Search found 60 matches

by taywebb
Sat Mar 16, 2019 8:19 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7581
Views: 1013854

Re: Post All Chemistry Jokes Here

What would you do with a dead scientist? Just Barium.
by taywebb
Sat Mar 16, 2019 8:17 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Calculating E*
Replies: 1
Views: 163

Re: Calculating E*

You can add them when it is a completed redox reaction where all of the electrons cancel out, but in that problem, the equations were not equivalent, so we could not add the E*'s together.
by taywebb
Sat Mar 16, 2019 8:15 pm
Forum: Zero Order Reactions
Topic: Graphs
Replies: 3
Views: 177

Re: Graphs

You might have to label the axes of the graphs and the slope if given the reaction order.
by taywebb
Sat Mar 16, 2019 8:12 pm
Forum: Phase Changes & Related Calculations
Topic: heat capacity of an object
Replies: 3
Views: 206

Re: heat capacity of an object

I believe that is the units for specific heat capacity because it has grams in it.
by taywebb
Sat Mar 16, 2019 8:09 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Approaches to mechanisms
Replies: 2
Views: 51

Re: Approaches to mechanisms

They are both just different ways to reach an associated reaction mechanism or rate, but he said not to worry about steady-state, so I would just focus on pre-equilibrium problems. You will get the same answer both ways.
by taywebb
Sat Mar 16, 2019 1:28 pm
Forum: First Order Reactions
Topic: Pseudo 1st order rate laws
Replies: 2
Views: 155

Pseudo 1st order rate laws

After you have identified the reactant(s) in large excess, making them negligible in terms of the rate law. Are there any fundamental differences when composing a pseudo-first-order rate law vs. a normal first-order rate law?
by taywebb
Sat Mar 16, 2019 1:23 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Test 2 Q 7 [ENDORSED]
Replies: 5
Views: 334

Re: Test 2 Q 7 [ENDORSED]

Because the outside environment is providing that heat directly, making this a naturally occurring reaction, no extra energy must be put in to make this reaction occur, so it is spontaneous.
by taywebb
Sat Mar 16, 2019 1:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: applying Le Chatelier's Principle
Replies: 4
Views: 233

Re: applying Le Chatelier's Principle

If your determined Q is less than K, then the reaction shifts forward.
by taywebb
Sat Mar 16, 2019 12:05 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate constants at equilibrium
Replies: 5
Views: 93

Re: Rate constants at equilibrium

The actual rates would be equal, but not the rate constants
by taywebb
Sat Mar 16, 2019 12:04 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 4
Views: 96

Re: Catalysts

I would assume no because catalysts increase a rate, so including it in the rate would not make sense
by taywebb
Fri Mar 15, 2019 3:07 pm
Forum: Second Order Reactions
Topic: 7th edition 7B.13
Replies: 3
Views: 235

Re: 7th edition 7B.13

First, you find k using the second order half-life equation, then you isolate t in the integrated rate law to solve for it. Because we already have the ratio of initial to final concentrations, you can use that to relate the two fractions together, making [A]t the same as [A]0. You can then subtract...
by taywebb
Fri Mar 15, 2019 12:08 pm
Forum: First Order Reactions
Topic: Half-life Formulas
Replies: 2
Views: 183

Half-life Formulas

I know we have to know how to derive the integrated rate laws, but will we have to solve for the half-life formulas as well? or will we just have to recognize which half-life formula is for which order?
by taywebb
Fri Mar 15, 2019 12:05 pm
Forum: General Rate Laws
Topic: Determining the order
Replies: 3
Views: 58

Re: Determining the order

You would have to be given enough information to calculate it, specific units that go along with a specific order, or data to graph.
by taywebb
Fri Mar 15, 2019 12:03 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: calculating A in Arrhenius equation
Replies: 2
Views: 41

Re: calculating A in Arrhenius equation

From the practice problems and textbook, I think it is safe to assume they will give us A in a chart or just in the question of the problem.
by taywebb
Wed Feb 27, 2019 10:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Water in Cell Diagrams
Replies: 2
Views: 68

Water in Cell Diagrams

Should water be included in cell diagrams? If not, y?
by taywebb
Mon Feb 25, 2019 10:48 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Redox Reaction Oxidizing Agent
Replies: 1
Views: 50

Redox Reaction Oxidizing Agent

Is the oxidizing agent in a redox reaction always the couple that has a higher standard cell potential (being that it is more positive on the table)?
by taywebb
Mon Feb 25, 2019 8:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams Example 14.4 in 6th Edition Book
Replies: 2
Views: 42

