Search found 109 matches

by vpena_1I
Sun Mar 15, 2020 5:56 am
Forum: Administrative Questions and Class Announcements
Topic: Final exam structure
Replies: 2
Views: 106

Re: Final exam structure

I would be prepared for either. Multiple choice would make the most sense for the computer to easily grade, but this can also be done with fill in the blank. I don't think we would be able to get partial credit with the latter, however.
by vpena_1I
Sun Mar 15, 2020 5:54 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed system
Replies: 3
Views: 64

Re: closed system

By definition, a closed system does not allow for the exchange of matter. A closed water bottle is an example of a closed system, its volume will not change over the course of the reaction.
by vpena_1I
Sun Mar 15, 2020 5:47 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding H20 to solution
Replies: 3
Views: 27

Re: Adding H20 to solution

What it is doing is decreasing the concentration of the solution. Diluting the anode will increase the cell potential, and diluting the cathode will decrease the cell potential.
by vpena_1I
Sun Mar 15, 2020 5:44 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: relationship of K and time
Replies: 3
Views: 42

Re: relationship of K and time

I believe it will always decrease because reactions tend to move towards equilibrium, not against it.
by vpena_1I
Sat Mar 14, 2020 9:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: + or - w
Replies: 2
Views: 72

Re: + or - w

Work is positive when it is done on a system (at least in our course). Think the video might've been using a physics equation.
by vpena_1I
Sat Mar 14, 2020 9:42 pm
Forum: Experimental Details
Topic: Data
Replies: 5
Views: 53

Re: Data

It's usually easier to do bigger concentration over smaller concentration, but yeah, either way will get you to the same answer.
by vpena_1I
Sat Mar 14, 2020 9:38 pm
Forum: Ideal Gases
Topic: T variable in pv=nrt
Replies: 10
Views: 89

Re: T variable in pv=nrt

All gas constants are in Kelvin, so unless you really wanted to convert these to Celsius, its easier to convert Celsius to kelvin from the get-go.
by vpena_1I
Sat Mar 14, 2020 9:34 pm
Forum: General Rate Laws
Topic: Rate Constant
Replies: 3
Views: 63

Re: Rate Constant

A rate constant is specific for the reaction at a given temperature. Change the temperature, change the rate constant.
by vpena_1I
Sat Mar 14, 2020 9:33 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Molecularity
Replies: 4
Views: 57

Re: Molecularity

I know that the rate law of an elementary unimolecular reaction is first-order and that of a
bimolecular elementary reaction is second-order. Don't know what else you can apply molecularity to.
by vpena_1I
Sat Mar 14, 2020 9:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: holding pressure/volume constant
Replies: 2
Views: 112

Re: holding pressure/volume constant

I'm guessing if you want certain measurements to be accurate, you'd wanna use a model in which you can control all variables. I don't think doing the kinds of experiments we talk about are very helpful in the situations you're describing.
by vpena_1I
Sat Mar 14, 2020 9:20 pm
Forum: Experimental Details
Topic: Data
Replies: 5
Views: 53

Re: Data

Bigger concentration over smaller concentration.
by vpena_1I
Sat Mar 14, 2020 9:06 pm
Forum: Balancing Redox Reactions
Topic: flipping equations
Replies: 7
Views: 109

Re: flipping equations

If I'm understanding your question correctly, you would flip the oxidation one, so that your electrons are on the right side of the equation, and on your left for the reduction half reaction.
by vpena_1I
Sat Mar 14, 2020 9:03 pm
Forum: Balancing Redox Reactions
Topic: changing half reactions
Replies: 6
Views: 93

Re: changing half reactions

you flip whichever one would give you the most positive delta E*cell
by vpena_1I
Sat Mar 14, 2020 8:59 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Activated Complex Model
Replies: 3
Views: 48

Re: Activated Complex Model

An activated complex is the structure that results in the maximum energy point along the reaction path
by vpena_1I
Sat Mar 14, 2020 7:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 2
Views: 22

Re: Platinum

Probably because it's cheaper than diamond, and not soft like graphite.
by vpena_1I
Sat Mar 14, 2020 7:00 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrolysis
Replies: 6
Views: 67

Re: Electrolysis

It was on the chapter outline, so I would assume so. Electrolysis is the chemical decomposition produced by passing an electric current through a liquid or solution containing ions.
by vpena_1I
Tue Mar 10, 2020 6:45 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7B.9(a)
Replies: 1
Views: 25

