Search found 100 matches
- Sun Mar 15, 2020 2:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Athena
- Replies: 34
- Views: 2119
Re: Athena
Thank you so much for two wonderful quarters of good chemistry! I really can't thank you enough, Dr. Lavelle! It's been a pleasure being in your class, and I wish you the best. Please stay safe and healthy. Take care! High five :D
- Sat Mar 14, 2020 2:47 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Midterm 6B
- Replies: 1
- Views: 109
Midterm 6B
I was wondering how we'd be able to answer this question without having any data for calculations For which process will deltaH nought and deltaG nought be expected to be most similar? (A) 2Al (s) + Fe 2 O 3(s) --> 2Fe (s) + Al 2 O 3(s) (B) 2Na (s) + 2H 2 O ...
- Sat Mar 14, 2020 2:30 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Endgame 1a
- Replies: 5
- Views: 148
Re: Endgame 1a
I believe we discussed in lecture that we should always make the lower concentration the product, so that "it is in solution", which means that the lower concentration will always be on the anode side
- Sat Mar 14, 2020 11:34 am
- Forum: Administrative Questions and Class Announcements
- Topic: UA Final Review - Kate, Riya, Matthew
- Replies: 13
- Views: 1320
Re: UA Final Review - Kate, Riya, Matthew
For question 11, the van't hoff equation is written like ln(K2/K1) = -(deltaH/R)((1/T2) - (1/T1)). However, in the constants and equations sheet, the T2 and T1 are swapped, which would result in K2=0.0169 instead of 0.0186. I was wondering which form of the equation is correct and which we should us...
- Sat Mar 14, 2020 6:59 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 8
- Views: 104
Catalysts
How are homogenous catalysts different from heterogeneous catalysts? What's the significance of that difference?
- Tue Mar 10, 2020 3:56 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7A.17
- Replies: 2
- Views: 79
7A.17
The question provides a table of values, with which we can work out the rate = k r [A][B] 2 [C] 2 (overall order of 5). When I calculate k r , I get the answer 2.85 L 4 *mmol -4 *s -1 . When I calculate the rate with that k, [A] = 3.01 mmol/L, [B] = 1.00 mmol/L, and [C] = 1.15 mmol/L, I get rate = 1...
- Sat Mar 07, 2020 10:04 am
- Forum: General Rate Laws
- Topic: Lecture Question
- Replies: 3
- Views: 126
Re: Lecture Question
The example given in class for a different phase was that if the product is a gas, that gas can escape the system and therefore not be returned to reactant
- Sat Mar 07, 2020 10:01 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow step
- Replies: 4
- Views: 103
Slow step
How does one determine which step in a multi-step reaction is the slowest?
- Sat Mar 07, 2020 9:59 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: temperature and k
- Replies: 5
- Views: 120
temperature and k
How does change in temperature affect k?
- Sat Mar 07, 2020 9:22 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: What is 'A'?
- Replies: 5
- Views: 122
What is 'A'?
In my notes, 'A' is defined as the frequency factor or pre-exponential factor (including # of collisions with correct orientation). What does this mean? Is this what we're trying to calculate with the Arrhenius equation?
- Mon Mar 02, 2020 9:42 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Water with dissolved ions
- Replies: 1
- Views: 45
Water with dissolved ions
Why is water more highly conducting when it has dissolved ions?
- Sun Mar 01, 2020 4:04 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: 6O.1
- Replies: 3
- Views: 141
Re: 6O.1
If the standard reduction potentials that we are meant to use are -0.23V and -0.83V, how is the minimum potential that must be supplied for the onset of electrolysis +1.46V?
- Sun Mar 01, 2020 3:35 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Ion-selective Electrodes and Corrosion
- Replies: 2
- Views: 83
Ion-selective Electrodes and Corrosion
Are we expected to be able to do problems concerning ion-selective electrodes and corrosion on test 2/the final? These topics are included in the reading, but we didn't really explore them much in lecture?
