## Search found 61 matches

Sat Mar 16, 2019 10:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: units
Replies: 1
Views: 278

### units

What unit is delta H supposed to be in?
Sat Mar 16, 2019 10:43 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: units
Replies: 1
Views: 262

### units

What unit is delta H supposed to be in?
Sat Mar 16, 2019 10:15 pm
Forum: Zero Order Reactions
Topic: Deriving Equations
Replies: 7
Views: 610

### Re: Deriving Equations

Most of them are given
Sat Mar 16, 2019 10:02 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Positive or Negative Ecell Values
Replies: 4
Views: 399

### Re: Positive or Negative Ecell Values

Ecell in electrocytic cells can be pos or neg, but also I have noticed in the textbook that there are a couple of problems where Ecell was pos for Galvanic cells. Usually, the value is supposed to be pos for Galvanic.
Sat Mar 16, 2019 9:52 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Elementary steps
Replies: 3
Views: 308

### Elementary steps

For naming the molecularity of elementary steps I know we take the species # into consideration but do we also look at the catalyst? What else is considered?
Sat Mar 16, 2019 9:43 pm
Forum: Ideal Gases
Topic: Nitrogen gas
Replies: 5
Views: 348

### Re: Nitrogen gas

Yes, it can be treated as an ideal gas.
Sat Mar 16, 2019 9:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E° is not a state function
Replies: 2
Views: 99

### Re: E° is not a state function

For those types, the Eo are voltages of half reactions. Together they make the whole reaction so we can add them.
Sat Mar 16, 2019 9:34 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: HW 15.27
Replies: 3
Views: 353

### Re: HW 15.27

Oh, I get it now thanks, guys.
Sat Mar 16, 2019 9:28 pm
Forum: Second Order Reactions
Topic: units
Replies: 5
Views: 322

### Re: units

that would be m^-1t^-1
Sat Mar 16, 2019 8:51 pm
Forum: Zero Order Reactions
Topic: third order
Replies: 11
Views: 480

### third order

Do we need to worry about third order anything?
Sat Mar 16, 2019 8:37 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8039
Views: 1409788

### Re: Post All Chemistry Jokes Here

Get it... xD
Sat Mar 16, 2019 7:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 282
Views: 134697

### Re: Saying Thank You to Dr. Lavelle

Dear Dr. Lavelle, Thank you so much for a great quarter. I honestly don't know how far I could have gotten without that UA session. You are one of the very few professors that actually care how students do in the class and what they understand. I learned a great deal from you and hope continue to co...
Sat Mar 16, 2019 6:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reducing/oxidizing power?
Replies: 2
Views: 129

### Re: Reducing/oxidizing power?

Could anyone please give an example of that I am also kind of confused.
Sat Mar 16, 2019 4:19 pm
Forum: General Science Questions
Topic: Easy ways to remember
Replies: 5
Views: 401

### Easy ways to remember

Does anyone have any quick or easy ways to remember rules and equations for the final?
i.e: mnemonics
Sat Mar 16, 2019 4:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Final [ENDORSED]
Replies: 9
Views: 332

### Re: Final[ENDORSED]

Yes, along with the periodic table they have to.
Sat Mar 16, 2019 8:14 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Calculating Equilibrium Constant (Example 14.8)
Replies: 1
Views: 106

### Re: Calculating Equilibrium Constant (Example 14.8)

You reverse one of the equation, preferably the one with a smaller value so that you can cancel out the electron charges and other species that appear on both sides, but for this question, I think they chose the second reaction because they wanted Ag+ and Cl- to be on the products side. I'm not enti...
Thu Mar 14, 2019 5:59 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8039
Views: 1409788

### Re: Post All Chemistry Jokes Here

Pick up line joke:

You must be a compound of Barium and Beryllium because you are a
BaBe.
Thu Mar 14, 2019 3:29 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8039
Views: 1409788

### Re: Post All Chemistry Jokes Here

I thought this was kind of cute when I saw it...
Tue Mar 12, 2019 4:20 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Determining the rate constant when given trials
Replies: 3
Views: 199