7B.9(a)

How does one begin this problem? For the first-order reaction A + 3B--->C, when [A]0= 0.015 M, the concentration of B increases to 0.018 M in 3.0 min. (a) What is the rate constant for the reaction expressed as the rate of loss of A? How do you incorporate [B] into the integrated rate law, and why d...
by vpena_1I
Tue Mar 10, 2020 1:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7B.3
Replies: 2
Views: 66

7B.3

7B.3(c) Determine the rate constant for each of the following first- order reactions, in each case expressed for the rate of loss of A: c) 2A--->B + C, given that [A]0 = 0.153 mol /L and that after 115 seconds, the concentration of B rises to 0.034 mol/L What differential/integrated rate law(s) woul...
by vpena_1I
Tue Mar 10, 2020 1:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reactant order
Replies: 4
Views: 34

Re: Reactant order

You wanna compare reactions in which the concentration of the species you are trying to solve with respect to is the only one being changed. That way, you know whatever change there is in the initial rate is purely the result of that species. If one of your "other species" is zero order ho...
by vpena_1I
Mon Mar 09, 2020 10:59 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reactant order
Replies: 4
Views: 34

Reactant order

For 7A.15, the solutions manual says to look at experiments 2 and 4 to solve for the order with respect to A. I thought this could only be done if in the experiments, the concentrations of all other species are constant while A is the only one being changed.
by vpena_1I
Mon Mar 02, 2020 7:59 pm
Forum: Balancing Redox Reactions
Topic: pH electrodes
Replies: 1
Views: 32

pH electrodes

For homework 6N.5(a), I'm good up until having
0.06V= -(0.0129 V) ln[H+]^2

How do I use this to find the pH? Im not sure how the solutions manual went from this step to
0.06V= -(0.0257 V) ln[H+]
= -0.0257V x (2.303 log[H+]
pH=1.0
by vpena_1I
Mon Mar 02, 2020 9:09 am
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 5
Views: 59

Re: Cell Diagrams

I know that the anode is on the left and cathode is on the right. My question is, that for species that are in the same phase, occurring in either cathode or anode, and separated by a comma, is there a particular order to them in the cell diagram? Eg Pb4+ +Sn2+ ---> Pb2+ +Sn4+ C(gr)| Sn4+(aq), Sn2+(...
by vpena_1I
Sun Mar 01, 2020 11:26 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 5
Views: 59

Cell Diagrams

For species separated by a comma, is there a particular order to the reactants/products? I remember Dr. Lavelle telling us in lecture that they should be in the form of Reactants(aq), Products(aq) , but I've seen them written in the solutions manual as Products(aq), Reactants(aq) . Does it depend on...
by vpena_1I
Sun Mar 01, 2020 11:25 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 2
Views: 34

Cell Diagrams

Is this the correct way we should order our cell diagrams? --> solid|gas|aqueous || aqueous|gas|solid
This is the first I've heard of it being that way, the book wasn't too clear about the exact order.
by vpena_1I
Thu Feb 27, 2020 10:12 am
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 2
Views: 30

Re: Cell Diagrams

also, why is H+(aq) included in the cell diagram while H2O(l) is not. Both are in the given balanced reaction.
by vpena_1I
Thu Feb 27, 2020 10:05 am
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 2
Views: 30

Cell Diagrams

For 6M.5(a), the cell diagram is
Hg(l)|Hg2 2+(aq)||No3-(aq), H+(aq)|NO(g)|Pt(s)

What is the electrode for the anode? I thought it would also need a platinum electrode since none of the species are a solid.
by vpena_1I
Wed Feb 26, 2020 11:25 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 3
Views: 34

Re: Cell Diagrams

Is that the only specific thing?
by vpena_1I
Wed Feb 26, 2020 8:27 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 3
Views: 34

Cell Diagrams

In 6L.3(e), the following cell diagram is given, Pt(s)| Sn4+(aq),Sn2+(aq) ||Cl-(aq)|Hg2Cl2(s)|Hg(l) the addition of half-reactions gives: Sn2+(aq) +Hg2Cl2(s)---> Sn4+(aq) +2Hg(l) +2Cl-(aq) I thought Dr. Lavelle said in lecture that species separated by a comma would be in the form R,P. The balanced ...
by vpena_1I
Sat Feb 22, 2020 8:39 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 6
Views: 76

