Search found 101 matches
- Mon Mar 16, 2020 2:00 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: ΔGionization
- Replies: 10
- Views: 820
Re: ΔGionization
I don't think there is another way, calculating for delta Gionization is the same as calculating for delta Go.
- Fri Mar 13, 2020 11:13 am
- Forum: First Order Reactions
- Topic: Units for t
- Replies: 30
- Views: 1164
Re: Units for t
It usually just depends on the units of the information you were given in the problem. I'm pretty sure you won't be marked wrong if you leave your t in either minutes or seconds (or even hour) as it is the correct number of sec/min/hr. I hope this helped!
- Fri Mar 13, 2020 11:06 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 3/2 overall order
- Replies: 3
- Views: 321
Re: 3/2 overall order
As the previous students, mentioned, it is not necessary to know fractional orders for this course. However, if you are curious, fractionals orders usually occur when products are also taken into consideration when writing the rate law. :)
- Fri Mar 13, 2020 11:02 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7A.11) 700K?
- Replies: 6
- Views: 459
Re: 7A.11) 700K?
Yes, you ignore the temperature, it's just extraneous information.
- Tue Mar 10, 2020 1:15 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Eqn, K2>K1
- Replies: 3
- Views: 984
Arrhenius Eqn, K2>K1
In regards to the Arrhenius equation that is: ln(k2/k1)=Ea/R(1/T1- 1/T2) One of the interpretation that the textbook stated was: "When T2 . T1, the right-hand side is positive, so ln(kr2/kr1) is positive, which means that kr2 > kr1. That is, the rate constant increases with temperature." I...
- Sun Mar 08, 2020 1:18 pm
- Forum: General Rate Laws
- Topic: Product in Rate Law
- Replies: 2
- Views: 254
Product in Rate Law
Usually, when we write out rate laws, we take only the reactants into consideration, i.e. for the reaction H 2 + I 2 <=> 2HI, the rate law= k[H 2 ][I 2 ] However, I know there are times that products are written into the rate law too, with a negative order,so my question is: when do we include produ...
- Fri Mar 06, 2020 10:28 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst
- Replies: 10
- Views: 718
Re: Nernst
When a problem is asking for you to solve for the pH or when you are given pH in a cell diagram, that's when you would usually use log instead of ln. Hope this helps!
- Fri Mar 06, 2020 10:26 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Figuring out n
- Replies: 15
- Views: 925
Re: Figuring out n
You would have to balance the redox half reaction to determine what n is, since n is the number of electrons needed to balance the redox reactions. Hope this helps!
- Fri Mar 06, 2020 10:23 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: HW 6L.9
- Replies: 4
- Views: 276
HW 6L.9
In homework 6L.9, the question asks us to write balanced half reaction and draw a cell diagram for the redox reaction of acidified solution of potassium permanganate and iron(II) chloride which I deduced as (KMnO 4 +FeCl <=> KCl + FeMnO 4 ). For the half reactions, I got from appendix 2B: Fe 3+ + e-...
- Mon Mar 02, 2020 4:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Hydrogen Electrode
- Replies: 2
- Views: 229
Standard Hydrogen Electrode
For clarifications, the Standard Hydrogen Electrode's significance is that it is utilized to help calculated the standard potential of other electrodes, correct? Thank you!
- Fri Feb 28, 2020 3:50 pm
- Forum: Balancing Redox Reactions
- Topic: How to tell if its being reduced or oxidized
- Replies: 15
- Views: 1907
Re: How to tell if its being reduced or oxidized
Another way you can find if the reaction is undergoing oxidation or reduction is through just balancing the half reactions. If you see that electrons needs to be added to the reactant side, then that half reaction is being reduced (Gain electron reduction); if you see that electrons needs to be adde...