### Determining the rate constant when given trials

For questions like finding the order of the reactant when you are given trials, I know the rule is to use two trials that keep the other reactants constant and have the reactant you are focusing on changing, but how come in som e questions that is not the case? For example in 15.17 part a). The solu...
Tue Mar 12, 2019 4:02 am
Forum: First Order Reactions
Topic: first order intergrated rate laws
Replies: 2
Views: 138

### first order intergrated rate laws

For integrated rate laws of the first order are there any keywords that can help determine which type of the equations to use in questions?
Tue Mar 12, 2019 1:09 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction mechanism on the final
Replies: 1
Views: 80

### Reaction mechanism on the final

How would questions for the reaction mechanism be asked? What does that mean? What process do we have to go through? I guess what I'm really asking is how would it be asked on the final?
Mon Mar 11, 2019 2:58 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 1
Views: 104

### Re: Cell Diagrams

>Your cathode goes on the right and your anode on the left. >two lines stand for a salt bridge >one line represents interference between phases in contact and you can also use it for adding the conductor(i.e platinum >and always put the new notation near the salt bridge That's about all I know
Mon Mar 11, 2019 2:33 am
Forum: Second Order Reactions
Topic: 2nd order
Replies: 4
Views: 174

### Half-life qraphs

Do we also have to know or study the graphs for half-life?
Mon Mar 11, 2019 2:28 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: HW 15.27
Replies: 3
Views: 353

### HW 15.27

A substance A decomposes in a first order reaction and its half-life is 355s. How much time must elapse for the concentration of A to decrease to :
a) 1/8[A]o

How would I go about starting to solve this question? Would I just use the first order half life equation?
Sat Mar 09, 2019 10:37 pm
Forum: *Organic Reaction Mechanisms in General
Topic: in lecture
Replies: 1
Views: 340

### in lecture

In the lecture, Friday Lavelle was talking about zero order rate reactions and its molecularity. I didn't quite catch what he was saying. Could someone please explain.
Mon Mar 04, 2019 8:43 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Galvanic Cells
Replies: 4
Views: 211

### Re: Galvanic Cells

The cell stops working after a period of time because the reaction has stopped. That means that the reactants have all transformed.
Sun Feb 03, 2019 5:30 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: HW
Replies: 3
Views: 133

### HW

Can we still do homework on thermochemistry or is it just thermodynamics now?
Sat Jan 26, 2019 3:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: In the last lecture
Replies: 3
Views: 114

### In the last lecture

In Friday's lecture when the professor was talking about method 2 (using bond enthalpies to calculate the change in the H reaction) I did not quite catch what he was saying when he was going over the example. What did he mean when he was talking about the carbon double bond? What happen to it?
Mon Jan 21, 2019 10:43 pm
Forum: Phase Changes & Related Calculations
Topic: How to tell acids and bases
Replies: 8
Views: 248

### How to tell acids and bases

Does anyone know a quick way to tell if a chemical is an acid or base without being given the formula?
Sun Jan 20, 2019 9:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure Notation
Replies: 5
Views: 254

### Pressure Notation

When we are writing out the concentrations to find the k constant if not all the products and reactants are gases, do we still use the P notation?
Tue Jan 08, 2019 7:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW questions for discussion
Replies: 2
Views: 62

### HW questions for discussion

Are we allowed to do the homework questions that were used in discussion?
Sun Jun 10, 2018 10:38 pm
Forum: Hybridization
Topic: pi bonds and sigma bonds [ENDORSED]
Replies: 4
Views: 385

### pi bonds and sigma bonds[ENDORSED]

Hi. I am still having trouble with Pi bonds and sigma bonds how do you draw them out on your own, how do you recognize which is which. Does anyone have a video or resource they use to understand this?
Sun Jun 10, 2018 9:00 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability for covalent bonds?
Replies: 3
Views: 490

### Re: Polarizability for covalent bonds?

It applies to covalent bonds. Since the Ionic bond is really one atom stealing from another it does not really apply. Polarity has to do with there being an unequal sharing of electrons. There is a stronger pull from one of the atoms.
Sun Jun 10, 2018 8:49 pm
Forum: Lewis Acids & Bases
Topic: CH3COOH vs CH3OH Acid Strength
Replies: 2
Views: 2420

