## Search found 57 matches

Sun Mar 17, 2019 9:47 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E cell
Replies: 3
Views: 317

### Re: E cell

it is not usually negative, but in some instances, we have allowed it to be negative. i think when you are not trying to make the most spontaneous and just solving for E, you should follow cathode-anode and hope it does us justice. I was also confused.
Sun Mar 17, 2019 9:46 am
Forum: First Order Reactions
Topic: First Order Equation
Replies: 3
Views: 296

### Re: First Order Equation

this equation is the integrated rate law for first order reactions and to add to what the previous post said, you are able to graph this as just a downward straight line, because of the -k (slope) and the y intercept, ln [A]0
Sat Mar 16, 2019 3:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Porous Disk vs Salt Bridge
Replies: 2
Views: 88

### Re: Porous Disk vs Salt Bridge

that clears things up. thank you so much! (:
Sat Mar 16, 2019 3:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Porous Disk vs Salt Bridge
Replies: 2
Views: 88

### Porous Disk vs Salt Bridge

I understand that a salt bridge prevents charge build up and allows for the salt ions to move in order for the reaction to continue, but does the porous disk allow charge build up? I know the solid expands in size throughout the experiment, but how does the porous disk motivate this?
Wed Mar 13, 2019 1:03 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exothermic vs. Endothermic
Replies: 10
Views: 476

### Re: Exothermic vs. Endothermic

All reactions use activation energy, but exothermic reactions just produce more energy than they consumed. So to answer your question, having activation energy does not declare a reaction being endothermic vs exothermic. They could have the same Ea, but they depend on the initial and final energy us...
Sat Mar 09, 2019 11:56 pm
Forum: General Rate Laws
Topic: integrals
Replies: 8
Views: 315

### Re: integrals

It is difficult to understand integrals without the knowledge of derivatives, which is just another word for slope. I have attached two links to explain the two.
https://youtu.be/IHaK3XzTse4
https://youtu.be/rAof9Ld5sOg
Sat Mar 09, 2019 11:48 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: k & K
Replies: 18
Views: 793

### Re: k & K

I am sure the question will tell us to use the k as a rate constant in kinetics in the question, whereas the k Boltzmann constant will be used to calculate the entropy. K will be given in an acids and base question. It is based off of context.
Sat Mar 09, 2019 11:38 pm
Forum: Second Order Reactions
Topic: rate constant k
Replies: 3
Views: 123

### Re: rate constant k

With regards to the integrated rate law, this is due to the fact that when you are integrating the derivative, because of the integrated version being 1/[A] there happens to be a -1, but they divided the negative from the k over to cancel these out.
Sun Mar 03, 2019 1:23 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Order of Cell Diagrams
Replies: 13
Views: 457

### Re: Order of Cell Diagrams

Coming from the left, it is solid|g,L|aq.||aq.|L,g|solid
Sun Mar 03, 2019 1:21 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E vs E naught
Replies: 5
Views: 194

### Re: E vs E naught

E naught is under standard conditions. 25° C, 1 atm.
Sun Mar 03, 2019 1:20 am
Forum: General Rate Laws
Topic: Unique vs instantaneous rate
Replies: 6
Views: 205

### Re: Unique vs instantaneous rate

The unique rate just takes coefficients into account and you multiply them to the concentration (the ones you use in an instantaneous rate).
Sun Feb 24, 2019 12:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Platinum
Replies: 3
Views: 145

### Re: Platinum

Whenever there’s no elements w the (s) subscript. That’s the element you add it to because Platinum is a non reacting element in these reactions.
Sun Feb 24, 2019 12:46 pm
Forum: Balancing Redox Reactions
Topic: Oxidation/Reduction
Replies: 2
Views: 95

### Re: Oxidation/Reduction

When you add the electrons to the right side, I believe it will be reduction and electrons to the left of the arrow is oxidation.
Sun Feb 24, 2019 12:45 pm
Forum: Balancing Redox Reactions
Topic: acidic vs basic solution
Replies: 1
Views: 71

### Re: acidic vs basic solution

There is importance in this because based off of the solution being acidic vs basic, you must add different components. Basic is very similar to acidic, but you would then add OH- ions to balance the half equations, whereas the acidic requires just H+ and electrons
Sat Feb 16, 2019 5:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: When does delta U equal zero?
Replies: 17
Views: 1857

