Search found 103 matches

by Izzie Capra 2E
Wed Mar 11, 2020 10:51 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Units for reaction rates
Replies: 9
Views: 266

Re: Units for reaction rates

I always think about units with a quick rule: - determine the overall order of the reaction -take the overall order and subtract 1 and add a negative. That is the number that will go with molarity (M) - also include time with -1. This makes sense when you write out all the units and see what cancels...
by Izzie Capra 2E
Wed Mar 11, 2020 10:49 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Approximating X
Replies: 13
Views: 99

Re: Approximating X

Make sure you always check using the 5% ionization rule when approximating, there are some odd cases where the K value is incredibly small but there can be a discrepancy of greater than 5%. In this case, you would have to use the quadratic formula.
by Izzie Capra 2E
Wed Mar 11, 2020 10:46 am
Forum: Zero Order Reactions
Topic: Graphs
Replies: 4
Views: 25

Re: Graphs

You can also derive the equation [A] = -kt + [A]o by using the graph of the zero-order reaction. Since the graph is concentration (y-axis) vs. time (x-axis), this equation makes sense because it is in y=mx+b form. [A] is substituted in for y, -k is the slope, t represents x and [A]o is the initial c...
by Izzie Capra 2E
Wed Mar 11, 2020 10:41 am
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2528

Re: ENDGAME Review Session

Thank you Lyndon! I honestly couldn't have done this class without you! You will be missed.
by Izzie Capra 2E
Wed Mar 11, 2020 10:39 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts and Reaction Pathways
Replies: 6
Views: 37

Re: Catalysts and Reaction Pathways

The catalyst essentially does the same thing for a reverse reaction. Just as a catalyst provides a new, quicker pathway for the forward reaction, it also creates a new pathway for the reverse reaction.
by Izzie Capra 2E
Wed Mar 11, 2020 10:37 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 3
Views: 24

Re: Catalysts

You can tell you have a catalyst when you have a species that is used up (on the left/reactant side of a reaction mechanism) then regenerated (ends up on the right/product side of another reaction mechanism). You can tell you have an intermediate when you have a species that is formed (right) then u...
by Izzie Capra 2E
Sun Mar 08, 2020 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K notation
Replies: 4
Views: 42

Re: K notation

I don’t think you’ll get marked down for not using subscripts. I could be wrong, but I think it is fine to just use K in these kinds of problems, like in the homework. I guess since we were using concentrations it would be Kc, but I wouldn’t worry about it! I bet you did well :)
by Izzie Capra 2E
Tue Mar 03, 2020 12:50 pm
Forum: Balancing Redox Reactions
Topic: Acidic/Basic Solution
Replies: 2
Views: 26

Re: Acidic/Basic Solution

If it's a redox reaction and it says it occurs under basic or acidic conditions, you will balance the reaction by adding H20 and H+ (and also OH- for reactions in basic solution) to make sure all the molecules match. It just depends on the problem you are given. However, if it's basic you should def...
by Izzie Capra 2E
Tue Mar 03, 2020 12:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 6
Views: 29

Re: Platinum

You use Pt and put it in the cell digram when the half-reactions/species you are working with do not have a conducting solid. So say, all your molecules are ions in an aqueous solution, then you need a conducting solid to function as the electrode. You can use Pt because it is one of the most common...
by Izzie Capra 2E
Mon Mar 02, 2020 12:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Notation Layout
Replies: 7
Views: 49

Re: Cell Notation Layout

Yes, anode goes on the left and cathode goes on the right. This makes sense because the flow of electricity flows from the anode to the cathode, so when you read the cell diagram, it should represent the flow of electrons with the salt bridge in the middle.
by Izzie Capra 2E
Mon Mar 02, 2020 12:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tips for Test
Replies: 23
Views: 211

Re: Tips for Test

Micah3J wrote:Does anyone have any good youtube videos that are short but helpful for the electro chemistry material?


I highly recommend the Organic Chemistry Tutor. Search him up on YouTube and the topic you are looking for, and there is a very high chance there will be a video for the topic you need.
by Izzie Capra 2E
Mon Mar 02, 2020 12:35 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: at equilibrium
Replies: 1
Views: 36

Re: at equilibrium

The Nernst equation relates the cell potential, standard cell potential and reaction quotient that accounts for the concentrations (Q, which is similar to K). You can use the equation to find missing information. You use Q in this situation because we don't know that the system being studied is at e...
by Izzie Capra 2E
Tue Feb 25, 2020 12:41 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: conducting solids
Replies: 5
Views: 39

Re: conducting solids

Katie Bart 1I wrote:So are groups 1 and 2 metals considered to be conducting solids?