- Fri Feb 28, 2020 3:43 pm
- Forum: Balancing Redox Reactions
- Topic: Oxygen's oxidation #
- Replies: 6
- Views: 424
Re: Oxygen's oxidation #
Oxygen also has an oxidation # of -1 when it is in peroxide (O22-)
- Fri Feb 28, 2020 3:39 pm
- Forum: General Rate Laws
- Topic: Deriving the Rate Equation
- Replies: 5
- Views: 444
Deriving the Rate Equation
While I know that knowing how to derive the equation is a great way to understand the equation, is it necessary to know how to derive the rate equations (like Prof. Lavelle did in 2/28 lecture) for the final exam? Thank you!
- Fri Feb 28, 2020 3:31 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation Energy
- Replies: 16
- Views: 1420
Re: Activation Energy
Activation energy can also be regarded as the "threshold energy" of a reaction, as it is the amount of energy needed for a reaction to actually occur. Hope that helps!
- Tue Feb 25, 2020 8:46 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5J.11 Halogen affect on K
- Replies: 2
- Views: 251
Re: 5J.11 Halogen affect on K
The reason that the reaction in part b is endothermic is because energy need to be absorbed into the reaction in order to break the X 2 bond. Therefore, since heat is being added into the reactant side of the reaction, increasing the temperature would then make the equilibrium shift towards the prod...
- Mon Feb 24, 2020 11:30 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5G.15
- Replies: 5
- Views: 323
Re: 5G.15
Rafsan Rana 1A wrote:for 5G.15 I keep getting -2.7 kj per mol but the answer says -27 kj per mol. Can someone tell me what I'm doing wrong is the answer key wrong.
Yeah! I kept getting -2.7 kj/mol too!
- Fri Feb 21, 2020 3:37 pm
- Forum: Balancing Redox Reactions
- Topic: Galvanic cells
- Replies: 2
- Views: 168
Re: Galvanic cells
Usually, if the (standard) cell potential is negative, then the galvanic cell is working reversibly. This is because if E is positive, the forward reaction is favored. Hope this helped!
- Fri Feb 21, 2020 3:33 pm
- Forum: Balancing Redox Reactions
- Topic: Adding Water in Redox Reactions
- Replies: 3
- Views: 361
Re: Adding Water in Redox Reactions
You add H 2 O whenever reactants and products in half reaction have different amounts of oxygen atoms in order to balance the reactions out. Then, depending on whether the reaction is in a basic solution or acidic solution, you at H+ or OH- to balance the reaction with the added water molecules out....
- Fri Feb 21, 2020 3:29 pm
- Forum: Balancing Redox Reactions
- Topic: Redox in Acid/ Basic Solutions
- Replies: 8
- Views: 496
Redox in Acid/ Basic Solutions
What is the difference between doing a redox reaction for an acidic reaction and a redox reaction for a basic reaction? Thank you!
- Fri Feb 21, 2020 3:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: E
- Replies: 5
- Views: 322
Re: E
A reaction is spontaneous when E is positive and delta G is negative. Hope that helps!
- Fri Feb 21, 2020 3:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating Standard Cell Potentials
- Replies: 2
- Views: 188
Calculating Standard Cell Potentials
When calculating standard cell potentials, if I multiply the one of the half equations by 2, do I multiply the corresponding standard cell potential by 2 too? Thank you!
- Sun Feb 16, 2020 1:03 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: K and Q and G
- Replies: 6
- Views: 399
Re: K and Q and G
In equilibrium, the activities constant Q is equivalent to the equilibrium constant K, that is why, when a reaction is at equilibrium, when can state that Q=K and replace Q in the equation delta G= -RTlnQ with K: delta G=-RTlnK. I hope this helps!
- Sun Feb 16, 2020 12:59 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free energy concept
- Replies: 16
- Views: 786
Re: Gibbs Free energy concept
The basic concept of Gibbs free energy is the energy *available* to do work by a system. It also tells us the spontaneity of a reaction, (another work to describe it is if the reaction is thermodynamically favorable). If delta G is negative, that means the reaction is spontaneous, and if delta G is ...
- Sun Feb 16, 2020 12:53 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Why is delta U = 0 for isothermal reactions?
- Replies: 11
- Views: 4205
Re: Why is delta U = 0 for isothermal reactions?
An isothermal system is one where no heat nor matter is transferred externally, meaning that the energy will always stay the same in the system. That is why U=0 in an isothermal reactions.