Cell Diagrams Example 14.4 in 6th Edition Book

Can anyone explain to me how they came up with the reduction and oxidation half-reactions for the cell diagram Pt(s)|H2(g)|HCl(aq)|Hg2Cl2(aq)|Hg(l)? I am confused at how they got Cl- as a separate component when it is not in the cell diagram and why the coefficient for H2(g) becomes 1/2 in the oxida...
by taywebb
Mon Feb 25, 2019 7:53 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs Units
Replies: 2
Views: 59

Gibbs Units

When calculating Gibbs free energy with the Delta G = -nFE equation and you are canceling units, is it necessary to change volts to J.C^-1 or can we keep the final answer in C.V?
by taywebb
Mon Feb 25, 2019 7:52 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs At Equilibrium
Replies: 3
Views: 93

Gibbs At Equilibrium

What will Gibbs free energy be when the reaction is at equilibrium?
by taywebb
Mon Feb 25, 2019 7:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 2
Views: 56

Salt Bridge

Do galvanic cells have to have a salt bridge?
by taywebb
Mon Feb 25, 2019 7:51 pm
Forum: Balancing Redox Reactions
Topic: Balancing Oxygens vs. Hydrogens
Replies: 1
Views: 56

Balancing Oxygens vs. Hydrogens

*When balancing redox reactions, is it necessary to balance the oxygen atoms before the hydrogen ones?
by taywebb
Mon Feb 11, 2019 7:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 7th Edition 4.7
Replies: 1
Views: 44

7th Edition 4.7

For part c, the internal energy change of formation is the change in enthalpy of formation plus work. Why is this? I'm just confused on if the enthalpy of formation is replacing heat in this equation?
by taywebb
Sun Feb 10, 2019 4:42 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Constant Pressue
Replies: 3
Views: 86

Constant Pressue

If the problem does not note a pressure change can we assume that no change in pressure was made?
by taywebb
Sun Jan 20, 2019 1:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th Edition 6B #9
Replies: 1
Views: 59

7th Edition 6B #9

When I fill in the table to find the [OH-] using the already given [H3O+] I keep getting 6.7x10^-14, but the solutions manual says the answer is 1.5x10^-14. I am just dividing 10^-14 by the given molarity (1.5). This is for the i part of the table. Can anyone explain what I am doing wrong?
by taywebb
Sat Jan 19, 2019 3:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in K
Replies: 4
Views: 75

Changes in K

Does anyone know what actually changes K? I know changing the reaction and the temperature changes it, but does anything else change it?
by taywebb
Sat Jan 19, 2019 2:52 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Partial Pressure and Moles
Replies: 3
Views: 93

Partial Pressure and Moles

When increasing and decreasing partial pressure and concentration in a chemical equilibrium reaction, does the number of moles matter? or do they only matter when considering increasing or decreasing pressure on the whole system?
by taywebb
Sun Jan 13, 2019 3:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Module Part 2 Question
Replies: 2
Views: 56

Module Part 2 Question

Can anyone explain what I am doing wrong on this question: 29. A researcher fills a 1.00 L reaction vessel with 1.84 x 10-4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place....
by taywebb
Wed Jan 09, 2019 10:10 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th edition 5G.5
Replies: 3
Views: 58

Re: 7th edition 5G.5

Here's what I could gather from looking at the solutions manual. We first have to recognize that the decomposition of X2 has an equilibrium equation of X2 <-> 2X, making the partial pressure ratio 1:2. Since the initial pressure is 0.10 bar, we must multiply it by the fraction of molecules that have...
by taywebb
Wed Jan 09, 2019 9:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G 1c 7th Edition
Replies: 1
Views: 36

5G 1c 7th Edition

Clarity on how pressure vs. temperature affects the K value?
by taywebb
Wed Jan 09, 2019 9:24 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs. Kp
Replies: 7
Views: 140

Re: Kc vs. Kp

Just for further clarification, when there are all gases, so you use Kp and partial pressure, the format for K would be Kp = and then use parenthesis with P and the molecule as the subscript, but for Kc and concentrations, the format for K would be Kc= and then use brackets?
by taywebb
Sat Dec 08, 2018 1:45 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy Levels
Replies: 2
Views: 256

Energy Levels

When an electron jumps from a lower energy level to a higher energy level does it gain or lose energy?
by taywebb
Sat Dec 08, 2018 1:43 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Ligands
Replies: 6
Views: 277

Ligands

I'm not sure where to put this so I'm putting it here.

