Search found 61 matches
- Sat Mar 16, 2019 8:42 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics Plots
- Replies: 5
- Views: 1023
Re: Kinetics Plots
If the line is straight for a graph, then the reaction is that order. For instance if the data points give you a straight line for lnA on the y-axis and t on the x-axis, you know you have a first order reaction.
- Sat Mar 16, 2019 8:34 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Bimolecular
- Replies: 13
- Views: 2269
Re: Bimolecular
Can a bimolecular reaction be third order if one of the reactants is second order?
- Sat Mar 16, 2019 8:31 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 418261
Re: Final Jitters
One tip I have is to not talk about the material and what you do and don't know right before the test. You're not going to learn anything in just five minutes but you can psych yourself out.
- Sat Mar 16, 2019 8:24 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Functional Groups
- Replies: 7
- Views: 2091
Re: Functional Groups
Hadji Yono-Cruz 2L wrote:Should we remember all of the functional groups mentioned in the slide in lecture?
All of these posts date back to last year so I don't think this applies to our 2019 final.
- Sun Mar 10, 2019 4:17 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: zero and first
- Replies: 5
- Views: 592
Re: zero and first
Are zero order reaction rates included in the rate law?
- Sun Mar 10, 2019 4:14 am
- Forum: General Rate Laws
- Topic: integrals
- Replies: 8
- Views: 1009
Re: integrals
Will we be expected to integrate or derive any formulas or will they be provided to us?
- Sun Mar 10, 2019 4:13 am
- Forum: General Rate Laws
- Topic: Units for Rate Constants
- Replies: 5
- Views: 558
Re: Units for Rate Constants
In the textbook there are questions with answers that have units in L per mol. Why is this and how do you generally determine the units for rate constants?
- Sat Mar 02, 2019 7:04 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Potential Spontaneity
- Replies: 7
- Views: 870
Re: Cell Potential Spontaneity
Is it possible for the cell potential to be negative?
- Sat Mar 02, 2019 7:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagrams and solids
- Replies: 9
- Views: 1023
Re: Cell diagrams and solids
So if there is a solid in the reaction then you don't include Pt at the end?
- Sat Mar 02, 2019 7:00 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Order of Cell Diagrams
- Replies: 13
- Views: 1603
Re: Order of Cell Diagrams
Should Pt always be included at the end of the cell diagram. Some textbook questions have answers that don't include a Pt or metal at the end.
- Sat Feb 23, 2019 11:06 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free energy
- Replies: 5
- Views: 608
Re: Gibbs Free energy
If the temperature is not given try the ideal gas law, however, if that isn't possible, then use k=298.
- Sat Feb 23, 2019 11:03 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: How can a change in entropy be negative?
- Replies: 3
- Views: 484
Re: How can a change in entropy be negative?
An example of this would be a liquid being cooled into a solid. The molecules have less possible positions and therefore have less entropy leading to a decrease in entropy or negative entropy change.
- Sat Feb 23, 2019 11:01 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity
- Replies: 8
- Views: 830
Re: Spontaneity
What does it mean if delta G is 0?
- Sat Feb 16, 2019 8:39 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Internal energy (U) of an isolated system
- Replies: 17
- Views: 2725
Re: Internal energy (U) of an isolated system
rkang00 wrote:If a system is isolated with + amount of energy, will it there be no change even after time passes?
There will be no change regardless of the amount of time passed. However, this is not the case for open and closed systems.
- Sat Feb 16, 2019 8:36 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of formation
- Replies: 2
- Views: 370
Re: Enthalpy of formation
Just to add to the previous response, only elements, compounds, molecules, etc. that are not in their most stable states have enthalpies of formation that are not 0.
- Sat Feb 16, 2019 8:32 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: units
- Replies: 7
- Views: 1019
Re: units
Is KJ per mol an acceptable unit of measurement when solving for the change in internal energy?
- Sat Feb 09, 2019 3:03 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: If not Gibbs Free Energy then what is the last topic for midterm?
- Replies: 4
- Views: 455
Re: If not Gibbs Free Energy then what is the last topic for midterm?
Kobe_Wright wrote:The outline says through entropy but gibbs free energy is last and theres a few other things so what is it?
The end of entropy, according to Friday's lecture, is finding the total change in entropy of the reaction based on the entropy of the products and reactants.
- Sat Feb 09, 2019 2:59 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Study Guides
- Replies: 15
- Views: 1287
Re: Study Guides
Kavvya Gupta 1H wrote:I know Sonia said she would post the sheet she made with questions that are similar to what questions are going to be on the midterm from today's review session, but I don't know when she's going to post it.
