Search found 100 matches

by Sydney Myers 4I
Sat Mar 14, 2020 1:21 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: pre equilibrium approach
Replies: 2
Views: 38

Re: pre equilibrium approach

You would need to find K for whatever step you're considering is at equilibrium. Whatever fast step happens before the slow step with the intermediate.
by Sydney Myers 4I
Sat Mar 14, 2020 1:19 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: reaction mechanisms
Replies: 2
Views: 22

Re: reaction mechanisms

Most reactions only have two molecules involved and not three because there are so many more ways that three molecules can collide than just two, which decreases the likelyhood of the correct orientation occurring and producing a sufficient amount of product to consider it.
by Sydney Myers 4I
Sat Mar 14, 2020 1:17 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 3
Views: 132

Re: Arrhenius Equation

That equation is simply derived from a different one where the activation energy and gas constant and etc are all to the power of e. In order to make it a linear equation, it can be transformed into the one that you have typed. A is just the pre-exponential factor, its a constant.
by Sydney Myers 4I
Sat Mar 14, 2020 1:15 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 5
Views: 33

Re: Catalysts

It must be introduced as a reactant, as opposed to an intermediate, which is produced as a product first, then maybe used as a reactant. Catalysts also must reappear as products in equal amount as was inputted.
by Sydney Myers 4I
Sat Mar 14, 2020 1:14 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: pre-exponential factor
Replies: 2
Views: 14

Re: pre-exponential factor

It is not affected by whatever is in the exponent basically.
by Sydney Myers 4I
Sun Mar 08, 2020 7:07 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction Profile
Replies: 2
Views: 25

Re: Reaction Profile

I think understanding the linear graphs also helps us understand why we write integrated rate laws in point slope form of a line.
by Sydney Myers 4I
Sun Mar 08, 2020 7:04 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow step vs. fast step
Replies: 3
Views: 37

Re: Slow step vs. fast step

Often, you can see which step of a reaction is slow by looking at its rate law. If there is a certain reactant in the rate law, you can tell that reactant is involved in the slow step of the reaction because it is the slow step that determines the rate. Whatever isn't involved in the rate is most li...
by Sydney Myers 4I
Sun Mar 08, 2020 7:02 pm
Forum: Zero Order Reactions
Topic: Half life of zero order runs
Replies: 3
Views: 25

Re: Half life of zero order runs

The concentration of A over time changes at a constant rate, k. K is not affected by anything as time goes on, which is why it's a straight line.
by Sydney Myers 4I
Sun Mar 08, 2020 7:00 pm
Forum: Second Order Reactions
Topic: 7B.3
Replies: 5
Views: 91

Re: 7B.3

You have to take into account that the rate of formation of B is not equal to the rate of consumption of A. They are separated by a factor of 2, the coefficient.
by Sydney Myers 4I
Sun Mar 08, 2020 6:58 pm
Forum: Second Order Reactions
Topic: half life
Replies: 6
Views: 28

Re: half life

The equation for the half life of a reaction can be derived from its integrated rate law. The rate of the reaction has a direct effect on the half life of the reaction.
by Sydney Myers 4I
Sun Mar 01, 2020 9:30 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 4
Views: 54

Re: Concentration Cells

The only reason that electrons flow is because of a difference in the concentration of the cells. They have the same species, which makes them generally have a lower E value than regular galvanic cells.
by Sydney Myers 4I
Sun Mar 01, 2020 9:20 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Method 1
Replies: 3
Views: 67

Re: Method 1

It's important to only change the concentration of one reactant at a time in order to isolate that reactant's relationship with the rate.
by Sydney Myers 4I
Sun Mar 01, 2020 9:16 pm
Forum: General Rate Laws
Topic: unique rate
Replies: 3
Views: 52

Re: unique rate

We use the coefficients to make fractions because the relationship is inverse. That's why we need the fraction.
by Sydney Myers 4I
Sun Mar 01, 2020 9:14 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: order of reactions
Replies: 7
Views: 102

Re: order of reactions

The order of the reaction also tells you which integrated rate law to use, so that's useful.
by Sydney Myers 4I
Sun Mar 01, 2020 9:13 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: kinetically stable?
Replies: 10
Views: 124

Re: kinetically stable?

