Search found 110 matches

by Ariel Davydov 1C
Tue Mar 10, 2020 4:42 pm
Forum: Administrative Questions and Class Announcements
Topic: final
Replies: 6
Views: 58

Re: final

It probably will be in order to make sure no one is cheating or accessing any online resources during the test.
by Ariel Davydov 1C
Tue Mar 03, 2020 3:56 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6N.9 Homework
Replies: 1
Views: 21

Re: 6N.9 Homework

1) We know it will be Sn -> Sn2+ + 2e- because the charge of Sn in the salt mentioned is +2. 2) When given the standard reduction potentials of each half reaction for a spontaneous reaction, we know that the half reaction with the highest reduction potential will be reduced and thus will be at the c...
by Ariel Davydov 1C
Tue Mar 03, 2020 3:53 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7 part b Homework Help
Replies: 2
Views: 27

Re: 6L.7 part b Homework Help

Hi! Since the cell possesses an aqueous solution, water is implied to be present in the cell, so there is no need to include it in the cell diagram. Hope this helps!
by Ariel Davydov 1C
Tue Mar 03, 2020 3:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Hw Problem 6M.1
Replies: 1
Views: 27

Re: Hw Problem 6M.1

We are finding the cell potential of the anode since M is being oxidized in this reaction.
by Ariel Davydov 1C
Tue Mar 03, 2020 3:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5 Part b
Replies: 2
Views: 18

Re: 6M.5 Part b

In this reaction, Br- is oxidized and Hg2+ is reduced, resulting in a cell potential of -0.17 V, which is nonspontaneous. Hope this helps!
by Ariel Davydov 1C
Tue Mar 03, 2020 3:49 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6O1
Replies: 1
Views: 37

Re: 6O1

This occurs in this particular example because the reaction begins with Ni2+ ions. Regardless of its standard reduction potential, the reaction begins with these ions since they are already present in the solution and thus is reduced to Ni(s).
by Ariel Davydov 1C
Wed Feb 26, 2020 12:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.11
Replies: 1
Views: 18

Re: 6M.11

Since all the species listed except for Co are ions, they more often than not will be in aqueous form, while those is solid form will have neutral charges. What helps me to remember this is picturing these ions as parts of a dissolved salt, i.e. aqueous ions. Hope this helps!
by Ariel Davydov 1C
Wed Feb 26, 2020 12:46 pm
Forum: Balancing Redox Reactions
Topic: Help on 6L.7 part a
Replies: 2
Views: 48

Re: Help on 6L.7 part a

Both of these redox reactions can be found in the SRP table on page A16 in the back of the textbook. Since the standard reduction potential of Ag+ + e- -> Ag(s) (0.80 V) is higher than that of AgBr + e- -> Ag + Br- (0.07 V), it will be at the cathode while the latter reaction will be at the anode.
by Ariel Davydov 1C
Wed Feb 26, 2020 12:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7
Replies: 3
Views: 33

Re: 6L.7

Since Ni is present in its charged aqueous forms, we can use solid nickel as a spectator that allows for current to flow. I believe we can still use C(graphite) or Pt(s) as the electrode.
by Ariel Davydov 1C
Wed Feb 26, 2020 12:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6N.9
Replies: 2
Views: 18

Re: 6N.9

You can also tell which one is the cathode and anode by calculating the E(not)cell through trial and error; the values you use to end up with an E(not)cell that is positive will tell you which species is reduced and which is oxidized.
by Ariel Davydov 1C
Wed Feb 26, 2020 12:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Lost Apple Pencil [ENDORSED]
Replies: 4
Views: 77

Re: Lost Apple Pencil [ENDORSED]

I did, thank you so much for your help.
by Ariel Davydov 1C
Sat Feb 22, 2020 7:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What the calorimeter allows you to calculate according to conditions
Replies: 5
Views: 49

Re: What the calorimeter allows you to calculate according to conditions

At a constant volume, deltaV is zero, so there is no expansion work occurring (w=0) and deltaU overall will only equal q. At a constant pressure, since there may be expansion work occurring, the heat given off can only be interpreted as deltaH or q, since the overall internal energy includes the en...
by Ariel Davydov 1C
Sat Feb 22, 2020 7:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L. 9
Replies: 2
Views: 31

Re: 6L. 9

An acidified half reaction will be balanced using H2O(l) and H+(aq) to balance the oxygen and hydrogen atoms present in reaction.
by Ariel Davydov 1C
Sat Feb 22, 2020 7:36 pm
Forum: Balancing Redox Reactions
Topic: 6K.3 D
Replies: 2
Views: 30

