Search found 62 matches
- Mon Mar 11, 2019 2:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 514013
Re: Saying Thank You to Dr. Lavelle
Thank you Dr. Lavelle for your assistance and patience. It has been a pleasure to be your student for the past two quarters!
- Mon Mar 11, 2019 2:27 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation Application?
- Replies: 1
- Views: 149
Arrhenius Equation Application?
What does the arrhenius equation determine and what would we use this equation for?
- Mon Mar 11, 2019 2:25 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: rate determining step
- Replies: 2
- Views: 311
Re: rate determining step
Why is the slow elementary step the rate-determining step and not the faster step?
- Thu Mar 07, 2019 1:48 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2 #5
- Replies: 1
- Views: 261
Test 2 #5
Can someone please explain how you would approach this problem? I was not sure on what to do with the change in enthalpy and Kw.
- Thu Mar 07, 2019 10:57 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst
- Replies: 6
- Views: 543
Re: Nernst
They are used interchangeably, but log is usually associated with pH!
- Thu Mar 07, 2019 12:01 am
- Forum: General Rate Laws
- Topic: Types of Rate Laws?
- Replies: 1
- Views: 194
Types of Rate Laws?
Can someone explain the difference between instantaneous, unique, differential, and average rate laws? How do we know when to use which?
- Sat Mar 02, 2019 12:54 pm
- Forum: General Rate Laws
- Topic: Calculus Review
- Replies: 8
- Views: 928
Re: Calculus Review
I believe we just need to know the simple derivative and integral rules.
- Sat Mar 02, 2019 12:42 pm
- Forum: General Rate Laws
- Topic: Rate Law
- Replies: 1
- Views: 195
Rate Law
Why do we need to conduct experiments to determine the rate law?
- Sat Mar 02, 2019 12:35 pm
- Forum: Balancing Redox Reactions
- Topic: 14.15 Tips?
- Replies: 1
- Views: 276
Re: 14.15 Tips?
First, you would have to write the half reactions and balance them. From there, you can figure out which is the anode and cathode and determine the E potentials from the back of the textbook. You might have to switch the direction of the anode, and therefore flip the sign of the E potential. The for...
- Sat Feb 23, 2019 4:18 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Units
- Replies: 4
- Views: 341
Re: Units
Joules or kj. I've also seen j/mol or kj/mol depending on the problem
- Sat Feb 23, 2019 4:10 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed vs Isolated
- Replies: 5
- Views: 1149
Re: Closed vs Isolated
closed systems - exchange only energy
examples: pressure cooker, thermometer, pot with lid
isolated systems - does not exchange matter and energy
examples: thermos
examples: pressure cooker, thermometer, pot with lid
isolated systems - does not exchange matter and energy
examples: thermos
- Sat Feb 23, 2019 4:04 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Order of species in cell diagram
- Replies: 1
- Views: 202
Re: Order of species in cell diagram
I believe so. We write it in the order of solids|gases|liquids|aqueous || aqueous|gases|liquid|solids
- Sun Feb 17, 2019 3:05 pm
- Forum: Van't Hoff Equation
- Topic: Concept behind Van't Hoff Equation
- Replies: 5
- Views: 655
Concept behind Van't Hoff Equation
Why do we use the Van't Hoff equation? What does it tell us in terms of K and temperature?
- Sun Feb 17, 2019 12:14 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy Signs
- Replies: 4
- Views: 434
Gibbs Free Energy Signs
What are the signs for gibbs free energy for both spontaneous and non-spontaneous reactions?
- Sat Feb 16, 2019 11:59 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Midterm Grades
- Replies: 35
- Views: 2652
Re: Midterm Grades
It will take about a week to grade!
- Mon Feb 04, 2019 10:13 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: residual energy
- Replies: 3
- Views: 812
Re: residual energy
I think you meant residual entropy (idk if there is a difference between residual energy and residual entropy haha). Residual entropy is the entropy at T=0 K. You can solve for it by using S=Kb*lnw (s=entropy, kb=boltzmann constant, w=degeneracy which is # of orientations^# of molecules). Degeneracy...