Cell Diagrams

Is there a way of telling what species are reactants/products when given just the cell diagram? I can tell once I see the standard potentials, but is there a way to know without searching them up? For example, 6L.3(b) gives: C(gr)| H2 (g)| H+ (aq)|| Cl- (aq)| Cl2 (g)|Pt(s) I thought the species in b...
by vpena_1I
Sat Feb 22, 2020 12:07 pm
Forum: Balancing Redox Reactions
Topic: Calculating the reaction Gibbs free energy
Replies: 7
Views: 58

Calculating the reaction Gibbs free energy

In ∆G*=-nFE*, is n the number of moles of the species that is being reduced?
by vpena_1I
Sat Feb 22, 2020 11:39 am
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 5
Views: 78

Cell Diagrams

Why was a platinum electrode used for both cells in 6L.5(b)? The solutions manual says: "Pt(s)| I-(aq) | I2(s) || Ce^4+(aq), Ce^3+(aq) | Pt(s) An inert electrode such as Pt is necessary when both oxidized and reduced species are in the same solution" When is says oxidized and reduced speci...
by vpena_1I
Sat Feb 22, 2020 11:25 am
Forum: Balancing Redox Reactions
Topic: 6k.5 part d
Replies: 2
Views: 45

Re: 6k.5 part d

In example 6K.2 (Balancing a redox equation in basic solution), it's done in this way though, and all other solutions in the solutions manual have done it like this too. For example, "6K5(c) Cr^3+ --->CrO4^2- balance O: Cr^3+ +4H2O --->CrO4^2- balance H: Cr^3+ +4H2O +8OH- --->CrO4^2- +8H2O I do...
by vpena_1I
Sat Feb 22, 2020 11:10 am
Forum: Balancing Redox Reactions
Topic: Cell Diagram
Replies: 1
Views: 14

Cell Diagram

How do we know when to put a line between species and when to put a comma? Theres always a line between the species and the conducting electrode, but what goes between the two other species?
by vpena_1I
Thu Feb 20, 2020 10:34 pm
Forum: Balancing Redox Reactions
Topic: Galvanic cells
Replies: 2
Views: 32

Galvanic cells

How do you know if a galvanic cell is working reversibly?
by vpena_1I
Thu Feb 20, 2020 9:36 pm
Forum: Balancing Redox Reactions
Topic: 6k.5 part d
Replies: 2
Views: 45

6k.5 part d

I'm confused as to how the solutions manual began this problem. P4(s) ---> H2PO2-(aq) +PH3(aq) takes place in a basic solution. I started with: P4 ---> H2PO2- balanced the P: P4 ---> 4H2PO2- balanced the O: 8H2O +P4 ---> 4H2PO2- balanced the H: 16OH- +8H2O +P4 ---> 4H2PO2- +16H2O balanced the charge...
by vpena_1I
Thu Feb 20, 2020 9:19 pm
Forum: Balancing Redox Reactions
Topic: 6K3, part d
Replies: 2
Views: 33

Re: 6K3, part d

Someone in another thread wrote that there was a typo in the textbook. I believe the question should say
Cl2 ---> HClO +2Cl-
by vpena_1I
Thu Feb 20, 2020 5:58 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reactions
Replies: 5
Views: 34

Balancing Redox Reactions

In our balanced equation, does it matter where our H20 and H+ go?
For example, I wrote:
4Cl2+ 5H2O +S2O3^2- --->2SO4^2- +10H+ +8Cl-
but the answer in the book was:
4Cl2 +S2O3^2 +5H2O - --->8Cl- +2SO4^2- +10H+

Does this matter at all? I don't wanna lose points on a test.
by vpena_1I
Thu Feb 20, 2020 5:09 pm
Forum: Balancing Redox Reactions
Topic: Oxidation numbers
Replies: 6
Views: 55

Oxidation numbers

I read somewhere online that one of the rules for finding the oxidation number of an element is that H is always +1.
If that's the case, how is H2 neutral? Or is the "rule" just an oversimplification?
by vpena_1I
Wed Feb 19, 2020 10:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Gibbs free energy
Replies: 9
Views: 123