Can anyone explain to me what a porpfyrin ligand is? Might be spelled wrong, but still confusing!
by taywebb
Sat Dec 08, 2018 1:40 pm
Forum: DeBroglie Equation
Topic: Calculating Wavelength of Ejected Electron
Replies: 1
Views: 233

Calculating Wavelength of Ejected Electron

If anyone has the same test #2 as me, I am confused on question 4c. It says to calculate the wavelength of the ejected electron, which I assumed would just be de Broglie (wavelength = h/mv). However, when I did that, I got the answer 3.64 x 10-10 m, but my TA wrote the 7.09 x 10-7 m as the write ans...
by taywebb
Sat Dec 08, 2018 1:29 pm
Forum: Quantum Numbers and The H-Atom
Topic: Determining Amount of Electrons From Quantum Numbers
Replies: 4
Views: 266

Re: Determining Amount of Electrons From Quantum Numbers

A really simple way to think about this is just knowing that the angular quantum number (l) specifies the subshells. If only n is given you can just use the formula 2(n)^2 to determine the number of electrons. If l is given it can mean multiple things. If l = 0, it is the s orbital, which has 1 subs...
by taywebb
Thu Dec 06, 2018 10:08 pm
Forum: Amphoteric Compounds
Topic: Amphoteric vs Amphiprotic
Replies: 4
Views: 115

Re: Amphoteric vs Amphiprotic

Can someone provide examples of compounds that are both amphoteric and amphiprotic and some that are one or the other? I understand what they are as defined terms, but some examples would be very helpful.
by taywebb
Thu Dec 06, 2018 6:18 pm
Forum: Naming
Topic: Knowing oxidation states
Replies: 11
Views: 145

Re: Knowing oxidation states

Is the oxidation state the same as an oxidation number? or do the oxidation numbers of each element determine the compound's state?
by taywebb
Thu Dec 06, 2018 4:43 pm
Forum: Bronsted Acids & Bases
Topic: Electronegativity and Acidity
Replies: 1
Views: 59

Electronegativity and Acidity

The book says the greater the electronegativity of A, the stronger the acid HA is, however, F if the most electronegative element, but the book also says that HF is the weakest acid. Can someone explain why?
by taywebb
Thu Dec 06, 2018 4:39 pm
Forum: Bronsted Acids & Bases
Topic: Zinc Nitrate
Replies: 2
Views: 81

Zinc Nitrate

If I am making zinc nitrate what base do I use?
by taywebb
Thu Dec 06, 2018 3:41 pm
Forum: Identifying Acidic & Basic Salts
Topic: Acids and Bases
Replies: 4
Views: 260

Re: Acids and Bases

Can someone differentiate when to use the Lewis acid definition of an acid vs. the Bronsted Lowry definition?
by taywebb
Mon Dec 03, 2018 11:57 pm
Forum: Bronsted Acids & Bases
Topic: Comparing pH levels
Replies: 3
Views: 71

Re: Comparing pH levels

I think there is a good probability of that showing up on the final mostly because he explicitly mentioned it in class. Also, it is really good information to know for checking your answer and comparing relative acidity.
by taywebb
Mon Dec 03, 2018 11:53 pm
Forum: Bronsted Acids & Bases
Topic: Strong Acids
Replies: 4
Views: 76

Re: Strong Acids

That helps! my only issue is if we are unsure of the Ka. Should we just go off of electronegativity and size of the atom? This still confuses me a little bit.
by taywebb
Mon Dec 03, 2018 11:51 pm
Forum: SI Units, Unit Conversions
Topic: bond angles
Replies: 5
Views: 356

Re: bond angles

Does anyone know if there are ways to figure out if the bond angles are not the standard 90, 109.5, 120, 180 and how we would denote on the final if they were more or less than that?
by taywebb
Sun Nov 25, 2018 3:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2.45
Replies: 2
Views: 42

2.45

Can anyone explain 2.45 to me? I understand how to get the lewis structure and what is a sigma and pi bond, but why is the C hybridization 2sp2 for a sigma bond and 2p for a pi bond?
by taywebb
Sun Nov 25, 2018 2:43 pm
Forum: Hybridization
Topic: Hybridization and Hybrid Orbitals
Replies: 4
Views: 101

Hybridization and Hybrid Orbitals

Can someone please explain to me the difference between hybridization of the central atom and the hybrid orbitals used by the central atom? (If there is a difference?)
by taywebb
Sun Nov 25, 2018 2:42 pm
Forum: Hybridization
Topic: SeF3+
Replies: 2
Views: 351