Yes, groups 1 and 2 are considered to be conducting solids. Any metals are good conductors. Dr. Lavelle also mentioned that Platinum is one of the most common conducting solids that we should worry about.
by Izzie Capra 2E
Tue Feb 25, 2020 12:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Writing Cell diagram
Replies: 2
Views: 27

Re: Writing Cell diagram

Yeah, I agree ^^. As long as you have all components in the right section of the cell diagram, I don't believe order matters. Just make sure you have the single lines separating the species and a double line representing a salt bridge (or a single line for a porous disk) in the middle of the anode a...
by Izzie Capra 2E
Tue Feb 25, 2020 12:34 pm
Forum: Balancing Redox Reactions
Topic: Which equation do we flip?
Replies: 6
Views: 44

Re: Which equation do we flip?

You flip the side that is being oxidized.
by Izzie Capra 2E
Tue Feb 25, 2020 12:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Lecture notes
Replies: 4
Views: 47

Re: Lecture notes

Seeing how changing the concentration would affect the cell potential works a lot like Le Chatlier's principle. If you increase the concentration of a reactants, the Ecell will be greater than the standard E value of the cell. If you increase the concentration of a product, then the standard E value...
by Izzie Capra 2E
Tue Feb 25, 2020 12:27 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Determining Voltage Values of Anode and Cathode
Replies: 1
Views: 15

Re: Determining Voltage Values of Anode and Cathode

I think they are measured values from experimentation. They are in a list of values much like standard enthalpy of formation or standard Gibbs free energy values because they have been calculate and observed through chemical experimentation. The voltage values represent the voltage for the half reac...
by Izzie Capra 2E
Thu Feb 20, 2020 10:19 am
Forum: Lewis Acids & Bases
Topic: Midterm Question 3B
Replies: 3
Views: 168

Midterm Question 3B

Hello! Can someone please explain how to reason through question 3B on the midterm. I understand that the combination of HCl and NaOH would be a strong base and a strong acid being titrated, but I am confused on how to pick which combination would give the largest deltaT. I guess I am just a bit con...
by Izzie Capra 2E
Thu Feb 20, 2020 10:16 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential Difference
Replies: 3
Views: 25

Re: Cell Potential Difference

Yes, these will correspond to the standard cell potentials for the half-reactions.
by Izzie Capra 2E
Thu Feb 20, 2020 10:14 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential
Replies: 3
Views: 20

Re: Cell Potential

It is basically the same thing, Dr. Lavelle was just using the equation instead of reasoning through the sign change. I like to flip the sign of the oxidation half-reaction then sum them together. I think the equation gets confusing with all the signs.
by Izzie Capra 2E
Thu Feb 20, 2020 10:07 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework Problem 6L.1
Replies: 2
Views: 30

Re: Homework Problem 6L.1

You have to look at all the oxidation numbers and find the oxidation and reduction agents. Then you see how many electrons were transferred and how the oxidation numbers change. Then you have to balance the half reactions so you can see how many total moles of electrons were transferred in the react...
by Izzie Capra 2E
Thu Feb 20, 2020 10:04 am
Forum: Balancing Redox Reactions
Topic: oxidation number
Replies: 3
Views: 31

Re: oxidation number

Many times, when you have a monoatomic ion, the oxidation number is just the charge. However, there are other cases when they are different. For example, when an element is in its standard state, the oxidation number is 0. And note that when you have a neutral molecule, the sum of the oxidation numb...
by Izzie Capra 2E
Tue Feb 11, 2020 3:45 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4H.1
Replies: 1
Views: 21

Re: 4H.1

Hi! So I know Lavelle doesn't talk much about disorder, but sometimes it's useful to think of "disorder" in addition/conjunction to thinking about the possible orientations of particles. So for a. HBr has a higher entropy because the molecule is larger and just has more particles in all, w...
by Izzie Capra 2E
Tue Feb 11, 2020 3:39 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Pizza Rolls Question 5!! Help
Replies: 3
Views: 66

Re: Pizza Rolls Question 5!! Help

Yes, you can add the moles together. Also, in the session we used 3/2R, because the volume isn't changing in this part of the question.
by Izzie Capra 2E
Tue Feb 11, 2020 3:36 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.7
Replies: 4
Views: 51

Re: 4A.7

You have to find the heat it takes to heat the pot and the heat required to heat the water and sum them together to get qtotal. So, qtotal = ncdeltaT(pot) + ncdeltaT (water). Make sure you use their respective specific heat capacities. Then, for part b, you see how much heat is needed to heat just t...
by Izzie Capra 2E
Tue Feb 11, 2020 3:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for Enthalpy
Replies: 2
Views: 16