- Sun Feb 16, 2020 12:51 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: R constants
- Replies: 40
- Views: 2109
Re: R constants
Look at the units of the constant and units of the problem to determine which constant to use! Usually, when doing thermodynamics we will be using 8.314. Hope that helps!
- Sun Feb 09, 2020 7:54 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Second Law Thermodynamics
- Replies: 4
- Views: 229
Re: Second Law Thermodynamics
Exactly! Just like how a room naturally gets messy over time, the entropy( disorder) of the universe is constantly increasing, and work must be put in in order to decrease the entropy of a system.
- Sun Feb 09, 2020 4:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: ΔH
- Replies: 4
- Views: 182
Re: ΔH
From what a recall, Delta H of formation and condensation will usually be given to you in a problem, and you will need to find the net delta H through the given values.
- Sun Feb 09, 2020 4:16 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Textbook question 4B.9
- Replies: 4
- Views: 162
Re: Textbook question 4B.9
Since no heat is exchanged with its surrounding, q=0. Thus since -q=w, w will also be 0.
- Sun Feb 09, 2020 12:49 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Vaporization and Condensation
- Replies: 1
- Views: 105
Re: Vaporization and Condensation
Enthalpy is vaporization should be addition because bonds are being broken, and energy needed to break bonds. On the other hand, during condensation, intermolecular bonds are being formed, therefore, energy is being released and it is a subtracted. I hope this helps!
- Sun Feb 09, 2020 12:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Calculating Bond Enthalpies
- Replies: 5
- Views: 175
Re: Calculating Bond Enthalpies
Since single, double, and triple bonds all have different bond enthalpies, I believe the safest way to go about solving bond enthalpy question would be to draw out the lewis structure, so you can see the number of bonds formed between molecules.
- Sun Feb 09, 2020 12:42 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: reversible vs irreversible work
- Replies: 7
- Views: 433
Re: reversible vs irreversible work
Usually, there are key works in the problems that tells you if a system is reversible or irreversible. For instance, constant pressure means that the system is irreversible and you would use the equation w=-P(delta)V to calculate work. Hope that helps!
- Fri Jan 31, 2020 10:00 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated vs Closed [ENDORSED]
- Replies: 34
- Views: 4086
Re: Isolated vs Closed [ENDORSED]
Yes, an insulated water bottle would definately be a isolated system because no heat nor matter can be transfered. On the other hand, a normal water bottle would be an example of a closed system because while matter cannot be transfered, heat still can be transfered.
- Fri Jan 31, 2020 9:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Work done by expansion
- Replies: 8
- Views: 152
Re: Work done by expansion
No we did not, so far we've only covered w= P(ex) * change in V.
- Fri Jan 31, 2020 9:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: internal energy
- Replies: 11
- Views: 561
Re: internal energy
The equation for calculating internal energy is u= q + w.
- Fri Jan 31, 2020 9:52 pm
- Forum: Phase Changes & Related Calculations
- Topic: Units
- Replies: 16
- Views: 771
Re: Units
It is probably interchangable because we usually only need the change in temperature, and regardless of whether the temperature is in Kelvin or in Celcius, the amount that changed will still be the same.
- Thu Jan 23, 2020 12:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Water in K constant
- Replies: 6
- Views: 229
Re: Water in K constant
If water is in its gas phase in the reaction, then you do include it in your equilibrium ratio.
- Thu Jan 23, 2020 12:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice table
- Replies: 13
- Views: 534
Re: ice table
No, you do not because you do not include them in your equilibrium ratio.
- Thu Jan 23, 2020 12:45 pm
- Forum: Ideal Gases
- Topic: ICE table approximation
- Replies: 10
- Views: 356
Re: ICE table approximation
If you have a K value that is smaller than 10^-3, then you can use the approximation shortcut. If you still need more clarification, Dr. Llavell talks about this in Video Module 3. Hope that helped!
- Thu Jan 23, 2020 12:41 pm
- Forum: Ideal Gases
- Topic: Acid and Bases
- Replies: 16
- Views: 498
Re: Acid and Bases
That is correct! The lower the pH, the more acidic a substance is, and the higher the pH, the more basic a substance is.