Re: 6K.3 D

I believe this is a typo, as Cl- is present in the answer shown in the answer key.
by Ariel Davydov 1C
Sat Feb 22, 2020 7:35 pm
Forum: Balancing Redox Reactions
Topic: Identifying Acidic/Basic Solutions
Replies: 2
Views: 42

Re: Identifying Acidic/Basic Solutions

The only case in which this wouldn’t be specified is if hydrogen ions or hydroxide ions are present in reaction, which would indicate whether the solution is acidic or basic.
by Ariel Davydov 1C
Sat Feb 22, 2020 7:34 pm
Forum: Balancing Redox Reactions
Topic: Reducing agent/oxidizing agent
Replies: 5
Views: 39

Re: Reducing agent/oxidizing agent

If the oxidation number of an element increases, that means the element is being oxidized (losing electrons) and thus is a reducing agent, since those electrons will be accepted by the element that is being reduced. If the oxidation number of an element decreases, the element is being reduced and th...
by Ariel Davydov 1C
Sat Feb 22, 2020 7:31 pm
Forum: Balancing Redox Reactions
Topic: Ozone's Oxidation Number
Replies: 2
Views: 27

Re: Ozone's Oxidation Number

Because in order for the all charge of ozone to be zero, the oxidation numbers of all the individual oxygen atoms must add up to zero as well. Since there are three oxygen atoms, the only case in which adding all three oxidation numbers of the individual atoms, as well as all three atoms having iden...
by Ariel Davydov 1C
Wed Feb 19, 2020 1:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Lost Apple Pencil [ENDORSED]
Replies: 4
Views: 77

Lost Apple Pencil [ENDORSED]

Hi everyone, I can’t seem to find my Apple Pencil, and the last time I used it was during lecture today in CS50. It was Lecture 1 at 11 AM, and it has my full name, Ariel Davydov, on it. If anyone picked it up by any chance or turned it in somewhere could you please let me know? Thank you so much!
by Ariel Davydov 1C
Fri Feb 14, 2020 8:08 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: reaction entropy
Replies: 7
Views: 47

Re: reaction entropy

You can also calculate deltaG the same way.
by Ariel Davydov 1C
Fri Feb 14, 2020 8:05 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Why is delta U a state function?
Replies: 4
Views: 29

Re: Why is delta U a state function?

All heat capacities are state functions since it does not matter how the heat was added or how the temperature was changed; you will still arrive at the same final temperature.
by Ariel Davydov 1C
Fri Feb 14, 2020 8:02 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: HW 4.45
Replies: 1
Views: 44

Re: HW 4.45

Delta S is entropy, not enthalpy. Since the reaction is endothermic (positive enthalpy), it requires heat input in order to occur, which indicates that this reaction is not typically spontaneous unless at a high temperature and with a high entropy.
by Ariel Davydov 1C
Fri Feb 14, 2020 7:59 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: PV=nRT
Replies: 5
Views: 38

Re: PV=nRT

If you are given the change in certain variables, you can use the individual ratios between that variable and one other variable to calculate the change. For example, if given the change in volume and asked to find the final pressure of the system, you can use P1V1=P2V2 and plug in the initial and f...
by Ariel Davydov 1C
Fri Feb 14, 2020 7:55 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G
Replies: 6
Views: 41

Re: Delta G

The purpose of the degree sign is to indicate that the relationship between enthalpy, entropy, and temperature in regards to spontaneity is deltaG = deltaH -T*deltaS only at standard conditions.
by Ariel Davydov 1C
Sat Feb 08, 2020 12:37 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What the calorimeter allows you to calculate according to conditions
Replies: 5
Views: 49

Re: What the calorimeter allows you to calculate according to conditions

At a constant volume, deltaV is zero, so there is no expansion work occurring (w=0) and deltaU overall will only equal q. At a constant pressure, since there may be expansion work occurring, the heat given off can only be interpreted as deltaH or q, since the overall internal energy includes the ene...
by Ariel Davydov 1C
Sat Feb 08, 2020 12:31 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 4D9
Replies: 1
Views: 27

Re: Question 4D9

Since we are calculating the enthalpy density solely for the combustion of TNT, it will be a positive value because it is only in terms of the energy absorbed in breaking the bonds of TNT, rather than the overall reaction as a whole.
by Ariel Davydov 1C
Sat Feb 08, 2020 12:28 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Larger S
Replies: 1
Views: 27

Re: Larger S

In this question you don’t necessarily have to calculate the degeneracy and entropy of each separate molecule; you can compare them contextually. In the trans molecule, you can see that there are much fewer positions the blue atoms can take (only among the X axis) compared to in the cis molecule, wh...
by Ariel Davydov 1C
Sat Feb 08, 2020 12:18 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy of transition
Replies: 8
Views: 49