Re: Gibbs free energy

So is ΔGrxn used when were trying to find the change in free energy at a different temp and/or when the reaction is not at equilibrium?
by vpena_1I
Wed Feb 19, 2020 9:35 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Gibbs free energy
Replies: 9
Views: 123

Gibbs free energy

What is the difference between ΔGrxn and ΔG*rxns?
by vpena_1I
Wed Feb 19, 2020 9:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: molar Gibbs free energy
Replies: 2
Views: 32

Re: molar Gibbs free energy

I think when you are referring to calculating the standard change in gibbs free energy, that is G not, the delta H and delta S in this case are the delta H not and delta G not at standard temperature and pressure, 25 degrees C and 1 atm. Thus, the delta H and delta S remain constant while the tempe...
by vpena_1I
Wed Feb 19, 2020 7:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: molar Gibbs free energy
Replies: 2
Views: 32

molar Gibbs free energy

For the change in molar Gibbs free energy of NH3(l) --> NH3(g), how is it that you can plug in any temperature for ΔG=ΔH-TΔS when the ΔH and ΔS are the change in enthalpy/entropy of vaporization? I thought you would need to use the specific temperature at which NH3 vaporizes to be able to use ΔHvap ...
by vpena_1I
Wed Feb 19, 2020 7:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies of formation
Replies: 2
Views: 33

Enthalpies of formation

Why are most enthalpies of formation in the appendix negative?
For example, ΔHf (H2O, g)= -241.82 KJ/mol.
I was expecting it to be positive considering it's 1 molecule being made from 2 different molecules, H2 and O2. I might be confusing it with exothermic/endothermic reactions. Thanks!
by vpena_1I
Sun Jan 26, 2020 11:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: checking approximation
Replies: 4
Views: 36

Re: checking approximation

That is correct, though it is not very common. The initial molarity of the reactants would have to be pretty small for that to happen.
by vpena_1I
Sun Jan 26, 2020 11:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy/state properties
Replies: 4
Views: 35

Re: enthalpy/state properties

Enthalpy is the internal energy added to the product of the pressure and volume of the system. It is a state function because it only depends on the initial and final conditions, and not on the path taken to establish these conditions.
by vpena_1I
Sun Jan 26, 2020 11:13 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: State Functions
Replies: 4
Views: 33

Re: State Functions

I think you meant it the other way around. Internal energy is a state function, while work and heat are not. The reason being, at least the way I think of it, is that an object can store internal energy. An object cannot, however, store work or heat. Work and heat is the process of internal energy b...
by vpena_1I
Wed Jan 15, 2020 9:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.15
Replies: 1
Views: 18

6D.15

Calculate the pH of (b) 0.055 m AlCl3(aq)


I know that AlCl3 will decrease pH and I need to do an ICE table, but the solutions manual writes the equilibrium expression as
Al(H2O)6^3+(aq) + H2O(l)<-->H3O+(aq) + Al(H2O)5OH^2(aq)

What happened to the Cl3, and how did they get this expression?
by vpena_1I
Wed Jan 15, 2020 9:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Negative pH
Replies: 2
Views: 24

Re: Negative pH

It's possible to have a negative pH for a very acidic solution.
by vpena_1I
Wed Jan 15, 2020 9:31 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Factors
Replies: 7
Views: 54

Re: Factors

Yes, temperature is the only factor that influences K. Q is influenced by pressure (when volume is decreased, NOT when adding inert gas) or adding/removing reactants/products.
by vpena_1I
Wed Jan 15, 2020 9:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to use Kc or Kp
Replies: 2
Views: 19

Re: When to use Kc or Kp

Equilibrium problems involving gasses can use either Kp or Kc, it just depends what values you're given. BUT this does not mean they are interchangeable. If you are given molarity values, you must use Kc as the Kp value would be different.
by vpena_1I
Wed Jan 15, 2020 9:11 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 5
Views: 39

Re: Inert Gas

An inert gas is a noble gas. They do not react with many substances, so they only affect pressure, not concentration or K.
by vpena_1I
Wed Jan 15, 2020 9:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE tables
Replies: 4
Views: 33

Re: ICE tables

For problems that give you the molarity of a strong acid or base, you do not need an ICE table because you can assume the acid/base dissociated completely. If you are given only the molarity of a weak acid/base, you will need an ice table because you do not know the concentrations of the other solut...
by vpena_1I
Wed Jan 15, 2020 8:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Kb and Ka
Replies: 2
Views: 24