### Re: When does delta U equal zero?

deltaU=0 when there is a constant temperature, or when temperature is 0. This is because of the equation U=3/2nRT. If constant temperature, Tf-Ti=0. However, if temperature=o, the equation would equal zero instantly.
Sat Feb 16, 2019 5:47 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Changes in Pressure
Replies: 5
Views: 180

### Re: Changes in Pressure

This is tied back to the equation PV=nRT. Due to 'P' and 'V' being multiplied together, they are inversely proportional. When volume goes up, pressure goes down and vice versa.
Sat Feb 16, 2019 5:36 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy equations
Replies: 8
Views: 513

### Re: Entropy equations

The one using V2/V1 is when volume is changing and you have a constant temperature. You would use the one with the T2/T1 when temperature is changing. In this case, you would use Cv or Cp as the constant values.
Sun Feb 10, 2019 1:40 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U
Replies: 8
Views: 276

### Re: Delta U

Delta U is 0 when you are dealing w a isothermal/reversible reaction.
Sat Feb 09, 2019 10:43 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Ideal Gas, U(tot)
Replies: 1
Views: 85

### Re: Ideal Gas, U(tot)

U(tot)=(3/2)nRT is the calculation of total internal energy. You use this equation for monoatomic ideal gases, which means just one atom. These problems will typically use the information from one of the ideal gases (aka noble gases). The questions also are typically reversible. The idea behind this...
Sat Feb 09, 2019 10:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K = 1
Replies: 2
Views: 129

### Re: K = 1

When K=1 the concentrations are the same of the products and the reactants. I am unsure as to what you mean by "intermediate," so I am sorry and I hope I answered your question.
Sat Feb 09, 2019 9:53 pm
Forum: Calculating Work of Expansion
Topic: Reversible Work and Maximum Work
Replies: 5
Views: 159

### Re: Reversible Work and Maximum Work

From my knowledge, reversible reactions happen simultaneously, whereas an irreversible goes in steps. For this reason, say we were to calculate the area under the curve of the two reactions, the work is greater in a reversible reaction. The graph of a reversible is a curve (which has more area under...
Sat Feb 02, 2019 9:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: calorimeters
Replies: 7
Views: 218

### Re: calorimeters

I believe we should understand the components (i.e. heat, work, enthalpy,) because we will be doing problems based off of bomb calorimeter situations.
Sat Feb 02, 2019 9:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: U=q+w
Replies: 3
Views: 128

### Re: U=q+w

Delta U insinuates you will be calculating the change in internal energy. Q in this equation represents the gained or lost heat and W represents the work being done on the system or work being done by.
Sat Feb 02, 2019 9:18 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Heat vs. Temp
Replies: 9
Views: 457

### Re: Heat vs. Temp

Heat is the measurable unit of transferable energy, while temperature is just a measurement of how fast the molecules are moving (i.e. this supports the idea of how gaseous molecules move much faster than those of a solid.
Sat Jan 26, 2019 8:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Units
Replies: 7
Views: 296

### Re: Enthalpy Units

I do not believe that there is a difference, but it follows the information given by the problem.
Sat Jan 26, 2019 8:54 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating Q
Replies: 11
Views: 790

### Re: Calculating Q

Q is calculated whenever the equation is not at equilibrium, so if there is a change or anything similar. Also, Q is calculated whenever you are trying to see the result of the reaction (i.e. if the reaction favors the reactants or products).
Sat Jan 26, 2019 8:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 5
Views: 166

### Re: Hess's Law

Yes that is the basics. The two strategies are to either flip the equations or multiply them by whole numbers. If you do decide to flip the equation you must make sure that you change the sign of the enthalpy. (I believe that is how you spell it)
Sun Jan 20, 2019 8:14 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Molar Concentration
Replies: 3
Views: 89

### Re: Molar Concentration

The only time you use the coefficients is when you’re trying to 1. solve an ice box and 2. using K equation.
K=[P]^coefficient/[R]^coefficient
Sun Jan 20, 2019 8:11 am
Forum: Ideal Gases
Topic: kc vs kp
Replies: 19
Views: 847

### Re: kc vs kp

Conceptually they are different, for Kp is utilised for partial pressure and Kc for concentration. However, solving them is the same method.
Sat Jan 19, 2019 6:38 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Partial Pressure and Moles
Replies: 3
Views: 182