Where on Chemistry Community can this worksheet be found?
- Sat Feb 09, 2019 2:51 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Constant Pressure/Volume
- Replies: 6
- Views: 1011
Re: Constant Pressure/Volume
If the pressure is not stated, it is assumed to be 1 atm. So in this case, it is assumed that the pressure is constant at 1 atm.
- Sat Feb 02, 2019 2:22 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Work
- Replies: 4
- Views: 533
Re: Work
Why does a system carried out reversibly do more work than that of an irreversible system?
- Sat Feb 02, 2019 2:20 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated System
- Replies: 5
- Views: 820
Re: Isolated System
Does an isolated system have a fixed volume?
- Sat Feb 02, 2019 2:16 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: 3 methods for enthalpy calculation
- Replies: 10
- Views: 1989
Re: 3 methods for enthalpy calculation
Usually you would want to use either the enthalpy of formation or of combustion methods. These are the most accurate and easiest to use. Using the mean bond enthalpy is less accurate and it can get confusing at times. It really depends on what equations you are given and what values you know. There...
- Sat Jan 26, 2019 3:50 pm
- Forum: Phase Changes & Related Calculations
- Topic: Sublimation
- Replies: 6
- Views: 572
Re: Sublimation
Yeah how do compounds like CO2 in the form of dry ice go straight from being a solid to a liquid? Does CO2 even have a liquid state, and if not, how is that possible?
- Sat Jan 26, 2019 3:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: Modules
- Replies: 17
- Views: 1359
Re: Modules
Are there any modules for any of the other topics or was it just chemical equilibrium?
- Sat Jan 26, 2019 3:46 pm
- Forum: Phase Changes & Related Calculations
- Topic: Severe burn from steam clarification
- Replies: 5
- Views: 1968
Re: Severe burn from steam clarification
So the burn was worse due to more energy being exerted on the skin? But, how does that energy manifest if it does not cause an increase in temperature? In other words, what happens to that excess energy? What is it doing if it isn't heating the steam?
- Sat Jan 19, 2019 4:44 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pKa and pKb
- Replies: 4
- Views: 955
Re: pKa and pKb
High pKa= weak acid/strong base
Low pKa= strong acid/weak base
High pKb= weak base/strong acid
Low pKb= strong base/weak acid
Low pKa= strong acid/weak base
High pKb= weak base/strong acid
Low pKb= strong base/weak acid
- Sat Jan 19, 2019 4:35 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Multiple protonation or deprotonations
- Replies: 1
- Views: 402
Re: Multiple protonation or deprotonations
I don't think so since it hasn't been discussed in lecture and is only featured in two of many homework problems.
- Sat Jan 19, 2019 4:33 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: difficulties recognizing weak acids and bases
- Replies: 9
- Views: 1532
Re: difficulties recognizing weak acids and bases
So one dead giveaway of a wake acid or base is the presence of acidity or basicity constant (Ka or Kb respectively). Only a weak acid/base would have one of these. A chemical reaction involving a weak acid/base would have a double arrow, as some of the reactants would form back from the product thr...
- Sat Jan 12, 2019 3:06 pm
- Forum: Ideal Gases
- Topic: Notation [ENDORSED]
- Replies: 5
- Views: 577
Re: Notation [ENDORSED]
So partial pressure is parentheses and concentration is brackets?
- Sat Jan 12, 2019 2:55 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Changing Pressure
- Replies: 6
- Views: 567
Re: Changing Pressure
Simran Rai 4E wrote:Adding an inert gas wouldn't affect the equilibrium because the concentrations of the reactant and product would remain the same, meaning there would be no change in the equation.
But if the volume changes, how is there not a change in the concentration if the concentration is affected by volume?
- Sat Jan 12, 2019 2:45 pm
- Forum: Ideal Gases
- Topic: Pv=nRT [ENDORSED]
- Replies: 12
- Views: 807
Re: Pv=nRT [ENDORSED]
What is the value of R?
- Sat Dec 08, 2018 6:44 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Conjugate?
- Replies: 5
- Views: 846
Re: Conjugate?
In the reaction Ba(OH)2 + H2O = Ba + 2OH + H2O, the conjugate base is H2O and the conjugate acid is OH. Whatever was the base before the reaction becomes the conjugate acid and whatever was the acid before the problem becomes the conjugate base.
- Sat Dec 08, 2018 6:40 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Difference Between Ka and Kb
- Replies: 2
- Views: 1265
Re: Difference Between Ka and Kb
Iris Bai 1E wrote:Ka is the equilibrium constant for acids, and Ka is the equilibrium constant for bases. For an acid that is ionized, you would fine Ka, not Kb.
