Search found 100 matches
- Sat Mar 14, 2020 8:18 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Internal Energy
- Replies: 6
- Views: 565
Re: Internal Energy
Temperature and internal energy are directly proportional. In a sense internal energy is a measure of temperature. If temperature is not changing, then internal energy is 0. If you are expanding then you must be inputting heat. If you are compressing then you must be releasing heat.
- Sat Mar 14, 2020 8:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 513820
Re: Saying Thank You to Dr. Lavelle
Dear Dr. Lavelle, I came into your chemistry classes with little chemistry knowledge and definitely no appreciation for the subject! But after these two quarters and your step by step explanations, I have learned more with ease than I never thought I would. It took extra hard work and time to succee...
- Sat Mar 14, 2020 8:05 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Electrolysis
- Replies: 6
- Views: 455
Re: Electrolysis
As long as you know how electrolysis can have a negative redox potential and why, I don't believe it is any too different from the regular galvanic problems.
- Sat Mar 14, 2020 8:04 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: rate determining step
- Replies: 4
- Views: 430
Re: rate determining step
You can also use the slow step to make the assumption that the product from the previous reaction is in excess and in equilibrium.
- Sat Mar 14, 2020 8:01 pm
- Forum: Balancing Redox Reactions
- Topic: YouTube videos for Redox Reactions
- Replies: 4
- Views: 494
Re: YouTube videos for Redox Reactions
I also suggest the Organic Chemistry Tutor. Super helpful for me and he does examples very similar to class with long reviews!
- Sat Mar 14, 2020 7:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student - Part II [ENDORSED]
- Replies: 298
- Views: 245078
Re: Advice from a Medical Student - Part II [ENDORSED]
Thank you for all your words and wisdom! As a current medical student, what similarities do you find between yourself and other medical students admitted in the program? It seems like as premeds, a lot of people follow the same path (volunteering, research, etc). Do you have any advice on how to set...
- Sun Mar 08, 2020 11:18 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Application
- Replies: 6
- Views: 461
Re: Application
Also remember you can combine these equations for the vant hoff equation
- Sun Mar 08, 2020 11:17 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Instantaneous Rate
- Replies: 41
- Views: 2095
Re: Instantaneous Rate
I believe instantaneous rate becomes 0 when the reaction reaches equilibrium
- Sun Mar 08, 2020 11:16 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: order
- Replies: 4
- Views: 381
Re: order
You can also think of it as n+m+....=order
- Sun Mar 08, 2020 11:15 pm
- Forum: Balancing Redox Reactions
- Topic: Why do we flip E for oxidation?
- Replies: 13
- Views: 1074
Re: Why do we flip E for oxidation?
Be careful that if you are using the formula Ecell= Ecathode- Eanode then you would NOT change the sign
- Sun Mar 08, 2020 11:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Use of Platinum
- Replies: 10
- Views: 575
Re: Use of Platinum
You need to use it on both ends when both the cathode and anode ends are aqueous solutions and have no way to conduct the electrons without a solid.
- Sun Mar 01, 2020 11:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: delta Phi & emf & cell potential
- Replies: 1
- Views: 175
Re: delta Phi & emf & cell potential
The emf (E) is the change in cell potential as current i goes to 0 from what I understand.
- Sun Mar 01, 2020 11:25 pm
- Forum: Balancing Redox Reactions
- Topic: Reducing Agent
- Replies: 5
- Views: 413
Re: Reducing Agent
Be sure to only use oxidizing agent and reducing agent for the reactants in your overall redox reaction,
- Sun Mar 01, 2020 11:23 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Ways to calculate Gibbs free energy
- Replies: 5
- Views: 346
Re: Ways to calculate Gibbs free energy
You use the second equation when given gibbs free energy standard formation measurements. You use the first equation when given enthalpy and entropy.