The conditions of the reaction will not favor the occurrence of the reaction, even if the reaction is spontaneous thermodynamically.
by Sydney Myers 4I
Sun Feb 23, 2020 9:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneity
Replies: 8
Views: 80

Re: Spontaneity

Since both are directly correlated with the spontaneity of the reaction, and they are inversely related, then it makes sense that if one is positive, the other must be negative and vice versa.
by Sydney Myers 4I
Sun Feb 23, 2020 9:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 9
Views: 88

Re: salt bridge

The purpose of a salt bridge is to allow electrons to flow back to the anode after they are transferred to the cathode. This allows a circuit to form and continuous flow of electrons.
by Sydney Myers 4I
Sun Feb 23, 2020 9:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram, what to include
Replies: 3
Views: 62

Re: Cell Diagram, what to include

There are three separate sections on the right because there are three different phases represented. They are all in contact with each other, just different phases.
by Sydney Myers 4I
Sun Feb 23, 2020 9:46 pm
Forum: Balancing Redox Reactions
Topic: Alkaline
Replies: 3
Views: 39

Re: Alkaline

Instead of balancing hydrogens with H+, you add twice the amount of hydrogens needed in the form of water on the side that need hydrogens, then you balance that with an equal amount of OH- on the other side.
by Sydney Myers 4I
Sun Feb 23, 2020 9:44 pm
Forum: Balancing Redox Reactions
Topic: Oxidation?
Replies: 10
Views: 134

Re: Oxidation?

You'll know based on the oxidation states of a certain element. If the oxidation state goes up from the left side of the equation to the right, then that element has been oxidized.
by Sydney Myers 4I
Sat Feb 15, 2020 12:22 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Irreversible, Adiabatic
Replies: 3
Views: 52

Re: Irreversible, Adiabatic

When the delta S is 0, it doesn't necessarily mean that there's no heat transfer, just that whatever heat is being transferred is being converted to work or being transferred elsewhere. In an adiabatic system, there is no heat transferred.
by Sydney Myers 4I
Sat Feb 15, 2020 12:19 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Analysis of Gibbs Free Energy Equation
Replies: 4
Views: 72

Re: Analysis of Gibbs Free Energy Equation

The relationship between delta H and delta S depends on which delta S you're referring to. If it's the entropy of the system, then as delta H increases, then delta S increases with it. If it's the entropy of the surroundings, then delta S would decrease with an increase in delta H. If its the total ...
by Sydney Myers 4I
Sat Feb 15, 2020 12:16 pm
Forum: Van't Hoff Equation
Topic: What is this? [ENDORSED]
Replies: 7
Views: 117

Re: What is this? [ENDORSED]

The equation allows us to relate a change in temperature to a change in the K value for a chemical reaction at equilibrium.
by Sydney Myers 4I
Sat Feb 15, 2020 12:11 pm
Forum: Balancing Redox Reactions
Topic: Redox reaction
Replies: 5
Views: 73

Re: Redox reaction

005324438 wrote:For the most part, O will always be -1, halogens will always be -1, and H will always be +1. Once we assign values to these elements, then the rest we just add up the rest of the molecule to equal the total charge.


I think Oxygen's oxidation states is usually -2, not -1.
by Sydney Myers 4I
Tue Feb 11, 2020 11:18 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Calculating Change in Entropy for Phase Changes
Replies: 1
Views: 30

Calculating Change in Entropy for Phase Changes

Why are there three steps to finding the change in entropy at a transition temperature? If entropy is a state function, then how does heating a substance then cooling a substance give us anything other than delta S = 0?
by Sydney Myers 4I
Sun Feb 09, 2020 9:40 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Degrees of Change in Entropy
Replies: 5
Views: 52

Re: Degrees of Change in Entropy

Whenever there is a degree symbol next to a delta S, delta H, or delta G, it means that the value was measured under standard conditions. When you say it out loud, its "delta S naught"
by Sydney Myers 4I
Sun Feb 09, 2020 9:33 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Difference between Cv and Cp?
Replies: 8
Views: 73

Re: Difference between Cv and Cp?