### Re: CH3COOH vs CH3OH Acid Strength

One compound is more likely to give away that H+ than the other. CH3OOH has its hydrogens delocalized more so it's easier for them to leave making it the better acid.
Sun Jun 10, 2018 8:23 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: metal oxides
Replies: 1
Views: 286

### Re: metal oxides

Metal Oxides react with water to form a strong base, and nonmetal oxides react with water to form strong acids.
Sun Jun 10, 2018 4:12 pm
Forum: Lewis Acids & Bases
Topic: HW 12.17 [ENDORSED]
Replies: 4
Views: 435

### Re: HW 12.17[ENDORSED]

For acidic oxides, they react with water to form a Bronsted acid, basic oxides will form a hydroxide when reacting with water, and amphoteric substances are just thing that has both acidic and basic character, like H2O.

These are just ways you can identify them, but I'm pretty sure there are more.
Sun Jun 10, 2018 3:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent/angular [ENDORSED]
Replies: 5
Views: 300

### Re: Bent/angular[ENDORSED]

Yes. Yes, it is.
Sun Jun 10, 2018 3:54 pm
Forum: Naming
Topic: Coordination number
Replies: 10
Views: 639

### Re: Coordination number

...and maybe also show an example?
Sun Jun 10, 2018 3:53 pm
Forum: Naming
Topic: Coordination number
Replies: 10
Views: 639

### Coordination number

Can someone just briefly explain to me what the coordination number is and how to find it?
Sat Jun 09, 2018 10:57 pm
Forum: Bronsted Acids & Bases
Topic: J.1
Replies: 2
Views: 251

### Re: J.1

Also, NH3 is a base because the Nitrogen atom in it contains a lone pair which can donate its electrons to other atoms, therefore, it can be considered as a base. Or you can think of it as it can accept a proton.
Fri Jun 08, 2018 2:46 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Solubility and Polarity
Replies: 3
Views: 368

### Solubility and Polarity

Hi. Just a quick question. Can someone please clarify the relationship between something being polar and something being soluble?
Fri Jun 08, 2018 2:42 am
Forum: Coordinate Covalent Bonds
Topic: Covalent Character
Replies: 4
Views: 697

### Covalent Character

Hi everyone, I just wanted a little clarification on what exactly covalent character would be. Is it used to describe ionic bonds right?
Fri Jun 08, 2018 2:14 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ph and pKa [ENDORSED]
Replies: 1
Views: 227

### ph and pKa[ENDORSED]

I know this was answered in class but I did not really understand what was being said. What is the relation between ph and pKa and pKb? How do find them using the other?
Sun Jun 03, 2018 10:12 pm
Forum: Ionic & Covalent Bonds
Topic: Polarizability
Replies: 7
Views: 466

### Re: Polarizability

Hi, This has to do with how easily the electrons can be taken away from an atoms electron cloud. The bigger the atomic radius, the higher the electron distortion, and therefore the higher polarizability. Since their electron cloud is so big they are farther away from the nucleus and can be affected ...
Wed May 23, 2018 9:59 pm
Forum: Dipole Moments
Topic: Non-polar and dipoles
Replies: 3
Views: 203

### Non-polar and dipoles

How is it that a molecule can have dipole moments in its bonds, and then nit be polar?
Mon May 21, 2018 8:11 pm
Forum: Octet Exceptions
Topic: He, Li and Be
Replies: 3
Views: 292

### Re: He, Li and Be

Okay, so Helium only has 2 electrons which means it doesn't need 8 or an octet. It is a noble gas. All its shells are filled. Now Lithium and beryllium are sort of the same in the sense that they don't need 8 electrons. They do give away valence electrons to have their next shell filled.
Sun May 20, 2018 4:28 pm
Forum: Ionic & Covalent Bonds
Topic: Monatomic Anions and cations
Replies: 2
Views: 475

### Re: Monatomic Anions and cations

The textbook is just talking about cations and anions made up of one atom. For example, Na+ is a monoatomic cation and Cl- is a monoatomic anion, because there is only one atom here. When we have covalent bonds acting as one they are polyatomic, more than one ion. They can be ions as well.
Sun May 06, 2018 11:10 pm
Forum: Trends in The Periodic Table
Replies: 2
Views: 184

