Search found 60 matches
- Thu Mar 14, 2019 1:00 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 4
- Views: 544
Re: Test 2
Rusting is spontaneous because it happens naturally over a long period of time.
- Thu Mar 14, 2019 12:59 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Largest E°cell question test #2
- Replies: 4
- Views: 570
Re: Largest E°cell question test #2
One would choose the largest reducing agent and the largest oxidizing agent.
- Thu Mar 14, 2019 12:58 pm
- Forum: Balancing Redox Reactions
- Topic: balancing water
- Replies: 8
- Views: 794
Re: balancing water
One can cancel out the waters or simply add the proper amount in the beginning.
- Thu Mar 14, 2019 12:57 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst
- Replies: 14
- Views: 1229
Re: Nernst
Yes, it must be for a balanced redox reaction.
- Thu Mar 14, 2019 12:56 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation Confusion
- Replies: 4
- Views: 765
Re: Nernst Equation Confusion
They both mean the same thing.
- Thu Mar 14, 2019 12:55 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Internal energy (U) of an isolated system
- Replies: 17
- Views: 2715
Re: Internal energy (U) of an isolated system
The amount of energy would be the same as it is an isolated system.
- Thu Mar 14, 2019 12:54 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Adiabatic and isothermal
- Replies: 6
- Views: 2271
Re: Adiabatic and isothermal
Adiabatic= no heat transfer (q=0)
Isothermal= no change in temperature (deltaT=0)
Isothermal= no change in temperature (deltaT=0)
- Thu Mar 14, 2019 12:53 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: difference in states
- Replies: 6
- Views: 773
Re: difference in states
Yes, different types of systems affect temperature and volume.
- Thu Mar 14, 2019 12:51 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Expansion of a system
- Replies: 8
- Views: 1197
Re: Expansion of a system
You can tell when work is being done and the volume of the system is changing.
- Thu Mar 14, 2019 12:50 pm
- Forum: Calculating Work of Expansion
- Topic: Work without change in volume
- Replies: 8
- Views: 1131
Re: Work without change in volume
There is no work done as there is no change in volume.
- Tue Mar 12, 2019 1:34 pm
- Forum: Calculating Work of Expansion
- Topic: Work
- Replies: 8
- Views: 952
Re: Work
There are charts on the internet that simplify which equation to use for a certain situation (ex: isobaric, isothermal, etc). Hope this helped!
- Tue Mar 12, 2019 1:32 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Difference in Answers?
- Replies: 2
- Views: 398
Re: Difference in Answers?
There will be a slight difference but nothing significant enough to warrant taking points off if work is done correctly.
- Tue Mar 12, 2019 1:31 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Determining Spontaneity
- Replies: 7
- Views: 983
Re: Determining Spontaneity
Because if delta S is small enough (negative enough = large negative number), then even if the reaction was slightly exothermic (delta H < 0), then delta G could be greater than 0, making it nonspontaneous.
- Tue Mar 12, 2019 1:28 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous Reaction
- Replies: 5
- Views: 781
Re: Spontaneous Reaction
I'm not completely sure. But I assumed that because it is precipitation, the water is going from liquid to solid state. Because the freezing point of liquid water was 0 degrees C, I assumed that the precipitation would be spontaneous as the surrounding temperature was -10 degrees C, which is less th...
- Tue Mar 12, 2019 1:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: Negative and Positive values of delta H and w
- Replies: 6
- Views: 3849
Re: Negative and Positive values of delta H and w
Work greater than 0 means work is done on the system; work less than 0 means that work is done on the surroundings. deltaH greater than 0 means heat is flowing in the system and deltaH less than 0 means that heat is flowing out of the system (assuming constant pressure).
- Tue Mar 12, 2019 1:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: rotational v vibrational energy
- Replies: 5
- Views: 886
Re: rotational v vibrational energy
Rotational energy is around an axis while vibrational is simply moving back and forth on one axis.
- Tue Mar 12, 2019 1:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: ΔH vs ΔU?
- Replies: 8
- Views: 1400
Re: ΔH vs ΔU?
When volume is constant, work = 0 J. This means that deltaU = q.
- Tue Mar 12, 2019 1:19 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4.18J or 0.38J
- Replies: 8
- Views: 1272
Re: 4.18J or 0.38J
4.18J is the specific heat capacity of water while 0.38J is the specific heat capacity of copper.
- Tue Mar 12, 2019 1:18 pm
- Forum: Phase Changes & Related Calculations
- Topic: joules conversion factor
- Replies: 7
- Views: 1064
Re: joules conversion factor
It is given on the constants and equations sheet on all of our exams and tests.
- Tue Mar 12, 2019 1:17 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 11
- Views: 1445
Re: Phase Changes
Yes, it is significant as many thermochemistry questions are based on this graph (ex: amt of energy needed from temp1 phase 1 to temp 2 phase 2). It is important to know this.
- Tue Mar 12, 2019 1:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam vs Boiling Water
- Replies: 8
- Views: 1196
Re: Steam vs Boiling Water
Steam has more heat energy (q), causing a worse burn. This is because it takes a certain amount of energy to execute the phase change from boiling water to steam, in which the temperature of the substance does not change, only heat energy q.
