Search found 59 matches
- Mon Mar 11, 2019 2:24 pm
- Forum: Zero Order Reactions
- Topic: Half-life
- Replies: 6
- Views: 904
Re: Half-life
It’s just the amount of time it takes for the reactant to become half its original concentration. What’s interesting with half life is that this time never changes no matter the amount of concentration you start with.
- Mon Mar 11, 2019 2:21 pm
- Forum: First Order Reactions
- Topic: Integration
- Replies: 3
- Views: 493
Re: Integration
Lavelle just showed us how to do it becasue it will help you understand how the two equations are related, but you will most likely not be asked to integrate a rate law on a test. I believe that the integrated rate laws are all on the equation sheet.
- Mon Mar 11, 2019 2:19 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: how is kinetics different?
- Replies: 17
- Views: 1599
Re: how is kinetics different?
Even if someone is thermodynamically favored, the reaction may not occur becasue of the rate of reaction. For example, Graphite is more Thermodynamically favored than diamond, but the activation energy for that reaction is extremely high for some reason so Diamond will never spontaneously turn into ...
- Mon Mar 11, 2019 2:16 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Melting of ice
- Replies: 9
- Views: 1012
Re: Melting of ice
The melting of ice on a hot summers day would be spontaneous, so delta g would be negative
- Sun Mar 03, 2019 3:29 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Recharging Batteries [ENDORSED]
- Replies: 10
- Views: 1331
Re: Recharging Batteries [ENDORSED]
IsabelLight2H wrote:I think it's because the battery is absorbing energy. A favorable reaction releases energy.
Exactly. For example, we supply energy to our phone battery by plugging it in.
- Sun Mar 03, 2019 3:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Does anyone know if test 2 will be curved?
- Replies: 15
- Views: 2951
Re: Does anyone know if test 2 will be curved?
Nope, unfortunately tests are not curved.
- Sun Mar 03, 2019 3:23 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic vs basic solutions
- Replies: 10
- Views: 980
Acidic vs basic solutions
What’s the difference between balancing is acid and base?
- Thu Feb 21, 2019 9:24 am
- Forum: Balancing Redox Reactions
- Topic: Helpful acronym for Redox Rxns
- Replies: 2
- Views: 2396
Helpful acronym for Redox Rxns
Hello, as I was studying Redox reactions, I found an acronym that I found very helpful when thinking about the movement of electrons!
It’s OIL RIG!
Oxidation is Loss (of electrons)
Reduction is Gain (of electrons)
Hope this helps everyone!!!
It’s OIL RIG!
Oxidation is Loss (of electrons)
Reduction is Gain (of electrons)
Hope this helps everyone!!!
- Thu Feb 21, 2019 9:15 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006893
Re: Post All Chemistry Jokes Here
Hello, while I was procrastinating my studies, I drew Lavelle! Thought I would share this with all of you!! Thanks for being a great professor !
- Thu Feb 21, 2019 9:09 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006893
Re: Post All Chemistry Jokes Here
@ the midterm thissss yearrrrrr
- Tue Feb 12, 2019 3:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22873
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Should number 4 on the midterm review be when delta T = 0?
- Tue Feb 12, 2019 3:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22873
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Can someone explain 5c?
- Tue Feb 12, 2019 3:19 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22873
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
For #6, how do we know that work is equal to 0? I was wondering the same thing. What I came up with was that is you use pv=nrt to find deltaV then you can see that since pressure, temperature, and R are constant the change in volume will depend on the change in moles. The equation has a 1:1 ratio f...
- Sun Feb 10, 2019 4:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Trouton's Rule
- Replies: 2
- Views: 402
Re: Trouton's Rule
I believe that Troutons rule is just stating that many liquids have about the same enthalpy of vaporization. Which means that they all take about the same amount of energy to vaporize.
- Sun Feb 10, 2019 4:18 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: methods
- Replies: 8
- Views: 916
Re: methods
If you are given (or took to look up) the bond enthalpies, you then just have to use the equation that someone put above.
- Sun Feb 10, 2019 4:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Q of reaction and Q of calorimeter
- Replies: 1
- Views: 274
Q of reaction and Q of calorimeter
I keep seeing the equation -qcal = qrxn. Can someone explain what this means.
- Sun Feb 03, 2019 10:23 pm
- Forum: Calculating Work of Expansion
- Topic: Work sign changes
- Replies: 3
- Views: 378
Re: Work sign changes
I think work is negative when the system is doing work, and positive when the system is getting work done to it. So when a system expands, work is negative, and when a system is compressed, work is positive.
I might be wrong though
I might be wrong though
- Sun Feb 03, 2019 10:21 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated systems
- Replies: 2
- Views: 263
Isolated systems
What is the importance of an isolated system? It seems like they dont really do anything?