Re: Units for Enthalpy

Yes, many times they will be in KJ/mol. Pay attention though because sometimes it can be written in just kilojoules.
by Izzie Capra 2E
Tue Feb 11, 2020 1:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity
Replies: 3
Views: 38

Heat capacity

Hello! I am confused how to know when you use the molar heat capacity or specific heat capacity...? When using the equation q=ncdeltaT, most of the time you use the specific heat capacity, especially when dealing with liquid water. I'm confused why on a problem like 4I5 in the homework, you use the ...
by Izzie Capra 2E
Tue Feb 04, 2020 9:55 pm
Forum: Phase Changes & Related Calculations
Topic: reversible reactions
Replies: 2
Views: 24

Re: reversible reactions

It depends on the volumes given. That could be possible, but I think it means that, in comparison to an irreversible reaction, both reactions can reach the same final volume. However, the reversible reaction occurs slowly, that's why the equations are different. More work is done in this instance as...
by Izzie Capra 2E
Tue Feb 04, 2020 2:25 pm
Forum: Calculating Work of Expansion
Topic: when to use...?
Replies: 4
Views: 43

Re: when to use...?

I think the other equation is w= -nRTln(V2/V1). Use this when work is being done at a non-constant pressure.
by Izzie Capra 2E
Tue Feb 04, 2020 2:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: C = K?
Replies: 5
Views: 36

Re: C = K?

I think it means that when you raise the temperature by 1 degree C, that is the same thing as raising by 1 degree K, because they are on the same number scale.
by Izzie Capra 2E
Tue Feb 04, 2020 2:21 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equation
Replies: 2
Views: 22

Equation

Can someone please explain when to use the equation 3/2nRT...? I am confused when this will be applicable/how it was obtained/what kind of problem to use it for.
by Izzie Capra 2E
Tue Feb 04, 2020 2:18 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 14
Views: 89

Re: closed vs isolated

Closed means that energy can exchange with the surroundings. It will be sealed but not completely... Isolate means completely sealed, so nothing can exchange with the surroundings (ex. bomb calorimeter). Isolated is even more "protected" from transfer into the surroundings if you will.
by Izzie Capra 2E
Thu Jan 30, 2020 10:02 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: State Functions
Replies: 6
Views: 54

Re: State Functions

I think of it like the climbing a mountain example Lavelle gave in class. Hikers took two different paths- one long and one direct route. They ended in the same place, but the distance the long one did was much greater than the short path. This is similar to work in a reaction because you can take d...
by Izzie Capra 2E
Thu Jan 30, 2020 9:57 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Mondays Lecture Question
Replies: 3
Views: 32

Re: Mondays Lecture Question

Density is needed to help find the mass of the solution. You had 100ml and the density was 1g/ml. This cancels out ml, so you are left with mass, which is what you need for q=mcdeltaT.
by Izzie Capra 2E
Thu Jan 30, 2020 9:53 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta H v. q
Replies: 5
Views: 48

Re: Delta H v. q

I believe that q is simply the heat that can be measured in a transfer. Enthalpy (delta H) is the total heat content in a system. It is energy, kind of like its potential energy RELATING to heat.
by Izzie Capra 2E
Thu Jan 30, 2020 9:49 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating enthalpy
Replies: 1
Views: 23

Re: Calculating enthalpy

You use Hess's Law when you are given multiple different reaction "steps" that will add up to the final reaction you are looking for. The enthalpies will be given for the reaction, and you will have to manipulate each reaction so they all add up to the final. The enthalpy values will chang...
by Izzie Capra 2E
Thu Jan 30, 2020 9:46 am
Forum: Calculating Work of Expansion
Topic: Integral
Replies: 4
Views: 36

Re: Integral

I believe Lavelle will simplify the integral equation next lecture. In the textbook, there is an equation that is much easier to work with--I believe he will be discussing that. This one was used when discussing reversible, isothermal expansion reactions: the ones done in small steps (hence the inte...
by Izzie Capra 2E
Sat Jan 25, 2020 1:35 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Reaction Enthalpies
Replies: 2
Views: 28

Standard Reaction Enthalpies

What happens if a reaction does not occur at standard conditions, specifically if it does not occur at 1atm? What other elements would you have to consider?
by Izzie Capra 2E
Sat Jan 25, 2020 1:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 5
Views: 38

