Search found 60 matches
- Sat Mar 16, 2019 1:06 pm
- Forum: Calculating Work of Expansion
- Topic: Integrate Rate Law
- Replies: 2
- Views: 518
Re: Integrate Rate Law
ln[A] vs time is the rate plot for a first order function.
- Sat Mar 16, 2019 1:05 pm
- Forum: Ideal Gases
- Topic: Cell Diagram/Ecell
- Replies: 8
- Views: 924
Re: Cell Diagram/Ecell
The anode is oxidized, loses electrons.
The cathode is reduced, gains electrons.
The cathode is reduced, gains electrons.
- Sat Mar 16, 2019 1:03 pm
- Forum: General Rate Laws
- Topic: Rate Law
- Replies: 1
- Views: 427
Re: Rate Law
The rate law depends on how quickly a product is formed, and that depends on how quickly the reactants used to make it up are used up.
- Thu Mar 07, 2019 9:54 am
- Forum: Balancing Redox Reactions
- Topic: Writing half reactions
- Replies: 7
- Views: 624
Re: Writing half reactions
The H+ would be with the Cr2O7 since the oxygen atoms in it are balanced with H20, and the H20 are balanced with H+
- Thu Mar 07, 2019 9:46 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: E cell
- Replies: 5
- Views: 487
Re: E cell
E^o is the standard reduction potential, or basically how badly the molecule wants to be reduced (positive means it wants to be reduced more, negative means it wants to be oxidized more). Ecell basically refers to the total standard reduction potential of the cell with E^o of the cathode - E^o of th...
- Thu Mar 07, 2019 9:42 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Galvanic Cells
- Replies: 4
- Views: 405
Re: Galvanic Cells
Being reversible allows the cell to do more work!!!
- Thu Mar 07, 2019 9:39 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Instantaneous vs Average
- Replies: 11
- Views: 987
Re: Instantaneous vs Average
Instantaneous change would imply a derivative, because you're finding the changing at a certain time t, versus average would be you finding the change over a period of time, from t1 to t2.
- Thu Mar 07, 2019 9:36 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: how is kinetics different?
- Replies: 17
- Views: 1647
Re: how is kinetics different?
Kinetics tells you the rate of the reaction; a reaction might be deemed spontaneous due to thermodynamics, but sometimes that reaction occurs very slowly. Kinetics tells you how fast or slow that reaction occurs.
- Tue Feb 19, 2019 12:46 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isobaric
- Replies: 12
- Views: 1659
Re: Isobaric
Isobaric basically means there is no change in pressure, which means you can have work and heat changing your internal energy.
- Tue Feb 19, 2019 12:44 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G a state function?
- Replies: 23
- Views: 2787
Re: Delta G a state function?
Free energy is a state function, because it involves enthalpy and entropy, two other state functions.
- Tue Feb 19, 2019 12:43 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Test 3
- Replies: 10
- Views: 955
Re: Test 3
It should cover whatever we learned on the Friday lecture of Week 6, and everything covered in Week 7.
- Tue Feb 19, 2019 12:42 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy
- Replies: 7
- Views: 761
Re: Gibbs free energy
Gibbs free energy is the amount of energy that is available to do work, and the equation shows the relationship between entropy and enthalpy as well.
- Tue Feb 19, 2019 12:41 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible Reactions
- Replies: 8
- Views: 1292
Re: Reversible Reactions
Are reversible reactions are isothermal!
- Tue Feb 19, 2019 12:39 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pressure Equation
- Replies: 7
- Views: 813
Re: Pressure Equation
When you are calculating an entropy change due to pressure, and not volume.
- Tue Feb 19, 2019 12:38 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: delta S
- Replies: 7
- Views: 732
Re: delta S
The change in entropy would be zero when the heat transferred into or out of the system is 0.
- Sun Feb 10, 2019 4:54 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U
- Replies: 8
- Views: 855
Re: Delta U
The change in internal energy could be 0
if q = -w
if T = 0
and if the system is isothermal and the reaction is reversible
if q = -w
if T = 0
and if the system is isothermal and the reaction is reversible
- Sun Feb 10, 2019 4:47 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Cv/Cp versus R
- Replies: 4
- Views: 465
Re: Cv/Cp versus R
Cv is for when volume is constant, and Cp is used for when pressure is constant.
