M [H3O+]. Can someone explain what this means?
- Wed Jan 15, 2020 6:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K cutoff
- Replies: 5
- Views: 229
Re: K cutoff
Use the five percent rule that was discussed in lecture to ensure that you can use the approximation though.
- Wed Jan 15, 2020 6:52 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: HW 5J.5 part C
- Replies: 3
- Views: 185
Re: HW 5J.5 part C
The question states for part c: 4NH3 (g) + 5O2 (g) <-> 4NO (g) + 6H2O (g) Since there are more moles of gas on the right, the reaction will shift to the left towards the reactants when there is compression. I think you just forgot some of the information in the problem.
- Tue Jan 14, 2020 8:12 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endothermic and exothermic reactions
- Replies: 11
- Views: 1106
Re: Endothermic and exothermic reactions
Also, the way I think about it is that endothermic reactions like heat because they absorb it, so more heat will help the reaction favor the products. If the reaction is exothermic, it "doesn't like heat" so it lets it go, and wouldn't want to create more products if the temperature rises.
- Mon Jan 13, 2020 10:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6A21
- Replies: 2
- Views: 119
6A21
The question states, "The value of Kw for water at body temperature (37 C) is 2.1x10^-14. (a) What is the molar concentration of H3O+ ions at 37C? (b) What is the molar concentration of OH- in neutral water at 37 C?" How does the temperature affect the equation? Also, how do they get Kw=[H...
- Thu Jan 09, 2020 5:57 pm
- Forum: Ideal Gases
- Topic: 5G.11
- Replies: 6
- Views: 219
Re: 5G.11
It’s the same equation, but the concentrations used are during a different time in the reaction, which may or may not be at equilibrium depending on if Q is less than, equal to, or greater than K.
- Wed Jan 08, 2020 10:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.29
- Replies: 2
- Views: 86
5I.29
After doing the ICE table for this problem, the equation is 3.2x10^-34=x^2/(0.22-2x^2). The book says that we can omit the 2x^2 because we can assume that x <<0.22 since K is so small. That means the denominator would just be (0.22)^2. I am not really sure how I would know to do this if I had anothe...
- Wed Jan 08, 2020 3:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equilibrium Part 2 #19
- Replies: 2
- Views: 171
Re: Chemical Equilibrium Part 2 #19
I am confused because your equation doesn’t match the question. Can you clarify please?
- Tue Jan 07, 2020 6:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc vs Kp
- Replies: 2
- Views: 144
Re: Kc vs Kp
It talks about it in the textbook under topic 5H.3.
- Tue Jan 07, 2020 6:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc vs K
- Replies: 6
- Views: 260
Re: Kc vs K
K or Kp is used when there are gases in the chemical equation, unless stated otherwise because gases can be discussed in terms of molar concentration. Meanwhile, Kc is for concentrations in mol/L for solutes in a condensed phase.
- Tue Jan 07, 2020 12:18 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Effect of High Initial Concentration of Reactant
- Replies: 5
- Views: 243
Re: Effect of High Initial Concentration of Reactant
I believe that if you increase the concentration of reactants, then it will drive the reaction to the right and create more product.
- Tue Dec 03, 2019 9:51 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: acidic trends
- Replies: 3
- Views: 189
Re: acidic trends
The strength of an acid depends on bond length or the stability of the anion, which occurs when there is an atom with a high electronegativity. So, if its just HF compared to HCl, then HCl is stronger by bond length. If its H-O-F and H-O-Cl being compared, then H-O-F is stronger due to electronegati...
- Tue Dec 03, 2019 4:39 pm
- Forum: Lewis Acids & Bases
- Topic: charges of transitional metals
- Replies: 3
- Views: 203
Re: charges of transitional metals
If they are in a coordination compound, you calculate the oxidation states based on the charges of the other elements in the compound.
- Mon Dec 02, 2019 9:41 pm
- Forum: Student Social/Study Group
- Topic: Practice Final
- Replies: 17
- Views: 1399
Re: Practice Final
I don't think so because there are so many review sessions and office hours, but a UA posted some extra problems to help for review. Search the word "marshmallow".