- Sun Feb 03, 2019 10:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Function
- Replies: 10
- Views: 824
Re: State Function
What isn’t a state function? Can someone give an example?
- Thu Jan 24, 2019 11:27 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: endothermic vs exothermic
- Replies: 6
- Views: 797
endothermic vs exothermic
What is the difference between endothermic and exothermic?
Also, since we just started discussing this on Wednesday, will we need to understand how it applies to Le Chatelier’s Principle?
Also, since we just started discussing this on Wednesday, will we need to understand how it applies to Le Chatelier’s Principle?
- Thu Jan 24, 2019 11:24 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Calculating Q
- Replies: 11
- Views: 3510
Calculating Q
When do you calculate Q? I am having some trouble understanding why you would need this and when to use it.
- Thu Jan 24, 2019 11:23 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Neutral solutions
- Replies: 2
- Views: 246
Neutral solutions
I have written in my notes “ if [h3o+] is less than 10^-7, then the solution is considered neutral”.
Can some one explain what this means, and why it is neutral?
Can some one explain what this means, and why it is neutral?
- Sat Jan 19, 2019 2:01 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solving weak acid/base dissociations
- Replies: 4
- Views: 289
Re: Solving weak acid/base dissociations
Depends. The reason you use the quadratic is because that is the values that the ice table gives you, but is the Ka is less than 10^-3, you can assume that when you are subtracting x from the initial concentration of the weak acid, that x is negligible because it is so small. This assumptions gets r...
- Sat Jan 19, 2019 1:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Determining when k is small or big
- Replies: 2
- Views: 466
Determining when k is small or big
K is big when it is greater than 10^3 and small when it is less than K^-3, but what is it when the K value is in between 10^3 and 10^-3
- Sat Jan 19, 2019 1:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K - small verses big
- Replies: 4
- Views: 396
K - small verses big
What does a small Ka mean verses a large kb?
- Thu Jan 10, 2019 5:31 pm
- Forum: Ideal Gases
- Topic: Value of K
- Replies: 6
- Views: 1550
Re: Value of K
When K is Larger than 1, the forward reaction is favored and more products are being produced.
When K is smaller than 1, the reverse reaction is favored and more reactants are being produced.
When K is smaller than 1, the reverse reaction is favored and more reactants are being produced.
- Thu Jan 10, 2019 5:24 pm
- Forum: Ideal Gases
- Topic: Q and K [ENDORSED]
- Replies: 35
- Views: 3016
Re: Q and K [ENDORSED]
No difference in the way you calculate Q and K, but there is a major difference in what they mean. Q means the ratio of Products and reactants at any given point of the reaction, but K is the ratio of Products and Reactants at equalibrium. When comparing Q and K, it can tell us which reaction rate i...
- Thu Jan 10, 2019 5:17 pm
- Forum: Ideal Gases
- Topic: Units
- Replies: 19
- Views: 1076
Re: Units
Use Kelvin. In most equations with temperature, you always use Kelvin
- Fri Dec 07, 2018 8:18 pm
- Forum: Conjugate Acids & Bases
- Topic: Chemical Equations
- Replies: 6
- Views: 672
Re: Chemical Equations
In the reactions HCL + H20 -> Cl- + H30+
HCl- is the acid with the conjugate base of Cl-
H20 is the base with the conjugate acid of H3O+
HCl- is the acid with the conjugate base of Cl-
H20 is the base with the conjugate acid of H3O+
- Fri Dec 07, 2018 8:15 pm
- Forum: Polyprotic Acids & Bases
- Topic: Significance of Polyprotic Acids & Bases
- Replies: 6
- Views: 935
Re: Significance of Polyprotic Acids & Bases
A lot of these polyprotic substances are things that have an ion in them that he went over in class when discussing Lewis structures. It’s important to note that these ions are stabilized with resonance so they are good acids
- Fri Dec 07, 2018 8:11 pm
- Forum: Amphoteric Compounds
- Topic: Difference between amphoteric and amphiprotic?
- Replies: 4
- Views: 858
Re: Difference between amphoteric and amphiprotic?
An example of something that is amphoteric is Water
An example of something that is amphiprotic is HSO4-
An example of something that is amphiprotic is HSO4-
- Fri Nov 30, 2018 6:15 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric Oxides
- Replies: 4
- Views: 727
Re: Amphoteric Oxides
I do believe we have to memorize them. It will probably be useful to know them so that you understand why a reaction with them may act a certian way
- Fri Nov 30, 2018 6:12 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Transition Metals
- Replies: 4
- Views: 313
Re: Transition Metals
Transition metals are good for electron transfer because they have multiple oxidation states.