Re: Hess's Law

Yes, and sometimes you will have to manipulate the steps of the reaction to form the proper additive, final reaction. For example, you can make a forward reaction a reverse reaction by multiplying the enthalpy value by a negative. Or, you can multiply a step of the reaction by an integer in order to...
by Izzie Capra 2E
Sat Jan 25, 2020 1:26 pm
Forum: Phase Changes & Related Calculations
Topic: Steam Burn
Replies: 6
Views: 54

Re: Steam Burn

Yes, I think the term he used was the enthalpy of condensation was very large (a large enthalpy to go from a vapor to a liquid), which will have a stronger and more painful effect on the skin.
by Izzie Capra 2E
Sat Jan 25, 2020 1:22 pm
Forum: Phase Changes & Related Calculations
Topic: Endothermic and Exothermic
Replies: 13
Views: 72

Re: Endothermic and Exothermic

Endothermic reactions absorb heat and use heat as a reactant. This way, the surrounding become cool because heat was absorbed in the reaction. Basically, heat goes in. Exothermic reactions release heat (heat is a product), which makes the surroundings warm. Here, heat goes out.
by Izzie Capra 2E
Sat Jan 25, 2020 1:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure vs. Concentration
Replies: 5
Views: 35

Re: Partial Pressure vs. Concentration

If it doesn't give a hint in the problem whether it is concentration (would give molarities) or partial pressure (atm or bar), you can use either as the ratio represents the same thing: products over reactants.
by Izzie Capra 2E
Wed Jan 15, 2020 12:02 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Real reason explaining Le Chatelier's principle
Replies: 4
Views: 42

Re: Real reason explaining Le Chatelier's principle

Due to the same logic as stated above, I think it's important to note that when pressure decreases, the reaction will shift to the side with more moles.
by Izzie Capra 2E
Wed Jan 15, 2020 12:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids and Base Equilibria
Replies: 4
Views: 51

Re: Acids and Base Equilibria

Yes, and when working with weak acids and bases (Ka and Kb), you will most likely be working with an ICE table to determine concentrations and percent dissociation (since weak acids and bases don't fully dissociate in water).
by Izzie Capra 2E
Wed Jan 15, 2020 11:57 am
Forum: Administrative Questions and Class Announcements
Topic: Test 1 Topics
Replies: 4
Views: 58

Re: Test 1 Topics

I would prepare for problems involving writing equilibrium constant expressions, solving for concentrations using ICE tables and conceptual questions involving Le Chatlier's principle. I think acids and bases will be tested heavily. But many of the concepts would probably be acid/base equilibrium, s...
by Izzie Capra 2E
Wed Jan 15, 2020 11:53 am
Forum: Ideal Gases
Topic: ICE Table
Replies: 11
Views: 102

Re: ICE Table

Yes, and when using an ice table, make sure you check to make sure the equation you are looking at is balanced because the stoichiometric coefficients will play a role in the Change in concentration step. The coefficient will proceed the x term.
by Izzie Capra 2E
Wed Jan 15, 2020 11:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to omit "x-term"
Replies: 6
Views: 51

When to omit "x-term"

Hello! I am a bit confused when calculating concentrations at equilibrium when you can omit the "minus x" (or assume x=0) term that we got from an ICE table. When solving for K and you have x^2/concentration - x, when do you know to omit the x from the denominator?
by Izzie Capra 2E
Thu Jan 09, 2020 4:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 2
Views: 16

Re: Kc and Kp

I don't think you can directly convert from Kc to Kp. But, you can convert partial pressures to concentrations and vice versa. You use the ideal gas law PV=nRT to do this. P=nRT/V=concentration x RT. Then, concentration=P/RT. So, you could potentially convert all the products and reactants from part...
by Izzie Capra 2E
Thu Jan 09, 2020 4:01 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: confused about ice table
Replies: 5
Views: 39

Re: confused about ice table

An ICE table is a method to keep track of initial and final concentrations during an equilibrium reaction. You will write down all your reactants and products and mark their initial concentrations (the I in ICE). Then you will look for the change, which is denoted by x. Reactants will lose concentra...
by Izzie Capra 2E
Thu Jan 09, 2020 3:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp v. Kc
Replies: 5
Views: 36

Re: Kp v. Kc

Yes, I think it is safe to say it would be Kp. If you have gases in a reaction without knowing if the products and reactants are denoted by concentrations or measurements of pressure, you can write it as partial pressures. However, if the problem gives concentrations for the gases in moles/L, then y...
by Izzie Capra 2E
Thu Jan 09, 2020 3:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Purity
Replies: 3
Views: 49

Re: Purity

^^ I agree with this statement. When calculating K, look at the products and reactants that are either in the gas or aqueous phase. Pure solids or liquids shouldn't be used in the K expression or calculations.
by Izzie Capra 2E
Thu Jan 09, 2020 3:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q
Replies: 4
Views: 34