The values differ because the heat capacity of a gas can be calculated with either a constant volume or a constant pressure. When it's calculated with a constant pressure, the gas can lose energy by doing work on whatever boundary is present, which makes the amount of energy to change its temperatur...
by Sydney Myers 4I
Sun Feb 09, 2020 9:29 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Law of Conservation Energy
Replies: 5
Views: 33

Re: Law of Conservation Energy

Energy can be gained or lost by a system, however, it always is gained or lost by another system in an equal amount, so it is conserved because it was neither created or destroyed.
by Sydney Myers 4I
Sun Feb 09, 2020 9:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 6
Views: 66

Re: Bond Enthalpies

If it's a confusing problem with bonds, you can count up all of the bonds on either side and write them out. For example, 3 carbon-carbon bonds, 2 oxygen-carbon bonds. Do this for the reactants and the products. Then you can easily figure out which bonds are present on both sides and ignore them, si...
by Sydney Myers 4I
Sun Feb 09, 2020 9:19 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 4c.3
Replies: 2
Views: 59

Re: HW 4c.3

You will also need to use q=c*g*deltaT in order to deal with the temperature changes in the problem.
by Sydney Myers 4I
Sun Feb 02, 2020 4:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U = Q
Replies: 8
Views: 43

Re: Delta U = Q

Kaitlyn Ang 1J wrote:Adding to this, you know work = 0 when because so 0 for (aka there is no change in volume, aka the volume is constant) makes the entire work equation 0



expanding on this, work is also 0 when pressure is 0, or when the system is in a vacuum.
by Sydney Myers 4I
Sun Feb 02, 2020 4:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: entropy?
Replies: 4
Views: 63

Re: entropy?

In order to account for the fact that energy is conserved, we must include entropy because some energy will be lost as entropy. Also, whether or a reaction increases or decreases entropy can have a effect on whether or not it is spontaneous.
by Sydney Myers 4I
Fri Jan 31, 2020 11:47 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies of Formation
Replies: 4
Views: 47

Re: Enthalpies of Formation

We probably wouldn't have to memorize any values, except to note that the standard enthalpy of formation of an element already in its most stable form is 0.
by Sydney Myers 4I
Fri Jan 31, 2020 11:43 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: qp and qv
Replies: 8
Views: 73

Re: qp and qv

It's simply that the definition of enthalpy is heat at a constant pressure. That's how it's defined as a function.
by Sydney Myers 4I
Fri Jan 31, 2020 11:31 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: H and q
Replies: 7
Views: 72

Re: H and q

The definition of enthaply is heat at a constant pressure. Q is heat, so the two are highly related. You can tell if delta H and q are the same if q has a subscript of p, meaning that it's the heat at a constant pressure.
by Sydney Myers 4I
Sat Jan 25, 2020 7:16 pm
Forum: Phase Changes & Related Calculations
Topic: Entropy vs Enthalpy
Replies: 9
Views: 63

Re: Entropy vs Enthalpy

Enthalpy is the total amount of energy absorbed or released in a chemical reaction. It's made up of two components: one of them is usable energy that is stored in the chemical bonds of whatever molecule is formed (which is called free energy - G), entropy is the energy that is released and is unusab...
by Sydney Myers 4I
Sat Jan 25, 2020 7:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Different methods
Replies: 4
Views: 31

Re: Different methods

A factor that may play into which method to use is if the reaction you're trying to find the enthalpy of occurs in standard states. If not, you may not be able to use standard reaction enthalpy of formation.
by Sydney Myers 4I
Sat Jan 25, 2020 7:09 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies of diatomic molecules
Replies: 2
Views: 21

Re: Bond enthalpies of diatomic molecules

All he meant by that is to just keep in mind that every bond enthalpy is slightly different, so when we are measuring a bond's enthalpy, we only know that its truly accurate if it's being measured from a diatomic molecule. A different bond, such as C-H, is going to be present in many different molec...
by Sydney Myers 4I
Sat Jan 25, 2020 7:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy reaction
Replies: 4
Views: 29

Re: enthalpy reaction

When you form a bond, you're taking atoms from a state of high energy (free floating) to a more stable state (in a bond). This is a net decrease in potential energy, and the excess is given off as heat and the reaction is exothermic. When you break a bond, you need some form of energy to take the at...
by Sydney Myers 4I
Thu Jan 23, 2020 4:56 pm
Forum: Phase Changes & Related Calculations
Topic: Steam vs liquid
Replies: 7
Views: 73