- Thu Jan 23, 2020 12:39 pm
- Forum: Ideal Gases
- Topic: solids and K
- Replies: 8
- Views: 308
Re: solids and K
We don't included solids and pure liquids when solving for K because they don't have affect the concentration of the other reactants and products and does not exhibit a partial pressure. Hope that helps!
- Thu Jan 23, 2020 12:37 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4369
Re: Kc vs Kp
It really depends what information the problems gives you. If the concentrations of the reactants and products are given, then you you Kc, on the other hand, if the pressure of the reactants and products are given then you use Kp.
- Thu Jan 23, 2020 12:35 pm
- Forum: Ideal Gases
- Topic: homework #3
- Replies: 16
- Views: 823
Re: homework #3
Homework #3 should probably on the Acid and Base Equilibria since that is what llavel is teaching in the past few lectures.
- Thu Jan 23, 2020 12:34 pm
- Forum: Ideal Gases
- Topic: ICE Tables
- Replies: 8
- Views: 460
Re: ICE Tables
If you are only given intial concentrations of the reactant and products and the K value, then create an equilibrium ratio and solve for Q. If Q < K, then the reaction is moving in the forwrd direction, and the reactants will have -x while the product is +x. On the other hand, if Q > K, then the rea...
- Thu Jan 23, 2020 12:28 pm
- Forum: Ideal Gases
- Topic: Inert Gases and Equilibrium
- Replies: 6
- Views: 257
Re: Inert Gases and Equilibrium
Inert gases usually won't react with reactants already present in the reaction, therefore, it will not change the concentration of the reactants nor products, and since the concentrations don't change, the equilibrium remains the same.
- Tue Jan 21, 2020 6:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chem Equilibrium Part 2 Post-Assessment, #29
- Replies: 2
- Views: 103
Re: Chem Equilibrium Part 2 Post-Assessment, #29
I'm redoing the post-assessments and can't quite figure out this problem either! I keep getting K= .25 (but the correct answer is 4.98).
- Fri Jan 10, 2020 5:32 pm
- Forum: Ideal Gases
- Topic: K value
- Replies: 14
- Views: 1087
Re: K value
A large K value indicates that there are more prouducts present in the reaction while a small K value indicates that there are less product (and thus more reactant) present in the reaction.
- Fri Jan 10, 2020 5:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K expression involving solids/liquids
- Replies: 7
- Views: 249
Re: K expression involving solids/liquids
Solid and pure liquids cannot really react effectively with other substances and doesn't have a concentratio, therefore they are not included in the equilibrium constant equation.
- Fri Jan 10, 2020 5:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 279
Re: Le Chatelier's Principle
As the previous posts stated, Le Chatelier's principle just means that a reaction will adjust in order to go back to equilibrium.
- Fri Jan 10, 2020 5:20 pm
- Forum: Ideal Gases
- Topic: Chatelier’s Principle
- Replies: 8
- Views: 194
Re: Chatelier’s Principle
Le Chatelier's principle means that a reaction will adjust itself to keep its equilibrium (constant K).
- Thu Jan 09, 2020 11:46 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constant
- Replies: 2
- Views: 109
Equilibrium Constant
This is sort of a dumb question, but what is the purpose of an equilibrium constant? Why are they useful? Thank you!
- Sat Dec 07, 2019 11:16 am
- Forum: Hybridization
- Topic: what are terminal atoms?
- Replies: 3
- Views: 8338
what are terminal atoms?
I read from the textbook that terminal atoms are not regarded as hybridized. (i.e. the Cl molecules in PCl5) What are the definition of terminal atoms? Thank you!
- Fri Dec 06, 2019 7:30 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Titrations
- Replies: 2
- Views: 272
Re: Titrations
^Exactly, if I remember correctly, we will only start doing calculations for titrations in 14B or 14BL.
