Search found 110 matches
- Sat Mar 14, 2020 3:13 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Calculating E cell at room temperature
- Replies: 1
- Views: 209
Re: Calculating E cell at room temperature
To solve this, use the equation E = Eo - (RT/nF)lnQ. Q is equal to [Cu^2+]/[Ag^+]^2 which is (0.20)/(0.10)^2. E = 0.460V - ((8.314*298)/(2*96485))ln(20).
- Sat Mar 14, 2020 3:05 pm
- Forum: General Rate Laws
- Topic: HW 7C.7
- Replies: 2
- Views: 215
Re: HW 7C.7
To write the overall reaction, cancel out any species that appears in both the reactants and products side, and then add the steps together. Cancelling out NOBr2 and then adding both reactions together gives you 2NO + Br2 ---> 2NOBr.
- Sat Mar 14, 2020 3:02 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells
- Replies: 8
- Views: 680
Re: Concentration Cells
In a concentration cell, the reaction is driven by a difference in concentration, with electrons flowing from the anode (which should be at a lower concentration) to the cathode (which should be at a higher concentration). The voltage is created as the two concentrations move towards equilibrium.
- Thu Mar 12, 2020 4:38 pm
- Forum: Student Social/Study Group
- Topic: Review Session???
- Replies: 3
- Views: 428
Re: Review Session???
In the email that Professor Lavelle sent out on March 10th, he said that all of the 60 hours of review and help have been cancelled and didn't mention anything about sessions being moved online. He has posted a week 10 review on his website that we can use for practice, but since most of the UA's ar...
- Thu Mar 12, 2020 4:31 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Determining the slow step
- Replies: 4
- Views: 323
Re: Determining the slow step
The slow step should be the one whose specific rate law that matches the rate law for the overall reaction
- Mon Mar 09, 2020 10:33 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: endothermic reaction
- Replies: 5
- Views: 397
Re: endothermic reaction
If deltaH is a positive value, the reaction is endothermic so heat is consumed in the reaction. In order for it to be consumed it would have to be in the reactants side but you wouldn't normally write it into the equation as a reactant, you just think of it as a reactant so that you can use Le Chatl...
- Mon Mar 09, 2020 10:30 pm
- Forum: General Rate Laws
- Topic: Equations
- Replies: 5
- Views: 411
Re: Equations
I doubt that he would ask us to derive the zero, first, second, and half life equations since they are given on the equation sheet. It probably wouldn't hurt to be able to go from the given rate laws to the integrated rate laws though.
- Mon Mar 09, 2020 10:28 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: midterm 6 b
- Replies: 6
- Views: 411
Re: midterm 6 b
A, because the reaction has the smallest deltaS values, meaning in the equation deltaG = deltaH - TdeltaS, change in gibbs and change in enthalpy will be the closest to each other
- Sun Mar 08, 2020 2:13 pm
- Forum: General Rate Laws
- Topic: Instantaneous and average reaction rate
- Replies: 4
- Views: 318
Re: Instantaneous and average reaction rate
A rate law is instantaneous because you are getting a value for a specific time t. I think that it would be considered an average rate if you're determining the rate based off of the slope of a graph for concentration v time.
- Sun Mar 08, 2020 2:05 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: determine n
- Replies: 16
- Views: 1364
Re: determine n
For kinetics, n is the exponent that a concentration is raised to in a rate law, the sum of these exponents is the overall order of the reaction. In the homework problems you can find n based off of given experimental data that shows the variation of rates with concentrations of reactants.
- Sun Mar 08, 2020 1:59 pm
- Forum: General Rate Laws
- Topic: integrated rate laws
- Replies: 7
- Views: 434
Re: integrated rate laws
The rate law is a differential equation that gives change in concentration of reactants with respect to time. When you integrate it, you get an equation that shows how reactants change as a direct result of changing the value of t.
- Sun Mar 08, 2020 1:54 pm
- Forum: Balancing Redox Reactions
- Topic: Cathode and Anode
- Replies: 24
- Views: 1531
Re: Cathode and Anode
From the equation deltaG = -nFE, you can tell that a reaction is spontaneous and does work if the value of Ecell > 0. Since to find E you would subtract the potential of the cathode by the potential of the anode, you will always get Ecell > 0 if the cathode value is larger.