- Sun Mar 01, 2020 2:17 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 6N.5(b)
- Replies: 1
- Views: 60
6N.5(b)
C(gr) | Cl2(g, 1.0 bar) | Cl-(aq, ?) || MnO4-(aq, 0.0010M), H+(pH=0.4), Mn2+(aq, 0.1M) | Pt(s) Ecell = -0.30V
What would be the balanced reaction for this cell? I'm having trouble finding the value of Q
What would be the balanced reaction for this cell? I'm having trouble finding the value of Q
- Sat Feb 29, 2020 5:51 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: delta G and E
- Replies: 1
- Views: 43
delta G and E
How come the value of delta G changes when the chemical equation is multiplied by some factor, but Ecell does not?
- Sat Feb 29, 2020 5:32 pm
- Forum: Balancing Redox Reactions
- Topic: cl2 in 6k part d
- Replies: 1
- Views: 60
Re: cl2 in 6k part d
Yes it does
- Sat Feb 29, 2020 4:24 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/reducing agent
- Replies: 18
- Views: 318
Oxidizing/reducing agent
What is meant by the terms 'oxidizing agent' and 'reducing agent'?
- Sat Feb 29, 2020 4:19 pm
- Forum: Balancing Redox Reactions
- Topic: 6K3d Reduction Reaction
- Replies: 2
- Views: 67
Re: 6K3d Reduction Reaction
I also had a question about this. Perhaps it was a typo? Since the solution has Cl- in the balanced equation, if we supposed that the Cl2 in the products side was Cl-, the problem works out. But I'm not exactly sure.
- Sat Feb 29, 2020 3:28 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Reactions
- Replies: 2
- Views: 80
Redox Reactions
What are the steps we should follow for balancing complicated redox reactions?
- Sun Feb 23, 2020 1:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge
- Replies: 4
- Views: 73
Re: Salt bridge
The salt bridge allows ion transfer, so the two solutions will remain neutral (prevent charge buildup)
- Sun Feb 23, 2020 1:14 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Anode & cathode
- Replies: 5
- Views: 123
Anode & cathode
Does anyone have any tips to memorize that the anode is where oxidation occurs, and the cathode is where reduction occurs?
- Sat Feb 22, 2020 2:41 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 3
- Views: 75
Van't Hoff Equation
In the Van't Hoff Equation, is the K1 value supposed to correlate with the T1 value, and the K2 with the T2? Or are they meant to be treated as separate things?
- Sat Feb 22, 2020 2:37 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5J.15
- Replies: 2
- Views: 91
5J.15
This question asks us to calculate the equilibrium constants for two reactions at 25C and 150C. Can someone walk me through the problem? I'm unsure of where to start. I assume we need to calculate delta G, but which equation would we use to calculate K? These are the reactions: (a) NH 4 Cl (s...
- Sat Feb 22, 2020 1:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5G.21
- Replies: 2
- Views: 98
5G.21
Calculate the equilibrium constant at 25C for each of the following reactions, by using data in Appendix 2A: (a) the combustion of hydrogen: 2H 2(g) + O 2(g) <--> 2H 2 O (g) (b) the oxidation of carbon monoxide: 2CO (g) +O 2(g) <--> 2CO 2 g) (c) the decomp...
- Fri Feb 14, 2020 5:30 pm
- Forum: Phase Changes & Related Calculations
- Topic: Expansion Work
- Replies: 6
- Views: 176
Re: Expansion Work
There is also no expansion work if there's a vacuum
- Fri Feb 14, 2020 4:41 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: State functions
- Replies: 5
- Views: 124
State functions
Is there an easy way to remember all the state functions? What about all the intensive/extensive properties we've looked at? I always end up confusing myself when I try to memorize them
- Fri Feb 14, 2020 4:33 pm
- Forum: Balancing Redox Reactions
- Topic: Redox reaction
- Replies: 5
- Views: 87
Redox reaction
For the example we looked at in class today (permanganate and iron), how come the oxidation numbers of hydrogen and oxygen don't change? How do we tell which ones were oxidized/reduced?