- Fri Dec 06, 2019 7:28 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: HF
- Replies: 4
- Views: 407
Re: HF
^Furthermore, because F is so electronegative, the H-F bond is shorter, and make it harder for the H+ ion (aka proton) to dissociate from the HF molecule.
- Fri Dec 06, 2019 7:24 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH vs. pOH
- Replies: 17
- Views: 2261
Re: pH vs. pOH
pH calculates is the amount of H+ in a solution while pOH calculates the amount of OH-. Both utilizes -log to determine their concentration, however, for pOH, you must subtract the value you get from the -log[OH-] to get the correct answer. I hope that helped!
- Fri Dec 06, 2019 7:20 pm
- Forum: Polyprotic Acids & Bases
- Topic: polyprotic v. bronsted
- Replies: 3
- Views: 324
Re: polyprotic v. bronsted
Yes they are, polyprotic acids/bases are simply bronsted acids/bases that can donate/accept more than one proton.
- Fri Dec 06, 2019 7:09 pm
- Forum: Polyprotic Acids & Bases
- Topic: How can you tell if an acid/base is polyprotic?
- Replies: 6
- Views: 940
Re: How can you tell if an acid/base is polyprotic?
Usually, if a molecule has more than one hydrogen molecule, it means it is polyprotic (I.e. H2SO4) since it shows that they are able to donate more than one proton. As for polyprotic bases, they are able to accept more than one protons, therefore, you can look out for those when you see a molecule w...
- Fri Dec 06, 2019 7:05 pm
- Forum: Polyprotic Acids & Bases
- Topic: Defintion
- Replies: 39
- Views: 2335
Re: Defintion
Usually, if a molecule has more than one hydrogen molecule, it means it is polyprotic (I.e. H2SO4) since it shows that they are able to donate more than one proton. Hope that helps!
- Fri Dec 06, 2019 7:00 pm
- Forum: Conjugate Acids & Bases
- Topic: Homework 6.A.1 #3: Polyprotic Acids
- Replies: 1
- Views: 167
Re: Homework 6.A.1 #3: Polyprotic Acids
I had that same question when I was doing the homework too! I believe unless specified otherwise, I would do a monoprotic proton transfer. (But technically, you are wrong! The two molecules are polyprotic.)
- Fri Dec 06, 2019 6:56 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acids/Bases vs. Lewis Acids/Bases
- Replies: 3
- Views: 248
Re: Bronsted Acids/Bases vs. Lewis Acids/Bases
805097738 wrote:So bronsted and lewis acids and bases are the same thing just described differently based off of e- or H+ action?
Exactly! Lewis and Bronsted acids/bases are kind of like the inverse of each other. I.e. Lewis acids are electron acceptors, bronsted acids are proton donors.
- Fri Dec 06, 2019 6:53 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Lewis Acid
- Replies: 5
- Views: 632
Re: Lewis Acid
Lewis acids are election acceptors, therefore since Ag+ and BF3 have the ability to accept electron, they are lewis acids. (Whereas electron donors are lewis bases.) Hope that helped!
- Thu Dec 05, 2019 5:13 pm
- Forum: Naming
- Topic: Question 9C1
- Replies: 1
- Views: 96
Question 9C1
In the coordinating compound [Fe(CN)6]4-, why is the name Hexacyanoferrate and not instead Hexacyano"iron-ate"?
- Fri Nov 22, 2019 5:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle of bent
- Replies: 17
- Views: 1227
Re: Bond Angle of bent
It really depends on how many lone pair the molecule have. If there is only one lone pair, then the angle will be slightly-less-than 120 degrees, if there are two lone pairs, then the angle will be slighty-less-than 109.5 degrees.
- Fri Nov 22, 2019 5:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Density Isosurface [ENDORSED]
- Replies: 1
- Views: 66
Density Isosurface [ENDORSED]
Is it necessary to know how density isourface and electrostatic potential surface works? (They were discussed in the textbook) Thanks!
- Fri Nov 22, 2019 5:22 pm
- Forum: Hybridization
- Topic: Valance Bond Theory
- Replies: 2
- Views: 213
Valance Bond Theory
Can someone please explain the valance bond theory? Thank you!