- Wed Mar 04, 2020 9:28 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 6N 13
- Replies: 4
- Views: 731
Re: 6N 13
The 0.19V should be divided by (RT/NF) which I got to be 0.012839. The result is 14.798 which is approximately 15.
- Tue Mar 03, 2020 9:32 pm
- Forum: Balancing Redox Reactions
- Topic: 6L.9 part a
- Replies: 2
- Views: 290
Re: 6L.9 part a
Since we're not given the cell diagram, I assume that you would determine the anode and cathode by looking up the reduction potentials for the half reactions. The more positive value is more likely to be the cathode because it is a better oxidizing agent and the less positive value will be the anode...
- Tue Mar 03, 2020 9:20 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 6N.15
- Replies: 1
- Views: 189
Re: 6N.15
Because it is a concentration cell, both of the half reactions involve nickel. The anode reaction is Ni-->Ni^2+ + 2e^- and the cathode is just that reaction in reverse.
- Mon Mar 02, 2020 4:53 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Order
- Replies: 5
- Views: 459
Re: Order
to find the order of the reaction, just add the exponents for all of the concentration terms of a rate
- Mon Mar 02, 2020 4:50 pm
- Forum: Balancing Redox Reactions
- Topic: Electrochemical series.
- Replies: 4
- Views: 333
Re: Electrochemical series.
The electrochemical series is a list of reduction half reactions, with the most positive standard electrochemical potentials at the top, and the least positive electrochemical potentials at the bottom. The most positive values of E are the strongest oxidizing agents going forming reducing agents.
- Mon Mar 02, 2020 4:45 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy equations
- Replies: 5
- Views: 394
Re: Gibbs free energy equations
I think you should be able to use all of the methods for finding gibbs free energy, just make to differentiate between gibbs free energy and standard gibbs free energy
- Mon Mar 02, 2020 3:08 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: G=-nFE
- Replies: 5
- Views: 383
Re: G=-nFE
n is the number of moles of electrons transferred in the reaction, and I find it easiest to use the coefficient from the balanced half reaction
- Mon Mar 02, 2020 3:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2 Material
- Replies: 16
- Views: 968
Re: Test 2 Material
The test contians material from the last page of thermodynamics, and all of electrochem but material from the kinetics lectures
- Wed Feb 19, 2020 6:34 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Delta G and Delta H
- Replies: 3
- Views: 401
Re: Delta G and Delta H
I don't know if this is right but using the equation deltaG = deltaH - TdeltaS, I assumed that G and H would be most similar at the smallest possible values of S. This means that the correct answer is A because solids -> solids have the lowest entropy.
- Wed Feb 19, 2020 6:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: midterm Q1A
- Replies: 7
- Views: 449
Re: midterm Q1A
Since the reaction is exothermic, an increase in temperature will favor reactants because you can think of heat as a product. Increasing the amount of a product will shift the reaction towards reactants to maintain equilibrium.
- Wed Feb 19, 2020 6:22 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox
- Replies: 5
- Views: 354
Re: Balancing Redox
Usually you can infer the charges of elements from looking at the periodic table and determining whether the element is likely to gain or lose electrons. However, some exceptions are peroxides that have a charge of -1, hydrogen that can have a charge of -1 or +1 depending on if it is bonded to a met...
- Wed Feb 19, 2020 6:18 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy
- Replies: 4
- Views: 322
Re: Gibbs free energy
If you get that the change in standard gibbs free energy or products is greater than reactants, the overall value of delta G will be positive which means the reaction is unvaforable
- Wed Feb 19, 2020 6:17 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: converting T to kelvin
- Replies: 46
- Views: 3278
Re: converting T to kelvin
Changes in temperature are fine since they will be the same for kelvin and celsius. The only time when you have to worry about converting between celsius and kelvin is if the problem specifically asks for the answer in terms of one, or if you are using a constant like R in PV = NRT when R is specifi...
- Sun Feb 16, 2020 7:36 pm
- Forum: Balancing Redox Reactions
- Topic: Reduction vs. oxidation
- Replies: 29
- Views: 1110
Re: Reduction vs. oxidation
Oxidation is a loss of electrons, reduction is a gain of electrons (not protons). I usually remember this with the acronym OIL RIG. The only way to tell if something is reduced or oxidized is by looking at the initial and final oxidation numbers of elements in a reaction.