### Re: Partial Pressure and Moles

You definitely can use an ICE table for partial pressure as well. You would solve the same exact way, just the concept is a little different. For instance, the unit used is atp rather than mol/L. However, you would still set it up and Kp=Pproduct/Preactants.
Sat Jan 12, 2019 7:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K
Replies: 4
Views: 108

### Re: Calculating K

In this case, you would use the equilibrium concentration because the initial insinuates that the reverse reaction has not happened yet. So we are calculating what the concentrations when equilibrium will return.
Sat Jan 12, 2019 7:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 3
Views: 101

### ICE Tables

How does one calculate the 'C' value? And the 'C' does stand for change, correct?
Sat Jan 12, 2019 7:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 4
Views: 123

### Kc and Kp

I enrolled a few days late and I am trying to catch up on the lecture notes. I am confused as to what the difference between Kc and Kp is. What is the difference and how am I supposed to acknowledge the differences.
Sat Dec 08, 2018 9:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: A X5 E
Replies: 6
Views: 267

### Re: A X5 E

Every molecule with this formula will be some variation of square pyramidal. The bond angles of square pyramidal molecules are typically <90 degrees due to the fact that there is a lone pair of electrons that have the greatest repulsive force.
Sat Dec 08, 2018 9:11 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: pH
Replies: 5
Views: 407

### Re: pH

Due to the fact that when concentration of [H+] increases, the substance becoming more acidic, the pH will be affected In the aspect that it will decrease.
Sat Dec 08, 2018 8:56 pm
Forum: Sigma & Pi Bonds
Topic: resonance
Replies: 3
Views: 375

### Re: resonance

Resonance is, in the most basic way, a way to say that there are more than one way to draw a lewis structure. For instance, if the compound were to have more than on oxygen and one of the many had a double bond, you could draw the lewis structure with the double bond on a different oxygen each drawi...
Sat Dec 08, 2018 8:52 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: inter- and intra-
Replies: 5
Views: 862

### Re: inter- and intra-

Inter- insinuates that the bond is between two molecules, while intra- insinuates that the bond is typically within the molecule between the separate atoms. The inter- forces are typically those of dipole-dipole etc. while the intra- are typically within covalent bonds.
Sat Dec 08, 2018 8:49 pm
Forum: Naming
Topic: bis-, tris-, etc.
Replies: 4
Views: 332

### Re: bis-, tris-, etc.

You use such prefixes when there is more than one polydentate ligands. So if there was two (en), you would use bis-prior to writing the name of the ligand.
Mon Nov 12, 2018 11:31 pm
Forum: Ionic & Covalent Bonds
Topic: What is Distortion?
Replies: 3
Views: 85

### Re: What is Distortion?

Distortion is a trend that happens when a highly polarizable atom is affected by a polarizing atom. The attraction results in the electron cloud to be shifted and misshaped. Also, if one is "highly polarizable", it is more likely to be distorted and affected by another atom.
Mon Nov 12, 2018 11:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: determining VSEPR models
Replies: 6
Views: 248

### Re: determining VSEPR models

At this point when they all look similar, it is important to locate and count the amount of lone pairs. This is because of repulsion and attraction rules. The fact that one molecule may have lone pairs affects the connection between elements inside the molecule.
Mon Nov 12, 2018 11:21 pm
Forum: Bond Lengths & Energies
Replies: 2
Views: 139

From my understanding, the fact that the bond is covalent, the bonds must be touching. They share a pair of electrons, so that means we do assume their is such space between the two.
Fri Nov 02, 2018 11:59 pm
Forum: Quantum Numbers and The H-Atom
Topic: Electrons in Orbitals
Replies: 2
Views: 142

### Re: Electrons in Orbitals

Also, a way to check if the number of orbitals you have are correct, you can use the formula n^2. The n is the energy level. And to check if you need the number of electrons, you can use the formula 2n^2. It is more important to understand the concept and the n,l,m levels.
Fri Nov 02, 2018 11:53 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent bonds with covalent/ionic characteristics
Replies: 3
Views: 135

### Re: Ionic and Covalent bonds with covalent/ionic characteristics

It has to do with the fact that not everything is black or white. because some elements have more electrons, they are much more spread out and easier to connect with other elements.
Fri Nov 02, 2018 11:50 pm
Forum: Quantum Numbers and The H-Atom
Topic: degeneracy of the a 4p orbital
Replies: 9
Views: 949