- Fri Nov 22, 2019 5:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shaped v. Trigonal pyramid
- Replies: 9
- Views: 516
T-shaped v. Trigonal pyramid
Just for clarification, T-shaped is 3 atoms with 2 lone pair and trigonal pyramidal is 3 atoms with 1 lone pair, correct? Thanks!
- Fri Nov 22, 2019 5:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bent v. angular
- Replies: 27
- Views: 1419
Re: bent v. angular
Bent and angular is the same shape :)
- Wed Nov 20, 2019 1:12 pm
- Forum: Hybridization
- Topic: pi bond orientation
- Replies: 4
- Views: 127
Re: pi bond orientation
The region of electron density for an pi bond is not actually on the bond axis, but rather parallel "on top" and "below" it, creating a bean-shaped region of e- density. Therefore, if the bond rotates, the bean-shape will break because the regions of electron density are no longe...
- Wed Nov 20, 2019 12:57 pm
- Forum: Hybridization
- Topic: Test 2
- Replies: 6
- Views: 359
Re: Test 2
Yes, Dr. Lavell confirmed that hybridization will not be on test two :)
- Wed Nov 20, 2019 12:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Difference between Electorn arrangement and VSEPR
- Replies: 5
- Views: 426
Re: Difference between Electorn arrangement and VSEPR
I was confused about this too, but I later realized that the key way to distinguish between the two is that e- arrangement takes into consider the numbers of lone e- pairs and shared e- paired (aka bonds) to determine the name while VSEPR only take into consideration on the number of atoms around th...
- Wed Nov 20, 2019 12:48 pm
- Forum: Sigma & Pi Bonds
- Topic: Resonance and Sigma/Pi Bonds
- Replies: 3
- Views: 640
Resonance and Sigma/Pi Bonds
Someone asked this question in my lecture a few days ago, but I would like to ask about it again: What kind of bond would a resonace bond be classified as? For instance, would a molecule with a double bond resonance consider to have a pi bond or sigma bond? Thanks!
- Wed Nov 13, 2019 11:47 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape Name
- Replies: 17
- Views: 817
Molecular Shape Name
Is it necessary to remember the names of all the molecular shapes? I know linear, triangular planarm, tetrahedral are very common molecular shapes so it's good to remember them, but what about the other shapes such as trigonal bipyramidal, square pyramidal, etc.? Thank you!
- Tue Nov 12, 2019 8:55 pm
- Forum: Octet Exceptions
- Topic: incomplete octet
- Replies: 6
- Views: 452
Re: incomplete octet
Kaylee Sepulveda 3C wrote:Usually, the elements that do this are B, Al, Li, and H. B and Al will usually form compounds where they only have six electrons instead of a complete octet.
Why does B and Al exhibit this behaviour (where they don't form a complete octet)?
- Tue Nov 12, 2019 8:49 pm
- Forum: Resonance Structures
- Topic: Formal Charge Question
- Replies: 16
- Views: 812
Re: Formal Charge Question
For all molecular structures the atoms should have a formal charge where the molecule equal zero or equal to the charged the molecule is assigned. I hope that helps!
- Tue Nov 12, 2019 8:44 pm
- Forum: Dipole Moments
- Topic: Ep Meaning
- Replies: 4
- Views: 462
Re: Ep Meaning
Please correct me if I am wrong, but does VE also stand for potential energy? Thanks!
- Tue Nov 12, 2019 8:38 pm
- Forum: Bond Lengths & Energies
- Topic: Dissociation Energy
- Replies: 9
- Views: 348
Re: Dissociation Energy
^ Dissociation energy is positive because energy is need to break the bond. On the other hand, when bonds are formed, energy is release and that value of energy is negative.
- Tue Nov 12, 2019 11:37 am
- Forum: Bond Lengths & Energies
- Topic: Week 7 Homework
- Replies: 15
- Views: 802
Re: Week 7 Homework
I am pretty sure we can still do homework in the Chemical Bond section, as long as it is from 2E-2F.
- Fri Nov 01, 2019 11:02 am
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 8
- Views: 239
Re: Electron Affinity
Electron affinity has a similar trend to ionization energy, where it increases up and to the right. Hope that helps!