I'm not sure about your second question but yes the electrons can get excited and move orbitals. Just think of atoms with an excited state and a ground state.
Sun May 06, 2018 10:42 pm
Forum: Sigma & Pi Bonds
Topic: Hybrid orbitals
Replies: 4
Views: 340

### Hybrid orbitals

I don't quite get how hybrid orbitals are formed. How do the s and p orbitals become hybridized?
Fri May 04, 2018 4:34 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 3d orbital
Replies: 3
Views: 217

### Re: 3d orbital

The 4d orbital is at a much higher energy level than 4s or 4p. The 3d orbital has a very close energy level to 4s and will alternate depending on its electron state. Just know that it is not 4d because it would not make sense to write 4d before 4s. It just all because of the d orbital's energy level.
Sun Apr 29, 2018 3:43 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron configuration
Replies: 8
Views: 325

### Re: Electron configuration

For subshells with more than one orbital we fill each on with one electron before coming back to add the second electron. This all the single electrons in the subshell will be rotating in the same direction making them parallel. When you add the second electron to the subshells the mush rotate in op...
Sun Apr 22, 2018 2:01 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Different element in Rydberg
Replies: 4
Views: 242

### Re: Different element in Rydberg

The formula for questions that don't use hydrogen is a little different, but I do not think we have to worry about it since the professor hasn't discussed it.
Sun Apr 22, 2018 2:00 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Different element in Rydberg
Replies: 4
Views: 242

### .

.
Sat Apr 21, 2018 2:22 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Finding the Energy of A Photon
Replies: 3
Views: 215

### Re: Finding the Energy of A Photon

Depending on the type of question this could be very simple. If you are given enough information in the question just use the formula E=hv. That would be the energy of the photon is equal to the frequency times Plank's constant.
Sat Apr 21, 2018 2:18 pm
Forum: Photoelectric Effect
Topic: Work function [ENDORSED]
Replies: 6
Views: 474

### Work function[ENDORSED]

I do not quite understand the purpose of the work function. Can someone please explain it to me? When would you use it? What type of questions would require you to use the work function?
Sun Apr 15, 2018 11:09 pm
Forum: Significant Figures
Topic: Logarithms
Replies: 3
Views: 290

### Re: Logarithms

You would have to see the number of significant figures in the log(excluding whats beyond the 10^x) and in your answer, that's the number of sig figs to the right of your decimal.
Sun Apr 15, 2018 10:56 pm
Forum: Molarity, Solutions, Dilutions
Topic: Practice Problem [ENDORSED]
Replies: 2
Views: 259

### Practice Problem[ENDORSED]

For the problem: how would you prep a 10mL of ).015M KOH solution starting from solid KOH?
would I have to find the molar mass to answer this question or is it straightforward?
Sun Apr 15, 2018 10:39 pm
Forum: Empirical & Molecular Formulas
Topic: Practice Problem
Replies: 2
Views: 288

### Practice Problem

A 0.2500g sample of a compound known to contain carbon, hydrogen, and oxygen undergoes complete combustion to produce 0.3664g of CO2 and 0.1500g of H2O. What is the empirical formula of this compound? The molar mass of hydrocarbon is 180.16g/mol, what is the molecular formula?
Sun Apr 15, 2018 9:57 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular to Empirical
Replies: 9
Views: 553

### Re: Molecular to Empirical

It would remain the same. The empirical formula is the formula of the chemical equation with the lowest ratio or the most simplified version of the formula. It would not be H5NO because that is a whole different formula.
Sun Apr 15, 2018 9:30 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Chap 1 #1.12 Rayberg formula
Replies: 1
Views: 88

### Chap 1 #1.12 Rayberg formula

I just need help on this question for practice: A photon generated as a result of which of the following transitions in the hydrogen atom will have the greatest energy? Explain your answer. (a) From n = 6 to n = 5; (b) From n =4 to n = 3; (c) From n=2 to n = 1.
Sun Apr 15, 2018 7:31 pm
Forum: Photoelectric Effect
Topic: Threshold Energy [ENDORSED]
Replies: 12
Views: 655

### Threshold Energy[ENDORSED]

I know this was covered in lecture but I'm still a bit confused. What exactly is the threshold energy and how does it relate to quantum equations?