Re: Q

I think Q is especially important in a lab setting because you can predict which direction a reaction will proceed, even if it is not at equilibrium. You can calculate Q at any point during a reaction, but K is only at equilibrium. Comparing the values will show you where you "are" in a ch...
by Izzie Capra 2E
Thu Dec 05, 2019 6:19 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acids/Bases vs. Lewis Acids/Bases
Replies: 3
Views: 41

Bronsted Acids/Bases vs. Lewis Acids/Bases

I apologize if this is a silly question... but I am having trouble knowing how to know which type of acid/base you are working with. I understand that in Bronsted, acids are proton donors and bases are H+ acceptors, and in Lewis, acids are e- acceptors and bases are e- donors. These seem very contra...
by Izzie Capra 2E
Thu Dec 05, 2019 4:25 pm
Forum: Bronsted Acids & Bases
Topic: J.7
Replies: 8
Views: 93

Re: J.7

Since this is a neutralization problem, your products are water and whatever they give you; now, you need to figure out what its reactants are from those. So, for A, you see that KBr and H2O are the products. So, the reactants must be KOH (base) and HBr (acid). This combination of H+ ions and OH- i...
by Izzie Capra 2E
Thu Dec 05, 2019 4:16 pm
Forum: Bronsted Acids & Bases
Topic: 6C.19
Replies: 1
Views: 22

Re: 6C.19

HClO4 is a stronger acid because Cl is more electronegative than P in the other molecule, which makes it more polar and acidic.
by Izzie Capra 2E
Thu Dec 05, 2019 4:13 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Shape of Coordination Compounds
Replies: 1
Views: 35

Re: Shape of Coordination Compounds

I think you should be able to determine the shape of a coordination compound by looking at how many ligands are attached to the central atom. This is similar to regions of electron density when determining VSPER shapes, so they usually follow that model. A common example is octahedral.
by Izzie Capra 2E
Thu Dec 05, 2019 4:01 pm
Forum: Bronsted Acids & Bases
Topic: Homework Problem 6A 17 c and d
Replies: 1
Views: 22

Re: Homework Problem 6A 17 c and d

Dr. Lavelle mentioned that certain elements possess amphoteric properties. These elements fall near the diagonal band of metalloids on the periodic table. I think you just have to be familiar with or memorize what elements would be amphoteric based on their placement in the table. Bi and As are two ...
by Izzie Capra 2E
Thu Dec 05, 2019 3:57 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Titrations
Replies: 2
Views: 92

Re: Titrations

I think we just need to know when a salt either increases the pH (above 7) or decreases (less than 7), showing whether the product is slightly acid or slightly basic. Basically, we can use what we know now to predict what would could happen during a titration (what the stoichiometric point would be)...
by Izzie Capra 2E
Tue Nov 26, 2019 7:14 pm
Forum: Naming
Topic: 9C.3
Replies: 6
Views: 56

Re: 9C.3

When going from the compound name to the formula, it does not matter the order of the ligands. As long as you have the correct number and all ligands present, you should be fine. Make sure though, that if going from formula to naming the compound that you put the ligands in alphabetical order.
by Izzie Capra 2E
Tue Nov 26, 2019 7:11 pm
Forum: Naming
Topic: Polydentate
Replies: 4
Views: 50

Re: Polydentate

Yes, and make sure that, when determining if a ligand is polydentate, that a molecule can bind to the SAME central metal atom. If they cannot bind to the same central transition metal, then it is not polydentate and it cannot form chelating complexes.
by Izzie Capra 2E
Tue Nov 26, 2019 7:02 pm
Forum: Hybridization
Topic: plane
Replies: 2
Views: 33

Re: plane

Yes, this is a good example^. I also like to visualize the atomic models that Dr. Lavelle had in class when discussing shapes. Being on the same plane means that a certain number of points are flat. So, trigonal planar, for example, all 3 atoms are in the same plane. We could see that in the model b...
by Izzie Capra 2E
Tue Nov 26, 2019 6:54 pm
Forum: Student Social/Study Group
Topic: Cyano vs. Cyanido
Replies: 3
Views: 142

Re: Cyano vs. Cyanido

There is not a difference, they represent the same thing. They are just two different naming conventions (the standard vs. the new IUPAC naming convention) that refer to the same thing. I believe you can use either and they will both be right. I like to use cyano because I think it's a little easier...
by Izzie Capra 2E
Tue Nov 26, 2019 6:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand of HN(CH2CH2NH2)2
Replies: 1
Views: 22