- Sun Mar 01, 2020 11:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Direction of flow
- Replies: 5
- Views: 431
Re: Direction of flow
The salt bridge is just used to balance the charge as electrons flow to one side. For electrolytic cells, the reaction occurs in the nonspontaneous direction. For galvanic cells, the reaction occurs in the spontaneous direction.
- Sun Mar 01, 2020 11:19 pm
- Forum: Balancing Redox Reactions
- Topic: 6K.3d
- Replies: 5
- Views: 366
Re: 6K.3d
What would be the half reaction for HClO3?
- Sun Feb 23, 2020 3:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Use of Platinum
- Replies: 10
- Views: 575
Re: Use of Platinum
However, as mentioned in lecture, remember that platinum one one side of the cathode or anode does not imply it is being used on both ends.
- Sun Feb 23, 2020 3:17 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: work
- Replies: 8
- Views: 411
Re: work
I may be wrong but I believe you are referring to the concept of deltaG=work(max). In the case of a battery, deltaG will always be negative so I believe work will also be negative.
- Sun Feb 23, 2020 3:14 pm
- Forum: Balancing Redox Reactions
- Topic: Identifying Half Reactions
- Replies: 4
- Views: 330
Identifying Half Reactions
In our discussion, we did an example of balancing redox reactions for: MnO4- (aq) + H2SO3 (aq) --> Mn2+ (aq) + HSO4- In section, it was said that MnO4- was reduced and H2SO3 was oxidized. I didn't quite understand this because to me it seemed like Mn2+ means that two electrons were lost meaning oxid...
- Sun Feb 23, 2020 3:08 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Spontaneous
- Replies: 20
- Views: 1176
Re: Spontaneous
It is also useful to note that temperature can affect the free energy in both ways either low or high temperature.
- Sun Feb 23, 2020 3:05 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox reactions
- Replies: 4
- Views: 223
Re: Balancing Redox reactions
In addition, make sure to correctly identify the reduction and oxidation half reactions in the beginning. Balance the equation with everything except H and O then balance your oxygen with H2Os.
- Sun Feb 16, 2020 10:40 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Is spontaneity determined by entropy or free energy?
- Replies: 9
- Views: 1897
Re: Is spontaneity determined by entropy or free energy?
In that case, what is the difference between the reaction and the process?
- Sun Feb 16, 2020 10:36 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated Systems.
- Replies: 5
- Views: 462
Re: Isolated Systems.
Be sure to not confuse this with the concept of isothermal which means U (internal energy change) is 0. But q and w do not have to be 0.
Your entropy or degeneracy would not change because the isolated system is not interracting with the surroundings in any way.
Your entropy or degeneracy would not change because the isolated system is not interracting with the surroundings in any way.
- Sun Feb 16, 2020 10:34 pm
- Forum: Calculating Work of Expansion
- Topic: Choosing work equation
- Replies: 10
- Views: 763
Re: Choosing work equation
For the most part, you will be explicitly told when the process is reversible. If you are not told, you can most likely tell from the context of the problem (pressure is constant, etc), that the process is irreversible.
- Sun Feb 16, 2020 10:31 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work
- Replies: 14
- Views: 951
Re: Work
An exception to the expanding concept is when the external pressure is 0. Then, a system can expand without doing any work (w=0)
- Sun Feb 16, 2020 10:26 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Wmax
- Replies: 4
- Views: 262
Re: Wmax
Wmax is the max work done at constant pressure and temperature and means all free energy is used for work. In an isothermal, reversible expansion Wmax= DeltaG
- Sun Feb 09, 2020 9:00 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 4G.1
- Replies: 3
- Views: 241
Re: 4G.1
You will generally be told how many states the individual atoms can take. If they are fixed, then there is only one state. Degeneracy is the number of possible states to the power of how many atoms. W= (# states)^ (# atoms). If there is only one possible state then W=1 and entropy is equal to S=kbln...