- Fri Feb 14, 2020 4:22 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Van't Hoff Equation
- Replies: 3
- Views: 61
Van't Hoff Equation
The Van't Hoff equation can be used to calculate K at a different temperature, but only if delta S nought and delta H nought are assumed to be constant. Will that always be the case in reality, though? Will delta S nought and delta H nought always be constant in the problems that we're asked to do?
- Fri Feb 14, 2020 4:18 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Delta S
- Replies: 2
- Views: 55
Delta S
How come delta S of surroundings is 0 when a system undergoes irreversible expansion?
- Sun Feb 09, 2020 11:35 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Boltzmann equation
- Replies: 5
- Views: 70
Boltzmann equation
When would we use the Boltzmann equation? How does it relate to entropy?
- Sun Feb 09, 2020 11:23 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.15
- Replies: 2
- Views: 40
4D.15
From the data the question gives, I did the calculation: -1500 - (-1300 + 2(-286)) = 312kJ/mol. However, the answer key shows that it's -312kJ/mol. What did I do wrong?
- Sun Feb 09, 2020 11:01 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat capacity
- Replies: 3
- Views: 25
Heat capacity
How come heat capacity is not an intensive property, but specific heat/molar heat capacity is?
- Sun Feb 09, 2020 10:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpies of Formation
- Replies: 2
- Views: 30
Enthalpies of Formation
Where can I find the standard enthalpies of formation for different molecules in the textbook?
- Sun Feb 09, 2020 10:17 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.7
- Replies: 5
- Views: 55
4D.7
"Oxygen difluoride is a colorless, very poisonous gas that reacts rapidly and exothermically with water vapor to produce O 2 and HF: OF 2 (g) + H 2 O (g) ----> O 2 (g) + 2HF (g) delta H = -318kJ What is the change in internal energy for the reaction of 1.00 mol O...
- Fri Jan 31, 2020 11:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4C.13
- Replies: 2
- Views: 41
4C.13
An ice cube of mass 50.0g at 0.0ºC is added to a glass containing 400.0g of water at 45.0ºC. What is the final temperature of the system? Assume that no heat is lost to the surroundings. How would this problem be solved? I understand that we need to use the enthalpy of fusion and the specific heat o...
- Fri Jan 31, 2020 9:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook section 4B.3: A Molecular Interlude
- Replies: 1
- Views: 20
Textbook section 4B.3: A Molecular Interlude
Is this reading section mandatory? It includes content that we have not covered in class, such as translational, rotational, and vibrational energy.
- Fri Jan 31, 2020 9:25 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 4B.13
- Replies: 2
- Views: 56
4B.13
Calculate the work for each of the following processes beginning with a gas sample in a piston assembly with T = 305K, P = 1.79 atm, and V = 4.29L: (a) irreversible expansion against a constant external pressure of 1.00 atm to a final volume of 6.52L; (b) isothermal, reversible expansion to a final ...
- Fri Jan 31, 2020 8:47 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook Question 4A.3
- Replies: 1
- Views: 33
Re: Textbook Question 4A.3
The question is assuming that only work is done, so heat is not a component of the change of the internal energy. In this case, delta U = w. Your answer for (c) should therefore be the same as (a)
- Fri Jan 31, 2020 8:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 4A.11
- Replies: 3
- Views: 26
Re: 4A.11
The question is asking for the heat capacity of the calorimeter. Notice that it's not asking for the specific heat capacity or the molar heat capacity. In general, the equation for calculating heat capacity is C = q/delta T (where C = heat capacity, q = heat supplied, and delta T = temperature rise ...