- Sun Feb 10, 2019 4:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: w=-PdeltaV
- Replies: 6
- Views: 588
Re: w=-PdeltaV
-PdeltaV would be used if your external pressure is constant, and with irreversible reactions.
- Sun Feb 03, 2019 4:34 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: open system
- Replies: 8
- Views: 1339
Re: open system
pressure of the system=the pressure of the exterior
- Sun Feb 03, 2019 4:32 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter
- Replies: 6
- Views: 531
Re: Calorimeter
We will have to know how to do calculations involving calorimetry.
- Sun Feb 03, 2019 4:32 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 3
- Views: 388
Re: Enthalpy
On the other hand, entropy is basically the degree of disorder.
- Thu Jan 24, 2019 11:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5%
- Replies: 10
- Views: 766
Re: 5%
Your x has to be less than 5% of the initial concentration for your assumption/approximation to be valid
- Thu Jan 24, 2019 11:14 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka and pH
- Replies: 6
- Views: 490
Re: Ka and pH
Not really. You'd have to use the Ka or Kb value to solve an ICE table and find the concentration of Hydronium ions to find that.
- Thu Jan 24, 2019 11:11 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Quiz #1 This friday
- Replies: 5
- Views: 665
Re: Quiz #1 This friday
I had Lavelle last quarter, and the best way to study is to do the homework problems, and the practice worksheets that UA's like Karen and Lyndon give and attend their sessions. Also read (or at least skim) the textbook.
- Sat Jan 19, 2019 5:20 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 8
- Views: 1130
Re: PV=nRT
PV = nRT shows the relationship between pressure and concentration so it would be used to convert Kp to Kc and vice versa.
- Sat Jan 19, 2019 5:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Weak Acid & Salt
- Replies: 4
- Views: 392
Re: Weak Acid & Salt
since it's a asalt, the potassium ions dissociate completely on both sides, and don't really count toward finding your equilibrium constant value.
- Sat Jan 19, 2019 5:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka vs. Kb
- Replies: 12
- Views: 4590
Re: Ka vs. Kb
Ka time Kb is Kw, and pKa + pKb is 14, and also equal to pKw
- Wed Jan 09, 2019 4:55 pm
- Forum: Ideal Gases
- Topic: Temperature in PV=nRT
- Replies: 9
- Views: 1109
Re: Temperature in PV=nRT
Kelvin is the SI unit for temperature.
- Wed Jan 09, 2019 4:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: What does it mean when a reaction is at equilibrium?
- Replies: 4
- Views: 438
Re: What does it mean when a reaction is at equilibrium?
However, make sure you remember that just because a reaction is at equilibrium, it doesn't necessarily mean that the reaction is over.
- Wed Jan 09, 2019 4:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Kc
- Replies: 8
- Views: 551
Re: K and Kc
You can determine whether you should be using Kc or Kp depending on the states of the molecules in the chemical equation, or also the information given to you.
Re: Naming
We know that potassium has a +1 charge, and we know that cyano has a -1 charge and there are 4 cyano so there's a -4 charge but nickelate has a +2 charge so in general the anion has a -2 charge. So there has to be 2 potassium ions so that it is a neutral compound.
- Thu Dec 06, 2018 11:54 pm
- Forum: Conjugate Acids & Bases
- Topic: 12.1 6th edition
- Replies: 2
- Views: 402
Re: 12.1 6th edition
The conjugate base is just the deprotonated acid.
- Thu Dec 06, 2018 11:53 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Salts cause acidity
- Replies: 5
- Views: 392
Re: Salts cause acidity
There has to be a proton (aka hydrogen) that can be pulled off the acid and create a H3O+ ion to increase the acidity of the solution.
- Sun Dec 02, 2018 2:43 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 10
- Views: 921
Re: Coordination Number
Coordination number is basically the number of bonded atoms to the central atom.