- Sun Feb 09, 2020 8:57 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy
- Replies: 3
- Views: 227
Re: enthalpy
A slight correction to the previous definition. I believe that the sum of work and heat given off in a reaction is equal to change in internal energy (U). Enthalpy is related to heat given off in a reaction during a constant pressure. The heat given off in a reaction is generally denoted by q but in...
- Sun Feb 09, 2020 8:51 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs. Extensive
- Replies: 15
- Views: 1297
Re: Intensive vs. Extensive
An example of this is heat capacity vs specific heat capacity. Heat capacity depends on the amount of substance but specific heat capacity does not.
- Sun Feb 09, 2020 8:49 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal and Reversible
- Replies: 6
- Views: 130
Re: Isothermal and Reversible
If a process is reversible then you can think of it as being done in infinetely small increments. Because of this the system remains in equilibrium with its surroundings and work can be calculated using the integral formula. If it is irreversible, the change is rapid and the system cannot be in equi...
- Sun Feb 09, 2020 8:46 pm
- Forum: Calculating Work of Expansion
- Topic: Isobaric and Isochoric
- Replies: 5
- Views: 363
Re: Isobaric and Isochoric
It is also useful to know that in an isochoric system work is equal to 0. In isothermal delta U is 0.
- Sun Feb 02, 2020 12:02 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible/Irreversible Reactions
- Replies: 6
- Views: 322
Re: Reversible/Irreversible Reactions
When you make infinetely small changes, your parameters such as pressure and volume are defined. When you make rapid changes, then they can no longer be defined. There is a khanacademy video that explains this topic well.
- Sun Feb 02, 2020 11:58 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Affect of temperature on entropy?
- Replies: 5
- Views: 222
Re: Affect of temperature on entropy?
Yes, and the amount of states the system can take increases.
- Sun Feb 02, 2020 11:57 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Constant Pressure vs Constant Volume
- Replies: 4
- Views: 315
Re: Constant Pressure vs Constant Volume
An open system will have constant pressure, and a closed system will have constant volume.
- Sun Feb 02, 2020 11:52 am
- Forum: Phase Changes & Related Calculations
- Topic: Multiple Phase Changes
- Replies: 4
- Views: 188
Re: Multiple Phase Changes
Yes, and just to add on you must also account for the specific heat of vaporization or the amount of heat to change phase from liquid to vapor.
- Sun Feb 02, 2020 11:51 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework 4.15
- Replies: 1
- Views: 102
Re: Homework 4.15
You can find these values in appendix 2 in the beginning of the book. Find the energy released by the oxidation of zinc. Then use the heat capacity of HCl (same as water) and mass q=mcdetaT to solve for final temp.
- Sun Jan 26, 2020 5:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: Physical or Phase Changes
- Replies: 7
- Views: 156
Re: Physical or Phase Changes
I believe they will be given to us.
- Sun Jan 26, 2020 5:52 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why is enthalpy additive?
- Replies: 3
- Views: 126
Re: Why is enthalpy additive?
Because since it is a state function only the endpoints count not the path taken. Another way to think of enthalpy is the heat content at a standard pressure. There is a khan academy video that can help explain a bit more.
- Sun Jan 26, 2020 5:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 1
- Views: 135
Re: Bond Enthalpies
Yes bond enthalpies (except diatomics) are inaccurate because they are averages since bond enthalpy depends on properties of surrounding atoms
- Sun Jan 26, 2020 5:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH
- Replies: 7
- Views: 244
Re: pH
Also be careful to check whether you’re given pKa or pKb and whether you want to find OH or H+ concentration
- Sun Jan 26, 2020 5:44 pm
- Forum: Phase Changes & Related Calculations
- Topic: Work and State Properties
- Replies: 2
- Views: 129
Re: Work and State Properties
To add on depending on the path taken distance can change and therefore work
- Mon Jan 20, 2020 6:41 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Difference in PH between strong and weak acids
- Replies: 11
- Views: 479
Re: Difference in PH between strong and weak acids
When adding a weak acid, how does the conjugate base affect pH?