- Sun Feb 16, 2020 7:34 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isobaric systems
- Replies: 16
- Views: 759
Re: Isobaric systems
For isobaric reactions, pressure is constant. This means that both equations for w can be used, as well as the relationship where delta H = q
- Sun Feb 16, 2020 7:32 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: delta S=qrev/t
- Replies: 4
- Views: 268
Re: delta S=qrev/t
Usually temperature will be given to you, and qrev just means q of a reversible reaction so you use the normal q=(heat capacity)(change in T).
- Sun Feb 16, 2020 7:31 pm
- Forum: Balancing Redox Reactions
- Topic: redox reaction
- Replies: 10
- Views: 538
Re: redox reaction
I remember oxidation and reduction with OIL RIG (oxidation is loss, reduction is gain). Write out the net equation and it becomes easier to see which elements gained or lost electrons.
- Sun Feb 16, 2020 7:29 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation Reduction
- Replies: 3
- Views: 237
Re: Oxidation Reduction
The overall charge of a compound is zero unless it is specifically written with a charge. The oxidation numbers for individual elements can be inferred just by looking at the periodic table and deciding which elements are likely to lose or gain electrons. An exception is oxygen which normally has a ...
- Sun Feb 16, 2020 7:24 pm
- Forum: Calculating Work of Expansion
- Topic: Irreversible and Reversible Expanision
- Replies: 9
- Views: 632
Re: Irreversible and Reversible Expanision
In irreversible expansion, there is a sudden significant change in external pressure that allows the contents of the system to expand. In a reversible expansion, external pressure is reduced gradually and in small increments so that Pexternal = Psystem. Usually in problems it will state whether it i...
- Wed Feb 12, 2020 10:46 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Irreversible Expansion
- Replies: 7
- Views: 423
Re: Irreversible Expansion
The example that was used in class was that in a reversible expansion, pressure is gradually decreased in amounts that are so small it remains in equilibrium with the surroundings. In an irreversible expansion the pressure is decreased suddenly and in large amount so that it can't be reversed.
- Thu Feb 06, 2020 10:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy and temperature
- Replies: 2
- Views: 126
enthalpy and temperature
Are we required to know how to predict how changes in temperature will affect the enthalpy value and Kirchhoff's law for the midterm?
- Thu Feb 06, 2020 3:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume and Pressure
- Replies: 8
- Views: 246
Re: Volume and Pressure
volume and pressure are inversely related (P1V1T2= P2V2T1), which allows us to derive alternative equations to find the entropy of a system.
- Thu Feb 06, 2020 3:30 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Degeneracy
- Replies: 9
- Views: 320
Re: Degeneracy
W, degeneracy is used in the equation S = kB*ln(W) to find the residual or positional entropy of a system
- Thu Feb 06, 2020 3:29 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy
- Replies: 4
- Views: 258
Re: Enthalpy
Enthalpy is made up of the change of the internal energy of the system as well as the pressure and volume which means that it is related to work but comprised of the total energy not just the work energy
- Thu Feb 06, 2020 3:26 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated vs Closed [ENDORSED]
- Replies: 34
- Views: 4084
Re: Isolated vs Closed [ENDORSED]
In a closed system, matter cannot be transferred but heat energy can. In an isolated system the transfer of both heat energy and matter are contained in the system.
- Thu Feb 06, 2020 3:25 pm
- Forum: General Science Questions
- Topic: Midterms
- Replies: 22
- Views: 864
Re: Midterms
Lavelle's website says that the midterm includes equilibrium, acid and base, thermodynamics, and thermochemistry so i assume it is cumulative
- Fri Jan 31, 2020 4:35 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated vs Closed [ENDORSED]
- Replies: 34
- Views: 4084
Re: Isolated vs Closed [ENDORSED]
In an open system, both heat and matter can be exchanged with the system's surroundings. In a closed system, energy but not matter can be exchanged, and in an isolated system neither can be exchanged with the surroundings. If the insulated water bottle has a lid and prevents heat from escaping or en...