### Re: degeneracy of the a 4p orbital

I may be definitely wrong but I thought that degeneracy meant same energy level, do it would be 4s?
Fri Oct 26, 2018 3:47 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Conceptual question
Replies: 3
Views: 198

### Re: Conceptual question

Due to the two being inversely proportional and that when you are sure of one, the other one is immeasurable.
Fri Oct 26, 2018 3:37 pm
Forum: Ionic & Covalent Bonds
Topic: Chemical Bonding
Replies: 8
Views: 293

### Re: Chemical Bonding

Today we discussed the basic chemical binding rules, as well as the basic Lewis structure rules. And we touched on polyatomic atomic species Lewis structures.
Fri Oct 26, 2018 3:33 pm
Forum: Ionic & Covalent Bonds
Topic: Calculating number of valence electrons in bonds
Replies: 5
Views: 655

### Re: Calculating number of valence electrons in bonds

You have to look at the periodic table and see which group the element is in and based off of which group, they have specific numbers of valence electrons. For instance, group one has 1 valence electron, while 2 has 2 and so on. Then based off of how many of that element is in the compound, you mult...
Fri Oct 19, 2018 10:43 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation
Replies: 4
Views: 214

### Re: Rydberg equation

The way I thought of it was that the energy that you find using this equation is the amount of energy that the electron gives off in order to return to a previous energy level. This is why the number is typically negative as well. The energy is the amount the it gives off say from the 6th energy lev...
Fri Oct 19, 2018 10:40 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Delta x
Replies: 2
Views: 60

### Re: Delta x

I am aware that they use the diameter because the electron is typically found outside of the diameter. In problems I have done I have noticed that the diameter was used to compare to the range of x values after solving the equation. Kind of a way to show that the electrons range even outside of the ...
Fri Oct 19, 2018 10:35 pm
Forum: DeBroglie Equation
Topic: Application to Classical Objects
Replies: 2
Views: 88

### Re: Application to Classical Objects

I was informed that whenever we are given a mass and are trying to find the wavelength, we must use De Broglie's equation. However, to answer your question, they do have wavelengths, but they are just too small for us to analyze. They can be as small as 10^-50 which is way past our capability. For i...
Fri Oct 12, 2018 7:01 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: En=-hR/n^2
Replies: 3
Views: 67

### Re: En=-hR/n^2

The negative in this equation is due to the idea of the answer being energy lost. This is also the same amount of energy that a photon has in this situation. A photon in the experiment would have the same amount of energy as the energy lost from the electron.
Fri Oct 12, 2018 6:57 pm
Forum: DeBroglie Equation
Topic: Measurable wavelengths
Replies: 3
Views: 96

### Re: Measurable wavelengths

Lavelle also discussed in class that the answers will usually be easy to distinguish. For instance, the answers will be about 10^-12 rather than 10^20. He will not make it to where we have to use our own judgement to see if it is one thing or the other. He said they will be obvious enough for us to ...
Thu Oct 11, 2018 8:42 pm
Forum: Properties of Light
Topic: Threshold Energy
Replies: 11
Views: 292

### Re: Threshold Energy

From my knowledge, the threshold energy is the minimum amount of energy it takes to remove one electron from the given metal, for each metal is different and requires a different threshold energy.
Thu Oct 04, 2018 11:39 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: writing the formula of a molecule
Replies: 5
Views: 1870

### Re: writing the formula of a molecule

I began this problem writing Magnesium Sulfate as MgSo4. Then the prefix hepta- refers to the number 7. Hydrate also refers to just water so it would result in MgSo4 7H2O.
Thu Oct 04, 2018 11:30 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: % Yield
Replies: 8
Views: 643

### Re: % Yield

From my experience I have been told it is based off of the experiment, for some are notorious for having low % yield and some high. It depends because some experiments' procedures have more impurities or are more difficult and require more intense care. A short answer is no due to every experiment b...
Thu Oct 04, 2018 1:30 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilutions
Replies: 3
Views: 166

### Re: Dilutions

Would it be any different if I were to add their given masses and then divide by their combined molar masses in one mole and then divide by the volume? Or is it necessary to perform each mole calculation separately?
Thu Oct 04, 2018 1:11 pm
Forum: Molarity, Solutions, Dilutions
Topic: Problem G5
Replies: 8
Views: 368

### Re: Problem G5

When finding the answer for 'a', would that be considered using the M1V1=M2V2 equation? I am just trying to conceptualize this process.