How would you find Ka?
- Sat Dec 08, 2018 6:38 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Calculating pH of salt solution with acidic cation
- Replies: 5
- Views: 738
Re: Calculating pH of salt solution with acidic cation
Alana Sur 3B wrote:I don't think we don't need to remember the constants but you should know the formula for calculating Ka and Kb
The formula for calculating Ka is just -log(PKa) and the formula for calculating Kb is just -log(PKb) right?
- Fri Nov 30, 2018 5:59 pm
- Forum: Sigma & Pi Bonds
- Topic: Pi bond concepts
- Replies: 4
- Views: 393
Re: Pi bond concepts
Pi bonds overlap side by side with sigma bonds preventing them from rotating.
- Fri Nov 30, 2018 5:45 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing power and polarizability
- Replies: 4
- Views: 545
Re: Polarizing power and polarizability
Polarizability is the measure of an atom's electron cloud's ability to become distorted by an anion. Polarizability follows the same trend as atomic radii on the periodic table.
- Fri Nov 30, 2018 5:29 pm
- Forum: Lewis Acids & Bases
- Topic: Difference Between Acids and Bases
- Replies: 4
- Views: 503
Re: Difference Between Acids and Bases
What are some of the main physical property differences between acids and bases?
- Fri Nov 23, 2018 12:19 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: 5
- Views: 568
Re: Hydrogen Bonding
Hydrogen is an intermolecular force between the hydrogen in one molecule being attracted to a hydrogen/oxygen/nitrogen/fluorine in another molecule. For example, the hydrogen in one water molecule being attracted to the oxygen in another water molecule. This is also a type of dipole-dipole attracti...
- Fri Nov 23, 2018 12:13 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: Polar v. Non Polar
- Replies: 7
- Views: 878
Re: Polar v. Non Polar
What are some common exceptions when trying to determine polar or non polar based on symmetry?
- Fri Nov 23, 2018 12:11 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: Energy of Intermolecular Forces
- Replies: 6
- Views: 948
Re: Energy of Intermolecular Forces
Why do atoms form bonds if it requires energy?
- Thu Nov 15, 2018 11:24 pm
- Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Topic: Shape and Boiling Point
- Replies: 12
- Views: 3173
Re: Shape and Boiling Point
charlotte_jacobs_4G wrote:Does the distance between the bonds effect the boiling point? Would this cause the bond to be stronger or weaker?
The longer the bond the weaker it is. For instance double bonds are shorter and stronger than single bonds and triple bonds are shorter and stronger than double and single bonds.
- Thu Nov 15, 2018 11:18 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bonds
- Replies: 20
- Views: 1574
Re: Hydrogen Bonds
In order for hydrogen bonding to occur, does there have to be a lone pair of electrons the hydrogen atom can attach to?
- Thu Nov 15, 2018 11:14 pm
- Forum: Dipole Moments
- Topic: Determining Intermolecular Forces
- Replies: 5
- Views: 3411
Re: Determining Intermolecular Forces
In order to determine what kind of molecular forces you are dealing with, you need to know if the atom is polar or not. How do you determine wether an atom is polar or non polar?
- Fri Nov 09, 2018 9:14 am
- Forum: Electronegativity
- Topic: Periodic Trends
- Replies: 10
- Views: 1244
Re: Periodic Trends
I think the easiest way to remember electronegativity, ionization energy, electron affinity, and atomic radius is that the first three all increase across a period, but decrease down a group. However, atomic radius is the exact opposite of that meaning if you can remember atomic radius and you can r...
- Fri Nov 09, 2018 9:10 am
- Forum: Electronegativity
- Topic: Electronegativity and Polarizability
- Replies: 4
- Views: 1915
Re: Electronegativity and Polarizability
Aidan Ryan 1K wrote:On a similar note, what is polarizing power compared to polarizability. Also are these only for ions?
Yes polarizing power is only for ions because it is a measure of the ability of one ion to polarize another ion or atom.
- Fri Nov 09, 2018 9:04 am
- Forum: Dipole Moments
- Topic: Dipole-Dipole vs Induced Dipole
- Replies: 5
- Views: 1080
Re: Dipole-Dipole vs Induced Dipole
This might be a very elementary question but what is a dipole?
- Fri Nov 02, 2018 2:18 am
- Forum: Lewis Structures
- Topic: How to determine central atom
- Replies: 8
- Views: 1503
Re: How to determine central atom
Is ionization energy related to formal charge because I thought the central atom was the one that always had the lowest formal charge.