- Fri Jan 31, 2020 4:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% Rule
- Replies: 9
- Views: 278
Re: 5% Rule
you only need to go back and use the quadratic formula if you check X and it is more than 5% of the initial value
- Fri Jan 31, 2020 4:29 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume and Pressure
- Replies: 8
- Views: 246
Re: Volume and Pressure
Volume and pressure are inversely related. If the volume of a system decreases, the pressure will increase due to more frequent collisions.
- Fri Jan 31, 2020 4:15 pm
- Forum: General Science Questions
- Topic: Midterms
- Replies: 22
- Views: 864
Re: Midterms
I think that the midterm is on thermochem and thermodynamics
- Fri Jan 31, 2020 4:14 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Degeneracy
- Replies: 9
- Views: 320
Re: Degeneracy
In class we determined the number of microstates by using the equation 2^N, where N is the number of atoms and 2 represents a 2-state system
- Fri Jan 24, 2020 11:57 pm
- Forum: Ideal Gases
- Topic: ICE table approximation
- Replies: 10
- Views: 356
Re: ICE table approximation
You can approximate that x is 0 when K<10^-3. You can always check to see if an approximation is valid if x is less than 5% of the initial concentration.
- Fri Jan 24, 2020 11:55 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4369
Re: Kc vs Kp
For a reaction that is entirely gasses, Kp can be used if the pressure is given. Kc can be used for gasses as well if the pressure is converted to concentration, or concentration is given initially.
- Fri Jan 24, 2020 11:54 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: pKa and pKb
- Replies: 17
- Views: 838
Re: pKa and pKb
Ka and Kb are calculated the same way as K but for weak acids and bases, with the concentration of products on the top and the concentration of reactants on the bottom. PKa and Pkb are the -log(Ka) and -log(Kb)
- Fri Jan 24, 2020 11:52 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: k<10^-3
- Replies: 9
- Views: 333
Re: k<10^-3
k<10^-3 is a weak acid because to have a small number, there has to be a high concentration of reactants. If there are a lot of reactants, the acid is weak because it does not completely dissociate.
- Fri Jan 24, 2020 11:50 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy
- Replies: 4
- Views: 258
Re: Enthalpy
Enthalpy is the heat lost or gained by a system in a reaction. Once that heat energy is lost it is available to do work.
- Fri Jan 17, 2020 4:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong or weak acid?
- Replies: 5
- Views: 1125
Re: Strong or weak acid?
I memorized a chart of the most common strong acids, for bases though it is any of the oxides or hydroxides of group 1 and 2 elements.
- Fri Jan 17, 2020 12:53 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pressure change
- Replies: 4
- Views: 113
Re: pressure change
If pressure is increased due to a decrease in volume, the reaction will favor the side with fewer moles. If pressure is increased due to the addition of an inert gas there is no change in equilibrium.
- Fri Jan 17, 2020 12:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Value of Kw
- Replies: 6
- Views: 124
Re: Value of Kw
Kw is always 1.0x10^-14 at 25 degrees celsius
- Fri Jan 17, 2020 12:48 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endo/Exothermic Reactions
- Replies: 6
- Views: 356
Re: Endo/Exothermic Reactions
when you form a bond, the process is exothermic because you are going from a state of higher to lower energy. when you break a bond the process is endothermic.
- Fri Jan 17, 2020 12:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Negative pH
- Replies: 2
- Views: 84
Re: Negative pH
Superacids can have negative pH if the concentration of H3O+ is greater than 1, because if you take the negative log of a value greater than 1 you get a negative value
- Fri Jan 10, 2020 4:34 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: K vs Q
- Replies: 9
- Views: 1635
Re: K vs Q
When Q>K, the numerator or [P] is larger for Q than K which means there are more products at the time Q is being calculated than there are at equilibrium. In order to compensate for the larger concentration of products, the reaction will produce more reactants and the reverse reaction is favored. Wh...