- Mon Feb 04, 2019 9:53 pm
- Forum: Calculating Work of Expansion
- Topic: Units for Work
- Replies: 2
- Views: 295
Re: Units for Work
Joules is also equal to N*m and (kg*m^2)/s^2. Not sure if we are required to know those. I haven't encountered a problem where we had to do that
- Mon Feb 04, 2019 9:51 pm
- Forum: Calculating Work of Expansion
- Topic: Difference between reversible and irreversible expansion?
- Replies: 2
- Views: 865
Difference between reversible and irreversible expansion?
Hi!
Can someone please explain the difference between reversible and irreversible expansion and how we are able to differentiate between the two
Thanks!
Can someone please explain the difference between reversible and irreversible expansion and how we are able to differentiate between the two
Thanks!
- Sat Feb 02, 2019 10:49 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy Equation Specific Heat Capacity
- Replies: 2
- Views: 275
Re: Entropy Equation Specific Heat Capacity
If you are referring to the (3/2)R constant for the ideal gas, Cv, you would use that when volume is constant.
- Sat Feb 02, 2019 10:42 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: constant pressure/volume vs specific/molar heat capacities
- Replies: 4
- Views: 385
constant pressure/volume vs specific/molar heat capacities
Any advice to approaching calorimetry problems and differentiating between which constant (constant pressure/volume and specific/molar heat capacities) to use?
Thanks!
Thanks!
- Sat Feb 02, 2019 10:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Material on Midterm?
- Replies: 9
- Views: 824
Re: Material on Midterm?
It will probably go until the end of 2nd&3rd law of thermo (or maybe halfway i just looked at the syllabus and there are a lot of topics haha) because we were just introduced to entropy at the end of Friday's lecture.
- Thu Jan 24, 2019 1:27 am
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam Papers
- Replies: 1
- Views: 279
Re: Final Exam Papers
You can pick them up at a window/office on the third floor of Young Hall. It’ll be easier to find if you use the right side entrance that’s facing the Court of Sciences.
- Wed Jan 23, 2019 9:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: How to tell acids and bases
- Replies: 8
- Views: 574
Re: How to tell acids and bases
Acids tend to have an H and bases OH
Also, the Bronsted-Lowry definition:
acid: proton (H+ ion) donor
base: proton acceptor
Also, the Bronsted-Lowry definition:
acid: proton (H+ ion) donor
base: proton acceptor
- Wed Jan 23, 2019 9:32 pm
- Forum: Phase Changes & Related Calculations
- Topic: ∆Hsub=∆Hfus+∆Hvap
- Replies: 3
- Views: 529
∆Hsub=∆Hfus+∆Hvap
How does ∆Hsub=∆Hfus+∆Hvap work?
Thanks!
Thanks!
- Mon Jan 14, 2019 7:53 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in pressure
- Replies: 2
- Views: 250
Re: Changes in pressure
When there is an increase in pressure, the reaction will occur in the direction w/ fewer moles of gas.
- Mon Jan 14, 2019 7:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th Edition 11.39
- Replies: 2
- Views: 196
6th Edition 11.39
The solutions manual says to add reactions 1 and 2 together. Where does the Cl2 go when you do this step?
Also, why do we multiply the two K values together?
Also, why do we multiply the two K values together?
- Mon Jan 14, 2019 7:13 pm
- Forum: Ideal Gases
- Topic: Homework for week 2 [ENDORSED]
- Replies: 10
- Views: 2952
Re: Homework for week 2 [ENDORSED]
Either one, as long as it's relevant to what we're learning in class and not too far ahead.
- Sat Jan 12, 2019 2:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibria Changes
- Replies: 3
- Views: 179
Equilibria Changes
Why does the value of K not change when we change the concentration of reactants or products?
- Sat Jan 12, 2019 2:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating K
- Replies: 4
- Views: 183
Calculating K
When calculating for K, do we use the initial or equilibrium concentrations?