- Fri Nov 02, 2018 2:15 am
- Forum: Ionic & Covalent Bonds
- Topic: Removing the second electron
- Replies: 8
- Views: 700
Re: Removing the second electron
Once the first electron is removed, the atom becomes a positive ion. It has an overall positive charge, so removing another electron from it would be much harder than removing an electron from a neutral atom due to the electrostatic attraction between the nucleus and electrons. Does this mean remov...
- Fri Nov 02, 2018 2:13 am
- Forum: Ionic & Covalent Bonds
- Topic: Covalent Bonds
- Replies: 16
- Views: 1653
Re: Covalent Bonds
If a metal bonds with a nonmetal is this considered a covalent bond?
- Fri Oct 26, 2018 1:37 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Ground state vs. excited state
- Replies: 5
- Views: 788
Re: Ground state vs. excited state
What is the difference between a cation and an anion?
- Fri Oct 26, 2018 1:33 am
- Forum: Trends in The Periodic Table
- Topic: Covalent Radius
- Replies: 4
- Views: 416
Re: Covalent Radius
Are covalent radius and atomic radius equal?
- Fri Oct 26, 2018 1:29 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation
- Replies: 7
- Views: 716
Re: Rydberg Equation
What is the difference between R(1/n1^2 - 1/n2^2) and -hR/n^2?
- Fri Oct 19, 2018 1:07 am
- Forum: *Black Body Radiation
- Topic: Black Body [ENDORSED]
- Replies: 4
- Views: 1085
Re: Black Body [ENDORSED]
If black bodies are only theoretical, then why does the book refer to heated metal, or a "hot object" as black body?
- Fri Oct 19, 2018 1:04 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Meaning of Delta and Uncertainty
- Replies: 2
- Views: 958
Re: Meaning of Delta and Uncertainty
Yes it is the range of the area we know that the actual number is in
- Fri Oct 19, 2018 1:02 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Equation [ENDORSED]
- Replies: 2
- Views: 389
Re: Heisenberg Equation [ENDORSED]
No, h bar is not a constant it is just shorthand for pi/2.
- Fri Oct 12, 2018 2:47 am
- Forum: Properties of Light
- Topic: How light behaves
- Replies: 8
- Views: 587
Re: How light behaves
"I cannot conceptualize light being both photon (PACKETS) of energy and wavelengths. I find it difficult to exercise this into equations when I do not understand how it can be both and have one number. Please explain and possibly use equations in your explanation if possible. If not that is ok...
- Fri Oct 12, 2018 2:34 am
- Forum: *Black Body Radiation
- Topic: The Importance of Black Body Radiation (?)
- Replies: 5
- Views: 852
Re: The Importance of Black Body Radiation (?)
Don't know if this is how it's defined in this class but you can think of it as what happens when a massive bulky object that absorbs all radiation and then emits its own form of radiation. One example would be like a burner of an oven that heats up and changes color as it gets hotter from black to...
- Fri Oct 12, 2018 2:31 am
- Forum: Properties of Light
- Topic: Threshold Energies
- Replies: 5
- Views: 469
Re: Threshold Energies
Different metals have different threshold energies because they have a different number of protons, electrons, and energy levels. If the metal has many protons and electrons, there will be more energy levels, resulting in the electrons being further away from the nucleus. These negatively charged e...
- Fri Oct 05, 2018 2:20 am
- Forum: SI Units, Unit Conversions
- Topic: formula units [ENDORSED]
- Replies: 69
- Views: 33034
Re: formula units [ENDORSED]
Danny Elias Dis 1E wrote:What was the unit of measurement only used by chemists, also known as 10 to the -10 power?
The unit that is 10^-10 is the Angstrom which has the symbol Å.
- Fri Oct 05, 2018 2:17 am
- Forum: SI Units, Unit Conversions
- Topic: formula units [ENDORSED]
- Replies: 69
- Views: 33034
Re: formula units [ENDORSED]
I think the "pm" you're referring to is the measurement unit of a picometer, which is 10^-12! So to convert that to the unit of a meter which most questions have been using, you would multiply your answer by 10^12. You're right the picometer is 10^-12 and you would multiply by 10^12 to ge...
- Fri Oct 05, 2018 2:10 am
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 36398
Re: All students read this sig fig post [ENDORSED]
How do significant figures work when the number is larger for instance if there was a problem that said find how many moles of hydrogen are in 2.00 kg of H. The answer is 1,984.127 but how do we know how many significant figures there are when you need more digits just to get back to 0 than were giv...