- Mon Dec 02, 2019 9:05 pm
- Forum: Amphoteric Compounds
- Topic: Oxides in Water
- Replies: 1
- Views: 104
Re: Oxides in Water
Metals form basic oxides and nonmetals form acidic oxides.
- Mon Dec 02, 2019 8:29 pm
- Forum: Bronsted Acids & Bases
- Topic: Determining Relative Strength of an Acid
- Replies: 1
- Views: 193
Re: Determining Relative Strength of an Acid
The inductive effect is the ability to polarize a bond based on the electronegativity of an atom. So, if an atom has more electronegativity, there’s more induction, so the acid would be stronger. It’s pulling at the negative charge more to stabilize the anion.
- Mon Dec 02, 2019 7:46 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pH, pKA, KA, and B
- Replies: 2
- Views: 227
Re: pH, pKA, KA, and B
Ka is the concentration of the A- and H+ divided by AH. As this increases, the pKa (-logKa) decreases. A lower pKa means it’s a stronger acid, so I’m guessing that a lower pKa means a lower pH.
- Tue Nov 26, 2019 5:14 pm
- Forum: Bronsted Acids & Bases
- Topic: J.17
- Replies: 2
- Views: 111
Re: J.17
I think the question was just telling you that they are weak. I don't think it was asking you to determine, but there is a table for strong acids and bases, so if its not included there, then its probably weak.
- Tue Nov 26, 2019 5:13 pm
- Forum: Hybridization
- Topic: Focus 2.57
- Replies: 4
- Views: 306
Re: Focus 2.57
It is asking for the hybrid orbitals for the central atoms.
- Mon Nov 25, 2019 6:21 pm
- Forum: Bronsted Acids & Bases
- Topic: Fundamental J problem 7
- Replies: 1
- Views: 177
Fundamental J problem 7
The instructions say to select an acid and a base for a neutralization reaction that results in the formation of a. potassium chloride, b. zinc nitrite, c. calcium cyanide, and d. potassium phosphate, and then write the balanced equation. I’m not really sure how to pick the acids and bases.
- Mon Nov 25, 2019 2:54 pm
- Forum: Naming
- Topic: Homework 9C.3
- Replies: 2
- Views: 115
Re: Homework 9C.3
The prefix before the ligand name tells you how many of that ligand there are. For example, pentaamminesulfatocobalt (III) chloride, there would be five (NH3) ligands. There is no prefix in front of the sulfate group so its just one SO4. The cobalt goes inside the brackets and in front of the ligand...
- Mon Nov 25, 2019 2:47 pm
- Forum: Hybridization
- Topic: Focus 2.57
- Replies: 4
- Views: 306
Re: Focus 2.57
When you draw out the Lewis structure, there will be a tetrahedral shape around one C atom and a linear shape on the other C atom. Then, you can determine the bond angles. For hybrid orbitals, you think about the number of bonding regions around the central atom you have. For tetrahedral, there are ...
- Mon Nov 25, 2019 2:42 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: charge and oxidation state
- Replies: 2
- Views: 196
- Mon Nov 25, 2019 2:41 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: charge and oxidation state
- Replies: 2
- Views: 196
Re: change and oxidation state
The charges of ligands are found in tables from which you have to memorize. To find the oxidation state of the transition metal, you set up an equation (x+ (#of ligand multiplied by the charge of it)= the charge of the compound as a whole), and then you solve for x.
- Tue Nov 19, 2019 9:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Big Molecule
- Replies: 2
- Views: 203
Re: Big Molecule
Connect all the carbons in a chain and attach the hydrogens to the outsides. Thats how I usually try to attack those. The N would connect to a carbon as well.
- Mon Nov 18, 2019 9:07 pm
- Forum: Lewis Structures
- Topic: lone pairs
- Replies: 7
- Views: 726
Re: lone pairs
check the formal charges and also if its a hydrogen, it wouldn't have more than a single bond or if its a halogen (Group 7 elements), they usually like single bonds too, so any extra electrons would go on the central atom.