Kb and Ka

For a problem like 6D.15, the Kb of the conjugate base of NH4Cl is given, but how would you get Ka from this and then pH?
by vpena_1I
Wed Jan 15, 2020 8:44 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: biological examples
Replies: 2
Views: 43

Re: biological examples

Osmosis is the net movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration. This results in the concentration on both sides of the membrane to be equal. Osmotic pressure, then, is how much pressure it would take to prevent osmosis from occu...
by vpena_1I
Tue Jan 14, 2020 7:48 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Hw 5J.11
Replies: 2
Views: 24

Re: Hw 5J.11

It is the other way around. A positive delta H corresponds to an endothermic reaction in which the products formed have greater energy than the reactants. Energy can be thought of as a reactant in this case, which explains why an increase in heat will result in greater product formation.
by vpena_1I
Tue Jan 14, 2020 7:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentration with gases
Replies: 7
Views: 64

Re: equilibrium concentration with gases

Yes, given moles of reactants and products, you will find molarity of each and use it to calculate Kc of the equation, not Kp. Only answer in Kp if the reactants and products are given in terms of bar or atm.
by vpena_1I
Wed Jan 08, 2020 7:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 3
Views: 62

5.33

Dissociation of a diatomic molecule, X2(g)<-->2 X(g) occurs at 500 K. The equilibrium state of the reaction is shown in 1 and the equilibrium state in the same container after a change has occurred is shown in 2. Which of the following changes will produce the composition shown? (a) Increasing the ...
by vpena_1I
Wed Jan 08, 2020 7:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.39
Replies: 1
Views: 71

Re: 5.39

My guess is that there are 2 typos, the first being that you are supposed to use table 5G.2. Here, it says the equilibrium constant of the reaction N2O4(g)<-->2NO2(g) at 298 K is 6.1x10^23. The second one being that the equilibrium constant of 2NO2(g)<-->N2O4(g) at the same temp should just be the i...
by vpena_1I
Sat Dec 07, 2019 7:59 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ph concept
Replies: 5
Views: 78

Re: ph concept

taking the -log of a smaller [OH-] gives you a higher pOH, making the pH smaller.
by vpena_1I
Sat Dec 07, 2019 7:45 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Negative pH
Replies: 5
Views: 62

Re: Negative pH

pH would be negative if an acid's Ka is greater than 1. This occurs is super acidic acids.
by vpena_1I
Sat Dec 07, 2019 6:58 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition Metal Valence Electrons
Replies: 1
Views: 38

Re: Transition Metal Valence Electrons

Most of them only have 2, because the highest energy level for a transition metal is the s orbital. If it is not 2, I'm pretty sure they will give us the oxidation number in the form of Roman numerals.
by vpena_1I
Sat Dec 07, 2019 6:49 pm
Forum: Naming
Topic: Latin Names
Replies: 3
Views: 40

Re: Latin Names

Look at the periodic table. If the letters are completely different than the way the element is spelled, its probably latin. Though, I believe for the test, we only really need to know Iron(Ferrate), copper(Cuprate), and lead (plumbate). Some other ones are silver (Argenate), gold (Aurate), and tin ...
by vpena_1I
Sat Dec 07, 2019 6:05 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bond differences
Replies: 2
Views: 90

Re: Sigma and Pi bond differences

Pi bonds are weaker, yes. They cannot rotate, or else they would break, but I don't know exactly what would force that rotation. Either way, this is the reason why pi bonds can't form hybrid orbitals.
by vpena_1I
Sat Dec 07, 2019 5:32 pm
Forum: Naming
Topic: Wrong order
Replies: 4
Views: 44

Re: Wrong order

In a coordination complex? If you are writing the formula for a coordination complex, the ligands do not have to be in a particular order, as long as the central metal cation is first, and whatever is in the coordination sphere is in brackets. If you're going from the formula to writing the whole na...
by vpena_1I
Sat Dec 07, 2019 5:27 pm
Forum: Bronsted Acids & Bases
Topic: Resonance and oxyacids?
Replies: 1
Views: 69

Re: Resonance and oxyacids?