- Fri Jan 31, 2020 7:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Reversible Process
- Replies: 4
- Views: 44
Reversible Process
What does it mean for a process to be reversible? I read the section in the textbook (4A.3), but it still doesn't make sense to me.
- Fri Jan 24, 2020 10:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Reaction Enthalpies calculation
- Replies: 2
- Views: 24
Reaction Enthalpies calculation
Among the 4 methods to calculate delta H, is there one that is the most accurate?
- Fri Jan 24, 2020 9:57 pm
- Forum: Phase Changes & Related Calculations
- Topic: Bond enthalpy
- Replies: 4
- Views: 36
Bond enthalpy
Is there a correlation between bond enthalpy and bond length?
- Fri Jan 24, 2020 9:55 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: O2 Delta Hf
- Replies: 2
- Views: 18
O2 Delta Hf
Why is the standard enthalpy of formation of O2 0? Why does this only apply to diatomic molecules?
- Fri Jan 24, 2020 9:52 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Calculation methods
- Replies: 6
- Views: 56
Calculation methods
Can someone provide a summary for all the methods we learned to calculate delta H? What are the notable differences between each one?
- Fri Jan 24, 2020 9:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam v. liquid
- Replies: 7
- Views: 84
Steam v. liquid
How is a steam burn worse than a liquid burn? Is it because steam condenses on the skin, which releases a lot of energy?
- Thu Jan 16, 2020 9:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6D.15 PART B
- Replies: 5
- Views: 66
Re: 6D.15 PART B
Al 3+ is a metal cation that can act as a bronsted acid and thus be hydrated by water molecules. Therefore, Al 3+ will produce acidic solutions. AlCl 3 is the substance that provides this metal cation in the solution; Cl - can be disregarded since it's the conjugate base of a strong acid. Metal cati...
- Wed Jan 15, 2020 6:49 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5.61
- Replies: 2
- Views: 33
Re: 5.61
Why is it that we only look at the moles of gas? I thought it was only solid and liquids that were not included in the equilibrium constant
- Wed Jan 15, 2020 6:13 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5.35
- Replies: 4
- Views: 65
Re: 5.35
The given values are in kPa, so you have to convert them to bar. 1 Pa = 1x10-5 bar, OR this can be written as 100 kPa = 1 bar. That's why you have to divide the values by 100 when you're plugging into the equilibrium constant :)
- Wed Jan 15, 2020 5:15 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Compression on Equilibrium
- Replies: 4
- Views: 27
Compression on Equilibrium
For the reaction: N2(g) + O2(g) <==> 2NO(g), which direction would be favored if the system was compressed?
- Wed Jan 15, 2020 2:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework Question 5I.13
- Replies: 2
- Views: 47
Homework Question 5I.13
(a) In an experiment, 2.0mmol Cl 2 (g) was sealed into a reaction vessel of volume 2.0L and heated to 1000. K to study its dissociation into Cl atoms. Use the information in Table 5G.2 to calculate the equilibrium composition of the mixture. (b) If 2.0mmol F 2 was placed into the reaction vessel ins...
- Sat Jan 11, 2020 4:49 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding inert gas [ENDORSED]
- Replies: 9
- Views: 100
Adding inert gas [ENDORSED]
How come adding inert gas to a reaction vessel would result in no change to the concentrations of the reactants and products? If nothing changes, what's the effect or purpose of adding the gas then (besides increasing pressure)?
- Sat Jan 11, 2020 4:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE box
- Replies: 9
- Views: 93
ICE box
When calculating the change in molar concentration with the quadratic equation, and the results are one positive number and one negative number, would there ever be a circumstance where the negative number is also an acceptable answer?
- Sat Jan 11, 2020 4:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium constant
- Replies: 1
- Views: 62
Equilibrium constant
When calculating the equilibrium constant in general, how come the stoichiometric coefficient becomes an exponent for the concentration of the reactant/product?