Re: Entropy of transition

Approach a problem in calculating the entropy of transition the same as you would in calculating the qtotal of a substance being raised from a non-boiling-point temperature to its boiling point and transition. Set up two separate components for the entropy for the system and add them: 1) the entropy...
by Ariel Davydov 1C
Sat Feb 08, 2020 12:11 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4H.7
Replies: 2
Views: 16

Re: 4H.7

The answer key says for that equation there is a decrease in entropy, not an increase.
by Ariel Davydov 1C
Wed Jan 29, 2020 10:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 1
Views: 13

Re: Heat Capacity

Finding the heat capacity can allow you to find the final temperature of a system when a certain amount of heat is provided to it, how much heat is required to raise the temperature of a certain amount of grams or moles of a substance to a specific temperature, and more. The specific heat capacity a...
by Ariel Davydov 1C
Wed Jan 29, 2020 9:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: explain terms
Replies: 2
Views: 30

Re: explain terms

1) Bond enthalpy is the amount of energy needed to break a singular bond. For example, the energy needed to break a C-C bond (single bond between two carbon atoms) is +346 kJ/mol. If a bond is broken, it will release the same amount of energy and will be a negative term. 2) Standard enthalpy of form...
by Ariel Davydov 1C
Wed Jan 29, 2020 9:48 pm
Forum: Phase Changes & Related Calculations
Topic: Work Equation
Replies: 3
Views: 49

Re: Work Equation

It is to accommodate for the sign of the change in volume. If work is being done on the system (meaning work is positive), the volume of the system will decrease (ex: piston being pushed in) and the change in volume will be negative. Without the negative in front of the equation to counterbalance th...
by Ariel Davydov 1C
Wed Jan 29, 2020 9:44 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Pressure vs. Equilibrium system
Replies: 1
Views: 13

Re: Constant Pressure vs. Equilibrium system

If the pressure is constant, this simply means that it is not changing. For example, the external pressure could be constant and held at 1 atm, while the internal pressure of a system could be constant and held at 2 atm. However, because these pressures differ, this system is not at equilibrium with...
by Ariel Davydov 1C
Wed Jan 29, 2020 9:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: List of elements that have value of zero
Replies: 1
Views: 16

Re: List of elements that have value of zero

These will typically be elements in their standard, lowest energy state. For elements found as diatomic molecules (Br, I, N, Cl, H, O, F), they will have an enthalpy of zero when found as diatomic gases, with the exception of Br2 being found in liquid form and I2 being in solid form. For other eleme...
by Ariel Davydov 1C
Fri Jan 24, 2020 10:29 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in Pressure
Replies: 9
Views: 47

Re: Changes in Pressure

In order to determine how a change in pressure affects the equilibrium of a system, it must be said how the pressure was changed in the first place. As the above comments said, if the pressure is increased by adding an inert gas, there will be no change in equilibrium, since the partial pressures of...
by Ariel Davydov 1C
Fri Jan 24, 2020 10:22 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: homework 6A.23
Replies: 2
Views: 24

Re: homework 6A.23

Since Ba(OH)2 is a strong base, it will dissociate almost entirely. Thus, if given the mass of Ba(OH)2 in this particular problem, you can calculate its molarity, set up a balanced equation of Ba(OH)2 dissociating, and use the ratios to find the concentrations of Ba2+ and OH-. From here, you can cal...
by Ariel Davydov 1C
Fri Jan 24, 2020 10:14 am
Forum: Phase Changes & Related Calculations
Topic: symbol of Heat
Replies: 3
Views: 24

Re: symbol of Heat

As the above comment says, delta H represents the change of energy in a reaction from its final state to its initial state, regardless of the path it took to get there. q is the heat given off by a system during a reaction, and its sign will tell us whether the reaction is exothermic (negative value...
by Ariel Davydov 1C
Fri Jan 24, 2020 10:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Assuming X
Replies: 3
Views: 23

Re: Assuming X

Yes, and if the percent protonation of the base or percent deprotonation of the acid is less than 5%.
by Ariel Davydov 1C
Fri Jan 24, 2020 10:04 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding OH concentration
Replies: 2
Views: 22

Re: Finding OH concentration

What the solutions manual is doing is converting the [OH-] concentration to pOH, finding pH by subtracting pOH from 14, and then calculating [H3O+] by using the pH value. This method will result in a different result if the concentration of H3O+ or OH- exceeds 1 M.
by Ariel Davydov 1C
Wed Jan 15, 2020 12:19 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.9 Hw problem
Replies: 3
Views: 54