It will not form a double bond; doing so would change the formal charge of whatever the central atom is. Instead, the oxygen will carry that negative charge, which it is happy to do so considering its electronegativity.
by vpena_1I
Sat Dec 07, 2019 5:23 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis Acids/Bases
Replies: 1
Views: 76

Re: Bronsted vs. Lewis Acids/Bases

A Lewis acid is anything that accepts a pair of electrons, a bronsted acid also accepts electron pairs, but specifically at an acidic hydrogen.
by vpena_1I
Sat Dec 07, 2019 2:04 pm
Forum: Coordinate Covalent Bonds
Topic: Hybridization
Replies: 1
Views: 89

Hybridization

I'm not really sure if I'm wording this right, but the hybridization of 2 bounded atoms can be, for example, σ(C2sp2, C2sp2).

How would this look between a lone pair of electrons and an atom?
How would this type of question be asked?
by vpena_1I
Sun Nov 24, 2019 8:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 4
Views: 47

Re: Polarity

If they are the same atom directly opposite of each other, they will cancel, as in the case of CH4, but if just one of those hydrogens is different, as in CH3Cl, they won't cancel completely and will result in a dipole.
by vpena_1I
Sun Nov 24, 2019 8:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs in Cation/ Anion
Replies: 2
Views: 38

Re: Lone Pairs in Cation/ Anion

Lone-Bonding pairs have higher repulsion strength than bonding-bonding pair, so the presence of a lone pair of electrons will push bounded atoms closer together, decreasing their angle.
by vpena_1I
Sun Nov 24, 2019 12:01 am
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 Sites
Replies: 3
Views: 57

Re: Hydrogen Bonding Sites

It can have up to 4. The lone pairs on the oxygen can attach to 2 hydrogens and the 2 hydrogens within the molecule can each bind to a lone pair.
by vpena_1I
Sat Nov 23, 2019 11:52 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Bronsted acids
Replies: 5
Views: 100

Re: Bronsted acids

A Bronsted base is a proton acceptor, a Lewis base is an electron pair donor. All bronsted bases are Lewis bases, but not all Lewis bases are bronsted bases. The reason for this being that a Lewis base can donate its electrons to a number of cations, not just to H+. You can figure out what's what by...
by vpena_1I
Sat Nov 23, 2019 3:11 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Bronsted acids
Replies: 5
Views: 100

Re: Bronsted acids

A Bronsted acid is an H+ donor (proton donor), and a bronsted base is an H+ acceptor (proton acceptor). In order for a bronsted base to accept an H+ ion, it uses its lone pair of electrons to bind to it. You can then see the connection between a bronsted base and a Lewis base (<- electron pair donor...
by vpena_1I
Sat Nov 23, 2019 3:03 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acids
Replies: 1
Views: 38

Re: Lewis Acids

The Lewis acid in a coordinate covalent bond is the transition metal cation. I don't know if it has a name any more specific than that.
by vpena_1I
Sun Nov 17, 2019 8:03 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: Electron repulsions
Replies: 1
Views: 21

Re: Electron repulsions

The Pauli Exclusion principle states that no 2 electrons occupying the same orbital can have the same spin. This is due to the fact that electrons have the same, negative charge and repel one another.
by vpena_1I
Sun Nov 17, 2019 7:44 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lines on Atomic Absorption Spectroscopy
Replies: 1
Views: 110

Re: Lines on Atomic Absorption Spectroscopy

The first part! Though the electron does not have to be ejected, it just moves to a higher orbit by absorbing energy. The lines on the absorption spectrum are unique to each element as each element can only absorb certain energies or wavelengths.
by vpena_1I
Sun Nov 17, 2019 7:36 pm
Forum: DeBroglie Equation
Topic: Slow Moving Large Objects
Replies: 2
Views: 97

Re: Slow Moving Large Objects

Interesting question.
Theoretically, yes, the numbers can be plugged into the De Broglie formula to prove so, but experimentally, I think it'd be very difficult to measure just how slow the object would have to move.
by vpena_1I
Sun Nov 17, 2019 7:31 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers for H-Atom and other atoms
Replies: 1
Views: 87

Re: Quantum Numbers for H-Atom and other atoms

I'm not sure if I'm interpreting your question correctly, but an electron in a hydrogen atom only occupies the 1s orbital. After 2 electrons, multi-electron atoms will fill 2s, 2p, and so on. These orbitals hold electrons of higher energy than what the electrons of hydrogen atoms occupy.
by vpena_1I
Sun Nov 17, 2019 7:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 3F.19
Replies: 2
Views: 45