- Sat Jan 11, 2020 4:21 pm
- Forum: Ideal Gases
- Topic: Pa and bar? [ENDORSED]
- Replies: 3
- Views: 37
Pa and bar? [ENDORSED]
What is Pa and how do we convert it to bar? Do we always have to do our work in the units of bar?
- Sat Jan 11, 2020 10:43 am
- Forum: Ideal Gases
- Topic: Solids and liquids [ENDORSED]
- Replies: 6
- Views: 77
Solids and liquids [ENDORSED]
I understand why solids cannot be included in the equilibrium constant, but how come liquids cannot? It's possible to measure the concentration of liquids right?
- Tue Dec 03, 2019 5:12 pm
- Forum: Hybridization
- Topic: Hybridization of terminal atoms
- Replies: 2
- Views: 50
Hybridization of terminal atoms
For the final, will we be expected to know how to assign hybridization schemes to terminal atoms?
- Sun Dec 01, 2019 6:32 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs amphiprotic
- Replies: 3
- Views: 60
Amphoteric vs amphiprotic
What's the difference between describing something as amphoteric vs. amphiprotic?
- Sun Dec 01, 2019 6:28 pm
- Forum: Amphoteric Compounds
- Topic: 6A.11
- Replies: 1
- Views: 39
6A.11
Write the chemical equations of the two proton transfer equilibria that demonstrate the amphiprotic character of (a) HCO3—; (b) HPO42—. Identify the conjugate acid-base pairs in each case.
What does it mean by amphiprotic character? How exactly would I format the answer for this question?
What does it mean by amphiprotic character? How exactly would I format the answer for this question?
- Sun Dec 01, 2019 6:07 pm
- Forum: Bronsted Acids & Bases
- Topic: Conjugate acids and bases
- Replies: 5
- Views: 140
Conjugate acids and bases
How do we write the formulas of conjugate acids and bases?
- Sun Dec 01, 2019 5:50 pm
- Forum: Bronsted Acids & Bases
- Topic: Names
- Replies: 1
- Views: 40
Names
Are we expected to know the names of common acids and bases? Like ammonia or phosphoric acid?
- Sun Dec 01, 2019 3:58 pm
- Forum: Bronsted Acids & Bases
- Topic: Relative acidity
- Replies: 2
- Views: 36
Relative acidity
Why is trichloroacetic acid a stronger acid than acetic acid? We went over this in lecture, but I didn't quite understand.
- Sun Nov 24, 2019 11:16 am
- Forum: Naming
- Topic: HW problem 9C.3(d)
- Replies: 2
- Views: 46
HW problem 9C.3(d)
sodium bisoxalato(diaqua)ferrate(III)
formula: Na[Fe(OH2)2(C2O4)2]
Does the order matter when writing the formula of the complex? Would it be possible to write the (C2O4)2 in front of the (OH2)2?
formula: Na[Fe(OH2)2(C2O4)2]
Does the order matter when writing the formula of the complex? Would it be possible to write the (C2O4)2 in front of the (OH2)2?
- Sun Nov 24, 2019 10:51 am
- Forum: Naming
- Topic: [Co(NH3)5Cl]Cl H2O
- Replies: 4
- Views: 103
Re: [Co(NH3)5Cl]Cl H2O
Dr. Lavelle also has a very helpful table on his website about the ligand names we will cover in this course. Just click on the link that says "Naming Coordination Compounds"
- Sun Nov 24, 2019 10:47 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Chelating complexes
- Replies: 4
- Views: 36
Chelating complexes
What is a chelating complex?
- Mon Nov 18, 2019 10:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Exact Bond Angles for Test 1
- Replies: 3
- Views: 49
Re: Exact Bond Angles for Test 1
We don't need to know the exact bond angles for those shapes! Just approximating it by saying it's less than 109.5 degrees, or less than 120 degrees is enough :)
- Mon Nov 18, 2019 8:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Pi bond
- Replies: 4
- Views: 49
Pi bond
Since a double bond consists of one sigma bond and one pi bond, does that mean a double bond does not allow atoms to rotate?