SeF3+

Does anyone know the lewis structure and geometric shape for SeF3+?
by taywebb
Sun Nov 25, 2018 2:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma and Pi bonds
Replies: 6
Views: 106

Re: Sigma and Pi bonds

When determining the number of sigma and pi bonds in a molecule, do you have to put them only for the most common resonance structure? (Referring to homework problem 2F #3 for the SO2 lewis structures)
by taywebb
Sun Nov 25, 2018 2:39 pm
Forum: Hybridization
Topic: Hybridization Orbitals
Replies: 2
Views: 105

Re: Hybridization Orbitals

When describing how a hybrid orbital is oriented on the test, would it be necessary to put the degrees? (Ex: 120 degrees for trigonal planar)
by taywebb
Sun Nov 04, 2018 5:47 pm
Forum: Octet Exceptions
Topic: What are the octet exceptions?
Replies: 9
Views: 226

Re: What are the octet exceptions?

I understand why H is an exception to the octet rule, but can someone explain why Hi, Le, and Be are as well?
by taywebb
Sat Nov 03, 2018 8:45 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: S-orbital and D-orbital
Replies: 2
Views: 112

Re: S-orbital and D-orbital

Would the configuration of Ni as [Ar]3d84s2 be considered wrong on a test? Is it always preferred to fill the shell in order to make it more stable?
by taywebb
Fri Nov 02, 2018 2:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons
Replies: 3
Views: 5618

Re: Valence Electrons

This really cleared things up for me! Does this mean that zinc has 12 valence electrons?
by taywebb
Fri Nov 02, 2018 2:29 pm
Forum: Ionic & Covalent Bonds
Topic: Valence electron
Replies: 4
Views: 70

Re: Valence electron

I'm still slightly confused. The solutions manual says that Mn has 7 valence electrons, but it is in the 7th group, so you're saying that it would have 9?
by taywebb
Fri Nov 02, 2018 2:26 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 14
Views: 351

Re: Drawing Lewis Structures

Can anyone confirm my understanding of ionic and covalent bonding in regards to lewis structures? I believe that when you have an ion you use ionic bonding with the brackets and if the atoms are a neutral charge you use covalent bonding? Is there anything more specific to drawing these diagrams?
by taywebb
Sun Oct 28, 2018 8:35 pm
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 69
Views: 22570

Re: formula units [ENDORSED]

I was confused about this as well. Thank you so much for the clarification! Does anyone know in what depth we need to know these bonds for the test? (just in terms of specific elements or molecules or even just sketching them out)
by taywebb
Thu Oct 25, 2018 10:39 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Everyday objects and Heisenberg's uncertainty
Replies: 3
Views: 731

Re: Everyday objects and Heisenberg's uncertainty

So, based on this response, it would be No because the uncertainties of a large moving object are small?
by taywebb
Sat Oct 20, 2018 4:36 pm
Forum: Properties of Light
Topic: energy required to remove an electron [ENDORSED]
Replies: 7
Views: 1056

Re: energy required to remove an electron [ENDORSED]

Yeah if you do the full problem out (by dividing Avogadro's number) you end up with 2.501 x 10^-19 J of energy as the work function, which after plugging it in to get the frequency of incident light gets you 6.78 x 10^14 Hz!
by taywebb
Sat Oct 20, 2018 3:55 pm
Forum: Properties of Light
Topic: Planck's constant
Replies: 5
Views: 148

Re: Planck's constant

Will I ever have a need to convert Hertz to Joules? or would they stay separate?
by taywebb
Sun Oct 07, 2018 3:26 pm
Forum: Empirical & Molecular Formulas
Topic: When to double moles
Replies: 13
Views: 241

Re: When to double moles

Just double checking that if I had 1.1 of something rounding to 1 would be ok, even though it is more than 0.05?
by taywebb
Sun Oct 07, 2018 3:21 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 115
Views: 10297

Re: All students read this sig fig post [ENDORSED]

Can someone help me with a quick review of zeros in sig figs? I always get confused as to which zeros count as significant and which ones do not.
by taywebb
Sun Oct 07, 2018 3:17 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 166
Views: 100748

Re: Rusty on High School Chem [ENDORSED]

Hi Guys!!
I definitely recommend making quizlets with basic SI units, conversions, and terms so that you can drill yourself on basic stuff before it gets too confusing!

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