- Tue Mar 12, 2019 1:12 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Edition 7 #5.61
- Replies: 2
- Views: 377
Re: Edition 7 #5.61
Only liquids and solids are not included in the equilibrium expression. Aqueous and gas phase molecules are included.
- Tue Mar 12, 2019 1:11 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE
- Replies: 19
- Views: 1504
Re: ICE
E stands for the equilibrium concentration of the reactants and products.
- Tue Mar 12, 2019 1:10 pm
- Forum: Ideal Gases
- Topic: Reading the textbook
- Replies: 262
- Views: 151745
Re: Reading the textbook
I read the textbook to understand the content in relation to the homework problems. However, if I don't understand something I go and watch a youtube video or something similar to help me understand.
- Tue Mar 12, 2019 1:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Increasing/Decreasing temp
- Replies: 8
- Views: 1122
Re: Increasing/Decreasing temp
If a reaction is endothermic, then increasing the temperature will shift the reaction to the right and decreasing the temperature will shift the reaction to the left. If a reaction is exothermic, then decreasing the temperature will shift the reaction to the right and increasing the temperature will...
- Tue Mar 12, 2019 1:04 pm
- Forum: Ideal Gases
- Topic: 5% rule
- Replies: 12
- Views: 3468
Re: 5% rule
If the change based on the approximation is less than 5% then an approximation can be made. Normally, this works for k values that are less than 10^-3.
- Tue Mar 12, 2019 1:01 pm
- Forum: Ideal Gases
- Topic: How do I know what is an Ideal Gas
- Replies: 11
- Views: 983
Re: How do I know what is an Ideal Gas
Most of the questions we will receive assume that the gas is an ideal gas. It will explicitly tell us.
- Tue Mar 12, 2019 1:00 pm
- Forum: Ideal Gases
- Topic: units
- Replies: 15
- Views: 1394
Re: units
K does not have units, which is why points were probably taken off for writing bar after k. The units should cancel each other out as well.
- Tue Mar 12, 2019 12:58 pm
- Forum: Ideal Gases
- Topic: Approximations for ICE
- Replies: 20
- Views: 1647
Re: Approximations for ICE
When the k value is less than 10^-3
- Tue Mar 12, 2019 12:57 pm
- Forum: Ideal Gases
- Topic: Q and K
- Replies: 13
- Views: 1328
Re: Q and K
Q is the concentrations of the products over the reactants when the equation is not at equilibrium; K is the concentration of the products over the reactants when the equation is at equilibrium.
- Fri Dec 07, 2018 11:15 am
- Forum: Conjugate Acids & Bases
- Topic: Neutralization Reactions
- Replies: 6
- Views: 982
Re: Neutralization Reactions
Use water as another product and fill in the reactants.
- Fri Dec 07, 2018 11:13 am
- Forum: Naming
- Topic: Final Exam
- Replies: 9
- Views: 902
Re: Final Exam
I would memorize for the final exam.
- Fri Dec 07, 2018 11:12 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Total Charge
- Replies: 5
- Views: 715
Re: Total Charge
Add up the charges of the ligands and the transition metal.
- Fri Dec 07, 2018 11:10 am
- Forum: Lewis Acids & Bases
- Topic: HCl vs. HI
- Replies: 7
- Views: 789
Re: HCl vs. HI
Whichever atom has a higher atomic radius means that there will be a longer bond, therefore a stronger acid because more H+ can disassociate easier.
- Fri Dec 07, 2018 11:08 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strongs Acids
- Replies: 4
- Views: 798
Re: Strongs Acids
The seven main ones you should memorize for the exam are:
HS04
HNO3
HClO4
HClO3
HBr
HI
HCl
HS04
HNO3
HClO4
HClO3
HBr
HI
HCl
- Fri Dec 07, 2018 11:06 am
- Forum: Lewis Acids & Bases
- Topic: Ligands
- Replies: 7
- Views: 921
Re: Ligands
A neutral ligand has no effect on charge because it is neutral.
- Sun Nov 25, 2018 10:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming
- Replies: 5
- Views: 502
Re: Naming
Yes, they will be the same!
- Sun Nov 25, 2018 10:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming the Shape
- Replies: 16
- Views: 1278
Re: Naming the Shape
I don't think we are required to draw the VSEPR model.
- Sun Nov 25, 2018 10:02 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 3
- Replies: 38
- Views: 2691
Re: Test 3
It says on the website to know the End of Bonding 6th(3.12), 7th(2D) and all of Molecular Shape and Structure.
- Sun Nov 18, 2018 11:54 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length
- Replies: 9
- Views: 1127
Re: Bond Length
I believe it would be the average of the two lengths.
- Sun Nov 18, 2018 11:52 pm
- Forum: Dipole Moments
- Topic: Test
- Replies: 15
- Views: 1325
Re: Test
The test will be given in Week 9 discussions.
- Sun Nov 18, 2018 11:51 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: hydrogen bonding
- Replies: 11
- Views: 999
Re: hydrogen bonding
Hydrogen bonding is stronger than most other IMF so it takes more energy to break.