Re: 6B.9 Hw problem

When calculating pH, if you end up with a negative value you must convert it to its positive form, which will be the answer. Since the pH scale ranges from 0 to 14, there cannot be a “true” negative pH value. This can be explained by the fact that strong acids at concentrations higher than 1.00 mol*...
by Ariel Davydov 1C
Wed Jan 15, 2020 12:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentration with gases
Replies: 7
Views: 50

Re: equilibrium concentration with gases

Yes, but if asked to solve for partial pressures or Kp, you can use the Ideal Gas Law (PV=nRT) to solve for individual partial pressures and plug them into the Kp expression to solve for Kp.
by Ariel Davydov 1C
Tue Jan 14, 2020 9:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5.35
Replies: 2
Views: 50

Re: 5.35

If you look at the graph provided in the question, you will be able to determine the amount of A consumed and the amount of B and C formed in reaction in establishing equilibrium. If you set up an ICE table and plug in the initial and equilibrium partial pressure values, you can determine the change...
by Ariel Davydov 1C
Tue Jan 14, 2020 8:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to approximate
Replies: 5
Views: 40

Re: When to approximate

According to Lavelle’s slides, we can only do this if the equation is cubed AND the K value is <<< 10^-3.
by Ariel Davydov 1C
Tue Jan 14, 2020 8:56 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Homework 5J.1
Replies: 4
Views: 28

Re: Homework 5J.1

When dealing with problems with shifts in equilibrium, try to approach problems with partial pressures as you would problems with molar concentrations. If you set up a K equation in terms of partial pressures, you will see that if you increase the partial pressure of a product, the system will shift...
by Ariel Davydov 1C
Tue Jan 07, 2020 6:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: AV Mods Chem Equilibrium Part 1B Post Exam [ENDORSED]
Replies: 2
Views: 74

Re: AV Mods Chem Equilibrium Part 1B Post Exam [ENDORSED]

If you balance the equation, use the values provided in the previous problem and convert them from bar to atm, you should get 2.96 x 10^3 (the inverse of K from #18). Hope this helps!
by Ariel Davydov 1C
Tue Jan 07, 2020 6:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Expression for K
Replies: 4
Views: 38

Re: Expression for K

P is used to express partial pressures of gases in equilibrium equations.
by Ariel Davydov 1C
Tue Jan 07, 2020 6:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.39
Replies: 1
Views: 68

5.39

In an experiment, 0.02 mol NO2 was introduced into a flask of volume 1.00 L and the reaction 2NO2 (g) ⇌ N2O4 (g) was allowed to come to equilibrium at 298 K. (a) Using information in Table 5E.2, calculate the equilibrium concentrations of the two gases. (b) The volume of the flask is reduced to hal...
by Ariel Davydov 1C
Tue Jan 07, 2020 6:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 2
Views: 40

Re: 5I.13

A molecule is more thermodynamically stable if more of it exists post-reaction, since less of it breaks up into parts in order to form its product form. Thus, the molecule with the smallest K value (most reactant-favored reaction) will be the most stable. Since the reaction with Cl2 has a smaller K ...
by Ariel Davydov 1C
Tue Jan 07, 2020 6:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.35 Part b
Replies: 2
Views: 32

Re: 5.35 Part b

Yes, the division of each factor by 100 is to convert from P/kPa to bar.
by Ariel Davydov 1C
Wed Dec 04, 2019 9:18 am
Forum: Bronsted Acids & Bases
Topic: CaO
Replies: 10
Views: 78

Re: CaO

CaO is a Lewis base, and since it is a metal oxide, it will be a strong base that, when reacting with water, will form Ca(OH)2, a strong base that entirely dissociates into Ca2+ and hydroxide ions.
by Ariel Davydov 1C
Mon Dec 02, 2019 9:53 am
Forum: Lewis Acids & Bases
Topic: 6.13
Replies: 2
Views: 44

6.13

Draw the Lewis structure of boric acid, B(OH)3. (a) Is resonance important for its description? (b) The proton transfer equilibrium for boric acid is given in a footnote to Table 6C.1. In that reaction does boric acid act as a Lewis acid, a Lewis base, or neither? Justify your answer by using Lewis...
by Ariel Davydov 1C
Mon Dec 02, 2019 9:48 am
Forum: Bronsted Acids & Bases
Topic: For J. 9., when do we separate H+ from the acid?
Replies: 2
Views: 47

Re: For J. 9., when do we separate H+ from the acid?

