Search found 63 matches
- Fri Mar 15, 2019 4:33 pm
- Forum: General Science Questions
- Topic: Standard Conditions/ Standard Temperature
- Replies: 2
- Views: 555
Standard Conditions/ Standard Temperature
What is the temperature in standard conditions? Is it 0 degrees C or 25 degrees C?
- Wed Feb 20, 2019 9:37 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: O2
- Replies: 5
- Views: 536
Re: O2
Because 02 occurs naturally.
- Wed Feb 20, 2019 9:36 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Test 3
- Replies: 10
- Views: 996
Re: Test 3
Yes it will cover Gibbs free energy and what we cover in lecture during week 7.
- Wed Feb 20, 2019 9:35 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gr and Gp from lecture
- Replies: 2
- Views: 352
Re: Gr and Gp from lecture
Yes the r in Gr corresponded to reactants and the p in Gp to products.
- Wed Feb 20, 2019 9:34 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous vs Not Spontaneous
- Replies: 7
- Views: 741
Re: Spontaneous vs Not Spontaneous
Yes the reaction is only spontaneous if the free energy is negative (-).
- Wed Feb 20, 2019 9:32 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G a state function?
- Replies: 23
- Views: 2871
Re: Delta G a state function?
Yes delta G is a state function because it is defined by other state functions.
- Wed Feb 20, 2019 9:31 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: gibbs free energy
- Replies: 10
- Views: 909
Re: gibbs free energy
If free energy is negative (-) then the reaction is spontaneous and if it is positive (+) then the reaction is not spontaneous (requires energy).
- Wed Feb 20, 2019 9:25 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Liquid and moles
- Replies: 8
- Views: 1153
Re: Liquid and moles
Since H20 is a liquid it would not be used in the calculation of the equilibrium constant and ICE table.
- Wed Feb 20, 2019 9:22 am
- Forum: Calculating Work of Expansion
- Topic: S=0
- Replies: 12
- Views: 1811
Re: S=0
S=0 in a perfect crystal (T= 0 Kelvin)
- Wed Feb 20, 2019 9:20 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work done vs work on system
- Replies: 18
- Views: 3942
Re: Work done vs work on system
When work is done BY the system w is negative and when work is done ON the system w is positive.
- Wed Feb 06, 2019 9:36 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Cup of Tea
- Replies: 17
- Views: 2570
Re: Cup of Tea
It is open because matter and energy can be transferred in and out of it.
- Wed Feb 06, 2019 9:35 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm [ENDORSED]
- Replies: 49
- Views: 5043
Re: Midterm [ENDORSED]
I have found it helpful to do all the homework problems and attend peer learning sessions.
- Wed Feb 06, 2019 9:34 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed and Isolated
- Replies: 10
- Views: 756
Re: Closed and Isolated
A closed system does not allow for matter transfer, but allows for energy transfer. An isolated system does not allow for both matter and energy transfer.
- Wed Feb 06, 2019 9:30 am
- Forum: Administrative Questions and Class Announcements
- Topic: Equation sheet for midterm
- Replies: 3
- Views: 494
Re: Equation sheet for midterm
Yes, the equation sheet, constants, and periodic table are always provided for tests and exams.
- Wed Feb 06, 2019 9:28 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pKa vs. pH
- Replies: 15
- Views: 3032
Re: pKa vs. pH
pH is the concentration f hydrogen ions in the solution.
- Wed Feb 06, 2019 9:26 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE
- Replies: 19
- Views: 1517
Re: ICE
E stands for equilibrium concentration.
- Wed Feb 06, 2019 9:25 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: isolated vs closed system
- Replies: 7
- Views: 902
Re: isolated vs closed system
Isolated system does not allow for the transfer of matter or energy while a closed system can transfer energy (but not matter).