- Mon Jan 20, 2020 6:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Low [H3O+]
- Replies: 1
- Views: 88
Re: Low [H3O+]
What this meant is that when you add a very weak acid or a small amount of acid to a neutral solution, sometimes it does not produce enough H3O to affect the pH. This is because there is already 10^7 (H3O) in a solution of neutral water at 25 degrees Celsius.
- Mon Jan 20, 2020 6:36 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: definition of a buffer
- Replies: 8
- Views: 400
Re: definition of a buffer
If you use a weak acid or weak base, wouldn't it's conjugate be a strong base/acid? So if the buffer demands equal concentrations of weak acid and base, how would it be created?
- Mon Jan 20, 2020 6:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE tables
- Replies: 5
- Views: 155
Re: ICE tables
When you are given Ka or Kb, that is another indicator you will be likely using an ICE table because you do not know how much of the reactant will dissociate.
- Mon Jan 20, 2020 6:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Delta H
- Replies: 10
- Views: 728
Re: Delta H
If it helps, another way to think of delta H or enthalpy is the energy stored in bonds. If the products are in a lower energy more stable configuration, the reaction will be exothermic.
- Sun Jan 12, 2020 4:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Different types of K
- Replies: 9
- Views: 256
Re: Different types of K
K is the equilibrium constant. It gives you the ratio between products and reactants. It can represent Kc or Kp
Kc is the equilibrium constant written in terms of concentration. So it is concentration of products over reactants.
Kp is the equilibrium constant in terms of partial pressure.
Kc is the equilibrium constant written in terms of concentration. So it is concentration of products over reactants.
Kp is the equilibrium constant in terms of partial pressure.
- Sun Jan 12, 2020 4:42 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction shifts right or left?
- Replies: 14
- Views: 1496
Re: Reaction shifts right or left?
Yes, shifting to the left means the reverse reaction is favored more reactants will be made. Shifting to the right means forward reaction is favored and more products will be made.
- Sun Jan 12, 2020 4:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Finding K: liquids and aqueous
- Replies: 7
- Views: 223
Re: Finding K: liquids and aqueous
Aqueous solutions have a defined concentration. For example 10 moles of salt in one liter of aqueous solution is 10M concentration. However, a liquid by itself cannot be measured in concentration. If you had just water, you would not be able to write it in terms of a concentration.
- Sun Jan 12, 2020 4:38 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert Gases and Equilibrium Constant
- Replies: 4
- Views: 223
Re: Inert Gases and Equilibrium Constant
I believe that's the point Dr. Lavelle was trying to make with that demonstration. Pressure itself does not change the reaction quotient. Rather, the change in concentration of the reactants is what affects the reaction quotient. When you add an inert gas, you are increasing the pressure in the cont...
- Sun Jan 12, 2020 4:32 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Equilibrium vs. Non-Equilibrium
- Replies: 4
- Views: 141
Re: Equilibrium vs. Non-Equilibrium
To add on, if Q<K that means there is either too much reactants or not enough products. So the reaction will continue in the forward direction.
If Q>K, then there is too many products and not enough reactants, so the reverse reaction is favored.
If Q>K, then there is too many products and not enough reactants, so the reverse reaction is favored.
- Sun Dec 08, 2019 10:38 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH
- Replies: 6
- Views: 324
Re: pH
The higher the H+ concentration, the higher the H3O+ concentration (they are the same thing H3O means reacted with water), which results in a lower pH. Same applies for OH.
- Sun Dec 08, 2019 10:37 pm
- Forum: Biological Examples
- Topic: Heme complex & O2
- Replies: 5
- Views: 277
Re: Heme complex & O2
Yes, I believe this is because the max electrons Fe can accomodate are 18 electrons with all its orbitals filled.
- Sun Dec 08, 2019 10:35 pm
- Forum: Student Social/Study Group
- Topic: Cyanide
- Replies: 5
- Views: 486
Re: Cyanide
When drawing the lewis structure, make sure each element has a complete octet then count the lowest charge configuration.