If an acid or base is strong, it will entirely ionize in solution. Thus, if the problem has a strong acid or base as a part of the equation, it must be written out in dissociated form (ex: HBr would be written as H+ and Br-). If the acid is weak (ex: CH3COOH, acetic acid), it does not entirely ioniz...
by Ariel Davydov 1C
Mon Dec 02, 2019 9:39 am
Forum: Naming
Topic: Oxidation States
Replies: 3
Views: 33

Re: Oxidation States

Finding the oxidation state of an element can be accomplished through finding the charges of other molecules in the compound and subtracting them from the overall charge of the complex. Since the oxidation state (aka charge of the element) + the charges of the other compounds in the complex = the ov...
by Ariel Davydov 1C
Mon Dec 02, 2019 9:36 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Electronegativity and acid strength
Replies: 2
Views: 22

Re: Electronegativity and acid strength

HClO is a stronger acid than HBrO because Cl is a more electronegative element than Br, meaning it has a greater pull on electrons and thus can delocalize the negative charge of the acid's conjugate base (ClO^-) better than Br can in its conjugate base (BrO^-). This means that HClO's conjugate base ...
by Ariel Davydov 1C
Mon Dec 02, 2019 9:32 am
Forum: Naming
Topic: Neutral Molecules
Replies: 2
Views: 28

Re: Neutral Molecules

On the chart Dr. Lavelle sent us with the names of compounds in regard to coordination complex naming, there is a section with entirely neutral compounds. These include H2O, NH3, CO, NO, ethylenediamine (en), and diethylenetriamine (dien).
by Ariel Davydov 1C
Mon Dec 02, 2019 9:24 am
Forum: Amphoteric Compounds
Topic: Acidic vs Basic oxides
Replies: 2
Views: 25

Re: Acidic vs Basic oxides

Based on Dr. Lavelle's lectures, it is safe to assume that metal oxides have basic character, nonmental oxides have acidic character, and certain elements that mirror the metalloid staircase on the periodic table are amphoteric, meaning they produce both an acid and a base in water. These elements a...
by Ariel Davydov 1C
Sun Dec 01, 2019 2:20 pm
Forum: Hybridization
Topic: Focus 2.63
Replies: 2
Views: 24

Re: Focus 2.63

Exactly. Typically, if a Lewis structure omits lone pairs, we must fill them in ourselves. Since the oxygen has two bonds, we can assume that it has two lone pairs, since oxygen has 6 shareable valence electrons and in this molecule has a formal charge of zero. Thus, with a VSEPR equation of AX2E2 a...
by Ariel Davydov 1C
Mon Nov 25, 2019 10:15 pm
Forum: Sigma & Pi Bonds
Topic: Unhybridized Orbital vs Spin Pair?
Replies: 8
Views: 38

Re: Unhybridized Orbital vs Spin Pair?

AGulati_4A wrote:An unhybridized orbital


Why?
by Ariel Davydov 1C
Mon Nov 25, 2019 9:53 pm
Forum: Sigma & Pi Bonds
Topic: Unhybridized Orbital vs Spin Pair?
Replies: 8
Views: 38

Unhybridized Orbital vs Spin Pair?

Will an electron prefer to occupy an unhybridized orbital or spin pair in hybridized orbital?
by Ariel Davydov 1C
Mon Nov 25, 2019 4:34 pm
Forum: Amphoteric Compounds
Topic: Bi2O3
Replies: 2
Views: 16

Re: Bi2O3

Bismuth was one of the exceptions mentioned in lecture today that acts as an amphoteric oxide.
by Ariel Davydov 1C
Mon Nov 25, 2019 12:21 pm
Forum: Coordinate Covalent Bonds
Topic: Ligandsc-Chelate
Replies: 1
Views: 59

Re: Ligandsc-Chelate

Typically, the VSEPR shapes of molecules will not allow for four lone pairs to bind to a transition metal. For example, if a tetrahedral molecule has shareable lone pairs on each attached atom, the shape will only allow for three lone pairs to bind to the transition metal, as the fourth lone pair wi...
by Ariel Davydov 1C
Mon Nov 25, 2019 12:19 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition metals
Replies: 4
Views: 56

Re: Transition metals

If water is present and written as a part of the coordination complex, the transition metal will bond with it.
by Ariel Davydov 1C
Mon Nov 25, 2019 12:17 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Complex
Replies: 3
Views: 40

Re: Chelating Complex

With the ligand's formula, you would generally be able to construct a Lewis structure and be able to analyze its shape and lone pairs available to share. If the ligand has numerous lone pairs that its geometry allows it to share simultaneously, it is a chelating complex.
by Ariel Davydov 1C
Mon Nov 25, 2019 12:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9c.5
Replies: 1
Views: 34

Re: 9c.5

A ligand can be polydentate if it has multiple locations where it can give up a lone pair AND its geometry allows for it to do so. An example of a ligand with multiple shareable lone pairs but that is not a polydentate is H2O, whose bent shape only allows for it to share one lone pair. Examples of p...
by Ariel Davydov 1C
Mon Nov 25, 2019 12:02 pm
Forum: Photoelectric Effect
Topic: Midterm Question
Replies: 4
Views: 82