- Wed Feb 06, 2019 9:24 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units
- Replies: 7
- Views: 670
Re: Units
J/C(mol) - Joules over Celsius times mole(s)
- Wed Feb 06, 2019 9:20 am
- Forum: Phase Changes & Related Calculations
- Topic: Type of systems
- Replies: 12
- Views: 1378
Re: Type of systems
An isolated system does not allow transfer of matter and energy.
- Wed Feb 06, 2019 9:18 am
- Forum: Phase Changes & Related Calculations
- Topic: Heat and Condensation
- Replies: 9
- Views: 970
Re: Heat and Condensation
Condensation releases heat.
- Wed Feb 06, 2019 9:17 am
- Forum: Phase Changes & Related Calculations
- Topic: State Function
- Replies: 10
- Views: 920
Re: State Function
A state function is a property that does not rely on the path taken from the initial state to the final state.
- Wed Jan 23, 2019 10:04 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q and K
- Replies: 10
- Views: 833
Re: Q and K
If Q > K then a reverse reaction is favored.
If Q < K then a forward reaction is favored.
If Q < K then a forward reaction is favored.
- Wed Jan 23, 2019 10:01 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: What Happens to a Reaction if Inert Gas is Added?
- Replies: 7
- Views: 2308
Re: What Happens to a Reaction if Inert Gas is Added?
No, there is no change to a reaction if an inert gas is added.
- Wed Jan 23, 2019 9:55 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Acids and Bases
- Replies: 6
- Views: 570
Acids and Bases
How can you tell if a molecule is an acid or a base (based on its chemical formula)?
- Wed Jan 23, 2019 9:53 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5% rule
- Replies: 12
- Views: 21884
Re: 5% rule
The 5% rule is just used to check if your approximation is valid. You can assume that you are allowed to approximate when the k value is <10^-3.
- Wed Jan 23, 2019 9:50 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong acids and bases
- Replies: 6
- Views: 608
Re: Strong acids and bases
I do not think you need to memorize because you can tell by the K value, however it would not hurt to know common strong acids and bases.
- Wed Jan 23, 2019 9:47 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Does [H3O+][OH-] always equal 10^-14?
- Replies: 9
- Views: 1231
Re: Does [H3O+][OH-] always equal 10^-14?
It is only equal to 10^-14 when water is at 25 degrees C. However, I believe (at least so far) our reactions will be given in this condition.
- Wed Jan 23, 2019 9:44 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Removing products
- Replies: 10
- Views: 3942
Re: Removing products
Removing products would only affect Q and K would remain unchanged.
- Sun Jan 13, 2019 7:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: equations
- Replies: 10
- Views: 760
Re: equations
You can find out by writing out the chemical equation.
- Sun Jan 13, 2019 7:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: True or False regarding reaction mixture [ENDORSED]
- Replies: 10
- Views: 834
Re: True or False regarding reaction mixture [ENDORSED]
Yes, the composition of the reaction mixture remains constant when at equilibrium.
- Sun Jan 13, 2019 7:21 pm
- Forum: Student Social/Study Group
- Topic: New to Lavelle
- Replies: 32
- Views: 5364
Re: New to Lavelle
Personally, I find it helpful to do all problems assigned for homework and attending review sessions during the week and also the ones right before midterms and finals.
- Thu Dec 06, 2018 10:54 am
- Forum: Hybridization
- Topic: lone pairs
- Replies: 20
- Views: 2178
Re: lone pairs
Yes, since hybridization relates to the # of areas of electron density and lone pairs are considered an area of electron density, then lone pairs are taken into consideration for hybridization.
- Thu Dec 06, 2018 10:51 am
- Forum: Hybridization
- Topic: tetrahedral
- Replies: 5
- Views: 540
Re: tetrahedral
4 areas of electron density equals sp3 hybridization.
- Thu Dec 06, 2018 10:48 am
- Forum: Hybridization
- Topic: Double and Triple Bonds
- Replies: 17
- Views: 4356
Re: Double and Triple Bonds
No, they do not change the hybridization of an atom, only areas of electron density change it.