- Sun Dec 08, 2019 10:35 pm
- Forum: *Titrations & Titration Calculations
- Topic: Type of Titration
- Replies: 3
- Views: 503
Re: Type of Titration
If a strong acid reacts with a weak base, then pH<7. If weak acid reacts with a strong base then pH>7. Strong acid strong base will be pH7
- Sun Dec 08, 2019 10:33 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Types of Salts
- Replies: 7
- Views: 584
Re: Types of Salts
You can notice how the salt would behave in water. This can only tell you neutral, acid, or basic. However, remember that group 2 elements can react in water although we overlooked that in class.
- Sun Dec 08, 2019 10:31 pm
- Forum: Hybridization
- Topic: 2sp2 and sp2
- Replies: 10
- Views: 804
Re: 2sp2 and sp2
If the question is asking for hybridization, then sp2 is fine. I don't believe it was asking for specific level and hybridization.
- Sun Dec 08, 2019 10:30 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: boiling point
- Replies: 9
- Views: 897
Re: boiling point
Also remember the respective strength of intermolecular forces. Hydrogen bonds are much stronger than LDF. Ion-dipole then dipole-dipole, etc. etc. Ionic bonds are weak in water.
- Sun Dec 08, 2019 10:29 pm
- Forum: Resonance Structures
- Topic: Bond lengths
- Replies: 2
- Views: 265
Re: Bond lengths
The electron is delocalized among the atoms. Not just one atom will have a double bond, but multiple ones will at different times (hybrid). This makes the molecule more stable.
- Sun Dec 08, 2019 10:26 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty
- Replies: 5
- Views: 314
Re: Uncertainty
Uncertainty in position is measured by diameter in meters. It is either provided or you must solve for it knowing delta p.
- Sun Dec 08, 2019 10:26 pm
- Forum: Limiting Reactant Calculations
- Topic: A different way
- Replies: 8
- Views: 825
Re: A different way
Also remember to always look at molar ratios when looking for the limiting reactant. This is a common mistake.
- Sun Dec 01, 2019 11:46 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strength of Acids - Example from Lecture
- Replies: 6
- Views: 447
Re: Strength of Acids - Example from Lecture
To add on to this, Yes because Chlorine has a greater electronegativity, it will be better in delocalizing electrons from the negative oxygen. He also mentioned that Fluorine would be an even stronger acid, because Fluorine is more electronegative and would delocalize electrons even more, giving mor...
- Sun Dec 01, 2019 11:42 am
- Forum: Hybridization
- Topic: Hybridization of Carbon and Nitrogen
- Replies: 2
- Views: 239
Re: Hybridization of Carbon and Nitrogen
For NH3: The electron arrangement would be tetrahedral and the shape using lewis structures would be trigonal pyrimadal. Nitrogen will have 4 areas of electron density. The hybridization of nitrogen will therefore be sp3, because sp3 correlates to 4 areas of electron density. In sp3, there is 1 hybr...
- Sun Dec 01, 2019 11:28 am
- Forum: Lewis Structures
- Topic: Octet Rule
- Replies: 7
- Views: 620
Re: Octet Rule
Formal charge will always be the greatest contributor to determining the bonding configuration in a molecule. Expanded octets may or may not form as a result of that.
- Sun Dec 01, 2019 11:25 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg
- Replies: 4
- Views: 322
Re: Rydberg
You can also think of this in terms of the potential energy equation. (PE=q1q2/r). R is the distance between the electron and nucleus. As R gets bigger and bigger, potential energy approaches 0. As an electron goes farther from the nucleus it reaches higher energy levels and approaches 0 or becomes ...
- Sun Dec 01, 2019 11:15 am
- Forum: Significant Figures
- Topic: Sig Figs on Tests
- Replies: 24
- Views: 2113
Re: Sig Figs on Tests
Also remember that it was mentioned in each step of a calculation, you may round to the proper amount of sig figs as your final answer. Rounding error from this will not be an issue from what I understand.