Re: Midterm Question

Hi! So on this graph, we were supposed to illustrate the number of electrons emitted once the photons reached a certain frequency. In order to approach this problem, you must remember that all the equations we are given (E=hv, E - work function = KE) is calculating the energy of ONE PHOTON or ONE EL...
by Ariel Davydov 1C
Wed Nov 20, 2019 5:37 pm
Forum: General Science Questions
Topic: Chem BL
Replies: 7
Views: 86

Re: Chem BL

I've heard Chem 14BL also picks up where Chem 14B left off, which would make taking them simultaneously kind of difficult.
by Ariel Davydov 1C
Wed Nov 20, 2019 5:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape vs. Geometry
Replies: 5
Views: 49

Re: Molecular Shape vs. Geometry

Moleuclar geometry and molecular shape are one and the same. What differs, however, is electron geometry, which takes into account all areas of electron density. Molecular shape/geometry considers electron repulsion between lone pairs and lone pairs and atoms. For example, NH3 will have a molecular ...
by Ariel Davydov 1C
Wed Nov 20, 2019 5:28 pm
Forum: Hybridization
Topic: hybridization on the test?
Replies: 10
Views: 111

Re: hybridization on the test?

From what I have heard, we will only be tested on sigma and pi bonds. Studying hybridization can help you understand sigma and pi bonds more, though!
by Ariel Davydov 1C
Wed Nov 20, 2019 5:25 pm
Forum: Naming
Topic: Naming Compounds (general question)
Replies: 5
Views: 47

Re: Naming Compounds (general question)

I believe the only compounds we will be asked to name (or come up with when given the name) are the coordinate covalent complexes, which Lavelle will be lecturing on during Friday's lecture.
by Ariel Davydov 1C
Wed Nov 20, 2019 5:21 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Covalent Bonds
Replies: 4
Views: 32

Re: Coordination Covalent Bonds

The coordinate covalent bond between a nonmetal and a TM metal is "provided" by the nonmetal in the form of an extra lone pair. For example, if we are discussing a coordinate covalent bond between Cl- and Pb2+, the bond between one chlorine atom and one lead atom would be provided by one v...
by Ariel Davydov 1C
Sun Nov 17, 2019 12:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for Seesaw Shape
Replies: 2
Views: 32

Bond Angles for Seesaw Shape

For seesaw shaped molecules, would the angles be less than 120 and less than 90 degrees, or flat out 120 and 90 degrees? I keep seeing different answers everywhere.
by Ariel Davydov 1C
Wed Nov 13, 2019 4:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shapes of Molecules with Radicals
Replies: 1
Views: 25

Molecular Shapes of Molecules with Radicals

How would we treat a molecule with a radical in regards to determining its VSEPR shape? For example, in part B of question 2E.5, the molecule OClO has an uneven number of electrons. Would you treat that one additional electron as another shell of electron density?
by Ariel Davydov 1C
Wed Nov 13, 2019 3:41 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: H-bonding & Dipole-Dipole (Problem 3F.1)
Replies: 4
Views: 53

Re: H-bonding & Dipole-Dipole (Problem 3F.1)

Yes! Hydrogen bonding is a special type of dipole-dipole attraction between molecules where hydrogen (a very not-electronegative element) displays dipole-dipole attraction with very electronegative elements, specifically N, O, and F.
by Ariel Davydov 1C
Wed Nov 13, 2019 3:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape
Replies: 8
Views: 57

Re: molecular shape

There are also some really great Youtube videos that help you visualize the shapes of these molecules and understand them rather than depending on sole memorization. I highly recommend Tyler DeWitt's video on VSEPR. Hope this helps!
by Ariel Davydov 1C
Wed Nov 13, 2019 3:29 pm
Forum: Ionic & Covalent Bonds
Topic: Bonding and Potential Energy
Replies: 1
Views: 41

Re: Bonding and Potential Energy

Sure! Listed from strongest to weakest, the intermolecular forces responsible for interaction between molecules are ion-ion, hydrogen bonding, ion-dipole, dipole-dipole, dipole-induced dipole, and London/dispersion forces. Overall, the major theme in strength of intermolecular forces is that the str...
by Ariel Davydov 1C
Tue Nov 12, 2019 7:10 pm
Forum: Bond Lengths & Energies
Topic: Boiling and Melting points
Replies: 8
Views: 66

Re: Boiling and Melting points

You are not expected to memorize the boiling and melting points of substances, but you are expected to be able to determine the strength of the intermolecular forces between like molecules and tell which substances will have higher or lower boiling and melting points based on their strength.
by Ariel Davydov 1C
Tue Nov 12, 2019 7:04 pm
Forum: Hybridization
Topic: Specifics
Replies: 3
Views: 46