- Mon Nov 18, 2019 8:14 pm
- Forum: Dipole Moments
- Topic: nonpolar and polar
- Replies: 2
- Views: 242
Re: nonpolar and polar
Dipole moments will cancel out in order for a molecule to be non polar.
- Mon Nov 18, 2019 8:05 pm
- Forum: Lewis Structures
- Topic: double and triple bonds
- Replies: 6
- Views: 755
Re: double and triple bonds
halogens, like F, usually like to have 3 lone pairs and one single bond.
- Mon Nov 18, 2019 7:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: dipole dipole
- Replies: 5
- Views: 318
Re: dipole dipole
I think you compare the sizes of the molecules if they have the same forces.
- Mon Nov 18, 2019 7:40 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: Distinguishing forces
- Replies: 2
- Views: 138
Re: Distinguishing forces
All molecules have London Dispersion Forces, and the strength of the LDF depends of the size of the atoms. Hydrogen bonds occur when an H is bonded to an N, O, or F. Nonpolar molecules can have LDF. Polar covalent molecules can have dipole-dipole and LDF. Ionic compounds can have ion-ion. Try to det...
- Sat Nov 16, 2019 1:09 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: Dipole-Dipole vs. Dipole-Induced Dipole
- Replies: 4
- Views: 622
Re: Dipole-Dipole vs. Dipole-Induced Dipole
A dipole to dipole interaction is between two polar molecules, and polar molecules always have dipole moments. By thinking about the molecules structures/shape, like we did in class, you can predict if it is polar or non polar. A dipole induced dipole interaction is usually between a polar molecule ...
- Thu Nov 14, 2019 8:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E21
- Replies: 2
- Views: 124
2E21
I’m not sure how they got 107 degrees for the angles of the molecule N2H4 in part d of the question. Can someone explain this?
- Thu Nov 14, 2019 3:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle
- Replies: 3
- Views: 189
Re: Bond Angle
180 degrees for linear,
120 degrees for trigonal planar, 109.5 degrees for tetrahedral, 120 degrees for the trigonal bond angles and 90 and 180 degrees for the axial bond angles in a trigonal bipyramidal, 90 and 180 degrees for octahedral
120 degrees for trigonal planar, 109.5 degrees for tetrahedral, 120 degrees for the trigonal bond angles and 90 and 180 degrees for the axial bond angles in a trigonal bipyramidal, 90 and 180 degrees for octahedral
- Wed Nov 13, 2019 2:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 15
- Views: 870
Re: Test 2
I am also wondering because my discussion is on Tuesday, and he said we will still be doing shape on Friday. I am not sure what will be covered Monday, so I am assuming all the intermolecular forces plus lewis structures and shape. Also, I would look out for practice problems from TAs.
- Tue Nov 12, 2019 9:06 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: Induced dipole vs dipole
- Replies: 3
- Views: 166
Re: Induced dipole vs dipole
Induced dipole is when one molecule has an instantaneous dipole moment and since the charges in the molecule shifted, it induces the other molecule to have a dipole because opposite forces attract. Dipole to dipole interaction is when there are two polar molecules which means they constantly have a ...
- Tue Nov 12, 2019 9:04 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing Power
- Replies: 4
- Views: 404
Re: Polarizing Power
The smaller the cation is, the more polarizing power it has. The larger an anion is, the easier it is to distort.
- Thu Nov 07, 2019 7:25 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: Question 3F 1
- Replies: 1
- Views: 177
Question 3F 1
How can you determine when there is a london force or dipole to dipole interaction in a molecule? Why would CBr4 be only a london force, but the others are like london and dipole-dipole, etc?
- Mon Nov 04, 2019 7:18 pm
- Forum: Resonance Structures
- Topic: Formal charge and resonance
- Replies: 5
- Views: 202
Re: Formal charge and resonance
resonance structures should all have the same formal charge because you're not changing the number of bonds and lone pairs on each element. You are just moving those around.