Re: Ligand of HN(CH2CH2NH2)2

Yes, it is possible to do this without drawing the Lewis structure. Since you have NH outside the parenthesis, you know you already have one Nitrogen atom with a lone pair. And then, since you have 2 (CH2CH2NH2), you also now have two more Nitrogen atoms with lone pairs. You now have a total of 3 Ni...
by Izzie Capra 2E
Thu Nov 21, 2019 11:25 am
Forum: Dipole Moments
Topic: Polar or nonpolar
Replies: 8
Views: 104

Re: Polar or nonpolar

Is CH2I2 polar or nonpolar? the lewis structure has the I atoms opposite from each other and the H atoms opposite from each other. It is polar because there are two different atoms (H and I) attached to the central C atom. Even though they are opposite each other in the Lewis structure, the molecul...
by Izzie Capra 2E
Thu Nov 21, 2019 11:18 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: Strongest force
Replies: 6
Views: 48

Re: Strongest force

Ion-ion and ion-dipole forces are stronger because they exhibit ionic character, which is the strongest kind of force. The bonds will be hardest to break in this case. After these forces, then hydrogen bonds are strongest, then dipole-dipole, then LDFs.
by Izzie Capra 2E
Thu Nov 21, 2019 11:13 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Which shape
Replies: 6
Views: 55

Re: Which shape

All the atoms surrounding the central atom must be the same in order for the molecule to be non-polar. Since there is Cl and H, that means this molecule will be non-polar because of the electronegativity differences, and the dipoles will not cancel out. The molecule can be either cis or trans, but i...
by Izzie Capra 2E
Thu Nov 21, 2019 11:07 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Double/Triple Bonds in Coordination Compounds
Replies: 2
Views: 38

Re: Double/Triple Bonds in Coordination Compounds

I believe coordination numbers only apply to the sigma (or single bonds) within a compound. You only look a the single bonds between the central atom and the ligands, not the pi bonds (double or triple bonds).
by Izzie Capra 2E
Tue Nov 19, 2019 7:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 3
Views: 97

Bond Angles

Say you have a molecule with VSEPR equation as AXE3. Although the electron geometry is tetrahedral (meaning bond angles of 109.5), the actual molecular shape is linear (180). Would this molecule would have bond angles of 180 since it is ultimately linear? Same thing with AXE2... Trigonal planar elec...
by Izzie Capra 2E
Sat Nov 16, 2019 11:11 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: Induced dipole-induced dipole force [ENDORSED]
Replies: 1
Views: 33

Induced dipole-induced dipole force [ENDORSED]

I understand that a dipole-induced dipole can occur when a polar and a non polar molecule interact because the polar molecule can distort the electron cloud of the non polar molecule, but I'm a bit confused on what an induced dipole-induced dipole force is? Does it involve two non polar molecules?
by Izzie Capra 2E
Sat Nov 16, 2019 11:05 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: Does dipole-dipole force only exist among polar molecules?
Replies: 9
Views: 172

Re: Does dipole-dipole force only exist among polar molecules?

Yes, because the temporary negative charge on an atom in a molecule will react with a temporary positive charge on a different atom in another molecule, which creates a dipole-dipole interaction between the two polar molecules.
by Izzie Capra 2E
Sat Nov 16, 2019 10:59 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: London Forces
Replies: 2
Views: 25

Re: London Forces

Yes, and more generally, London dispersion forces are present in any molecule or atom with an electron cloud, which is anything. There will always be a random moment in which the electrons in the electron clouds are moving and creating a dispersion force.
by Izzie Capra 2E
Sat Nov 16, 2019 10:57 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: Polarizability vs. Electronegativity
Replies: 3
Views: 25

Re: Polarizability vs. Electronegativity

Polarizability is a measure of how easily an electron cloud can be distorted. Atoms with a greater number of electrons generally have a higher polarizability. Electronegativity is a measure of how likely an atom is to draw electrons towards itself, which also increases from left to right across a ro...
by Izzie Capra 2E
Sat Nov 16, 2019 10:48 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 9
Views: 81

Re: Bond Angles

Yes, and the more lone pairs a molecule has, the more repulsion it experiences, so the bond angle will become smaller than the one you can predict based off of the shape.
by Izzie Capra 2E
Sun Nov 10, 2019 1:07 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: H20 and H2S melting/boiling point
Replies: 4
Views: 38

Re: H20 and H2S melting/boiling point

Since the strength of interactions in H20 is greater, the bonds in this molecule are also stronger and harder to break. Therefore, since the bonds are stronger, the boiling must be higher in order to break them.
by Izzie Capra 2E
Sun Nov 10, 2019 1:02 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: dipole moment and intermolecular forces
Replies: 3
Views: 74

Re: dipole moment and intermolecular forces

805291863 wrote:In addition, the intermolecular forces produced by dipole moments would be ion-dipole, dipole-dipole, or dipole-induced dipole interactions.