Re: Specifics

We will be learning how to determine bond order with hybridization at a later time this quarter.
by Ariel Davydov 1C
Wed Nov 06, 2019 10:46 am
Forum: Octet Exceptions
Topic: Expanded Octet
Replies: 2
Views: 27

Re: Expanded Octet

Also make sure the amount of electrons in the central atom allows for the formal charge to be equal to zero! Since the central element in a molecule is almost always the least electronegative of the molecule, it will usually have a formal charge of zero or a positive value.
by Ariel Davydov 1C
Wed Nov 06, 2019 10:44 am
Forum: Octet Exceptions
Topic: octet exceptions
Replies: 3
Views: 41

Re: octet exceptions

In addition, with elements with expanded octets, the best way to determine the amount of extra electrons they typically store is through calculating its formal charge. For example, with S, if it forms four bonds with other elements, it will typically have one additional lone pair of electrons in ord...
by Ariel Davydov 1C
Wed Nov 06, 2019 10:42 am
Forum: Ionic & Covalent Bonds
Topic: Correcting Ionic Model
Replies: 4
Views: 63

Re: Correcting Ionic Model

And thus conversely, a molecule displaying low covalent character (and high ionic character) would be more soluble in water than those of high covalent character. The character of a molecule can be determined either through the differences in electronegativity between the cation and anion of the mol...
by Ariel Davydov 1C
Wed Nov 06, 2019 10:24 am
Forum: Lewis Structures
Topic: HW Question 2C5
Replies: 2
Views: 54

Re: HW Question 2C5

I also struggled with this problem, and after searching it up, I believe your structure is the actual correct structure and that there is an error in the solutions manual, as using the formal charge of the elements would tell us that your structure is the lowest energy state of the molecule.
by Ariel Davydov 1C
Wed Nov 06, 2019 10:22 am
Forum: Octet Exceptions
Topic: Limit to expanded octet
Replies: 7
Views: 106

Re: Limit to expanded octet

It would most likely be limited to the number of electrons available in the element's d-orbital. Typically though, you would use the formal charge of the element to determine how many electrons its expanded octet would typically hold at its lowest energy state.
by Ariel Davydov 1C
Wed Oct 30, 2019 5:25 pm
Forum: Resonance Structures
Topic: 2C.3
Replies: 2
Views: 60

2C.3

Hi, For part C of this question, I'm a little confused as to how there is resonance with the structure for HClO3. The structure you end up with (with the lowest formal charge) doesn't have any bonds that can be switched without changing the number of double/single bonds in the molecule, yet the answ...
by Ariel Davydov 1C
Tue Oct 29, 2019 8:45 am
Forum: Octet Exceptions
Topic: aufbau principle
Replies: 8
Views: 87

Re: aufbau principle

As for writing out electron configurations, Lavelle said that he prefers us to write 3d before 4s, and the same goes for the f-block and other d-orbitals.
by Ariel Davydov 1C
Tue Oct 29, 2019 8:39 am
Forum: Trends in The Periodic Table
Topic: Question 2B.9
Replies: 3
Views: 30

Re: Question 2B.9

Because potassium has a positive charge (+1) and phosphorus has a negative charge (-3), it is safe to assume that they will bond ionically, especially since the molecule is K3P.
by Ariel Davydov 1C
Tue Oct 29, 2019 8:35 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic spectra post assessment question 42
Replies: 2
Views: 65

Re: Atomic spectra post assessment question 42

It helps if instead of using the frequency equation you derive it through this basic equation: deltaE = Efinal - Einitial. From here, you can sub in En = -hr(1/n^2) for the final and initial energy values and solve from there. This will help prevent any future mixups with n values since they are ass...
by Ariel Davydov 1C
Tue Oct 29, 2019 8:31 am
Forum: Ionic & Covalent Bonds
Topic: When is the midterm?
Replies: 5
Views: 54

Re: When is the midterm?

He posted a pdf briefly with several locations listed based on last name and lecture but took it down due to the fires. It will probably be reposted shortly as a link on his class website.
by Ariel Davydov 1C
Tue Oct 29, 2019 8:29 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Number of orbitals
Replies: 1
Views: 23

Re: Number of orbitals

The number of orbitals per angular momentum quantum number can be obtained by looking at the total number of potential m(l)-numbers for an l-number. For example, for l=3 (the f block), m(l) can be anything from 3 to -3 (3, 2, 1, 0, -1, -2, -3) meaning the total number of potential quantum numbers is...
by Ariel Davydov 1C
Tue Oct 29, 2019 8:24 am
Forum: Ionic & Covalent Bonds
Topic: Valence Electrons?
Replies: 15
Views: 121

Re: Valence Electrons?