- Thu Dec 06, 2018 10:44 am
- Forum: Hybridization
- Topic: hybridization
- Replies: 2
- Views: 231
Re: hybridization
sp3 should be enough.
- Thu Dec 06, 2018 10:43 am
- Forum: Hybridization
- Topic: Hybridization
- Replies: 11
- Views: 1328
Re: Hybridization
Trigonal planar is considered sp^2 hybridization because it has 3 regions of electron density.
- Thu Dec 06, 2018 10:40 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polarity
- Replies: 11
- Views: 873
Re: polarity
If a Lewis structure is symmetric it is non-polar and if it is not symmetric it is polar.
- Thu Dec 06, 2018 10:35 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Structures
- Replies: 12
- Views: 1329
Re: Bent Structures
Yes bent structures are polar.
- Thu Dec 06, 2018 10:34 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Notation
- Replies: 10
- Views: 1240
Re: VSEPR Notation
Ethan Breaux 1J wrote:Is VSEPR Notation also referred to as VSEPR Formula?
I believe they are the same thing.
- Thu Dec 06, 2018 10:32 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 11
- Views: 968
Re: Lone Pairs
Lone pairs are able to repel bond pairs more than bond pairs are able to repel each other, therefore the bond angles are made smaller by lone pairs.
- Thu Dec 06, 2018 10:30 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX3E
- Replies: 18
- Views: 3312
Re: AX3E
The electron arrangement would be tetrahedral, however since one is a lone pair the shape is trigonal pyramidal.
- Thu Dec 06, 2018 10:28 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs angular?
- Replies: 15
- Views: 1215
Re: Bent vs angular?
Bent and angular are the same shape
- Thu Dec 06, 2018 10:25 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX2E2
- Replies: 14
- Views: 4623
Re: AX2E2
Yes this is a bent shape with bond angles less than 109.5
- Thu Dec 06, 2018 10:24 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Trigonal Bipyramidal
- Replies: 6
- Views: 752
Re: Trigonal Bipyramidal
Ethan Breaux 1J wrote:Maybe I'm just reading this wrong but are you referring to see saw?
I don't think it's see saw, I think it is T-shape because I believe the structure being described has 3 bonds and 2 lone pairs, but maybe I also read it wrong.
- Thu Dec 06, 2018 10:19 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 3
- Replies: 38
- Views: 2757
Re: Test 3
A trick I found helpful is memorizing the VSEPR equations such as AX3E2 and knowing what shape corresponds to those equations because as soon as you drew the Lewis Structure you could conclude the VSEPR equation and therefore concluding the shape. This also helps with knowing the hybridization.
- Fri Nov 09, 2018 3:10 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Lengths
- Replies: 6
- Views: 618
Re: Bond Lengths
I don't think you have to memorize specific bond lengths but should probably know that a single bond is longer the a double bond which is longer than a triple bond.
- Fri Nov 09, 2018 3:06 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge of Oxygen
- Replies: 6
- Views: 1658
Re: Formal Charge of Oxygen
Oxygen is more electronegative than carbon which attracts the electrons to them usually giving it a negative charge.
- Fri Nov 09, 2018 3:04 pm
- Forum: Dipole Moments
- Topic: Polarizability
- Replies: 5
- Views: 390
Re: Polarizability
The polarizability of a molecule depends the size of the molecule and the number of electrons that the molecule has.
- Thu Nov 01, 2018 10:11 pm
- Forum: Resonance Structures
- Topic: Most Stable Configuration
- Replies: 11
- Views: 1214
Re: Most Stable Configuration
The most stable configuration for a resonance structure would be one where the formal charge is closest to 0, which could be find with the equation FC= V (valence electrons) - (L (lone pair electrons) + s/2 (shared electrons divided by 2).
- Thu Nov 01, 2018 10:06 pm
- Forum: Electronegativity
- Topic: Test 3. Question 7.
- Replies: 6
- Views: 1081
Re: Test 3. Question 7.
Difference in electronegativity defines ionic character.