Are Van der Waal's forces or dispersion forces not brought about by dipole moments?
by Izzie Capra 2E
Sun Nov 10, 2019 12:42 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Lone pairs on central atom
Replies: 3
Views: 38

Re: Lone pairs on central atom

Yes, and when there are more lone pairs on the central atom, the shape becomes less symmetric and more variety in the shape of the atom.
by Izzie Capra 2E
Sun Nov 10, 2019 12:34 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: Is there a difference between Van der Waals and LDF?
Replies: 5
Views: 45

Re: Is there a difference between Van der Waals and LDF?

Yes, the answers above are correct. And since LDFs are usually the weakest and temporarily attractive intermolecular forces, most molecules will experience LDFs.
by Izzie Capra 2E
Sun Nov 10, 2019 12:28 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond
Replies: 8
Views: 164

Re: Coordinate Covalent Bond

In a regular covalent bond, the atoms involved in the bonding contribute the same number of electrons.
In a coordinate covalent bond, two electrons are contributed by a single atom.
by Izzie Capra 2E
Wed Oct 30, 2019 6:25 pm
Forum: Lewis Structures
Topic: Radicals
Replies: 2
Views: 31

Radicals

How often will you encounter radical structures? If they are highly reactive, will we see them a lot? Are they desirable?
by Izzie Capra 2E
Wed Oct 30, 2019 6:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Expanded Octet
Replies: 2
Views: 34

Expanded Octet

Which other elements besides P, S and Cl can have an expanded octet, or more than 8 valence electrons?
by Izzie Capra 2E
Wed Oct 30, 2019 6:12 pm
Forum: Electronegativity
Topic: Electronegativity trends
Replies: 5
Views: 55

Re: Electronegativity trends

I would agree that we just need to know general trends. Electronegativity increases bottom to top in a group and left to right across a period. The top right corner of the periodic table has the highest electronegativity.
by Izzie Capra 2E
Wed Oct 30, 2019 6:07 pm
Forum: Lewis Structures
Topic: Charges on Lewis Structures
Replies: 7
Views: 76

Re: Charges on Lewis Structures

I would be sure to check and make sure you have the correct number of valence electrons when you draw the structure. If not already indicated, you also have to account for the electron that is gained. You will most likely place that electron around the central atom. Then, you can place the brackets ...
by Izzie Capra 2E
Mon Oct 28, 2019 9:00 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 57

Formal Charge

How do you recognize when an atom can have a "better" representation or more stable structure? Should you complete formal charge calculations for each structure you draw or only for atoms involving P, S and Cl?
by Izzie Capra 2E
Mon Oct 28, 2019 8:43 pm
Forum: Resonance Structures
Topic: Resonance Clarification
Replies: 8
Views: 85

Re: Resonance Clarification

Also, I think it's important to know that the resonance is the average of the different positions of the bonds.
by Izzie Capra 2E
Mon Oct 28, 2019 8:41 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Losing electrons
Replies: 3
Views: 53

Losing electrons

I am still confused why, for Titanium, you would take electrons away from the 4s orbital before the 3d orbital even though 3d2 is the outermost shell...
by Izzie Capra 2E
Mon Oct 28, 2019 8:36 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Drawing Lewis Structures
Replies: 5
Views: 87

Re: Drawing Lewis Structures

Also, resonance would be an exception as the bond locations could be different. The resonance, then, becomes the average of the different positions of the bond.
by Izzie Capra 2E
Mon Oct 28, 2019 8:33 pm
Forum: Electronegativity
Topic: Calculating Electronegativity
Replies: 3
Views: 49

Re: Calculating Electronegativity

Electronegativity is a measure, specifically of the tendency of an atom to attract to a bonded pair of electrons. Most of the time, you will see the Pauling scale associated with electronegativity, but I believe these are already determined values.
by Izzie Capra 2E
Mon Oct 28, 2019 8:30 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: f-orbitals
Replies: 2
Views: 43

Re: f-orbitals

The f orbital is rarely used because it deals with radioactive elements, which are elements that are rarely used in the type of bonding we are doing. I don't believe we will need to know how to do problems with the f orbital. The f orbital comes into play when you get to these higher elements in the...
by Izzie Capra 2E
Sun Oct 20, 2019 11:46 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: configurations for p-orbital
Replies: 3
Views: 25