- Tue Jan 08, 2019 11:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Difference between brackets and parentheses?
- Replies: 4
- Views: 2682
Difference between brackets and parentheses?
I noticed that when calculating K/Kc in questions 11.3 and 11.9 (6th edition), the solutions had either brackets or parentheses. Is there a difference between the two? How would I know which one to use?
- Tue Dec 04, 2018 2:01 am
- Forum: Biological Examples
- Topic: Transition metals
- Replies: 3
- Views: 559
Transition metals
Are we required to know the transition metals (such as Cr, Fe, Co, Mn, Ni, Cu, and Zn) and their functions for the final?
- Tue Dec 04, 2018 1:58 am
- Forum: Biological Examples
- Topic: CH 17 6TH EDITION HW 17.31d
- Replies: 4
- Views: 404
Re: CH 17 6TH EDITION HW 17.31d
the brackets indicate that the contents inside are the coordination compound. I assume that sodium is not part of it.
- Tue Dec 04, 2018 1:32 am
- Forum: Naming
- Topic: Roman Numerals
- Replies: 3
- Views: 253
Roman Numerals
How do we know when to include roman numerals when naming?
- Mon Dec 03, 2018 8:43 pm
- Forum: Bronsted Acids & Bases
- Topic: Difference
- Replies: 2
- Views: 224
Re: Difference
Bronsted-Lowry definition:
acid: proton (H+ ion) donor
base: proton acceptor
Lewis definition:
acid: electron acceptor
base: electron donor
acid: proton (H+ ion) donor
base: proton acceptor
Lewis definition:
acid: electron acceptor
base: electron donor
- Tue Nov 27, 2018 8:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Exam
- Replies: 3
- Views: 378
Re: Exam
According to the chem 14a website, "Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details)."
- Tue Nov 27, 2018 8:08 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polar and Nonpolar
- Replies: 3
- Views: 281
Re: Polar and Nonpolar
In polar covalent bonds, electrons are not equally shared. Thus, there is a charge difference in electronegativities and a dipole moment is formed.
In nonpolar covalent bonds, electrons are equally shared and there is no charge difference.
In nonpolar covalent bonds, electrons are equally shared and there is no charge difference.
- Mon Nov 26, 2018 8:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 6th Edition 4.7 Part B
- Replies: 2
- Views: 187
6th Edition 4.7 Part B
The solutions manual doesn't give a clear answer on how many bond angles there are for the molecule, SOCl2. Would there be two bond angles, one for the O-S-CL bonds and the CL-S-CL? Or does the lone pair on the S alter the angle because of repulsion, thus there is only one bond angle in the molecule...
- Fri Nov 23, 2018 3:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Models and Resonance Structures
- Replies: 4
- Views: 1000
VSEPR Models and Resonance Structures
Do we take into account resonance structures when determining the lewis structure and vsepr model of a molecule?
- Fri Nov 23, 2018 3:36 pm
- Forum: Dipole Moments
- Topic: 6th Edition 4.29
- Replies: 2
- Views: 350
6th Edition 4.29
How can you determine whether or not the three different structures are polar or nonpolar?
Also, how can the dipole moment be determined based on the figures?
Also, how can the dipole moment be determined based on the figures?
- Fri Nov 23, 2018 3:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 7
- Views: 744
Re: Polarity
In polar molecules, dipoles do not cancel (e.g. CHCl3). The lewis structure of this molecule has one side that is more electronegative (Cl) than the other (H). An arrow would be drawn towards the more electronegative side -- Cl, indicating a dipole moment.
- Mon Nov 12, 2018 1:08 pm
- Forum: Dipole Moments
- Topic: Interaction Potential Energy
- Replies: 1
- Views: 219
Re: Interaction Potential Energy
The negative sign has to do with the potential energy decreasing due to the interactions occurring in London Forces. This decrease in energy is dependent on the distance between the two molecules that are interacting. If you want to read more on it, pages 191-196 (page 195 specifically on London For...
