Search found 51 matches

by Hammad Khan 2B
Sun Mar 11, 2018 10:21 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7425
Views: 980865

Re: Post All Chemistry Jokes Here

Chemistry Joke
by Hammad Khan 2B
Tue Mar 06, 2018 10:32 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7425
Views: 980865

Re: Post All Chemistry Jokes Here

What is a physical chemists favorite show?
Law and Order
by Hammad Khan 2B
Mon Mar 05, 2018 8:02 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: What is Molecularity?
Replies: 9
Views: 661

What is Molecularity?

From what I understand it’s just the number of reactants forming to a product. But I don’t think we went over moleuclarity as it applies to intermediate products. How would we calculate that?
by Hammad Khan 2B
Sun Mar 04, 2018 10:11 pm
Forum: Zero Order Reactions
Topic: Using Half Life with Zero Order
Replies: 2
Views: 121

Re: Using Half Life with Zero Order

I’m guessing that half life of a zero order reaction would be itself?
by Hammad Khan 2B
Sun Mar 04, 2018 10:07 pm
Forum: Zero Order Reactions
Topic: Zero Order Reactions and Catalysts
Replies: 2
Views: 134

Re: Zero Order Reactions and Catalysts

From what I understand, it’s because with a catalyst it increases reaction rate but after increasing reaction concentration we get to a point where and increase in concentration doesn’t change reaction rate. So it’s kind of like reaching the maximum reaction rate and not going any faster.
by Hammad Khan 2B
Sun Mar 04, 2018 10:03 pm
Forum: Zero Order Reactions
Topic: Determining Reactions
Replies: 2
Views: 108

Re: Determining Reactions

We can also use the k constant to narrow it down to what order it might be. 0 and 1storder have negative k constant and 2nd order has positive k constant.
by Hammad Khan 2B
Sun Feb 18, 2018 10:20 pm
Forum: Balancing Redox Reactions
Topic: Half reaction
Replies: 2
Views: 83

Re: Half reaction

When the reaction is balanced then E is usually the same.
by Hammad Khan 2B
Sun Feb 18, 2018 10:19 pm
Forum: Balancing Redox Reactions
Topic: Writing cell diagram and reaction equation
Replies: 3
Views: 138

Re: Writing cell diagram and reaction equation

Anode is usually not the left side and cathode on the right. Anode is also usually being oxidized and cathode is being reduced.
by Hammad Khan 2B
Wed Feb 14, 2018 3:35 pm
Forum: Van't Hoff Equation
Topic: Derivation
Replies: 9
Views: 403

Re: Derivation

You should at least know how to derive the Van't Hoff equation and how to get work for an reversible process.
by Hammad Khan 2B
Wed Feb 14, 2018 3:33 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Practice Midterm #3b Equation
Replies: 3
Views: 183

Re: Practice Midterm #3b Equation

How would you use the equation to solve for pressure?
by Hammad Khan 2B
Sun Feb 11, 2018 9:36 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Practice Midterm 3A
Replies: 3
Views: 163

Re: Practice Midterm 3A

Cv with constant volume and Cp with constant pressure.
by Hammad Khan 2B
Sun Feb 11, 2018 9:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 2
Views: 147

Re: Test 2

I would assume it to be on Electrochemistry exclusively as we have just started it and it on 2/20/18
by Hammad Khan 2B
Fri Feb 09, 2018 2:16 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: What is a Faraday? [ENDORSED]
Replies: 3
Views: 148

What is a Faraday? [ENDORSED]

I don’t really grasp the concept of what a faraday is and what it is used for. If anyone can help elaborate that would be great.
by Hammad Khan 2B
Sun Feb 04, 2018 12:19 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Limit of Entropy as temperature approaching 0 K
Replies: 2
Views: 133

Re: Limit of Entropy as temperature approaching 0 K

With this, entropy approaches near zero and such that there is only the vibrational motion of molecules and no movements around. Meaning that we know exactly where molecules are.
by Hammad Khan 2B
Sun Feb 04, 2018 12:17 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Third Law
Replies: 3
Views: 180

Re: Third Law

Meaning that the degeneracy of the process is also 1 meaning that we can calculate exactly where molecules are in a perfect crystal.
by Hammad Khan 2B
Sun Feb 04, 2018 12:14 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy change at higher temperature
Replies: 2
Views: 102