Re: configurations for p-orbital

Technically, I think the (px1)(py1)(pz1) is more accurate because it indicates exactly where the electrons will be found and on which axes. However, I think it is easier to write (p3) and this can be used when doing shorthand (or writing out longer) electron configurations.
by Izzie Capra 2E
Sun Oct 20, 2019 11:38 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Unpaired electrons
Replies: 1
Views: 9

Re: Unpaired electrons

Unpaired electrons are electrons that fills an orbital alone; it doesn't have another electron to provide opposite spin. It's best to think about this when you are drawing arrows to represent the electrons filling orbitals. For example, C: (atomic number =6) 2p _ _ _ 2s _ 1s _ Since there are 6 elec...
by Izzie Capra 2E
Sun Oct 20, 2019 11:32 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing Electron Configurations
Replies: 3
Views: 14

Re: Writing Electron Configurations

You choose these elements because they are the Noble Gases (column 18). This means their outer electron shells are full with electrons (they fulfill max capacity for the outer most shell), so you can use them to substitute. Instead of writing out the initial sub-shells each time, you can just pick t...
by Izzie Capra 2E
Sun Oct 20, 2019 11:22 am
Forum: Photoelectric Effect
Topic: The Work Function
Replies: 15
Views: 149

Re: The Work Function

Nare Arakelian Dis 3E wrote:Is the work function the same as the ionization energy then?


No, work function is the energy required to remove an electron from a solid, like the metals we have been talking about in lecture. The ionization energy is the energy required to move an electron from an atom in the gas phase.
by Izzie Capra 2E
Sun Oct 20, 2019 11:17 am
Forum: *Shrodinger Equation
Topic: Wave Function
Replies: 3
Views: 53

Re: Wave Function

I believe so... Photons also have wave-like and particle-like properties, so they will behave in a similar manner.
by Izzie Capra 2E
Sun Oct 13, 2019 12:42 pm
Forum: Properties of Light
Topic: Diffraction
Replies: 1
Views: 47

Diffraction

In lecture we discussed how IN GENERAL, light (waves) show different diffraction patterns. What would be an an example of a light (wave) that doesn't have these patterns or properties?
by Izzie Capra 2E
Sun Oct 13, 2019 12:23 pm
Forum: Properties of Electrons
Topic: Diffraction Patterns
Replies: 3
Views: 37

Re: Diffraction Patterns

X-ray passing through a crystal demonstrates diffraction because the wavelengths of the x-rays are so small that react with the crystal to produce unique interference. The waves bend around the medium and produce the phenomenon of diffraction.
by Izzie Capra 2E
Sun Oct 13, 2019 11:58 am
Forum: Properties of Electrons
Topic: wave properties of electrons
Replies: 5
Views: 35

Re: wave properties of electrons

Constructive interference is when waves are "in phase" (they line up and have the same frequency; the reach their maximum peak at the same time). When constructive interference happens, the maxima of the two waves add together to get a combined amplitude. They are able to "construct&q...
by Izzie Capra 2E
Sun Oct 13, 2019 11:50 am
Forum: Quantum Numbers and The H-Atom
Topic: Circular Standing Waves and "in phase"
Replies: 2
Views: 56

Re: Circular Standing Waves and "in phase"

"In phase" means that waves line up and have the same frequency. Thus, nothing is cancelled out. I believe this means that the waves surrounding the nucleus are all aligned, even though there are different energy levels. They all have the same frequency and reach their peaks/troughs at the...
by Izzie Capra 2E
Sun Oct 13, 2019 11:43 am
Forum: Properties of Electrons
Topic: circular standing wave
Replies: 2
Views: 29

Re: circular standing wave

The circular standing wave is a vibration in which there are points around the circular atom that remain fixed while other points move up and down with maximum amplitude. The wave of electrons forms around the nucleus of an atom, and the waves oscillates with fixed points around the circle with othe...
by Izzie Capra 2E
Wed Oct 02, 2019 11:19 am
Forum: Administrative Questions and Class Announcements
Topic: Tips for Tests [ENDORSED]
Replies: 4
Views: 95

Re: Tips for Tests [ENDORSED]

Watch the online modules again and do the pre and post assessments to ensure that you have the basic information.
by Izzie Capra 2E
Wed Oct 02, 2019 10:46 am
Forum: Balancing Chemical Reactions
Topic: Stoichiometric Coefficients [ENDORSED]
Replies: 8
Views: 173

Stoichiometric Coefficients [ENDORSED]

Would there ever be a case, or is it even possible to have multiple correct answers for the stoichiometric coefficients when balancing a chemical equation? Could there ever be two different "sets" of coefficients that abide to conservation of mass, or is there always one specific way to ba...

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