- Fri Jan 10, 2020 4:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: using Kp vs Kc
- Replies: 13
- Views: 1514
Re: using Kp vs Kc
Kp is used when you have the partial pressures of a gas, and Kc is used for concentration which can be found using PV=nRT
- Fri Jan 10, 2020 4:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pressure and Volume
- Replies: 8
- Views: 201
Re: Pressure and Volume
Equilibrium constant for a single reaction is affected by temperature changes, not pressure
- Fri Jan 10, 2020 4:25 pm
- Forum: Ideal Gases
- Topic: R in PV=nRT
- Replies: 34
- Views: 5847
Re: R in PV=nRT
R is a gas constant that is on the constants and formulas sheet that we get on tests (also on Lavelle's website)
R= 8.314 J·K-1·mol-1 = 8.206 x 10-2 L·atm·K-1·mol-1 = 8.314 x 10-2 L·bar·K-1·mol-1= 62.364 L·Torr·K-1·mol-1
R= 8.314 J·K-1·mol-1 = 8.206 x 10-2 L·atm·K-1·mol-1 = 8.314 x 10-2 L·bar·K-1·mol-1= 62.364 L·Torr·K-1·mol-1
- Fri Jan 10, 2020 4:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Exercise 5G.1
- Replies: 4
- Views: 208
Re: Exercise 5G.1
As long as the temperature is constant, K will have the same value for a reaction even if more reactants are added. This is because K is a [P]/[R], so adding more reactant will eventually lead to more product which will reduce to the same value of K.
- Sun Dec 08, 2019 10:56 am
- Forum: Biological Examples
- Topic: chelate
- Replies: 2
- Views: 249
Re: chelate
If it has multiple bonding sites/if it is polydentate
- Sun Dec 08, 2019 10:55 am
- Forum: Hybridization
- Topic: 2sp2 and sp2
- Replies: 10
- Views: 800
Re: 2sp2 and sp2
I think that sp2 is fine for hybridization, but if it asks which orbitals are overlapping like in the Marshmallow review question 17 it might be safer to just write 2sp2
- Sun Dec 08, 2019 10:48 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4033
Re: Bent vs linear
Linear comes from the parent electron geometries of trigonal bipyramidal and octahedral, whereas bent comes from trigonal planar and tetrahedral
- Sun Dec 08, 2019 10:45 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: Hydrogen bonding
- Replies: 3
- Views: 281
Re: Hydrogen bonding
A hydrogen bond can occur between and H bonded to a N,O,F or any N,O,F with a lone pair
- Sun Dec 08, 2019 10:41 am
- Forum: Lewis Acids & Bases
- Topic: Strong Acids vs weak
- Replies: 2
- Views: 330
Re: Strong Acids vs weak
I memorized the most common strong acids and I'm going to hope that all the rest are weak.
- Sun Dec 08, 2019 10:40 am
- Forum: Lewis Acids & Bases
- Topic: all acids and bases
- Replies: 4
- Views: 361
Re: all acids and bases
Yes, a lewis acid is an electron acceptor and a Bronsted acid is a proton donor. A Bronsted acid or base is always either a lewis acid or base but some Lewis acids and bases are not Bronsted.
- Sun Dec 08, 2019 10:37 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH sig figs
- Replies: 11
- Views: 603
Re: pH sig figs
During one of the review sessions they said that sig figs for pH count after the decimal so 12.22 has 2 sig figs.
- Mon Nov 25, 2019 6:23 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Why HF is a weaker acid than HCl
- Replies: 17
- Views: 16061
Re: Why HF is a weaker acid than HCl
HF is a weaker acid because the strength of an acid is determined by how completely that acid will dissociate. Since the bond between HF is stronger than the bond between HCl, HCl will more completely dissociate which makes it a stronger acid.
- Mon Nov 25, 2019 6:21 pm
- Forum: Hybridization
- Topic: Sigma and Pi Bonds
- Replies: 21
- Views: 941
Re: Sigma and Pi Bonds
A single bond has a sigma bond, a double is one sigma and one pi, and a triple is one sigma and two pi. I think this is something that is best to just memorize.
- Mon Nov 25, 2019 6:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2.27b
- Replies: 4
- Views: 280
Re: 2.27b
A single electron is still considered a region of electron density, so the molecule that you mentioned would have 4 regions.
- Mon Nov 25, 2019 6:16 pm
- Forum: General Science Questions
- Topic: Coordination Compounds
- Replies: 7
- Views: 565
Re: Coordination Compounds
I think it's more important to know the biological functions of molecules like cisplatin and hemoglobin than it is to memorize what they look like. He said in class that we wouldn't be asked to draw the compound from memory on the test I think.