- Sat Nov 16, 2019 3:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sulfite Ion example in class
- Replies: 6
- Views: 155
Re: Sulfite Ion example in class
Since lone pair electrons have stronger repulsion force, bonded atoms will be pushed further from it and gather closer to each other. This is more stable, since atom-atom repulsion is weaker than lone pair-atom repulsion. We don't need to memorize that the particular bond angle is 106 degrees. We on...
- Sat Nov 16, 2019 3:12 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shape of ClO2+
- Replies: 6
- Views: 135
Re: Shape of ClO2+
Trigonal planar would be the shape when taking into consideration the bonds AND the lone pairs, which the textbook calls the "electron arrangement" around the central atom. However, since we name shapes based only on bonds, the final answer would be bent or "angular."
- Sat Nov 16, 2019 3:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T Shape
- Replies: 7
- Views: 144
Re: T Shape
katrinawong3d wrote:There's still one more slide that he's going to cover on Monday, so maybe he'll cover it then?
I believe Dr. Lavelle will be going over sigma and pi bonds on Monday. I'd recommend familiarizing yourself with all the molecular shapes
- Sat Nov 16, 2019 11:12 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs and Bond Angles
- Replies: 2
- Views: 56
Re: Lone Pairs and Bond Angles
Lone pairs have a more strongly repelling effect than elections in bonds because the electron cloud of a lone pair can spread over a larger volume than a bonding pair can. That's why the strengths of repulsions are in the order: lone pair-lone pair > lone pair-atom > atom-atom. This will not change
- Sat Nov 09, 2019 2:47 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 Bonding
- Replies: 4
- Views: 49
Hydrogen Bonding
How come hydrogen bonding occurs with only molecules that have N, O, F? Why can't hydrogen be bonded with other electronegative atoms and become partially positive?
- Sat Nov 09, 2019 2:42 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: 3F.5 (b)
- Replies: 4
- Views: 54
3F.5 (b)
Question 3F.5 is:
Suggest, giving reasons, which substance in each of the following pairs is likely to have the higher normal melting point
(b) C2H5OC2H5 (diethyl ether) or C4H9OH (butanol)
I'm confused why the answer is butanol? Is it because of how the atoms are arranged?
Suggest, giving reasons, which substance in each of the following pairs is likely to have the higher normal melting point
(b) C2H5OC2H5 (diethyl ether) or C4H9OH (butanol)
I'm confused why the answer is butanol? Is it because of how the atoms are arranged?
- Sat Nov 09, 2019 2:22 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: Intermolecular forces
- Replies: 3
- Views: 49
Intermolecular forces
Is hydrogen bonding generally stronger than london forces?
- Sat Nov 09, 2019 2:18 pm
- Forum: Dipole Moments
- Topic: London forces
- Replies: 9
- Views: 141
London forces
Why is the london interaction considered "universal"?
- Sat Nov 09, 2019 2:14 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarisability
- Replies: 3
- Views: 77
Polarisability
Why does the polarisability of molecules increase with size?
- Sun Nov 03, 2019 5:27 pm
- Forum: Trends in The Periodic Table
- Topic: Element Trend Rankings
- Replies: 2
- Views: 43
Re: Element Trend Rankings
1) Electronegativity increases across a period and up a group. P<S<Cl<N<O<F 2) Atomic Radius increases down a group and decreases across a period. F<O<N<Cl<S<P 3) Electron Affinity increases across a period and up a group, like electronegativity. P<S<Cl<N<O<F 4) Ionization Energy increases across a ...
- Sun Nov 03, 2019 5:14 pm
- Forum: Octet Exceptions
- Topic: Radical
- Replies: 6
- Views: 108
Radical
Why is a radical highly reactive?