- Fri Nov 30, 2018 6:11 pm
- Forum: Naming
- Topic: Coordination number
- Replies: 10
- Views: 2019
Re: Coordination number
Can the term coordination number apply to all molecules? or only some? I’m pretty sure a coordination number can only apple to coordination compound, which is the product of a Lewis acid-base reaction in which neutral molecules or anions (called ligands) bond to a central metal atom (or ion) by coo...
- Thu Nov 22, 2018 8:30 pm
- Forum: Hybridization
- Topic: Sixth Edition, Example 4.6
- Replies: 2
- Views: 278
Re: Sixth Edition, Example 4.6
The numbers are just something extra he wrote out on the board, but they aren’t really talked about in the textbook. I would still recommend putting it on the test if asked.
- Thu Nov 22, 2018 8:27 pm
- Forum: Hybridization
- Topic: unhybridized pi bonds
- Replies: 2
- Views: 320
Re: unhybridized pi bonds
I am also not too sure on my answer, but I am pretty sure that a sigma bond has just hybridized orbitals, but the reason a pi bond can form is because of an extra (not hybridized) p orbital. This allows for a double and triple bond to form.
- Thu Nov 22, 2018 8:23 pm
- Forum: Hybridization
- Topic: Help with Confusion
- Replies: 6
- Views: 568
Re: Help with Confusion
I think the most important thing to know is to understand what makes something a sigma bond and what makes something a pi bond. I don’t think he would directly ask us to draw how they are bonded, more like ask us to explain how they are bonded. In order to explain, it could help to draw a picture.
- Fri Nov 16, 2018 2:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Distance from Central Atom
- Replies: 8
- Views: 556
Re: Distance from Central Atom
The completely dark wedge represents the atom coming towards you, and the dashed wedge represents the atom going away. I’m not quite sure why, but I also don’t think it matters that much as long as you know that they are on a diferent plane.
- Fri Nov 16, 2018 2:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Tetrahedral shape
- Replies: 5
- Views: 430
Re: Tetrahedral shape
A molecule can always be slightly distorted. This can happen because of what atoms are attached to central atom. If all 4 of the attached atoms are the same, then you will have a normal tetrahedral shape, but the second that one of the atoms are different, there will be a slight distortion to the mo...
- Fri Nov 16, 2018 2:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Octahedral Shape
- Replies: 4
- Views: 836
Re: Octahedral Shape
There are 6 areas of electron density, but only 4 bonding regions. This is because there are two electron pairs. The molecular geometry of the molecule is only dependent on the bonding regions. While the number of areas of electron density says thats the shape is octahedral, the actual shape is squa...
- Fri Nov 09, 2018 3:43 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: Boiling point
- Replies: 12
- Views: 2111
Re: Boiling point
Rod and spherical shaped were just an example of two possible shapes. He then used pentane and 2,2-dimethylpropane as two examples of those shapes. Pentane is rod shaped and 2,2-dimethylpropane is spherical. Pentane has a higher boiling point because the intermolecular forces are stronger because th...
- Fri Nov 09, 2018 3:35 pm
- Forum: Lewis Structures
- Topic: Formal charge question
- Replies: 9
- Views: 879
Re: Formal charge question
Formal charge is usually what I check last. It’s a good way to check that you didn’t do something completely wrong because if you had a formal charge of like -4 somewhere, thats a big clue that there is a big mistake. If the formal charges all make sense and are where they should be (negative on mos...
- Fri Nov 09, 2018 3:30 pm
- Forum: Dipole Moments
- Topic: Dipole - Dipole vs. Hydrogen Bonding
- Replies: 7
- Views: 1649
Re: Dipole - Dipole vs. Hydrogen Bonding
H-Bonding isn’t actually a type of bond. A lot of people get this confused because of the word bonding in it. H-Bonding is another type of Intermolecular force (or interaction). Compared to Ionic and Covalent bonds, H-bonding is very weak, but it is definitely stronger than Dipole-Dipole.
- Sun Nov 04, 2018 6:12 pm
- Forum: Lewis Structures
- Topic: Exceptions to the Octet Rule
- Replies: 4
- Views: 275
Re: Exceptions to the Octet Rule
Any atom in the 3 orbital or lower can have an expanded octet. It is very common to see it on S, P, and Cl. A good example is PCl5. Phosphorus has an expanded octet with all 5 chlorine’s bonded to it.
- Sun Nov 04, 2018 5:59 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Spin Magnetic Quantum Number
- Replies: 6
- Views: 921
Re: Spin Magnetic Quantum Number
505168807 wrote:Is there a possible way to determine whether the spin is +1/2 or -1/2?
No, I dont think that there is any way determine this, and if there is, we haven’t learned it.