- Mon Nov 04, 2019 4:39 pm
- Forum: Lewis Structures
- Topic: Electron Configuration & Formal Charge for Cu
- Replies: 4
- Views: 185
Re: Electron Configuration & Formal Charge for Cu
Its easier if you just think about it in the order you write out the configuration. 3d comes before 4s when you write out the configuration. So, you would remove the 4s1, and then one from the 3d.
- Mon Nov 04, 2019 4:37 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 9
- Views: 376
Re: Formal Charge
The lowest energy lewis structure would typically be the one where most of the elements have a formal charge of zero. If the molecule as a whole has a charge though, the formal charges of the elements should add up to that charge.
- Mon Nov 04, 2019 10:46 am
- Forum: Lewis Structures
- Topic: 2C.11
- Replies: 1
- Views: 145
Re: 2C.11
When you draw lewis structures, you calculate the number of electrons you need first. For example, XeF4 would need 36 electrons. Once you give each fluorine a single bond to the Xe and fill in their lone pairs, you have 4 electrons left, so you attach them to the Xe because F cannot have more than 8...
- Mon Nov 04, 2019 10:37 am
- Forum: Lewis Structures
- Topic: Lewis Structure
- Replies: 4
- Views: 285
Re: Lewis Structure
It’s typically the one with the lower ionization energy. After doing a lot of practice problems, I just noticed which atoms typically are in the center like carbon and such.
- Mon Nov 04, 2019 10:35 am
- Forum: Ionic & Covalent Bonds
- Topic: Electron Configuration
- Replies: 2
- Views: 269
Re: Electron Configuration
Aufbaus Principle explains this. It’s like a pyramid looking diagram if you google it, and it explains which orbitals should be filled in which order.
- Sat Nov 02, 2019 3:32 pm
- Forum: Lewis Structures
- Topic: Topic 2C question 5
- Replies: 2
- Views: 121
Re: Topic 2C question 5
In the answer, it’s on the Cl.
- Sat Nov 02, 2019 3:26 pm
- Forum: Lewis Structures
- Topic: Topic 2C question 5
- Replies: 2
- Views: 121
Topic 2C question 5
It says draw the Lewis structure of the reactive species chlorine monoxide, ClO. How do we know which element to leave an unpaired electron on?
- Thu Oct 31, 2019 1:43 pm
- Forum: Octet Exceptions
- Topic: Radicals: Homework Problem #2C1
- Replies: 8
- Views: 463
Re: Radicals: Homework Problem #2C1
In the answer key, it says it’s not a radical.
- Tue Oct 29, 2019 2:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm review sessions
- Replies: 3
- Views: 278
Re: Midterm review sessions
He said he is going to schedule a whole bunch more, and I would assume so since he liked to schedule a lot of hours for UA peer learning sessions and TA office hours.
- Tue Oct 29, 2019 2:48 pm
- Forum: Ionic & Covalent Bonds
- Topic: Exceptions to the Octet
- Replies: 2
- Views: 157
Re: Exceptions to the Octet
There are the 4 elements that form duplets like H,He,Li, and Be, and then also elements in period 3 and up could potentially have an expanded valence. That's what I would try to remember.
- Tue Oct 29, 2019 2:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Topics
- Replies: 3
- Views: 221
Re: Midterm Topics
That is what was listed on his email, so I am pretty sure that is it.
- Mon Oct 28, 2019 10:30 am
- Forum: Lewis Structures
- Topic: Lone Pairs
- Replies: 3
- Views: 86
Re: Lone Pairs
I typically put one dot on each side first and then add another to form pairs if there are more left.
- Mon Oct 28, 2019 10:28 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E.11
- Replies: 1
- Views: 171
Re: 1E.11
Use the period table to help you write out the configurations. For a shortcut, you can use the noble gas the comes before the element and then write out the rest of the configuration. For example,Na would be [Ne] 3s1.
- Wed Oct 23, 2019 7:41 pm
- Forum: Ionic & Covalent Bonds
- Topic: Focus 2.B problem B9
- Replies: 2
- Views: 100
Focus 2.B problem B9
For part B, I do not understand how that structure came about. Can someone explain and also why are the K+ ions floating around the P?