Re: Steam vs liquid

Water can only hold so much energy until it is converted to steam, but once it has been converted, it has the capability to hold much more energy, making the burn worse.
by Sydney Myers 4I
Sun Jan 19, 2020 11:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic and Endothermic Reactions
Replies: 5
Views: 55

Re: Exothermic and Endothermic Reactions

It's true that breaking bonds releases energy, but only apply this when the breaking of a single bond in a very simple reaction. Otherwise there are too many factors to simplify to just breaking or forming bonds.
by Sydney Myers 4I
Sun Jan 19, 2020 11:05 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Conjugates
Replies: 2
Views: 32

Re: Conjugates

Conjugates are useful to know for setting up buffer solutions.
by Sydney Myers 4I
Sun Jan 19, 2020 11:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE tables for reverse rxns
Replies: 4
Views: 43

Re: ICE tables for reverse rxns

The reason we haven't dealt with reverse reactions in class is because usually we assign the chemical that we start with to be the reactant, so the reaction will go mostly in the forward direction and we can assume that the initial concentration will decrease be some amount (x).
by Sydney Myers 4I
Sun Jan 19, 2020 10:58 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Buffers
Replies: 3
Views: 32

Re: Buffers

The effectiveness of buffers comes from their ability to both accept protons from any acids added, as well as donating protons to any base added, so that water is unaffected and the concentrations of H+ and OH- stay relatively constant.
by Sydney Myers 4I
Sun Jan 19, 2020 10:57 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding a molecule thats not in reaction
Replies: 2
Views: 24

Re: Adding a molecule thats not in reaction

Adding a molecule that is not in the reaction wouldn't affect the reaction or the equilibrium because it doesn't change the concentration of the reactants or the products.
by Sydney Myers 4I
Wed Jan 08, 2020 8:19 pm
Forum: Ideal Gases
Topic: K
Replies: 10
Views: 97

Re: K

Since the concentration and the pressure can be related by a factor of R*T (using the ideal gas law), the K should be the same whether you use partial pressures of temperature.
by Sydney Myers 4I
Wed Jan 08, 2020 8:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Partial Pressures
Replies: 3
Views: 271

Re: Partial Pressures

When it comes to partial pressures, there are two ways that a system at equilibrium can change. Either 1) The entire volume of the container is being reduced. This would increase pressure on all of the molecules in the system and it would respond by shifting the equilibrium to whichever side has a s...
by Sydney Myers 4I
Wed Jan 08, 2020 8:11 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's and Endo/Exothermic
Replies: 5
Views: 72

Re: Le Chatelier's and Endo/Exothermic

We won't be expected to just look at a chemical equation and know which side the heat is on, instead we will get an energy value. If the energy value is negative, then the heat is on the right, it is being lost. If the value is positive, then heat is being added to the system as a result of the forw...
by Sydney Myers 4I
Mon Jan 06, 2020 4:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: The Significance of K
Replies: 5
Views: 52

Re: The Significance of K

Kc is the equilibrium constant calculated using the concentrations of the products and reactants, while Kp is the equilibrium constant calculated using the partial pressures of the products and reactants.
by Sydney Myers 4I
Mon Jan 06, 2020 4:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant
Replies: 4
Views: 40

Re: Equilibrium Constant

K also tells us which of the products or reactants is more stable. If K is large, then the products are favored, which means they are more stable. If K is small, then the reactants are favored, meaning that they are more stable.
by Sydney Myers 4I
Sat Dec 07, 2019 6:18 pm
Forum: Hybridization
Topic: Promoting electrons
Replies: 1
Views: 96

Re: Promoting electrons

The electrons would separate to different energy levels when an atom bonds with another atom. This is when hybridization orbitals are used.
by Sydney Myers 4I
Fri Dec 06, 2019 10:45 am
Forum: Dipole Moments
Topic: Dipole Moments Cancel in Tetrahedral?
Replies: 5
Views: 154

Dipole Moments Cancel in Tetrahedral?