- Sun Nov 04, 2018 5:57 pm
- Forum: Trends in The Periodic Table
- Topic: Effective Nuclear Charge
- Replies: 5
- Views: 511
Re: Effective Nuclear Charge
Effective Nuclear Charge increases when the number of protons increases, and the number of protons increases as you go across a table
- Sun Oct 28, 2018 4:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grading
- Replies: 3
- Views: 287
Grading
I had a few questions about the grading of this course. 1) how do I check my grade? 2) Is their any curve applied to the Tests? And 3) Is their any way to make up points lost on Tests?
- Sun Oct 28, 2018 4:02 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: The values of L and ML
- Replies: 3
- Views: 287
Re: The values of L and ML
L just refers to what sub shell the electron is in. The point of L=n-1 is to show the max value of L that it could be. So the value of L is not always going to be n-1.
- Sun Oct 28, 2018 3:50 pm
- Forum: Trends in The Periodic Table
- Topic: Transition metal question
- Replies: 3
- Views: 312
Re: Transition metal question
there’s no rule that I know of, but I do know that when we do nomenclature of molecules, the name gives the number of valence electrons that the atom is loosing. For example, Copper (II) Oxide is the nomenclature for CuO. The nomenclature gives that Copper looses 2 electron.
- Sat Oct 20, 2018 1:54 pm
- Forum: Properties of Light
- Topic: Grades
- Replies: 7
- Views: 638
Grades
This question isn’t related to properties of light but I didn’t know where to put it. Does anyone know where to go to check our grades in the class?
- Sat Oct 20, 2018 1:49 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: H bar
- Replies: 5
- Views: 556
Re: H bar
H bar will not be given, which just means you need to do one more step when using Heisenberg indeterminacy equation. But, h will definitely be given.
- Sat Oct 20, 2018 1:47 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: energy emission
- Replies: 1
- Views: 244
Re: energy emission
When electromagnetic radiation is emitted from an atom, I believe it means that the electron is dropping from a high energy level, to a low energy level. This means that the statement is false because when an electron does make that drop, energy is being emitted from the atom, therefor it is loosing...
- Sat Oct 20, 2018 1:32 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shielding [ENDORSED]
- Replies: 15
- Views: 2036
Re: Shielding [ENDORSED]
Technically the 2s and 2p are the same orbital, but they have different suborbital. S is the closest suborbital to the nucleus, then P, then D, and so on.
- Sun Oct 14, 2018 2:55 pm
- Forum: DeBroglie Equation
- Topic: "Wave-like Properties" of Matter
- Replies: 6
- Views: 239
Re: "Wave-like Properties" of Matter
The reason he gave us something with an unmeasurable wavelike property is so that we could understand that no matter what the velocity of that object is, if the mass is too big, it wont act like a wave. Like he said, a baseball, no matter how fast it is traveling, will never act like a wave. Only sm...
- Sun Oct 14, 2018 2:48 pm
- Forum: Photoelectric Effect
- Topic: Work Function
- Replies: 4
- Views: 227
Re: Work Function
In order to find the velocity, you would need the Energy of the ejected election. That means that you would either need the given the energy of the ejected electron or have a way to calculate it with the given information using the equation E(photon) - Threshold energy = E(electron).
- Sun Oct 14, 2018 2:43 pm
- Forum: Properties of Light
- Topic: Rydberg Equation
- Replies: 3
- Views: 170
Re: Rydberg Equation
He basically said that it could be used but he doesn’t recommend it. I learned it in high school and it always confused me (even thought it is just plugging numbers into an equation). I didnt get it because I didnt get the basic understanding of what was happening. The way Levelle teaches this secti...
- Sun Oct 07, 2018 6:23 pm
- Forum: Balancing Chemical Reactions
- Topic: States of Matter
- Replies: 11
- Views: 978
Re: States of Matter
I have always struggled on knowing the state of a given molecule so I am hoping that they will be given until we go over it in class.
As far as if it affects calculations, it doesn’t. All it does is help us visualize the reaction.
As far as if it affects calculations, it doesn’t. All it does is help us visualize the reaction.
- Sun Oct 07, 2018 6:20 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing reactions tips
- Replies: 29
- Views: 2045
Re: Balancing reactions tips
I don’t know if this will help anyone, but every time I balance a combustion reaction, I am always thinking in even numbers. The reason for this is that if there is an odd number of oxygen on the product side of the reaction, the coefficient will end up being a number and a half. If I am always thin...
- Sun Oct 07, 2018 6:12 pm
- Forum: Significant Figures
- Topic: Rounding numbers ending in 5
- Replies: 9
- Views: 851
Re: Rounding numbers ending in 5
I have once been told that if the number were something like 2.652 and I had to round to the 1st decimal place, it would be rounded to 2.6, but I have never really payed attention to that rule. Typically, I would still round to 2.7.