Re: Entropy change at higher temperature

The analogy that can be used to explain this is starting a fire during a snowstorm v starting a fire on a volcano. Although there is a higher temperature on a volcano entropy doesn't change much as the place already has high entropy. While a snowstorm would be affected more since there isn't much en...
by Hammad Khan 2B
Sun Jan 28, 2018 10:49 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Perfect Crystal
Replies: 9
Views: 297

Re: Perfect Crystal

Moreover, it means that we can pinpoint exactly where the particles are within an object which we have never been able to do before.
by Hammad Khan 2B
Mon Jan 22, 2018 5:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: ΔU = ΔH for biological reactions
Replies: 2
Views: 101

Re: ΔU = ΔH for biological reactions

Same can also be said about pressure as a cell in the body doesn’t change pressure so w=0 in that case. Making .
by Hammad Khan 2B
Mon Jan 22, 2018 5:46 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Material in Book but not in Lectures
Replies: 5
Views: 154

Re: Material in Book but not in Lectures

I would recommend to see outline 1 on his website to see what to focus on.
by Hammad Khan 2B
Mon Jan 22, 2018 9:35 am
Forum: Calculating Work of Expansion
Topic: When to use equation [ENDORSED]
Replies: 3
Views: 148

Re: When to use equation [ENDORSED]

The first equation is used to find the work done by a reversible process which will not be on the upcoming test. The second equation however, will be on the test as it is the work by expansion.
by Hammad Khan 2B
Fri Jan 19, 2018 6:38 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible process
Replies: 2
Views: 183

Re: Reversible process

My TA told me that reversible processes do the most work because instead of the work being performed instantly and staying constant, the work is gradually done which should look like this. Then if we take the integral of the graph we can adds that reversible processes do the most work. 2A5535FE-45B7...
by Hammad Khan 2B
Fri Jan 19, 2018 6:15 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Internal Energy
Replies: 4
Views: 172

Re: Internal Energy

Internal energy is the energy of the whole system work + enthalpy. While enthaply is just heat released or absorbed, a part of internal energy.
by Hammad Khan 2B
Fri Jan 19, 2018 6:05 am
Forum: Calculating Work of Expansion
Topic: Work
Replies: 2
Views: 108

Re: Work

I would believe that if the piston would move then yes pressure would be the same since work would drive the piston back and forth trying to equalize pressure.
by Hammad Khan 2B
Mon Jan 15, 2018 6:53 pm
Forum: Phase Changes & Related Calculations
Topic: Signs on energy changes
Replies: 3
Views: 183

Re: Signs on energy changes

In problem 5,the compression is a positive value because work is being DONE TO the system meaning that energy is being added to it in the form of work. In problem 7, when it says "absorbed heat" it's saying how heat is essentially being taken into a system as it's increasing in energy. The...
by Hammad Khan 2B
Fri Jan 12, 2018 11:08 am
Forum: Phase Changes & Related Calculations
Topic: Work done BY vs. Work done ON [ENDORSED]
Replies: 5
Views: 235

Re: Work done BY vs. Work done ON [ENDORSED]

From what I understand. when a system DOES work it loses energy, thus the work has to be negative as you lost it. While having work DONE to a system means that energy is being added to the system, thus the work is positive. Picture a car trying to move, it has a certain amount of gas (internal energ...
by Hammad Khan 2B
Thu Jan 11, 2018 9:27 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 8.1 part c [ENDORSED]
Replies: 8
Views: 414

Re: 8.1 part c [ENDORSED]

This is because an isolated system is where there is no contact with surroundings. A bomb calorimeter is made such that whatever is happening outside it never affects the water that the bomb calorimeter is usually in. As such, it has no contact with its surroundings and it is an isolated system.
by Hammad Khan 2B
Thu Jan 11, 2018 9:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.23
Replies: 3
Views: 182

Re: 8.23

I'll try a bit little more specific if it helps. So we use the equation q_{cal}=C\bigtriangleup T which is the equation for heat transfer for a calorimeter. So then we move around to equation to get \frac{q_{cal}}{\bigtriangleup T}=C which is the heat capacity of a calorimeter. Lastly, just plug in ...
by Hammad Khan 2B
Fri Dec 08, 2017 9:17 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Negative pH
Replies: 2
Views: 115

Re: Negative pH

I believe Lavelle went over this in class but you can calculate negative pH of a superacid but I don't know if you can measure it since most litmus tests for pH go from 0-14.
by Hammad Khan 2B
Fri Dec 08, 2017 9:16 am
Forum: Naming
Topic: What is delocalized bonding? [ENDORSED]
Replies: 5
Views: 380