- Mon Nov 12, 2018 12:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 1
- Views: 121
Bond Angles
What causes a bond angle to be less than their ideal values?
- Mon Nov 12, 2018 12:39 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: Dipoles and Electronegativity
- Replies: 4
- Views: 577
Re: Dipoles and Electronegativity
Dipole moments occur when there is a difference in charge between the two atoms or ions. The smaller the difference in electronegativity, the smaller the dipole moment is. The larger the difference in electronegativity, the larger the dipole moment.
- Tue Nov 06, 2018 9:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond Lengths, Bond Order, and Bond Strength
- Replies: 2
- Views: 593
Bond Lengths, Bond Order, and Bond Strength
Can someone please explain the relationship between bond length and bond order? And bond strength and bond order?
Thank you!
Thank you!
- Tue Nov 06, 2018 9:31 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond Length
- Replies: 8
- Views: 587
Re: Bond Length
SydBenedict3H wrote:So the shorter the bond,the stronger it also is?
Yes. Multiple bonds are shorter than single bonds. Adding bonding electrons attract nuclei more and pulls the atoms closer.
- Tue Nov 06, 2018 7:25 pm
- Forum: Sigma & Pi Bonds
- Topic: Definition and distinguishing
- Replies: 3
- Views: 469
Re: Definition and distinguishing
Bonds form between two atoms when: 1. orbital on one atom occupies the same region of space as an orbital on the other atom. When this occurs, the two orbitals overlap. 2. total # of electrons in both orbitals is no more than two sigma bonds: two atomic orbitals overlap head-to-head - These are cyli...
- Tue Oct 30, 2018 8:18 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Config for period 5
- Replies: 2
- Views: 233
Re: Electron Config for period 5
The TA and UA sessions I've been to just said that the only exceptions we need to know are chromium and copper.
- Tue Oct 30, 2018 8:09 pm
- Forum: Trends in The Periodic Table
- Topic: Diagonal Orbitals
- Replies: 1
- Views: 324
Re: Diagonal Orbitals
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 5p10 This diagram tells you the order of filling out orbitals on the energy level diagram or electron configurations. For example, when you draw out the diagonal arrows, you would get 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, etc. You don't really need th...
- Tue Oct 30, 2018 8:00 pm
- Forum: Ionic & Covalent Bonds
- Topic: 3.19 6th edition
- Replies: 1
- Views: 485
Re: 3.19 6th edition
The electron configuration for Tungsten is [Xe] 4f^14 5d^4 6s^2. Because it's W2+, we take away two electrons from the s energy level. The electron configuration is now [Xe] 4f^14 5d^4. If you were to draw out the orbitals, you'll find that d energy levels have five orbitals. The four electrons will...
- Tue Oct 30, 2018 7:19 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 2.45 6th Edition
- Replies: 1
- Views: 220
2.45 6th Edition
I am a bit confused with part d of this question:
2.45 Which elements are predicted to have the following ground-state electron configurations:
(d) [Rn]7s2 6d2
The solutions manual says that the element with that electron configuration is thorium, but isn't thorium part of the f-block?
2.45 Which elements are predicted to have the following ground-state electron configurations:
(d) [Rn]7s2 6d2
The solutions manual says that the element with that electron configuration is thorium, but isn't thorium part of the f-block?
- Fri Oct 26, 2018 10:46 pm
- Forum: General Science Questions
- Topic: Midterm studying
- Replies: 10
- Views: 1418
Re: Midterm studying
I find completing practice problems extremely helpful! Try to do all the hw problems and other problems in the textbook. Also, reviewing the tests and going over the problems again and your mistakes.
- Fri Oct 26, 2018 7:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: Exceptions
- Replies: 4
- Views: 492
Re: Exceptions
Octet rule --> atoms completing their octets (noble-gas configuration) by sharing electron pairs H, He, Li, and Be are exceptions to the rule, meaning that they do not need the complete set of 8 electrons around them. Be and B commonly form compounds in which the central atom has fewer than four pai...
