Search found 60 matches
- Sun Mar 17, 2019 5:19 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Bimolecular
- Replies: 13
- Views: 2181
Re: Bimolecular
Molecularity refers to the number of reactants in an elementary reaction so a bimolecular reaction contains two reactants.
- Sun Mar 17, 2019 5:17 pm
- Forum: Second Order Reactions
- Topic: Half Life
- Replies: 7
- Views: 1232
Re: Half Life
The half lives are provided on the formula sheet.
- Sun Mar 17, 2019 5:16 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Plot of Arrhenius function
- Replies: 4
- Views: 770
Re: Plot of Arrhenius function
the y axis is lnk as can be seen in the equation lnk= -Ea/RT + lnA
- Sun Mar 10, 2019 3:30 pm
- Forum: Zero Order Reactions
- Topic: Half-life
- Replies: 6
- Views: 904
Re: Half-life
The half life of a reactant is simply the time needed for its concentration to fall to 1/2 its initial value.
- Sun Mar 10, 2019 3:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2 averages
- Replies: 4
- Views: 568
Re: Test 2 averages
I heard the test 2 average was around a 36/50.
- Sun Mar 10, 2019 3:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm average
- Replies: 5
- Views: 627
Re: Midterm average
I think the midterm average was 80%.
- Sun Mar 03, 2019 3:21 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy and Entropy
- Replies: 6
- Views: 909
Re: Gibbs Free Energy and Entropy
The sign of delta G is dependent on enthalpy, temperature, and entropy so entropy doesn't necessarily have to be negative; it depends on all three.
- Sun Mar 03, 2019 3:13 pm
- Forum: Van't Hoff Equation
- Topic: units of T
- Replies: 5
- Views: 810
Re: units of T
Even if T is given in Celsius, you can just add 273 to get Kelvin but yes you will need to use K in the actual calculation.
- Sun Mar 03, 2019 3:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagrams and solids
- Replies: 9
- Views: 971
Re: Cell diagrams and solids
Usually an inert solid like Platinum is added when a solution does not already have a conducting solid.
- Sun Feb 24, 2019 12:47 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity
- Replies: 8
- Views: 788
Re: Spontaneity
When change in Gibbs free energy is negative, the reaction is spontaneous; when delta G is positive, the reaction is not spontaneous.
- Sun Feb 24, 2019 12:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode vs. Anode
- Replies: 9
- Views: 776
Re: Cathode vs. Anode
The anode is where oxidation takes place (electrons leave) and the cathode is where reduction takes place (gains electrons).
- Sun Feb 24, 2019 12:40 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: test 3
- Replies: 10
- Views: 959
Re: test 3
I don't believe it will cover old stuff, but it covers Gibbs free energy and electrochemistry (everything covered in week 6 and 7 lectures).
- Sun Feb 17, 2019 3:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 8
- Views: 836
Re: Bond Enthalpies
Yes, thats right. The bonds broken (reactants) require energy and are endothermic/positive. The bonds formed (products) release energy and are exothermic/negative.
- Sun Feb 17, 2019 2:57 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Midterm Grades
- Replies: 35
- Views: 2652
Re: Midterm Grades
It should take about a week, so hopefully by the end of week 7.
- Sun Feb 17, 2019 1:52 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: state functions and properties
- Replies: 11
- Views: 5937
Re: state functions and properties
A state function does not depend on the path taken to achieve that state. This includes density, internal energy, enthalpy, etc.
- Sun Feb 10, 2019 6:48 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: midterm
- Replies: 5
- Views: 508
Re: midterm
Yes, the midterm covers outlines 1-4 up until entropy; it does not cover Gibbs free energy.
- Sun Feb 10, 2019 6:45 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Midterm Next Week
- Replies: 6
- Views: 656
Re: Midterm Next Week
The midterm does not cover Gibbs free energy.
- Sun Feb 10, 2019 6:44 pm
- Forum: Student Social/Study Group
- Topic: Lyndon's Review Sess
- Replies: 3
- Views: 413
Re: Lyndon's Review Sess
yes, just look up hotdog!
- Fri Feb 01, 2019 5:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Open, closed, or isolated systems
- Replies: 10
- Views: 38997
Re: Open, closed, or isolated systems
open system- matter and energy can exchange with surroundings beaker of water- water can evaporate and breaker does not insulate closed system- energy can exchange with surroundings sealed beaker of water does not insulate isolated system- nothing exchanges with surroundings combustion of glucose in...
- Fri Feb 01, 2019 5:10 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm
- Replies: 4
- Views: 372
Re: Midterm
The date is listed on the website and is February 13, 6-8pm (week 6).
- Fri Feb 01, 2019 5:09 pm
- Forum: Ideal Gases
- Topic: pV=nRT
- Replies: 12
- Views: 2050
Re: pV=nRT
This equation shows the relationship between pressure, volume, moles, gas constant, and temperature and can be moved around to find these different values.