Would two dipole moments cancel if they are on opposite sides of a tetrahedral molecule? Because they're not exactly in line with each other!
by Sydney Myers 4I
Thu Dec 05, 2019 10:55 pm
Forum: Naming
Topic: Compounds that can form chelates [ENDORSED]
Replies: 1
Views: 66

Compounds that can form chelates [ENDORSED]

I know Lavelle told us that commonly, compounds that can form chelates have two atoms that aren't boding sites in between them. He said that was the most common form, but is it possible to have a compound that can form a chelate with only one atom in between the two atoms that can form a chelate?
by Sydney Myers 4I
Thu Dec 05, 2019 10:43 pm
Forum: Naming
Topic: Using alternate Greek prefixes
Replies: 2
Views: 39

Using alternate Greek prefixes

I know that there's a different set of prefixes to use when a molecule is polydentate, but are there any tricks to use in figuring out if a ligand is polydentate?
by Sydney Myers 4I
Thu Dec 05, 2019 10:30 pm
Forum: Naming
Topic: Double A in Pentaammine?
Replies: 1
Views: 36

Double A in Pentaammine?

Are there two a's in pentaammine, or would you just combine it into pentammine?
by Sydney Myers 4I
Sun Dec 01, 2019 9:52 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Ionization in Water
Replies: 8
Views: 599

Re: Ionization in Water

Strong bases fully dissociate in water, while weak bases only partially dissociate, as the strength of the base depends on its ability to fully dissociate. Is this why the balanced equation for strong acids have a one-way arrow while weak acids have a two-way arrow? Technically, even strong bases a...
by Sydney Myers 4I
Sun Dec 01, 2019 9:49 pm
Forum: Lewis Acids & Bases
Topic: Protons in Acids
Replies: 6
Views: 57

Re: Protons in Acids

An acid is considered strong if a hydrogen ion is easily separated from it, which then raises the concentration of the hydronium ions in the solution, which lowers pH.
by Sydney Myers 4I
Mon Nov 25, 2019 11:19 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: strength of base
Replies: 8
Views: 376

Re: strength of base

805097738 wrote:
Michael Torres 4I wrote:If something is a strong acid, then it will be a weaker base. Weaker acids will also be stronger bases.


how can acids be bases?



I think that is referring to the equilibrium that acid-base reactions can reach. If something is a strong acid, then it is a weak conjugate base.
by Sydney Myers 4I
Mon Nov 25, 2019 11:15 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Nonmental Oxides as Acids
Replies: 4
Views: 61

Re: Nonmental Oxides as Acids

Mariepahos4D wrote:yes, the co2 and so2 would be considered an acid in that reaction because they donate the proton to water to create 2 oh- and a gas



If a proton is donated to water, it would form hydroxide (H30+)
by Sydney Myers 4I
Mon Nov 25, 2019 10:51 pm
Forum: Amphoteric Compounds
Topic: amphoteric compounds
Replies: 2
Views: 60

Re: amphoteric compounds

There are certain elements that you have to know will form amphoteric molecules. They are near the metalloids but do not correspond exactly to them.
by Sydney Myers 4I
Sun Nov 24, 2019 3:45 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Tetrahedral and Square Planar
Replies: 3
Views: 85

Re: Tetrahedral and Square Planar

He also mentioned that any coordination compound with 6 ligands will be octehedral.
by Sydney Myers 4I
Fri Nov 22, 2019 1:18 am
Forum: Hybridization
Topic: Knowing when hybridization occurs
Replies: 6
Views: 65

Re: Knowing when hybridization occurs

It is mainly helpful to know the hybridization when bonding occurs because it can help visualize which bonds are placed where. Like double bonds can be comprised of a hybrid orbital and a regular orbital, because the bond is counted as a single region of electron density.
by Sydney Myers 4I
Fri Nov 22, 2019 12:13 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: Problem 3F10 b
Replies: 6
Views: 84

Re: Problem 3F10 b

Daniel Martinez 1k wrote:Si2F2


Is this due to the shape? because Si2F2 would have a more linear structure, compared with a round structure of SiF4, and higher surface area makes for higher intermolecular forces, specifically London Dispersion Forces.
by Sydney Myers 4I
Mon Nov 18, 2019 4:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Notation
Replies: 2
Views: 23

Re: Notation

Not super important, but just know that its VSEPR, not VSEPER
by Sydney Myers 4I
Mon Nov 18, 2019 4:37 pm
Forum: Hybridization
Topic: DSP^3
Replies: 1
Views: 27