- Sun Dec 02, 2018 2:40 pm
- Forum: Biological Examples
- Topic: acids
- Replies: 5
- Views: 405
Re: acids
The stomach and digestive system in general have a layer of protection. Your ski is that layer of protection for the rest of your body (like the outside) so when you have a cut, there's no protection.
- Sun Dec 02, 2018 2:38 pm
- Forum: Naming
- Topic: With Respect to the Final
- Replies: 9
- Views: 938
Re: With Respect to the Final
Probably both. What if you're asked to find the molarity of a solution that is made up of water and a compound but they give you the name of the compound rather than the molecular formula?
- Sun Nov 25, 2018 3:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape
- Replies: 7
- Views: 694
Re: Molecular Shape
The arrangement of the electron density would be trigonal bipyramidal, but the arrangement of the atoms would be tetrahedral, since there's a lone pair. As a result, you would end up with seesaw structure.
- Sun Nov 25, 2018 3:14 pm
- Forum: Hybridization
- Topic: sp orbitals
- Replies: 3
- Views: 321
Re: sp orbitals
Furthermore, sp3 means there's one sigma bond, sp2 means one sigma bond, one pi bond, and sp means there's one sigma bond and two pi bonds.
- Sun Nov 25, 2018 3:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shapes Not covered in Lecture
- Replies: 10
- Views: 1097
Re: Shapes Not covered in Lecture
It's probably a good idea to know that, especially if it shows up in the textbook. We can probably assume from previous tests that it would be fair game for the test since the same thing happened with nodes on the second test.
- Mon Nov 19, 2018 1:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Octahedral to Square Planar
- Replies: 7
- Views: 928
Re: Octahedral to Square Planar
A square planar has an octahedra; electron density arrangement, but since two of those areas of electron density are lone pairs, and only four atoms are bonded to the central atom, it is square planar in molecular shape.
- Mon Nov 19, 2018 1:19 pm
- Forum: Hybridization
- Topic: Sigma/Pi bonds
- Replies: 6
- Views: 834
Re: Sigma/Pi bonds
Also, it's good to know that:
single bond - one sigma
double bond - one sigma, one pi
triple bond - one sigma, two pi
etc.
single bond - one sigma
double bond - one sigma, one pi
triple bond - one sigma, two pi
etc.
- Mon Nov 19, 2018 1:17 pm
- Forum: Hybridization
- Topic: Electron Density Shape
- Replies: 2
- Views: 152
Re: Electron Density Shape
Basically the electron density arrangement is what would give you your hybridization orbitals. So if your electron density arrangement is tetrahedral, then you would have sp3 hybridization. However, your molecular shape is actually based on the number of atoms bonded to the central atom, so if you h...
- Sun Nov 11, 2018 7:03 pm
- Forum: Octet Exceptions
- Topic: Radicals
- Replies: 16
- Views: 1691
Re: Radicals
Also, you wouldn't make the atom that has the most electronegativity a radical, because it would want a full octet.
- Sun Nov 11, 2018 7:02 pm
- Forum: Resonance Structures
- Topic: Resonance structures
- Replies: 7
- Views: 855
Re: Resonance structures
The actual structure is the resonance hybrid, but we draw out the resonance structure to show the possible positions of the delocalized electrons.
- Sun Nov 11, 2018 7:00 pm
- Forum: Electronegativity
- Topic: Electron Affinity vs. Ionization Energy
- Replies: 8
- Views: 810
Re: Electron Affinity vs. Ionization Energy
Electron affinity is the amount of energy released when an atom is given an electron, and ionization energy is the energy not takes to remove an electron.
- Sun Nov 04, 2018 10:08 pm
- Forum: Electronegativity
- Topic: Garlic Bread Review 10d
- Replies: 3
- Views: 398
Re: Garlic Bread Review 10d
also, this half shell stability extends to things like Boron and why it doesn't need a full octet.
- Sun Nov 04, 2018 5:15 pm
- Forum: Resonance Structures
- Topic: Resonance Structures on the Midterm
- Replies: 3
- Views: 329
Re: Resonance Structures on the Midterm
Also if you draw all the resonance structures, draw arrows between them!