- Thu Oct 25, 2018 11:15 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: H spectrum
- Replies: 3
- Views: 413
Re: H spectrum
The empirical formula does not work for atoms other than hydrogen and multi-electron atoms. For multi-electron atoms, we would use the other formula (the one with Zeff) because of electron shielding and repulsion caused by multiple electrons.
- Wed Oct 17, 2018 5:38 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Number L [ENDORSED]
- Replies: 3
- Views: 343
Re: Quantum Number L [ENDORSED]
Quantum number l (angular momentum) distinguishes orbitals of the given n by different shapes. Additionally, it also tells you which suborbital an electron is located in. Here are a few l-values and their corresponding letters: 0=s, 1=p, 2=d, 3=f, 4=g S orbitals have a spherical shape. P orbitals ha...
- Wed Oct 17, 2018 12:12 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: subshells & orbitals
- Replies: 1
- Views: 203
Re: subshells & orbitals
each n: a shell each l and n: a subshell each n, l, and ml: an atomic orbital principle quantum # n: n = 1, 2, 3, etc. angular momentum l: - distinguishes orbitals of given n by different shapes - l = from 0 to (n-1) --> depends on n value - orbitals of same n and l belong to the same "subshell...
- Mon Oct 15, 2018 6:19 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg
- Replies: 5
- Views: 426
Re: Heisenberg
The location (delta x) and the linear momentum (delta p) of a particle cannot be known simultaneously with arbitrary precision.
The two values are inversely proportional. If one is high, the other value is low.
The two values are inversely proportional. If one is high, the other value is low.
- Wed Oct 10, 2018 9:15 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical & Molecular Formulas
- Replies: 11
- Views: 1496
Re: Empirical & Molecular Formulas
Yes, they can! Empirical formula tells you the most reduced form of elements in a compound, while the molecular formula gives you the actual number of those elements. Sometimes a molecular formula's compound can no longer be reduced.
- Wed Oct 10, 2018 9:12 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: H-Atom and multi-electron atoms
- Replies: 3
- Views: 238
H-Atom and multi-electron atoms
Is there a reason why we use two different equations for the hydrogen atom and the multi-electron model?
- Wed Oct 10, 2018 9:10 pm
- Forum: Einstein Equation
- Topic: sig fig numbers
- Replies: 4
- Views: 307
Re: sig fig numbers
Hi!
Answers on the hw and exam should always use the least number of sig figs.
Answers on the hw and exam should always use the least number of sig figs.
- Sat Oct 06, 2018 1:59 pm
- Forum: Limiting Reactant Calculations
- Topic: Calculating the amount of moles
- Replies: 3
- Views: 1609
Re: Calculating the amount of moles
Hello! I would convert the 1 kg of CaCO3 into grams and then moles (1kg CaCO3) x (1000g/1kg) x (1mol/100.0869g -- molar mass of CaCO3) = 9.99131 which is about 10 mol CaCO3 Based on the molar ratio in the balanced equation, 1 mole of CaCO3 = 1 mole of CO2 Therefore, 10 moles of CO2 will be produced ...
- Wed Oct 03, 2018 11:40 pm
- Forum: SI Units, Unit Conversions
- Topic: Problem E7
- Replies: 3
- Views: 1333
Re: Problem E7
1 mole of objects means 6.0221 x 10^23 of 'objects', which in this case is carbon atoms. N=total number of objects (2.1 x 10^9) n=number of moles (unknown -- chemical amount of carbon atoms in moles) N_A= Avogadro's constant (6.0221 x 10^23) N=n x N_A --> n=N/N_A --> plug in the known values to solv...
- Wed Oct 03, 2018 11:09 pm
- Forum: Significant Figures
- Topic: Sig Figs?
- Replies: 3
- Views: 462
Re: Sig Figs?
Hello, One important rule about significant figures is that the zeroes on the left do not count as sig figs. Terminal zeroes on the right count. For example: 8.23, 0.845, 9.00, 5.60, and 0.000123 all have three significant figures. When multiplying and dividing w/ sig figs, the answers will be in th...