Re: What is delocalized bonding? [ENDORSED]

Think of the benzene that Lavelle talks so much about. It looks like a diamond structure with alternating double bonds. However, through resonance we can see that the bonding can be moved around but still be alternating. That is what I can think of as delocalized bonding.
by Hammad Khan 2B
Fri Dec 08, 2017 9:14 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Br- (Bromide ion)
Replies: 2
Views: 946

Re: Electron Configuration for Br- (Bromide ion)

It should say if it has the long or short way but if not specified then do short-hand usually.
by Hammad Khan 2B
Fri Dec 08, 2017 9:13 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: dipole moment of PO4 3-
Replies: 1
Views: 153

Re: dipole moment of PO4 3-

Yes, I agree with you that PO4^-3 has no dipole moment has all the oxygens are pulling on the phosphorus thus making the dipoles cancel out. However, to truly understand whether there is a dipole moment, we need to draw the lewis structure of O3 where we get that the molecule in the middle has a lon...
by Hammad Khan 2B
Tue Nov 28, 2017 8:50 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE box
Replies: 1
Views: 109

Re: ICE box

So the 18.3% is how much we have left of BrCl so we multiply that by the moles to get the grams and we get .183(1.84x10^-4)=3.36 x10^-5g BrCl. So now we use the ICE table 2BrCl(g) ⇌ Br2 (g) + Cl2(g) I 1.84x10^-4, 0, 0 C -2x, +x, +x E 3.36 x10^-5, x, x So now solve for x using 1.84x10^-4 - 2x= 3.36 x...
by Hammad Khan 2B
Tue Nov 28, 2017 8:46 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q and K
Replies: 2
Views: 137

Re: Q and K

When Q is greater than K it means that the reaction moves to the reactants or from right to left and vice-versa.
by Hammad Khan 2B
Fri Nov 17, 2017 9:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron Density
Replies: 3
Views: 182

Re: Electron Density

It's because as the name implies, the molecule has six regions of electron density.
by Hammad Khan 2B
Fri Nov 17, 2017 9:13 am
Forum: Hybridization
Topic: Triple bond sigma vs. pi
Replies: 3
Views: 137

Re: Triple bond sigma vs. pi

From what I understand is that the first bond is always a Sigma bond as it can handle only one bond. The the next two bonds can only be Pi bonds as they can have upto two bonds. Hence 1 Sigma (Bonds it can have) + 2 Pi (Bonds it can have) = a triple bond.
by Hammad Khan 2B
Thu Nov 09, 2017 11:12 am
Forum: Lewis Structures
Topic: 3.41
Replies: 2
Views: 148

Re: 3.41

So this problem is a doozy. First, you wanna try and separate the element into groups such as H2C,NH2, and COOH so we get that C and H are bonded such that it is a single bond between C and H giving C four bonded electrons meaning that it connects to two other elements on its sides. So we can place ...
by Hammad Khan 2B
Thu Nov 09, 2017 10:56 am
Forum: Lewis Structures
Topic: N2O LEWISH STRUCTURE
Replies: 3
Views: 243

Re: N2O LEWISH STRUCTURE

So first find the element with lowest ionization energy which is N and then find the shape of the lewis structure which would be linear since you have 3 elements with one in the middle. Second, find the structure which makes each element have an octet. Lastly, find the formal charge of each element ...
by Hammad Khan 2B
Thu Nov 09, 2017 10:43 am
Forum: Ionic & Covalent Bonds
Topic: 3.25
Replies: 6
Views: 350

Re: 3.25

RenuChepuru1G wrote:what happens when there is a number in parentheses for example Bismuth(III)?


The number in the parentheses just means the charge of the element. Ex) Cu (II) would be Cu2+ and so on.
by Hammad Khan 2B
Thu Nov 09, 2017 10:16 am
Forum: Bond Lengths & Energies
Topic: dissociatioin energies
Replies: 3
Views: 242

Re: dissociatioin energies

I would assume that with CH the atom of H achieves the two electrons it needs to have a full valence shell compared to CN where neither element gets their valence shell full. So because H gets its shell full it would have a stronger bond with C to prevent it's electron being taken compared to CN whe...
by Hammad Khan 2B
Thu Nov 09, 2017 10:10 am
Forum: Lewis Acids & Bases
Topic: Lewis Acid or Base: AlCl3 [ENDORSED]
Replies: 3
Views: 1190

Re: Lewis Acid or Base: AlCl3 [ENDORSED]