- Sat Nov 23, 2019 8:57 pm
- Forum: Limiting Reactant Calculations
- Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
- Replies: 68
- Views: 6595
Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Only your final answer needs the correct sig fig amount. However, I remember a post that also mentioned for each individual step you only need to round for the final sig fig number. This way, any rounding errors you may have are okay as long as you use the correct number of sig figs as the final ans...
- Sat Nov 23, 2019 8:52 pm
- Forum: Resonance Structures
- Topic: Resonance and Naming
- Replies: 11
- Views: 841
Re: Resonance and Naming
Remember that resonance gives partial double bond characteristics to all surrounding atoms. No, it will not affect the naming.
- Sat Nov 23, 2019 8:51 pm
- Forum: Biological Examples
- Topic: Ring structure
- Replies: 2
- Views: 162
Re: Ring structure
A ring structure forms when a chelate (a complex containing a ligand) attaches to a metal to form the structure. I believe the ring formation is due to the shape of the ligand attaching. An example was done in class with NH2-CH2-CH2-NH2
- Sat Nov 23, 2019 8:44 pm
- Forum: Lewis Acids & Bases
- Topic: Acid and Base Consumption in Humans
- Replies: 2
- Views: 251
Re: Acid and Base Consumption in Humans
To add on to this, there is a biological instinct to avoid bitter foods because they are associated with poisonous substances.
- Sat Nov 23, 2019 8:40 pm
- Forum: *Black Body Radiation
- Topic: Equation
- Replies: 8
- Views: 634
Re: Equation
I believe we do not need to know the equation. It is useful to know, however, that Planck's constant was formed to explain the data from blackbody radiation.
- Sun Nov 17, 2019 10:40 pm
- Forum: Sigma & Pi Bonds
- Topic: Test 2 Sigma and Pi bonds
- Replies: 5
- Views: 179
Re: Test 2 Sigma and Pi bonds
I am confused as to why these bonds occur. Wouldn't you have electron-electron repulsion between adjacent electron clouds?
- Sun Nov 17, 2019 10:38 pm
- Forum: Lewis Structures
- Topic: 2D13
- Replies: 4
- Views: 276
Re: 2D13
This is correct. Because it is in row 3, it has access to the d orbital.
- Sun Nov 17, 2019 10:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: SF4
- Replies: 3
- Views: 216
Re: SF4
Yes, just like the above post says. Another thing to remember is that this only applies for the trigonal bipyramidal arrangement or seesaw shape
- Sun Nov 17, 2019 10:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR shapes
- Replies: 3
- Views: 148
Re: VSEPR shapes
Yes, make sure to be able to differentiate between electron arrangement and shape. While those are the only electron density arrangements we need to know, the number of shapes we need to know is indicated above.
- Sun Nov 17, 2019 10:28 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Wavelength Plausibility
- Replies: 31
- Views: 2574
Re: Wavelength Plausibility
It would, but I think for the purposes of the class we only need to remember 700-400 nm.
- Sun Nov 10, 2019 10:50 pm
- Forum: Empirical & Molecular Formulas
- Topic: Midterm question 1
- Replies: 6
- Views: 516
Re: Midterm question 1
The empirical formula of Riboflavin is C17H20N4O6.
I solved it by identifying the conservation of matter in the reaction, and counted the number of atoms on each end of the reaction to form the empirical formula with the remaining atoms.
I solved it by identifying the conservation of matter in the reaction, and counted the number of atoms on each end of the reaction to form the empirical formula with the remaining atoms.
- Sun Nov 10, 2019 10:40 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation Number
- Replies: 6
- Views: 377
Re: Oxidation Number
Yes, the oxidation number of a molecule would be the sum of the formal charges.