Re: 3F.19

Yes, considering CH3(CH2)CH3 is written separately and not C3H8, you know that these are 3 different molecules that are covalently bonded. The only way for that to be possible is in a rod shape.
by vpena_1I
Sun Nov 10, 2019 11:48 pm
Forum: Coordinate Covalent Bonds
Topic: carbon monoxide formal charges
Replies: 4
Views: 138

Re: carbon monoxide formal charges

A triple bond between the C and O gives them both a full octet with the 10 available electrons. Because each has a lone pair, you end up with a positive and negative charge. This, however, cancels out. Any other configuration would get you a formal charge even further away from 0.
by vpena_1I
Sun Nov 10, 2019 11:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Principle Quantum Number
Replies: 1
Views: 87

Re: Principle Quantum Number

I believe you'd be able to calculate energy with E=1/2mv^2, and then use E/ = - h R/n^2. Solving for n will give you the principle quantum number.
by vpena_1I
Sun Nov 10, 2019 11:38 pm
Forum: Dipole Moments
Topic: 3F.3
Replies: 2
Views: 30

Re: 3F.3

Usually just looking at the a/symmetry is enough to tell whether a molecular is polar or not.
by vpena_1I
Sun Nov 10, 2019 11:26 pm
Forum: Dipole Moments
Topic: Different types of attractive forces
Replies: 2
Views: 41

Re: Different types of attractive forces

A dipole results from the uneven distribution of electrons within a molecule, so covalently bonded atoms with different electronegativities will usually have a dipole moment. They can then interact with other molecules with dipoles, or induce a dipole that didn't originally have one. It's just a mat...
by vpena_1I
Sun Nov 10, 2019 11:18 pm
Forum: Dipole Moments
Topic: Instantaneous Dipole
Replies: 2
Views: 28

Re: Instantaneous Dipole

An instantaneous dipole occurs to the random movement of electrons in an atom/molecule. The uneven distribution leads to an instantaneous dipole, and it can't be predicted.
by vpena_1I
Sun Nov 03, 2019 3:54 pm
Forum: Ionic & Covalent Bonds
Topic: observed bond length
Replies: 2
Views: 23

Re: observed bond length

We expect double bonds to be shorter than single bonds within the same molecule, but through experimentation, we can see that the observed bond length, or the actual bond length, is a blend of the different resonance structures possible for that molecule. The real structure is known as the resonance...
by vpena_1I
Sun Nov 03, 2019 3:46 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 5
Views: 49

Re: Resonance structures

Yes, as long as they have the same overall charge as the molecule/ion.
by vpena_1I
Sun Nov 03, 2019 3:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Amount of electrons in each shell
Replies: 3
Views: 42

Re: Amount of electrons in each shell

When looking at transition metals, you count the electrons in the s orbital and d orbital as its valence electrons.
by vpena_1I
Wed Oct 30, 2019 7:23 pm
Forum: Dipole Moments
Topic: London Forces
Replies: 1
Views: 16

Re: London Forces

I don't think there are any periodic trends for determining LDFs since they occur when atoms/molecules interact with other atoms/molecules. LDFs are, however, influenced by electronegativity in that atoms in a molecule can be more electronegative than others and cause a dipole moment.
by vpena_1I
Tue Oct 29, 2019 8:29 pm
Forum: Ionic & Covalent Bonds
Topic: finding chemical formula based on charges of ions
Replies: 1
Views: 29

Re: finding chemical formula based on charges of ions

You start off by calculating the charges of each element if they were to reach noble gas configuration. For example, magnesium is [Ne] 3s2, so it will most likely lose 2 electrons and have a charge of +2. Sulfur gains 2 electrons and acquires a charge of -2. You then combine these elements with such...
by vpena_1I
Sat Oct 26, 2019 10:15 pm
Forum: Properties of Electrons
Topic: Textbook question 1.31
Replies: 1
Views: 58

Re: Textbook question 1.31

Using E=hv/入, you find that the energy of the red ruby laser is 2.86x10^-19 J, and the energy of the GaN laser is 4.90x10^-19 J. The work function can be converted to J by using 1 eV=1.602x10^-19 J. 2.93 eV(1.602x10^-19)= 4.69x10^-19J. This means a photon would need at least 4.69x10^-19 J of energy ...
by vpena_1I
Sat Oct 26, 2019 10:06 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 5
Views: 42