- Wed Jan 23, 2019 6:39 pm
- Forum: Ideal Gases
- Topic: Units for concentration
- Replies: 5
- Views: 507
Re: Units for concentration
Yes, both of these are equal to one another.
- Wed Jan 23, 2019 6:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Table Clarification
- Replies: 4
- Views: 421
Re: ICE Table Clarification
When K is less than 10^-3, you can neglect x because it will probably be small enough to where it does not have any significant effect on the calculation.
- Wed Jan 23, 2019 6:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE boxes
- Replies: 5
- Views: 472
Re: ICE boxes
Yes, both can be found using an ICE table.
- Fri Jan 18, 2019 12:26 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 3
- Views: 319
Re: Le Chatelier's Principle
Le Chatelier's principle simply states that chemical reactions adjust so as to minimize the effect of changes. For instance, if more reactant is added, more product will form to account for this change.
- Fri Jan 18, 2019 12:18 pm
- Forum: Ideal Gases
- Topic: Homework Week 2
- Replies: 10
- Views: 962
Re: Homework Week 2
Homework is now due in every discussion section.
- Fri Jan 18, 2019 12:16 pm
- Forum: Ideal Gases
- Topic: Chemistry Community Posting
- Replies: 7
- Views: 592
Re: Chemistry Community Posting
Post by 11:59 on Sunday night.
- Fri Jan 11, 2019 5:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Liquids and Solids in Equilibrium Constants
- Replies: 5
- Views: 354
Re: Liquids and Solids in Equilibrium Constants
Their effect is not significant enough to be taken into consideration.
- Fri Jan 11, 2019 5:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp
- Replies: 9
- Views: 733
Re: Kp
Kp helps specify that the question is asking for partial pressures for gases instead of the equilibrium constant for concentrations.
- Fri Jan 11, 2019 5:08 pm
- Forum: Ideal Gases
- Topic: Q and K [ENDORSED]
- Replies: 35
- Views: 3022
Re: Q and K [ENDORSED]
Both Q and K use the same formula.
- Thu Dec 06, 2018 12:54 pm
- Forum: Hybridization
- Topic: tetrahedral
- Replies: 5
- Views: 500
Re: tetrahedral
Since there are four areas of electron density, it is sp3.
2=sp 3=sp2 4=sp3 5=sp3d 6=sp3d2
2=sp 3=sp2 4=sp3 5=sp3d 6=sp3d2
- Thu Dec 06, 2018 12:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Structures
- Replies: 12
- Views: 1233
Re: Bent Structures
Due to the shape, they are polar.
- Thu Dec 06, 2018 12:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs angular?
- Replies: 15
- Views: 1130
Re: Bent vs angular?
Bent and angular are the same thing.
- Thu Nov 29, 2018 10:37 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma bonds
- Replies: 6
- Views: 739
Re: Sigma bonds
Sigma bonds overlap side by side.
- Thu Nov 29, 2018 10:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining polar and non polar molecules from a lewis structure
- Replies: 8
- Views: 2761
Re: Determining polar and non polar molecules from a lewis structure
You can usually tell from a lewis structure is a molecule is polar by seeing if they're dipole moments cancel out, which usually happens based off their symmetry.
- Thu Nov 29, 2018 10:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole moment
- Replies: 7
- Views: 692
Re: Dipole moment
Dipole moments depend on polarity and polarity depends on electronegativity, so dipole moments are dependent on these things.
- Sat Nov 24, 2018 11:05 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 8
- Views: 3479
Re: Formal Charge
Basically the formula can be see as FC= # of valence electrons-( # of dots + # of lines)
the # of dots are just the lone pairs and the # of lines is just the S/2 or number of bonds between atoms
the # of dots are just the lone pairs and the # of lines is just the S/2 or number of bonds between atoms
- Sat Nov 24, 2018 11:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3
- Replies: 10
- Views: 1110
Re: Test 3
Yea so it covers the whole Molecular Shape and Structure unit (look at outline 4) and section 2D from the previous Chemical Bonds unit (look at outline 3).
- Sat Nov 24, 2018 10:57 pm
- Forum: Student Social/Study Group
- Topic: curve?
- Replies: 20
- Views: 2880
Re: curve?
According to the syllabus, final grades won't be known until the class average is known at the end but there is no curve and a 50% is considered passing with a C-
- Sun Nov 18, 2018 6:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem Community Posts
- Replies: 3
- Views: 410
Re: Chem Community Posts
I'm not sure but I would play it safe and post weekly so you remain active on the website.
- Sun Nov 18, 2018 6:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grades
- Replies: 7
- Views: 837
Re: Grades
I believe so but he will also adjust the grading scale according to the amount of points people tend to have by the end of the course.
- Sun Nov 18, 2018 6:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving week
- Replies: 10
- Views: 1280
Re: Thanksgiving week
I believe that there is no class on Wednesday.