I would expect it to be a Lewis Acid since its going to try and become a full octet meaning it will accept electron which is a characteristic of Lewis Acids. It is also the element with lowest ionization energy so it has to be in the middle accepting electron from other elements. It also doesn't com...
by Hammad Khan 2B
Wed Nov 01, 2017 9:51 am
Forum: Lewis Structures
Topic: Formal Charge and Lewis Structures
Replies: 2
Views: 148

Re: Formal Charge and Lewis Structures

What I understand is that the central atom should try and achieve FC=0 and the other atoms should also try to approach this value if possible. But if there are multiple arrangements where the central atom has FC=0 and the other atoms just interchange charge, then we can show resonance between the st...
by Hammad Khan 2B
Tue Oct 31, 2017 3:18 pm
Forum: Lewis Structures
Topic: Elements that have extended octets
Replies: 3
Views: 159

Elements that have extended octets

So I know that Phosphorus (P) and Sulfur (S) both have extended octets meaning that they can have more than 8 electrons with them. Are all elements below them also extended octets for only certain ones like Xenon (Xe)?
by Hammad Khan 2B
Fri Oct 27, 2017 10:55 am
Forum: Quantum Numbers and The H-Atom
Topic: Problem 2.29 parts, b and c
Replies: 2
Views: 171

Re: Problem 2.29 parts, b and c

Leon, I think you messed up a bit on part b and d. As when l=2 then the orbital is of the d orbital so shouldn't it be 4d instead of 4p? The electron number is correct its just that and that part d should be 3d. Again, because when l=2 then it's a d orbital with the same number of electrons. Other t...
by Hammad Khan 2B
Fri Oct 27, 2017 10:33 am
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number ml
Replies: 2
Views: 197

Re: Quantum number ml

In addition, ml ranges from -l to l so if the value of l is 2 then the ml numbers would be -2,-1,0,1,2.
by Hammad Khan 2B
Fri Oct 27, 2017 10:31 am
Forum: Quantum Numbers and The H-Atom
Topic: Trouble on a question I seen on the internet relating to this topic we learned in class!
Replies: 3
Views: 213

Re: Trouble on a question I seen on the internet relating to this topic we learned in class!

You would first go to Ar which is Argon and continue on from there. Then we use 3d10 which references to the d-orbital part of the periodic table and tells us to go to the 10th element on that row which is Zinc. Then it also as 4s2 which tells us to go to the 4th s-orbital row and the second element...
by Hammad Khan 2B
Wed Oct 18, 2017 11:28 am
Forum: Properties of Electrons
Topic: Problem 1.38 [ENDORSED]
Replies: 3
Views: 259

Problem 1.38 [ENDORSED]

Hello, I'm having some trouble finding out the when wavelength=velocity when the distance traveled is 1s. I looked online and the equation that I got was lamba=sqrt(h/m) but I have no idea where this equation came from and how to derive it. Does anyone know how to do it? h=planks constant m=mass of ...
by Hammad Khan 2B
Fri Oct 13, 2017 10:05 am
Forum: Properties of Light
Topic: Prefix Conversion
Replies: 12
Views: 530

Re: Prefix Conversion

I would say to convert the problem to whatever the other variables are, so if you have meters in one and nm in another then convert both to meters to solve it and once solved, then put it back into what its asking or meters.
by Hammad Khan 2B
Fri Oct 13, 2017 10:02 am
Forum: Properties of Light
Topic: Converting Units [ENDORSED]
Replies: 11
Views: 529

Converting Units [ENDORSED]

Hello, I'm wondering if we should look to convert units when we finish the problem. So if I have an answer lets say, 290*10^-9m then should I convert it into nm or should I just leave it as is?
by Hammad Khan 2B
Thu Oct 05, 2017 9:15 pm
Forum: Balancing Chemical Reactions
Topic: Order of Elements to Balance [ENDORSED]
Replies: 5
Views: 420

Re: Order of Elements to Balance [ENDORSED]

Usually to balance the equation you would start from the chemical with the lowest stoichiometric coefficient so it is easier. Then you would work your way up from there. If there are two numbers with the same coefficient then you can just choose which one to do.
by Hammad Khan 2B
Wed Oct 04, 2017 9:46 am
Forum: Significant Figures
Topic: Sig Figs in 0.0380 [ENDORSED]
Replies: 5
Views: 373

Re: Sig Figs in 0.0380 [ENDORSED]

I would recommend going to Dr. Lavelle's website as it has a helpful text on Sig Figs for more practice.

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