Most transition metals have 2 valence electrons. Valence electrons are the sum total of all the electrons in the highest energy level (principal quantum number n). Most transition metals have an electron configuration that is [noble gas]ns2(n−1)d, so those ns2 electrons are the valence electrons. Ty...
by Ariel Davydov 1C
Mon Oct 21, 2019 12:47 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: What's the right equation?
Replies: 7
Views: 64

Re: What's the right equation?

If I'm thinking of the same question you're referring to (1B.27), there is an error in the solutions manual that Lavelle noted in his "Solution Manual Errors 7th Edition" PDF on his website. In this question, the textbook utilized that equation (1/2 h) instead of the one taught in class. I...
by Ariel Davydov 1C
Mon Oct 21, 2019 12:36 pm
Forum: Quantum Numbers and The H-Atom
Topic: Ionization Energy
Replies: 4
Views: 30

Re: Ionization Energy

When losing an electron, the nucleus's pull on the electrons grows stronger, as with less negative energy the positive charge of the nucleus has a stronger pull on the electrons surrounding it, thus decreasing the size of the atomic radius. Because of this, it will require a greater amount of energy...
by Ariel Davydov 1C
Mon Oct 21, 2019 12:24 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Minimum uncertainty?
Replies: 2
Views: 40

Re: Minimum uncertainty?

Because this equation provides us with the minimum uncertainty in position/momentum, this means that the actual uncertainty in position/momentum is equal to or greater than the value given or calculated, which means that, yes, the uncertainty can be greater than the value obtained. Hope this helps!
by Ariel Davydov 1C
Mon Oct 21, 2019 12:14 pm
Forum: Quantum Numbers and The H-Atom
Topic: Test Question
Replies: 3
Views: 60

Re: Test Question

From what I have gathered, you will need to know and understand the basic concepts surrounding the practice problems to an extent great enough to apply it to more difficult questions. Your knowledge of these concepts will be tested through your ability to apply them to sometimes even never-before se...
by Ariel Davydov 1C
Mon Oct 21, 2019 12:11 pm
Forum: Photoelectric Effect
Topic: 0KE electron?
Replies: 2
Views: 41

Re: 0KE electron?

We examine the photoelectric effect through this equation theoretically . Theoretically, if the energy of the photon equals that of the metal's work function, electrons will be emitted. While we know this in reality does not occur, we still utilize this equation in that sense, since the work functio...
by Ariel Davydov 1C
Wed Oct 16, 2019 1:29 pm
Forum: Properties of Electrons
Topic: Intensity vs. Energy
Replies: 10
Views: 93

Re: Intensity vs. Energy

The intensity of a light source is directly related to the number of photons and the rate at which they are projected onto the sample. The frequency is not related to the number of photons or intensity.
by Ariel Davydov 1C
Wed Oct 16, 2019 12:05 pm
Forum: Properties of Electrons
Topic: electron mass
Replies: 8
Views: 71

Re: electron mass

It will typically be given on the equation sheet provided during the test, but for personal reference, it is 9.1 x 10^-31 kg.
by Ariel Davydov 1C
Wed Oct 16, 2019 12:04 pm
Forum: Properties of Light
Topic: 1B #3
Replies: 2
Views: 42

Re: 1B #3

D, the photoelectric effect, best explains that electrons have particle-like properties. This experiment shows that, when light is shone onto a metal sample, electrons are emitted at a one-to-one ratio to the photons that are absorbed by the sample. This is also supported by the equation E=hv, which...
by Ariel Davydov 1C
Wed Oct 16, 2019 11:29 am
Forum: *Particle in a Box
Topic: 1B. Quantum Theory and model of an atom
Replies: 2
Views: 86

Re: 1B. Quantum Theory and model of an atom

You would draw the atom as a circle and label its radius and diameter, since the diameter of the atom is the uncertainty in position for the electron in this problem.
by Ariel Davydov 1C
Wed Oct 16, 2019 11:26 am
Forum: Quantum Numbers and The H-Atom
Topic: hw help
Replies: 1
Views: 57

Re: hw help

All of the answers will be the same for a hydrogen atom. Even though the atoms' outermost electrons have different values of n (lithium's being n=2, while hydrogen's is n=1), the energy of the electron would increase in both a hydrogen and lithium atom. The value of n for the electron will also incr...
by Ariel Davydov 1C
Tue Oct 08, 2019 3:47 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty of speed
Replies: 5
Views: 51

Re: Uncertainty of speed

Yes, this is exactly what it means, because that is the range in which the speed could potentially fall into.

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