- Mon Nov 25, 2019 6:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4033
Re: Bent vs linear
A bent molecule will have a lone pair that forces the other two bonded atoms into a bent bond angle, and the linear molecules either have no lone pairs, or the lone pairs are evenly distributed so that the molecule is still linear (in molecules with 5 or 6 electron density regions)
- Fri Nov 22, 2019 3:53 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: LDF vs dipole-dipole
- Replies: 4
- Views: 357
Re: LDF vs dipole-dipole
Unless the dipole-dipole IMF is hydrogen bonding, LDF can have a significant effect on the boiling/melting point of a molecule.
- Fri Nov 22, 2019 3:51 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Cisplatin binding
- Replies: 1
- Views: 90
Re: Cisplatin binding
Guanine in the n7 position has an exposed nitrogen. The Cl in cisplatin will displace the nitrogen, and bond to the guanine.
- Fri Nov 22, 2019 3:49 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polarizability
- Replies: 9
- Views: 742
Re: polarizability
Larger molecules have more polarizable electrons which means they will be more distorted. This makes dispersion stronger and the melting/boiling point of the compound higher
- Fri Nov 22, 2019 3:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bent v. angular
- Replies: 27
- Views: 1419
Re: bent v. angular
bent and angular are the same thing
- Fri Nov 22, 2019 3:47 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Best Way To Study?
- Replies: 56
- Views: 3343
Re: Best Way To Study?
I think that doing the homework problems assigned and going to the review sessions before midterms and tests are the most helpful
- Sat Nov 16, 2019 8:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Melting Points
- Replies: 7
- Views: 432
Re: Melting Points
It might be helpful to know the order of strength for intermolecular forces so that you can determine which molecules will have higher or lower melting points based on their bonds. I don't think we are expected to have memorized melting points of specific molecules.
- Sat Nov 16, 2019 8:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 8
- Views: 298
Re: Bond Angles
I think that you should probably just memorize them since we haven't learned a way to calculate them. Trigonal planar is 120 though not 107.
- Sat Nov 16, 2019 8:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: seesaw
- Replies: 9
- Views: 623
Re: seesaw
The seesaw shape occurs when there are 4 bonding pairs and 1 lone pair
- Sat Nov 16, 2019 8:17 pm
- Forum: Bronsted Acids & Bases
- Topic: Test2
- Replies: 7
- Views: 366
Re: Test2
Everything since the midterm, so intermolecular forces, dipoles, VSEPR/molecular shape
- Sat Nov 16, 2019 8:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: How to treat Radicals
- Replies: 5
- Views: 283
Re: How to treat Radicals
yes, it would still alter the bond angles and create repulsion
- Thu Nov 07, 2019 3:43 pm
- Forum: Bond Lengths & Energies
- Topic: Bond strengths
- Replies: 9
- Views: 501
Re: Bond strengths
I think that for intramolecular bonds, the shorter it is the stronger it is. This might not be the case for IMF's between molecules though.
- Thu Nov 07, 2019 3:41 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: HW 2D.3
- Replies: 5
- Views: 579
Re: HW 2D.3
there is the greatest difference in electronegativity between Ba and Br, which means it is the most ionic
- Tue Nov 05, 2019 11:25 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shape of Orbitals?
- Replies: 6
- Views: 318
Re: Shape of Orbitals?
I don't think that orbital shape will likely be tested on the midterm, but you should probably know how the quantum numbers n,l,ml relate to the location of an electron
- Tue Nov 05, 2019 11:21 pm
- Forum: Einstein Equation
- Topic: e=hv used for particles?
- Replies: 10
- Views: 1341
Re: e=hv used for particles?
E=hv can be used for the energy of a photon, so if you think of light as acting like a particle rather than a wave you can use that equation.
- Tue Nov 05, 2019 11:18 pm
- Forum: DeBroglie Equation
- Topic: Midterm Review Problem 6 a
- Replies: 1
- Views: 204
Re: Midterm Review Problem 6 a
First convert the mass of GarBreadium from g/mol to one kg/atom using avogadro's number. Then you should be able to just use de broglie's equation plugging in the mass of one atom, and the velocity that is given to you.