- Sun Nov 10, 2019 10:39 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation Number
- Replies: 6
- Views: 377
Re: Oxidation Number
Oxidation number is based on the number of electrons an atom in ground state gains or loses. Depending on an atom's ionization energy and electron affinity, they are either found as cations or anions.
- Sun Nov 10, 2019 10:35 pm
- Forum: Empirical & Molecular Formulas
- Topic: 11/08 Friday Lecture
- Replies: 1
- Views: 270
Re: 11/08 Friday Lecture
Fluidity, hydrogen bonds, and induced dipole dipole interactions were discussed in detail
- Sun Nov 10, 2019 10:11 pm
- Forum: Lewis Acids & Bases
- Topic: Why Lewis Acid?
- Replies: 3
- Views: 152
Re: Why Lewis Acid?
If it helps, I like to think of it as a modified version of the Bronsted Lowry acid and base idea. In the bronsted definition, an acid donates a hydrogen proton and a base accepts a hydrogen proton. Without a proton, you are left with an electron. The Lewis definition allows you to broaden and apply...
- Sun Nov 10, 2019 10:00 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: The exceptions
- Replies: 6
- Views: 380
Re: The exceptions
Another exception that showed up on the midterm was Nitrogen. Because these atoms have a half filled orbital and are stable, they have a higher ionization energy than expected.
- Sun Nov 10, 2019 9:57 pm
- Forum: Coordinate Covalent Bonds
- Topic: Coordinate covalent bonds
- Replies: 9
- Views: 738
Re: Coordinate covalent bonds
As stated before, a coordinate covalent bond has one atom supplies the electron pair. To add on, this relates to Lewis acids because they accept electrons and Lewis bases donate electrons.
- Sun Oct 27, 2019 11:53 pm
- Forum: Octet Exceptions
- Topic: Octet Rule Exceptions
- Replies: 2
- Views: 171
Re: Octet Rule Exceptions
They aren't used by atoms regularly because atoms in period 3 themselves do not have enough electrons to use the d orbitals. Remember until 4s2, the d is higher energy than s orbital.
- Sun Oct 27, 2019 11:40 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge and Covalent Bonds
- Replies: 3
- Views: 165
Re: Formal Charge and Covalent Bonds
From what I understood, since covalent bonds share electrons the formal charge formula indicates s/2 to represent an equal sharing. However, in reality there are atoms with higher electronegativities in many cases which cause unequal sharing that is a thing the formula does not account for.
- Sun Oct 27, 2019 11:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: Confusion with covalent
- Replies: 3
- Views: 124
Re: Confusion with covalent
It is the most stable form for an atom to have their s and p orbitals filled. When their s and p orbitals are filled (octet rule=8 electrons), they reach noble gas configuration
- Sun Oct 27, 2019 11:36 pm
- Forum: Lewis Structures
- Topic: Lewis symbols
- Replies: 5
- Views: 287
Re: Lewis symbols
Remember that the dots represent unpaired electrons. The octet rule aims to fill the s and p orbitals completely (8 electrons)
- Sun Oct 27, 2019 11:20 pm
- Forum: Properties of Electrons
- Topic: What's the difference between a shell, a subshell, an energy level, and an orbital?
- Replies: 8
- Views: 561
Re: What's the difference between a shell, a subshell, an energy level, and an orbital?
Just to add on, a hydrogen atom (or any single electron atom), has s,p, and d orbitals that are degenerate. This means they all have equal energy level because there are no electrons interacting with each other.
- Sun Oct 20, 2019 4:33 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Spin
- Replies: 3
- Views: 159
Re: Spin
Electron spin is a property that relates to the direction an electron rotates about its axis. It was discovered by shining a beam of silver atoms in a magnetic field. Because the electrons spin in different directions, their magnetic properties change. This caused atoms to split into two beams. http...
- Sun Oct 20, 2019 4:26 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: What does the H mean?
- Replies: 9
- Views: 751
Re: What does the H mean?