- Sun Nov 03, 2019 5:09 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length
- Replies: 2
- Views: 51
Bond Length
What exactly does it mean when a bond length is long/short? The distance between nuclei is larger/smaller? How is this related to the electrons the atoms share?
- Sun Nov 03, 2019 4:12 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Aufbau Principle
- Replies: 2
- Views: 42
Aufbau Principle
How is the Aufbau principle related to the Pauli Exclusion principle and Hund's rule? Is it like a fusion of the two?
- Sun Nov 03, 2019 4:06 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy of Group 16
- Replies: 3
- Views: 44
Ionization Energy of Group 16
If oxygen has a lower ionization energy than nitrogen, does that apply to all the other elements in group 16? As in, they will all have lower ionization energies compared to their neighbor to the left?
- Sat Oct 26, 2019 8:13 pm
- Forum: Trends in The Periodic Table
- Topic: Stable Structures
- Replies: 5
- Views: 134
Re: Stable Structures
Remember that if a formal charge of 0 is not possible, the atoms on the outside of the central atom generally have the formal charges that are not 0
- Sat Oct 26, 2019 8:05 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Homework Problem 1E.13
- Replies: 3
- Views: 86
Homework Problem 1E.13
Part e of this question asks for the ground-state electron configuration for tungsten. The answer is [Xe]4f145d46s2. Why is the f block included in this electron configuration? And how come 5d46s2 isn't written as 5d56s1 even though it's more stable in the latter configuration?
- Sat Oct 26, 2019 7:50 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Ionization Energy
- Replies: 4
- Views: 73
Re: Ionization Energy
It's harder to remove a second electron from an atom because removing the first one gives the atom an overall net positive charge. Therefore, the attraction that's exerted on each electron gets larger, making it harder to remove. And yes, there are multiple ionization energies for an element
- Sat Oct 26, 2019 7:46 pm
- Forum: Lewis Structures
- Topic: Triple bonds
- Replies: 1
- Views: 35
Triple bonds
In a lewis structure, double bonds can be drawn in different equivalent locations to indicate resonance. How come triple bonds are unlikely to do this?
- Sat Oct 26, 2019 7:33 pm
- Forum: Resonance Structures
- Topic: Expanded valence shells
- Replies: 3
- Views: 114
Expanded valence shells
How come P, S, and Cl can accommodate more than 8 valence electrons? I don't understand how they can use d-orbitals to expand their shells
- Thu Oct 17, 2019 5:40 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Textbook question 1b.21
- Replies: 2
- Views: 52
Re: Textbook question 1b.21
This additional information about the baseball's weight is not necessary at all to do the problem. It's probably just supplemental information given for the context of the problem :)
- Thu Oct 17, 2019 5:37 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Homework Problem 1B.27
- Replies: 6
- Views: 94
Re: Homework Problem 1B.27
When doing your calculation, the Δv you should use is 10m/s, which is your maximum uncertainty.
- Thu Oct 17, 2019 5:24 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 1B.25 HW
- Replies: 1
- Views: 38
1B.25 HW
"What is the minimum uncertainty in the speed of an electron confined within a lead atom of diameter 350. pm? Model the atom as a one-dimensional box with a length equal to the diameter of the actual atom. I understood the first part of the question and got the correct answer of Δv = 1.65 x 10 ...
- Thu Oct 17, 2019 5:19 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 1B.27 Hw Help
- Replies: 5
- Views: 79
Re: 1B.27 Hw Help
RRahimtoola1G wrote:For ∆x, I got 6.6 x 10-36m also, but the answer in the back of the book and the solution manual is 1.3 x 10-36m. Which is the correct answer?
The correct answer would be 6.6 x 10-37m. There was an error in the solutions manual (Δv = 5m/s when Δv should've been 10m/s)
- Thu Oct 17, 2019 5:10 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: electron position
- Replies: 3
- Views: 75
Re: electron position
You can't specify the precise location of a particle if it behaves like a wave, because a wave is not localized at a precise point. Since waves don't have a location, you can't describe the location of a particle that has a precise linear momentum.