- Fri Nov 01, 2019 10:58 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: What is the x, y, z?
- Replies: 4
- Views: 1429
Re: What is the x, y, z?
The xyz helps to identify what position the subshell that the electron are located are in. (i.e. 2px the subshell is horizontal, 2py diagonal, and 2pz vertical) Hope that sort of helped!
- Fri Nov 01, 2019 10:52 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing electron configuration
- Replies: 7
- Views: 323
Writing electron configuration
When reaching the d block, which is the correct way to the write the electron configuration, 3d 4s or 4s 3d? I've noticed it written both ways, and it made me kind of confused. Thank you!
- Fri Nov 01, 2019 10:44 am
- Forum: Lewis Structures
- Topic: Central atom
- Replies: 6
- Views: 233
Central atom
When drawing lewis structures, how should I go about determining the central atom? I noticed on a lot of molecules that even though Oxygen has the higher ionization energy, Carbon or Sulfur is the central atom. Thanks!
- Fri Nov 01, 2019 10:41 am
- Forum: Coordinate Covalent Bonds
- Topic: Distinguishing a coordinate covalent bond
- Replies: 5
- Views: 246
Distinguishing a coordinate covalent bond
How can I distinguish that a molecule is bonded by a coordinate colvalent bond? Thanks!
- Thu Oct 24, 2019 1:26 pm
- Forum: Resonance Structures
- Topic: bond lengths
- Replies: 4
- Views: 143
Re: bond lengths
The bond length was 1.24 Angstrom because that molecules was exhibits resonance. The 1.24 Angstrom means that the bonds in the NO3 molecule are hybrid between a double bond and a single bond. Hope that helps!
- Thu Oct 24, 2019 1:20 pm
- Forum: Lewis Structures
- Topic: Electronegativity
- Replies: 5
- Views: 227
Re: Electronegativity
I believe an atom's electronegativity is relative to their ionization energy (increases from left to right and down to up of the periodic table) , so I would just follow the trend for ionization energy to determind an atom's electronegativity.
- Thu Oct 24, 2019 1:14 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic v.covalent bonds
- Replies: 7
- Views: 320
Ionic v.covalent bonds
Just to clarify, the way we distinguish between whether a compund is bonded "covalently" or "ionically" is to see if the atoms in the compound are bonded metals to nonmetal(ionic) or nonmetal to nonmetal (covalent)? Sorry this is such a terribly worded question, I hope you guys c...
- Thu Oct 24, 2019 1:09 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 14
- Views: 596
Re: Electronegativity
Jorge Ramirez_4H wrote:Is electronegativity important when doing electron configurations?
Not particularly, electronegativity is important for determining the bond that will form between atoms, so for drawing lewis structures but not electron configurations.
- Thu Oct 24, 2019 1:05 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 14
- Views: 596
Re: Electronegativity
Electronegativity is an atom's ability to hold on to an electron. Therefore, it increases across a period because the ionization energy of an atom also increases across a period, meaning the atom is able to "hold on" to its electron better.
- Fri Oct 18, 2019 11:56 am
- Forum: Photoelectric Effect
- Topic: Spectrum of light
- Replies: 6
- Views: 276
Re: Spectrum of light
sbottomley3a wrote:A helpful mnemonic device to remember the order is "I saw my Grandma's X-rated Underpants Visible In My Room" (Gamma, x-ray, uv, visible, infrared, micro, radio). It's a little wacky, but it works!
Haha! This is great! Thanks for the mnemonic device
- Fri Oct 18, 2019 11:52 am
- Forum: Properties of Light
- Topic: Black Body Radiation
- Replies: 2
- Views: 119
Black Body Radiation
I know we've disscussed this topic a a few weeks back, but can someone clarify the idea of black body radiation? Thanks in advance!
- Fri Oct 18, 2019 11:47 am
- Forum: Einstein Equation
- Topic: why do we use these equations?
- Replies: 5
- Views: 266
Re: why do we use these equations?