- Sun Nov 04, 2018 5:11 pm
- Forum: Lewis Structures
- Topic: 12b from the GarBreadium worksheet
- Replies: 3
- Views: 337
Re: 12b from the GarBreadium worksheet
It just symbolizes that the molecule is negatively charged, and that charge should be equal to your overall formal charge.
- Sun Oct 28, 2018 4:26 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 8
- Views: 754
Re: Atomic Radius
You just need to know trends, and maybe why the trends make sense.
- Sun Oct 28, 2018 4:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence electrons
- Replies: 8
- Views: 1484
Re: Valence electrons
The last shell is the valence shell, and the number of valence electrons is the number of electrons in the last shell (determined by n value).
- Sun Oct 28, 2018 3:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bonds
- Replies: 5
- Views: 476
Re: Hydrogen Bonds
Hydrogen bonds, from what I remember from high school chem, were the strongest intermolecular forces, but bonds are technically between molecules, which would explain why they're actually bonds like someone had mentioned earlier.
- Sun Oct 21, 2018 9:11 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Px. Py, Pz
- Replies: 6
- Views: 1672
Re: Px. Py, Pz
Hi Nikitha xD
Basically there's 3 p orbitals, px py and pz. The x,y, and z simply tell you the orientation of the orbitals. However, it doesn't really matter in terms of when you're doing electron configuration or anything like that.
Basically there's 3 p orbitals, px py and pz. The x,y, and z simply tell you the orientation of the orbitals. However, it doesn't really matter in terms of when you're doing electron configuration or anything like that.
- Sun Oct 21, 2018 9:05 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation on Test
- Replies: 5
- Views: 388
Re: Shrodinger Equation on Test
Really, the concepts you should know based on Schrodinger's are the fact that there's different energy levels and the types of orbitals you can find at each one, as well as properties of them. (For example, the s-orbital is the only orbital with symmetric electron distribution).
- Sun Oct 21, 2018 9:02 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Equation Confusion
- Replies: 4
- Views: 371
Re: Heisenberg Equation Confusion
Given that you know either the change in momentum or position, you should be able to find the minimum value of the other using Heisenberg's.
- Thu Oct 11, 2018 6:00 pm
- Forum: Photoelectric Effect
- Topic: work function
- Replies: 4
- Views: 455
Re: work function
Basically, the work function (threshold energy) is going to be equal to the energy of the photon (hv) minus the kinetic energy of the electron upon removal (excess energy). Of course, if the threshold energy is not equal to or less than the energy of the photon, then the electron will not be removed...
- Thu Oct 11, 2018 5:49 pm
- Forum: Properties of Light
- Topic: Photon energy
- Replies: 3
- Views: 307
Re: Photon energy
Also, it's important to note that the energy of a photon is determined by E = hv, where h is Planck's constant and v is the frequency of light.
- Thu Oct 11, 2018 5:47 pm
- Forum: Photoelectric Effect
- Topic: Empirical Equation
- Replies: 4
- Views: 396
Re: Empirical Equation
The threshold energy differs between various metals, just like the spectra for different elements is different. This is because the change in energy from level to level is different depending on the element.
- Fri Oct 05, 2018 1:28 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing Chemical Reactions with Heat
- Replies: 6
- Views: 1371
Re: Balancing Chemical Reactions with Heat
Regardless of the heat, it's still a chemical reaction. So the Law of Conservation of Mass applies as it usually would, and you balance the equation normally.
- Fri Oct 05, 2018 1:15 pm
- Forum: Empirical & Molecular Formulas
- Topic: When to double moles
- Replies: 13
- Views: 1007
Re: When to double moles
It's never going to be completely accurate. You just have to round to the nearest whole number.
- Fri Oct 05, 2018 1:06 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: % Yield
- Replies: 8
- Views: 1595
Re: % Yield
There's no such thing as an unacceptable % yield. % yield is simply the comparison of the actual yield to the theoretical yield.