- Sun Nov 11, 2018 8:38 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length
- Replies: 9
- Views: 1020
Re: Bond Length
The trend follows that triple are are the shortest while single are the longest.
- Sun Nov 11, 2018 8:34 pm
- Forum: Dipole Moments
- Topic: Dipole Moments [ENDORSED]
- Replies: 10
- Views: 1006
Re: Dipole Moments [ENDORSED]
We don't have to calculate them.
- Sun Nov 11, 2018 8:33 pm
- Forum: Dipole Moments
- Topic: Dipole
- Replies: 8
- Views: 798
Re: Dipole
I'm pretty sure dipole moments are only relevant in VSPER and not Lewis structures.
- Sun Nov 04, 2018 3:52 pm
- Forum: Octet Exceptions
- Topic: The center atom
- Replies: 20
- Views: 3317
Re: The center atom
The central atom would have the lowest ionization energy, which in this case is Oxygen.
- Sun Nov 04, 2018 3:50 pm
- Forum: Ionic & Covalent Bonds
- Topic: determining bond strength
- Replies: 3
- Views: 422
Re: determining bond strength
Compare the difference of electronegativity between the two atoms to determine what type and how strong the bond is.
- Sun Nov 04, 2018 3:47 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 4
- Views: 375
Re: Drawing Lewis Structures
Draw the all the resonance structures with a double-headed arrow in between.
- Sun Oct 28, 2018 7:45 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond
- Replies: 9
- Views: 909
Re: Bond
They are rare and we do not need to worry about it for this course.
- Sun Oct 28, 2018 7:44 pm
- Forum: Ionic & Covalent Bonds
- Topic: the Octet rule
- Replies: 21
- Views: 4137
Re: the Octet rule
Elements usually abide by the octet rule or want a half octet.
- Sun Oct 28, 2018 7:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: bound atoms
- Replies: 8
- Views: 1252
Re: bound atoms
There is a release of energy when atoms bind together, resulting in less energy than single atoms.
- Sun Oct 21, 2018 10:45 pm
- Forum: *Black Body Radiation
- Topic: Question 1.21
- Replies: 5
- Views: 2366
Re: Question 1.21
The correct answer is the photoelectric effect because it best supports the idea that electromagnetic radiation is like particles. This is because in the photoelectric effect the radiation consists of packets of energy (photons) with a fixed energy based on a multiple of h(planck's constant).
- Sun Oct 21, 2018 10:42 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Q 42 on post assessment
- Replies: 5
- Views: 618
Re: Q 42 on post assessment
Use the equation for the energy level of an H-atom. (1/lambda=R((1/n^2 (initial)-(1/n^2(final))). Since we have the frequency, the lambda can be calculated. As well plug in n=4 for the final energy level and solve for the initial energy level.
- Sun Oct 21, 2018 10:24 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 2
- Views: 262
Re: Orbitals
Because the electrons that are in the orbitals closer to the nucleus block the outer electrons, there is less "pull" toward the nucleus for the outer electrons and slight repulsion from inner electrons.
- Sun Oct 14, 2018 10:52 pm
- Forum: Einstein Equation
- Topic: Symbol for frequency
- Replies: 12
- Views: 2293
Re: Symbol for frequency
I have not seen Dr. Lavelle introduce "f" yet so I would just stick with "v" (nu).
- Sun Oct 14, 2018 10:48 pm
- Forum: Properties of Electrons
- Topic: Midterm #2 question 4a,b
- Replies: 5
- Views: 808
Re: Midterm #2 question 4a,b
The question is essentially asking if the wavelength of the ejected electron is too small to be detected. I'm pretty sure this means is it smaller than 10^-18 power.
- Sun Oct 14, 2018 10:43 pm
- Forum: Properties of Light
- Topic: Problem A9
- Replies: 5
- Views: 331
Re: Problem A9
The trick is to first convert 2.5nm to 2.5x10^-9 meters (SI unit). Then plug into the rearranged equation of v=c/lambda to solve for the frequency.
- Sat Oct 06, 2018 6:21 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant
- Replies: 8
- Views: 1309
Re: Limiting Reactant
Instead of calculating both theoretical yields, one can use the mole ratios in the balanced chemical equation to determine which substance is the limiting reactant. Of course this may only be completed after the amount in moles for the substances are converted from grams or otherwise determined.
- Sat Oct 06, 2018 6:18 pm
- Forum: Significant Figures
- Topic: sig figs urgent question!
- Replies: 12
- Views: 2202
Re: sig figs urgent question!
In this case, the two zeros in the number would be considered significant because they are between two other significant figures. This results in the entire number in having a total of four significant figures.
- Sat Oct 06, 2018 6:15 pm
- Forum: Limiting Reactant Calculations
- Topic: Calculating the amount of moles
- Replies: 3
- Views: 1688
Re: Calculating the amount of moles
In the beginning you should convert the 1kg of CaCO3(s) to grams (1kg=1000g). Secondly, divide by the molar mass for CaCO3 in order to get the number of moles. Because the chemical equation is already balanced, simply look at the mole ratio between CaCO3 and see how many moles of the product will be...