H is planck's constant. If you are curious as to what it represents, it was the constant that was used to explain the blackbody radiation model because it accounts for energy that is quantized.
- Sun Oct 20, 2019 4:21 pm
- Forum: Photoelectric Effect
- Topic: One photon one atom interaction
- Replies: 14
- Views: 533
Re: One photon one atom interaction
As you increase the frequency, you increase the energy of the photon. So yes, you must have a minimum frequency to eject an electron. Increasing the frequency further will just make the electron leave at a higher velocity. As you increase the amplitude, you increase the amount of photons. Therefore,...
- Sun Oct 20, 2019 4:16 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: paired and parallel electrons
- Replies: 3
- Views: 136
Re: paired and parallel electrons
For electrons to be paired, they will have the opposite spin and will be in the same orbital. For parallel electrons, they will have the same spin but be in different orbitals. This is to create the least electron repulsive force.
Hope that helps,
Hussain
Hope that helps,
Hussain
- Wed Oct 16, 2019 9:25 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbital Conceptual Question
- Replies: 1
- Views: 178
Orbital Conceptual Question
Hello everyone, I had a conceptual question about the orbitals. From what I understand, orbitals are mathematical models that show where an electron is most likely to be found. However, I am confused about a few things. 1. A s orbital is a sphere that encloses around the nucleus. According to the de...
- Sun Oct 06, 2019 8:38 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: G5
- Replies: 6
- Views: 489
Re: G5
I also don't understand this. Intuitively, for every one mole of Na2CO3, shouldn't there be 2 moles of Na? And why is the multiplication done in the last step? 2.11g Na2Co3= 0.0199 moles Na2Co3 (1 mole Na2Co3)*(2 mol Na/1 mole Na2Co3)= 0.0398M Na Solution (0.0398)(x)=(2.15*10^3)(0.25) x= 3.4 mL Can ...
- Thu Oct 03, 2019 11:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent
- Replies: 32
- Views: 43279
Re: Ionic vs Covalent
Just curious. Does anyone know if polarity affects bond strength? If so, how?
- Thu Oct 03, 2019 11:28 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: G. 25
- Replies: 3
- Views: 260
Re: G. 25
To add on, think of it intuitively as salt and water. If you have a 10 grams of salt in 10 mL of water and then double the water amount 90 times you would eventually have 10 grams of salt now dispersed in a huge body of water (10*(2)^90) mL. So if you were to take a small sample of this new diluted ...
- Thu Oct 03, 2019 11:21 pm
- Forum: SI Units, Unit Conversions
- Topic: Can someone explain why we use kg for mass as the base unit?
- Replies: 9
- Views: 915
Re: Can someone explain why we use kg for mass as the base unit?
This is just another note to add. One common misconception I had is that 1 kg/m^3 is equal to 1 g/cm^3. This is not true, however, because you have to take into account the powers. So like Dr. Lavelle said, make sure to perform conversions beforehand.
- Thu Oct 03, 2019 11:19 pm
- Forum: Empirical & Molecular Formulas
- Topic: Homework Question F.9
- Replies: 6
- Views: 241
Re: Homework Question F.9
Yes, you are looking for the empirical formula because of the key word "ratio" of atoms. And just to clarify, converting between percentages to moles does NOT mean divide by a hundred. It means we are taking a hypothetical sample of 100 grams and taking respective percentages of that. Once...
- Thu Oct 03, 2019 11:15 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Solutions vs. Dilutions
- Replies: 4
- Views: 234
Re: Solutions vs. Dilutions
Just to add on, a dilution is more evident when you have already been given a solution. Try to pay close attention to the last statement where it will usually clarify.
- Thu Oct 03, 2019 11:11 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Aqueous, solid, gas
- Replies: 11
- Views: 16035
Re: Aqueous, solid, gas
Remember, an aqueous solution is formed when an ionic compound such as NaCl dissociates. It is represented by (aq) because it's technically a solid but in water dissociates