- Sun Nov 11, 2018 12:13 am
- Forum: Dipole Moments
- Topic: Bond Lengths
- Replies: 5
- Views: 588
Re: Bond Lengths
Single bonds are longer than double and triple bonds, however the shorter bonds are the strongest.
- Sun Nov 11, 2018 12:12 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Isoelectronic
- Replies: 14
- Views: 2093
Re: Isoelectronic
isoelectronic: having the same numbers of electrons or the same electronic structure.
- Sun Nov 11, 2018 12:11 am
- Forum: Electronegativity
- Topic: Electronegativity and Electron Affinity
- Replies: 4
- Views: 478
Re: Electronegativity and Electron Affinity
Electron affinity: the energy change when a neutral atom attracts an electron to become a negative ion.
Electronegativity: the ability of an atom in a molecule to draw bonding electrons to itself.
Electronegativity: the ability of an atom in a molecule to draw bonding electrons to itself.
- Sun Nov 04, 2018 2:18 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal planes
- Replies: 6
- Views: 1284
Re: Nodal planes
A nodal plane is where the wave function passes through 0 and the probability of finding an electron there is 0. Essentially the number of nodal planes is equal to l, the angular momentum quantum number.
- Sun Nov 04, 2018 2:14 pm
- Forum: Electronegativity
- Topic: MIDTERM
- Replies: 5
- Views: 495
Re: MIDTERM
The Midterm covers Fundamentals, Quantum, Bonding to end of 3.11 (6 Ed.) and to end of 2C (7 Ed) which was up until Wednesday's lecture.
- Sun Nov 04, 2018 2:11 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Degeneracy
- Replies: 6
- Views: 670
Re: Degeneracy
All electrons that have the same value for n are in the same shell. Within a shell (same n), all electrons that share the same l (the angular momentum quantum number, or orbital shape) are in the same sub-shell When electrons share the same n, l, and ml, we say they are in the same orbital (they hav...
- Sat Oct 27, 2018 12:03 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Test #2
- Replies: 2
- Views: 319
Re: Test #2
It depends on the question because it could ask for all possible values or just one.
- Fri Oct 26, 2018 11:59 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: nodal/radial planes
- Replies: 5
- Views: 561
Re: nodal/radial planes
The number of nodal/radial planes is equal to the value of l. Therefore, s has 0, p has 1, and d has 2.
- Fri Oct 26, 2018 11:56 pm
- Forum: Einstein Equation
- Topic: E=hv [ENDORSED]
- Replies: 52
- Views: 18083
Re: E=hv [ENDORSED]
E represents the energy of the photon, while the work function is the minimum energy needed to remove an electron.
- Fri Oct 19, 2018 8:27 pm
- Forum: *Black Body Radiation
- Topic: Test
- Replies: 9
- Views: 1249
Re: Test
I believe he said that we would not need to know about black body radiation.
- Fri Oct 19, 2018 8:25 pm
- Forum: Properties of Light
- Topic: Inverse Relationships?
- Replies: 4
- Views: 419
Re: Inverse Relationships?
In the equation (c)=wavelength(lambda) x frequency(v), the speed (c) is a constant. Therefore if wavelength increases, frequency must decrease and vice versa because c must remain the same.
- Fri Oct 19, 2018 8:21 pm
- Forum: Photoelectric Effect
- Topic: Test 2
- Replies: 16
- Views: 1113
Re: Test 2
I believe this test will only cover the quantum world section, however, it may be useful to remember and apply content from the previous section.
- Sat Oct 13, 2018 3:03 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1
- Replies: 5
- Views: 605
Re: Test 1
I'm pretty sure our TA said there will be partial credit and that being off a few significant figures won't matter much.
- Sat Oct 13, 2018 3:01 pm
- Forum: SI Units, Unit Conversions
- Topic: mol vs. mmol
- Replies: 12
- Views: 2659
Re: mol vs. mmol
The prefix "milli" represents a factor of 10^-3, so a mmol Is 10^-3 mol.
- Sat Oct 13, 2018 2:58 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1
- Replies: 5
- Views: 753
Re: Test 1
The TA said we will be getting scores in discussion, I don't think there is any way to get them before that.
- Sun Oct 07, 2018 4:39 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Percision and Accuracy
- Replies: 5
- Views: 656
Re: Percision and Accuracy
If you were trying to pour exactly 5 mL of water in a beaker and the first three times you poured 5, 5.1, and 4.9, then your accuracy and precision is pretty high because it's close to 5 and the numbers are close together. Precision is related to repeatability so if the next three times you poured 5...
- Sun Oct 07, 2018 4:34 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula Sheet?
- Replies: 6
- Views: 560
Re: Formula Sheet?
I believe we just get the periodic table so I would be safe and memorize the main formulas we have been working with. However, you can always ask or email the TA.
- Sun Oct 07, 2018 4:31 pm
- Forum: Empirical & Molecular Formulas
- Topic: When to double moles
- Replies: 13
- Views: 995
Re: When to double moles
If the number is within about .1, then round to the nearest whole number.