- Sat Nov 02, 2019 10:41 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Work function units
- Replies: 5
- Views: 290
Re: Work function units
I think since you're likely to be using it with planck's constant, it's safest for units to be in joules
- Sat Nov 02, 2019 10:24 am
- Forum: Resonance Structures
- Topic: Tips for drawing resonance structures
- Replies: 3
- Views: 128
Re: Tips for drawing resonance structures
I would use formal charge to find the most likely structure, and then for resonance check to see if any of the double or single bonds can have different orientations/locations
- Sat Nov 02, 2019 10:22 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: how to draw lewis structure
- Replies: 9
- Views: 882
Re: how to draw lewis structure
The chlorine atom in the middle would not have a complete octet, so normally they would give you ClO2 as an ion (-1) which gives it 20 electrons
- Sat Nov 02, 2019 10:20 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Moles and Molar Mass
- Replies: 2
- Views: 332
Re: Moles and Molar Mass
The atomic weight is the weight of just one atom, and you don't have to calculate it because it's given to you on the periodic table. The molecular mass is the mass of multiple atoms in a molecule and it can be calculated by adding atomic masses together.
- Sat Nov 02, 2019 10:17 am
- Forum: DeBroglie Equation
- Topic: When to use the de Broglie equation?
- Replies: 5
- Views: 271
Re: When to use the de Broglie equation?
For finding the wavelength of anything that is not light, or in the photoelectric effect if you need to find velocity of an electron
- Thu Oct 24, 2019 9:42 am
- Forum: Ionic & Covalent Bonds
- Topic: What are the exceptions to the octet rule?
- Replies: 5
- Views: 342
Re: What are the exceptions to the octet rule?
I don't think we have gone over this yet, but in addition to H, He, Li, Be, some elements can have an expanded octet by using the d/f orbitals.
- Thu Oct 24, 2019 9:34 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: What's the difference between subshell vs orbitals?
- Replies: 8
- Views: 624
Re: What's the difference between subshell vs orbitals?
I think that subshells are s,p,d,f, and the orbitals are the different possible orientations of the subshells.
- Thu Oct 24, 2019 9:31 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Order of electron configuration
- Replies: 6
- Views: 230
Re: Order of electron configuration
3d is at a lower energy state than than 4s so it is written first, even though the d block comes after the s block in the periodic table.
- Thu Oct 24, 2019 9:27 am
- Forum: Ionic & Covalent Bonds
- Topic: ground state electron configuration
- Replies: 3
- Views: 259
Re: ground state electron configuration
The + and 3+ charges tell you that you have a cation that lost electrons. To write the electron configuration just write the expected ground state, and remove the necessary amount of electrons. For example for Bi3+ the electron configuration for Bi is [Xe]5d106s26p3 and after removing 3 electrons be...
- Wed Oct 23, 2019 11:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: What topic are we on?
- Replies: 11
- Views: 506
Re: What topic are we on?
I did the problems from the Quantum World section because the syllabus says that the section covers electron configuration which we went over this week.
- Fri Oct 18, 2019 12:08 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Wave Function
- Replies: 2
- Views: 96
Re: Wave Function
I think that the wave function squared is the same as the s,p,d,f orbitals because they both represent the electron density or probability of finding an electron.
- Fri Oct 18, 2019 12:05 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg constant
- Replies: 3
- Views: 132
Re: Rydberg constant
The rydberg constant only works for the hydrogen atom because it only has one electron. It doesn't take into account electron-electron repulsion.
- Fri Oct 18, 2019 12:01 am
- Forum: Properties of Electrons
- Topic: Wave Function
- Replies: 5
- Views: 222
Re: Wave Function
The wave function is just a way to describe the position of an electron, since electrons have wavelike properties. The wave function squared is the probability of finding an electron (electron density) which is what the s,p,d,f orbitals represent.
- Thu Oct 17, 2019 11:56 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Numbers
- Replies: 3
- Views: 139
Re: Quantum Numbers
I think ψ2,0,0 is a valid combination if you're talking about quantum numbers (n, l, ml) to describe position of an electron.
- Thu Oct 17, 2019 11:50 pm
- Forum: Properties of Electrons
- Topic: effective nuclear charge
- Replies: 5
- Views: 318
Re: effective nuclear charge
Zeff is also helpful in comparing sizes of elements by looking at how strongly the positive charge of the nucleus is holding electrons.