Re: Ionic and Covalent Bonds

Ionic bonds are the transfer of electrons between metals and nonmetals, whereas covalent bonds are the sharing of electrons between nonmetals.
by vpena_1I
Sat Oct 26, 2019 9:52 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Pd electron configuration
Replies: 1
Views: 13

Re: Pd electron configuration

In general, you take electrons from the s subshell in order to create a half-full or full d subshell, as this configuration is more stable. Palladium is a good example of that, but I'm not sure why platinum doesn't follow the same rule.
by vpena_1I
Sat Oct 26, 2019 8:13 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration
Replies: 3
Views: 41

Re: Electron Configuration

Vanadium's electron configuration would be written [Ar]3d3, 4s2. Remember 3d has lower energy than 4s, so it is written first. You would only take electrons from the s orbital if it's to complete a half-full or full d subshell, as in the instance of Cr:[Ar]3d5,4s1.
by vpena_1I
Sat Oct 26, 2019 7:46 pm
Forum: Electronegativity
Topic: Transition Metals and Periodic Table Trends
Replies: 2
Views: 63

Re: Transition Metals and Periodic Table Trends

Mn has electron configuration [Ar]3d5,4s2. It will typically only lose its outermost 2 electrons to form Mn2+: [Ar]3d5, which is a pretty stable configuration. Remember that half-full (d5) and full (d10) sub-shells have lower energy, and are therefore more stable. This is the same reason why Iron wi...
by vpena_1I
Sat Oct 26, 2019 7:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Shortcut
Replies: 3
Views: 49

Re: Electron Configuration Shortcut

The number of orbitals an electron can occupy is dependent on what sub-shell you're talking about. The s subshell has 1 orbital, p has 3, d has 5, and f has 7. Hund's rule states that electrons will occupy different orbitals with a parallel spin until all orbitals are occupied. They will then pair u...
by vpena_1I
Sun Oct 20, 2019 12:43 pm
Forum: Properties of Electrons
Topic: Wave-like and particle-like properties
Replies: 7
Views: 75

Re: Wave-like and particle-like properties

Yes, but as the mass of an object increases, the wavelength becomes practically undetectable.
by vpena_1I
Sun Oct 20, 2019 12:23 pm
Forum: Quantum Numbers and The H-Atom
Topic: d orbitals
Replies: 4
Views: 82

Re: d orbitals

In this case, the electrons are in different shells, as seen by the principle quantum number, n. As n increases, so does energy. If you were looking at electrons in the same shell, then s would have less energy than d. s<p<d<f.
by vpena_1I
Sun Oct 20, 2019 11:57 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The order in which subshells are filled
Replies: 3
Views: 39

Re: The order in which subshells are filled

Are you talking about cases like chromium? I know half-full (d5) and full (d10) d sub shells have lower energy than if the electrons were spread out in different, incomplete subshells. It's the symmetry that results in a more stable electron configuration.
by vpena_1I
Sun Oct 20, 2019 11:52 am
Forum: Quantum Numbers and The H-Atom
Topic: Electrons Spinning???
Replies: 3
Views: 51

Re: Electrons Spinning???

I'm pretty sure you're correct. The spin magnetic quantum number describes the momentum of the electrons. This has direction (+ or -) and magnitude (1/2). Based on this definition, the electrons will spin around an axes in opposite directions, though, I've heard the same that it's not really that si...
by vpena_1I
Sun Oct 20, 2019 11:36 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1.E.5
Replies: 1
Views: 28

Re: 1.E.5

a) False. The more electrons an atom contains, the more shells they will occupy. Those at lower energy levels will "shield" outer electrons from the electrostatic attraction of the positive nucleus. These outer electrons will experience an effective nuclear charge. b) True. They are the cl...
by vpena_1I
Sat Oct 12, 2019 10:49 pm
Forum: Properties of Light
Topic: Rydberg constant
Replies: 7
Views: 83

Rydberg constant

In what case would we use the formula En=-hR/n^2?
We went through a few examples using ΔE=Ef-Ei =, but I don't know what a problem requiring the first equation would look like.

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