Re: DSP^3

It mirrors the order in electron configuration. Since the d orbital is from a lower energy level, even though it fills later, it is put before. Today in class Lavelle said that it doesn't really matter what the order is though.
by Sydney Myers 4I
Sun Nov 17, 2019 5:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs vs Bonding Pairs
Replies: 2
Views: 35

Re: Lone Pairs vs Bonding Pairs

If you wanted to think of it spatially, bonding pairs are being shared with another atom, so they don't take up as much space on an atom because their orbital is larger. Lone pairs tend to stay on one atom, so they would have a higher repulsion force.
by Sydney Myers 4I
Sun Nov 17, 2019 5:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: linear versus angular
Replies: 5
Views: 64

Re: linear versus angular

Yes, it has to do with lone pairs and polarity, so if these charges are present they will repel other elements and cause the bent shape that is observed in water rather than the linear shape present in co2 when there are 2 lone pairs that repel the other elements equally. I'm not quite sure that th...
by Sydney Myers 4I
Sun Nov 17, 2019 5:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 5
Views: 44

Re: VSEPR

It's not so much a formula as a concept to understand. Essentially, the shape of a molecule is dependent on how many regions of electron density it has. A region can be a bond or a lone pair.
by Sydney Myers 4I
Thu Nov 14, 2019 12:04 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: 3F 13
Replies: 1
Views: 45

Re: 3F 13

It would be the second option because the dipole moments are the most directly lined up.
by Sydney Myers 4I
Fri Nov 08, 2019 10:23 pm
Forum: Bond Lengths & Energies
Topic: dissociation energy
Replies: 5
Views: 56

Re: dissociation energy

I think it would be better to just memorize the values for dissociation energy for the different interactions we went over in class.
by Sydney Myers 4I
Fri Nov 08, 2019 10:21 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 2
Views: 36

Re: Bond Length

Another thing to note is that the bonds get weaker when they get longer.
by Sydney Myers 4I
Wed Nov 06, 2019 3:34 pm
Forum: Octet Exceptions
Topic: Xenon and Expanded Octets
Replies: 2
Views: 52

Xenon and Expanded Octets

In 2C.9 and 2C.11, there are Lewis structures involving Xenon that have expanded electron shells, but the formal charge in the atom still appears to be zero, even though by all of the rules we have learned, it should be negative? Is there some kind of noble gas exception to the rule?
by Sydney Myers 4I
Tue Nov 05, 2019 2:11 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Molecular Spectroscopy
Replies: 1
Views: 41

Molecular Spectroscopy

In Outline 2, it says we have to know the difference between atomic and molecular spectroscopy, but I couldn't find anything on molecular spectroscopy in the textbook. Can anyone explain it/know where it is in the text?
by Sydney Myers 4I
Tue Nov 05, 2019 1:46 pm
Forum: Dipole Moments
Topic: Interactions between Ions and Molecules
Replies: 5
Views: 61

Re: Interactions between Ions and Molecules

For the record, anything on that slide will not be included on the midterm.
by Sydney Myers 4I
Sun Nov 03, 2019 12:55 pm
Forum: Dipole Moments
Topic: Significance
Replies: 2
Views: 29

Re: Significance

A dipole moment can also affect the shape of a molecule, since a molecule's shape is essentially its electron cloud. If the electrons are shifted or distorted by a dipole moment, then the molecule's shape and properties are changed as well.
by Sydney Myers 4I
Sun Nov 03, 2019 12:49 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power
Replies: 3
Views: 52

Re: Polarizing Power

The polarizing power follows the same trends as electronegativity, because electronegativity is a measure of how much an electron is attracted to an atom. It follows that an atom that attracts electrons will be effective at polarizing them.
by Sydney Myers 4I
Sun Nov 03, 2019 12:41 pm
Forum: Resonance Structures
Topic: All Molecules?
Replies: 4
Views: 56

Re: All Molecules?