- Thu Nov 01, 2018 10:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent Bonds
- Replies: 18
- Views: 1828
Ionic vs Covalent Bonds
What is the difference between ionic and covalent bonds?
- Tue Oct 23, 2018 11:13 pm
- Forum: *Shrodinger Equation
- Topic: Test 2
- Replies: 5
- Views: 737
Re: Test 2
Test 2 covers everything from lecture #4 to lecture #10 (October 5 to October 19) which is the quantum world to multi-electron atoms.
- Tue Oct 23, 2018 11:04 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: m with subscript l
- Replies: 4
- Views: 585
m with subscript l
what does m with subscript l tell you about the atom?
- Tue Oct 23, 2018 10:54 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Px. Py, Pz
- Replies: 6
- Views: 1708
Re: Px. Py, Pz
I understand that Px Py Pz tell you something about the orientation of the orbital, however, what about the orientation does it tell you about, most specifically what does Pz tell you?
- Wed Oct 17, 2018 10:37 pm
- Forum: Properties of Electrons
- Topic: 7th edition 1A.11
- Replies: 3
- Views: 424
Re: 7th edition 1A.11
I say just do it just in case and it is pretty well-explained in the book if you do take a look.
- Wed Oct 17, 2018 10:32 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: > vs =
- Replies: 1
- Views: 172
> vs =
Why does the Heisenberg Indeterminacy equation have a greater than or equal to sign instead of an equal sign? Will this always be the case?
- Wed Oct 17, 2018 10:15 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Plane
- Replies: 2
- Views: 103
Nodal Plane
Can someone explain to me what a nodal plane is and its function?
- Sat Oct 13, 2018 3:21 pm
- Forum: DeBroglie Equation
- Topic: Angstrom?
- Replies: 8
- Views: 1584
Re: Angstrom?
An angstrom is equivalent to 1x10^-10 m and Dr. Lavelle stated that it would be common to find wavelengths to the ^-10m, therefore, the angstrom is used for convenience in writing these lengths.
- Sat Oct 13, 2018 3:14 pm
- Forum: Einstein Equation
- Topic: Units for v(frequency)
- Replies: 11
- Views: 1265
Re: Units for v(frequency)
Hz and s^-1 are interchangeable because they are equivalent. I see Hz used more often than s^-1, but I doubt that you will be marked wrong for using one or the other.
- Sat Oct 13, 2018 3:11 pm
- Forum: DeBroglie Equation
- Topic: Equations
- Replies: 9
- Views: 856
Re: Equations
I believe we will be given all the equations and constants for every test/exam we take, but I believe you should still memorize the formulas because I find that it helps me to know exactly what to use when reading a problem. However, the formulas given on the test could be good for double checking t...
- Thu Oct 04, 2018 4:35 pm
- Forum: Significant Figures
- Topic: SIG FIGS in ratios
- Replies: 4
- Views: 2359
SIG FIGS in ratios
When a problem asks for a ratio would we also need to make sure all values of the ratio are in terms of significant figures? For example in exercise F.9 (of the 7th edition), the ratio of the answer would be 1O:2.67C:2.67H, however, the lowest number of significant figures from the problem is three ...
- Thu Oct 04, 2018 4:09 pm
- Forum: SI Units, Unit Conversions
- Topic: SI Units
- Replies: 10
- Views: 784
Re: SI Units
Do all our final answers need to be converted to the base SI unit (ex:meter, kilogram, mole) or do we just use the closest prefix to it? And if we leave our answer in the base SI unit and do not use a prefix simplifying the value would our answer be wrong even if both answers would be mathematically...
- Thu Oct 04, 2018 3:51 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formula
- Replies: 6
- Views: 616
Re: Empirical Formula
You do not need to do it every time, you can use any amount you want for mass to solve for how much the percentage accounts for, however, since percent means a part of ONE HUNDRED, then it is much easier to use 100g as the mass because you would only need to change the percent sign to grams.