- Mon Oct 14, 2019 9:35 am
- Forum: Properties of Light
- Topic: 1B. 3
- Replies: 2
- Views: 51
Re: 1B. 3
The answer is (d) photoelectric effect because during the photoelectric experiment, scientists noticed that increasing the intensity of the light did not eject electrons. This means that the incident light was not acting like a wave. Therefore, they concluded that electromagnetic radiation had prope...
- Fri Oct 11, 2019 5:26 pm
- Forum: Properties of Light
- Topic: Using the Rydberg Equation in HW 1A.15
- Replies: 4
- Views: 75
Re: Using the Rydberg Equation in HW 1A.15
You would first use the wavelength you have and find the energy change using E=(hc)/wavelength. Once you have the energy change, use the equation E=(-hR)/n^2 with n=1 to find the energy of the electron at n=1. Once you have the energy change and the energy of the electron at n=1, you can set up thi...
- Fri Oct 11, 2019 5:20 pm
- Forum: DeBroglie Equation
- Topic: Electrons in a box
- Replies: 2
- Views: 35
Electrons in a box
During lecture, Dr. Lavelle mentioned something about the QM description of an election in a box. What did he mean by that/what exactly is he referring to?
- Fri Oct 11, 2019 5:14 pm
- Forum: Photoelectric Effect
- Topic: HW problem 1B.5
- Replies: 1
- Views: 29
HW problem 1B.5
"The y-ray photons emitted by the nuclear decay of a technetium-99 atom used in radiopharmaceuticals have an energy of 140.511 keV. Calculate the wavelength of these y-rays."
What is meant by keV? How should I go about starting this problem?
What is meant by keV? How should I go about starting this problem?
- Fri Oct 11, 2019 3:27 pm
- Forum: Properties of Light
- Topic: Homework Question 1A.7
- Replies: 2
- Views: 32
Homework Question 1A.7
For part b of this question, it asks for the wavelength of the x-rays. I got my answer of 150pm. However, the answer written at the back of the textbook says 150nm. Is this simply a typo or were my calculations off?
- Fri Oct 04, 2019 7:18 pm
- Forum: SI Units, Unit Conversions
- Topic: SI Units
- Replies: 3
- Views: 89
SI Units
In my high school, my teacher never really went over the different prefixes, names, and meanings for the SI units. How come they ascend and descend in degrees of 3? Would it be good practice to memorize all of them for the tests?
- Fri Oct 04, 2019 7:12 pm
- Forum: Significant Figures
- Topic: Sig figs for percent yield
- Replies: 2
- Views: 94
Sig figs for percent yield
In a question, say it asks me to calculate percent yield of some compound. The given sig fig is 1. If my answer is something like 56%, would I have to round it to 60% to maintain that sig fig of 1? Sig figs in the answer should match the given ones right?
- Fri Oct 04, 2019 7:02 pm
- Forum: Properties of Light
- Topic: Amplitude
- Replies: 6
- Views: 171
Amplitude
There's an inverse relationship between frequency and wavelength. Do they have any relationship with the amplitude of a wave?
- Fri Oct 04, 2019 6:55 pm
- Forum: Properties of Light
- Topic: Emission and Absorption
- Replies: 1
- Views: 37
Re: Emission and Absorption
Yes, electrons gain energy by absorbing light. When they jump down energy levels, light is emitted
- Fri Oct 04, 2019 6:53 pm
- Forum: Properties of Light
- Topic: Electromagnetic vectors
- Replies: 1
- Views: 35
Electromagnetic vectors
In lecture, we briefly went over a diagram showing the vectors for electric fields and magnetic fields. What exactly is the significance of these vectors? Is there a reason they're perpendicular to each other?