Resonance only occurs in molecules which could theoretically switch some of their bonds (single vs double) and it would still be the same molecule but in a different orientation. In other words, there several combinations of possibilities of bonding that are equally correct. Only then will resonance...
by Sydney Myers 4I
Sun Nov 03, 2019 12:39 pm
Forum: Resonance Structures
Topic: Delocalized electrons
Replies: 2
Views: 47

Re: Delocalized electrons

Electrons are delocalized in a resonant structure, meaning they cannot be represented as a part of a single, double, or triple, bond. They are involved with multiple bonds, resulting in a sort of average bond length and strength.
by Sydney Myers 4I
Sun Nov 03, 2019 12:37 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Stability
Replies: 3
Views: 73

Re: Formal Charge Stability

Since the formula is Valence electrons minus a value, it would follow that the closer that value is to the number of valence electrons the smaller the formal charge is. The value subtracted from valence electrons is the lone pairs and half of the shared electrons. If you think about it, this value w...
by Sydney Myers 4I
Mon Oct 21, 2019 9:13 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 6
Views: 121

Re: Electron Affinity

It is important to note also that electron affinity can be a negative value. This occurs when it requires energy in order to add an electron to an atom. This happens with noble gases, for example.
by Sydney Myers 4I
Mon Oct 21, 2019 8:32 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electrostatic potential energy
Replies: 2
Views: 59

Re: Electrostatic potential energy

As long as you understand that two charges interact with each other and we can measure their interaction, and that it affects the energy of electrons in a multi-electron atom, you're good. We don't do calculations with that equation.
by Sydney Myers 4I
Mon Oct 21, 2019 8:30 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Specifics
Replies: 3
Views: 43

Re: Electron Configuration Specifics

He did this in order to demonstrate Hund's Rule, that electrons fill each orbital before they are paired in one orbital. He was representing each electron in its own orbital instead of just giving the total number of electrons in the subshell. He said that it's BETTER and more specific to do it in t...
by Sydney Myers 4I
Mon Oct 21, 2019 8:27 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 3
Views: 37

Re: Atomic Radius

One difference between atomic and covalent radii versus ionic radii is that when we measure an ionic radius, it's more complicated than simply dividing the distance between the nuclei of two atoms in the ionic bond because they are of different size. Also, the ionic radius of, for example, chlorine,...
by Sydney Myers 4I
Mon Oct 21, 2019 8:22 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 7
Views: 50

Re: Effective Nuclear Charge

Effective nuclear charge is the phenomena of inner electrons shielding the effects of the attraction from the nucleus on outer electrons. Because the outer electrons are more loosely bound, the radius of the atom increases.
by Sydney Myers 4I
Sat Oct 19, 2019 9:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Two electrons per orbital
Replies: 2
Views: 23

Re: Two electrons per orbital

The reason that each orbital is limited to two electrons is because of electron-electron repulsion. The reason that two electrons can coexist in an orbital is because they have opposite spins, which is the lowest energy state. Since there are only two states that electrons can exist in an orbital, t...
by Sydney Myers 4I
Fri Oct 18, 2019 12:26 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 4
Views: 54

Re: Rydberg Equation

Lavelle advised us not to use Rydberg's Equation because it's easier to understand what's going on if you calculate the energies at both the levels (using E= -hR/n^2) then subtract the initial from the final.
by Sydney Myers 4I
Fri Oct 18, 2019 12:23 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminacy in Position [ENDORSED]
Replies: 5
Views: 108

Re: Indeterminacy in Position [ENDORSED]

To answer Leila's question, Δx represents the indeterminacy in position of the e-, or the possible places to find the e-. Since we suppose that the e- is possibly in the nucleus, we would use the diameter of the nucleus to represent the uncertainty in position. It would not have anything to do with...
by Sydney Myers 4I
Wed Oct 16, 2019 12:00 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1B.25
Replies: 4
Views: 76

Re: 1B.25

I'm confused about this one as well, particularly on how a one-dimensional box can even exist?? Boxes are two-dimensional right?
by Sydney Myers 4I
Tue Oct 15, 2019 11:09 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Wave Model or Particle Model?
Replies: 3
Views: 43

Re: Atomic Spectra Wave Model or Particle Model?