Just from doing some problems, I believe the reason we combined the two equtions is solely dependent on the amount of information given in the problem. For instance, when we are solving for the energy of the photon, we have to combine the equation because we need/ were given wavelenght and thus need...
- Thu Oct 17, 2019 10:36 pm
- Forum: Properties of Light
- Topic: What are the units of hertz
- Replies: 41
- Views: 1940
Re: What are the units of hertz
cycle .s-1
- Thu Oct 17, 2019 9:55 pm
- Forum: Properties of Light
- Topic: 1A.9 Energy of Photon
- Replies: 12
- Views: 434
1A.9 Energy of Photon
On question 1A.9 I understand that the key equation is C=(wavelength)(frequency), however the question also asks for the energy of photon, how do I calculate for that? Thank you!
- Fri Oct 11, 2019 6:18 pm
- Forum: *Black Body Radiation
- Topic: Black Body Radiation
- Replies: 6
- Views: 375
Re: Black Body Radiation
If this helps, I associate black bodies with black holes, where, as the previous comments have already explained it emits and absorbs all frequencies of radation, just like how a black hole absorbs light and both the black holes and the black bodies are invisible. :)
- Fri Oct 11, 2019 6:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent
- Replies: 32
- Views: 43266
Re: Ionic vs Covalent
Ionic bonds are much stronger since electrons from one atom is given to another and the two atoms basically are glued together through the bond. On the other hand, in covalent bonds the atoms are merely 50/50 sharing the electrons, therefore not as strong as an ionic bond.
- Fri Oct 11, 2019 6:07 pm
- Forum: Properties of Light
- Topic: Circular Standing Waves and electrons
- Replies: 2
- Views: 174
Circular Standing Waves and electrons
Can anyone clarify why circlular standing waves around the nucleus illustrates why electrons have qunatized energy states in atoms? Thank you!
- Fri Oct 11, 2019 5:59 pm
- Forum: Significant Figures
- Topic: %Mass Composition
- Replies: 12
- Views: 714
Re: %Mass Composition
Yeah I agree with the previous few answers, look at number that has the least amount of significant figures in the problem, but usually it is just four or five sig figs.
- Fri Oct 11, 2019 5:11 pm
- Forum: SI Units, Unit Conversions
- Topic: Showing work/ rearranging equations
- Replies: 8
- Views: 714
Re: Showing work/ rearranging equations
To reaffirm the previous comments, just work out the porblem in the way you are comfortable with. As long as you show how you did it, I'm sure points will be given. :)
- Tue Oct 01, 2019 10:32 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Balancing Equations [ENDORSED]
- Replies: 25
- Views: 1961
Re: Balancing Equations [ENDORSED]
I think I can confidently say yes, since stoichiometric coefficients must be whole numbers.
- Tue Oct 01, 2019 10:29 pm
- Forum: Balancing Chemical Reactions
- Topic: Tips on what number to multiply the entire equation if needed
- Replies: 8
- Views: 1615
Re: Tips on what number to multiply the entire equation if needed
Sorry this is reptitive of other posts, and I actually didn't know to do this before myself(!), but the best way to balance a non whole number stoichometric coefficient is to write the coeifficient in improper fractions and multiply both the reactant and product compounds by the denominator of the f...
- Tue Oct 01, 2019 10:17 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Dilution and Molarity Questions
- Replies: 8
- Views: 557
Re: Dilution and Molarity Questions
Personally, the dilution/molarity problems that confuses me are ones with more than two compounds, and in those cases, the key to solving the problem is to find the ratios of those ions/compouds in relation tto either the other ions/elements.
- Tue Oct 01, 2019 9:56 pm
- Forum: Significant Figures
- Topic: Sig Fig Rules
- Replies: 3
- Views: 188
Re: Sig Fig Rules
From what I remembered, for + and -, you look at the sig figs AFTER the decimal point (i.e. 1.36 + 3.5 = 4.9 [1 sig fig after decimal point]) , while for multiplication and division, you look at the entire numbers to evaluate the sig figs (i.e. 2.51 x 6.111 = 15.3 [3 sig figs]).