In general, associate the photoelectric effect with electrons being treated as particles (because the intensity of the electron doesn't change its energy, which is counterintuitive when thinking about a wave) and the three fundamental equations we learned (deBroglie's, Heisenberg's Uncertainty Equat...
by Sydney Myers 4I
Mon Oct 14, 2019 4:53 pm
Forum: Properties of Light
Topic: Matching Wavelength to Type of EM Radiation
Replies: 2
Views: 31

Re: Matching Wavelength to Type of EM Radiation

Lavelle has said that we don't have to know all of the specifics, but know that visible light ranges from 400-700 nm, and radiation with more energy (UV, gamma rays for example) has shorter wavelengths (<400) and radiation with less energy have longer wavelengths.
by Sydney Myers 4I
Wed Oct 09, 2019 10:33 pm
Forum: Properties of Electrons
Topic: Energy Levels
Replies: 8
Views: 70

Re: Energy Levels

I think that electrons generally only drop one energy level at a time so they would emit one photon when they drop the first level and then emit a second photon when they drop the second level. I'm not 100% sure about this though so if anyone knows for sure, please correct me if I'm wrong Electrons...
by Sydney Myers 4I
Wed Oct 09, 2019 10:29 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Typical wavelength for spectrum
Replies: 2
Views: 58

Re: Typical wavelength for spectrum

For atomic spectroscopy, it is necessary to expose an element or molecule to every wavelength of light in the electromagnetic spectrum in order to find all of the wavelengths of light that the element/molecule absorbs/emits. I don't think that UV is given special consideration, but maybe a lot of el...
by Sydney Myers 4I
Wed Oct 09, 2019 10:25 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Photon Absorption/Emission
Replies: 8
Views: 202

Re: Photon Absorption/Emission

Absorption of a photon will excite electrons to a higher energy level only if the photon contains enough energy to move electrons to energy levels beyond their ground state. When the electrons drop back down to their ground state, a photon will be emitted. This isn't technically correct and is conf...
by Sydney Myers 4I
Wed Oct 09, 2019 10:19 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework Problem A11
Replies: 4
Views: 62

Re: Homework Problem A11

The gaps between energy levels get larger the further from the nucleus you go, so the jumps (or emissions) with the largest energy will have to do with the largest gap because it would require the most energy to jump. Since the largest gap will always involve n=1, it is said to be associated with th...
by Sydney Myers 4I
Wed Oct 09, 2019 10:14 pm
Forum: Properties of Light
Topic: Work Function
Replies: 3
Views: 36

Re: Work Function

Another thing to note is that there is actually no formula for the work function that we learned. It's a constant that is usually given in a problem (if not, it can be found if you have an electron's excess energy after being removed and the energy that the photon had when it hit the electron)
by Sydney Myers 4I
Wed Oct 02, 2019 4:46 pm
Forum: Empirical & Molecular Formulas
Topic: HW problem F9
Replies: 8
Views: 133

Re: HW problem F9

If by molar ratio you're talking about the whole numbers that you get once you've manipulated the number of moles of each substance into a ratio (dividing by the smallest amount then multiplying all of those ratios by a scalar until they're all whole numbers), then yes, they are the same as the atom...
by Sydney Myers 4I
Wed Oct 02, 2019 4:41 pm
Forum: Significant Figures
Topic: Quick General Question!
Replies: 5
Views: 123

Re: Quick General Question!

In my high school chemistry class we were allowed to truncate, but my teacher said it was a bit ambiguous on what any college professor would want. She also said that rounding is generally safer, so I would get in the habit of rounding.
by Sydney Myers 4I
Wed Oct 02, 2019 4:36 pm
Forum: Limiting Reactant Calculations
Topic: How do you oxidize a formula?
Replies: 2
Views: 37

Re: How do you oxidize a formula?

The previous reply is right; in this problem, all you need to know about oxidation is that it occurs during combustion. If you want to understand what oxidation is though, it is what happens when an atom loses some of its electrons during a chemical reaction. Oxygen has a high electronegativity, so ...
by Sydney Myers 4I
Wed Oct 02, 2019 4:32 pm
Forum: Limiting Reactant Calculations
Topic: Topics on Upcoming Test [ENDORSED]
Replies: 7
Views: 344

Re: Topics on Upcoming Test [ENDORSED]

I think by fundamentals he means more than just the four modules, because there is more than that covered in the fundamentals section of the textbook that he told us to read.
by Sydney Myers 4I
Wed Oct 02, 2019 4:28 pm
Forum: Properties of Light
Topic: Frequency and Hertz
Replies: 5
Views: 78

Frequency and Hertz

So I know that Hertz is the number of oscillations per second, but is there a unit for oscillation? In other words, if we were to break down the unit Hz, it would be *blank*/s. What's the blank?

Go to advanced search