Search found 50 matches
- Fri Mar 16, 2018 3:45 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.65
- Replies: 1
- Views: 106
Re: 15.65
it increases the rate constant of both reactions, but more substantially for the one with the higher activation energy
Re: Carbonyls
carbonyls are C=O, and both ketones and aldehydes have a C=O bond
- Fri Mar 16, 2018 3:16 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation
- Replies: 3
- Views: 273
Re: Arrhenius Equation
k2/k1
- Fri Mar 16, 2018 3:15 pm
- Forum: Balancing Redox Reactions
- Topic: Basic conditions with OH
- Replies: 3
- Views: 141
Re: Basic conditions with OH
pH + pOH = 14
- Fri Mar 16, 2018 3:14 pm
- Forum: *Alkanes
- Topic: The symbol R
- Replies: 4
- Views: 463
Re: The symbol R
R represents a carbon chain of any length
- Thu Mar 15, 2018 10:02 pm
- Forum: *Electrophiles
- Topic: what is going to be on the final? [ENDORSED]
- Replies: 12
- Views: 855
Re: what is going to be on the final? [ENDORSED]
Lavelle distributes the range of questions relatively evenly, but since we learned some new material after the last test, I'd watch out for those
- Thu Mar 15, 2018 9:55 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Fast or Slow
- Replies: 8
- Views: 333
Re: Fast or Slow
I'm pretty sure this fact will be given in a problem
- Thu Mar 15, 2018 9:51 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Please explain k'
- Replies: 3
- Views: 170
Re: Please explain k'
k' is the reverse rate constant of the reaction
- Thu Mar 15, 2018 9:42 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.97
- Replies: 1
- Views: 114
Re: 14.97
I may be wrong but I think it's because there's a coefficient of 2 in front of H+
- Thu Mar 15, 2018 9:38 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: The Effect of Temperature
- Replies: 3
- Views: 130
Re: The Effect of Temperature
Raising the temperature increases the speed of the reaction, essentially increasing the rate constant
- Thu Mar 15, 2018 9:36 pm
- Forum: *Ethers
- Topic: Nucleophile
- Replies: 3
- Views: 699
Re: Nucleophile
Nucleophiles donate electrons just like a Lewis Base
- Thu Mar 15, 2018 3:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb calorimeter
- Replies: 2
- Views: 221
Re: Bomb calorimeter
I think the constant volume refers to the entire container, as it doesn't change as the pressure increases or decreases inside, as it is a isolated system
- Thu Mar 15, 2018 2:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.29
- Replies: 2
- Views: 158
Re: 14.29
All the states should be given in a standard reduction potential chart
- Thu Mar 15, 2018 2:31 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Questions in the second test
- Replies: 2
- Views: 129
Re: Questions in the second test
The same goes for the other way around, the lower a substance's reduction potential, the better of a reducing agent it is
- Thu Mar 15, 2018 2:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 b
- Replies: 4
- Views: 200
Re: 14.13 b
I'm pretty sure you're correct, it shouldn't need to be written on the left side
- Thu Mar 15, 2018 2:22 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Coefficients when writing cell diagrams
- Replies: 3
- Views: 159
Re: Coefficients when writing cell diagrams
Coefficients are not in the cell diagram, only the chemical equation
- Mon Mar 12, 2018 2:02 am
- Forum: Zero Order Reactions
- Topic: Half life
- Replies: 7
- Views: 591
Re: Half life
Yes, first order half lives apply to radioactive decay. Zero order and Second order half lives exist in real life with other processes
- Mon Mar 12, 2018 1:59 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 65.b
- Replies: 2
- Views: 132
Re: 65.b
Yes you can determine that the reaction is endothermic because the formation of one product is favored over that one product being broken up into two different molecules
- Sun Mar 04, 2018 11:22 pm
- Forum: General Rate Laws
- Topic: zero order in rate laws
- Replies: 8
- Views: 286
Re: zero order in rate laws
Unless the problem wants you to write it out specifically, probably not
- Tue Feb 13, 2018 5:48 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: "Ideal"
- Replies: 6
- Views: 255
Re: "Ideal"
Usually on these tests, we are given the fact that the gases are ideal
- Sun Feb 11, 2018 11:39 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: delta H vs delta H naught
- Replies: 2
- Views: 437
Re: delta H vs delta H naught
yes, this way delta H naught can be used for any amount of compound given, instead of the specific value that is produced when solving for simply delta H
- Sun Feb 11, 2018 11:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: calculating a phase change in a reaction
- Replies: 5
- Views: 254
Re: calculating a phase change in a reaction
I think as a general rule if you're calculating heat you need to account for phase changes, but on the midterm things should be a little clearer.
- Sat Feb 10, 2018 9:21 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy
- Replies: 3
- Views: 138
Re: Entropy
all variations of delta S = nRln(V2/V1), S = kBlnW, the gibb's free energy equation, delta S = qrev/T
these are just some I could think of right now, but there's probably more
these are just some I could think of right now, but there's probably more
- Sat Feb 10, 2018 9:02 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Derivations of Equations
- Replies: 5
- Views: 217
Re: Derivations of Equations
The derivations are just nice to know in order to understand the relationships of each term with another, but it's not necessary for the midterm.
- Sat Feb 10, 2018 7:54 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.101 (b) [ENDORSED]
- Replies: 4
- Views: 535
Re: 9.101 (b) [ENDORSED]
Just further developing on the previous reply, since delta S is q/T, the greater T is, the smaller delta S is. It's simply an inverse relationship
- Mon Jan 22, 2018 5:16 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hesss Law
- Replies: 6
- Views: 237
Re: Hesss Law
It's also in the textbook on chapter 8, section 16 for a quick reference
- Mon Jan 22, 2018 5:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units of Standard Enthalpies of Formation
- Replies: 2
- Views: 121
Re: Units of Standard Enthalpies of Formation
Essentially, it doesn't really matter whether it's kj or kj/mol, just use whatever you end up with as you work through the problem.
- Mon Jan 22, 2018 5:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Concepts for Chapter 8 [ENDORSED]
- Replies: 5
- Views: 263
Re: Concepts for Chapter 8 [ENDORSED]
It helps to work through all of the homework questions he assigns if you haven't done that already.
- Sun Jan 14, 2018 3:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat Capacity vs. Specific Heat Capacity
- Replies: 3
- Views: 277
Re: Heat Capacity vs. Specific Heat Capacity
Heat capacity isn't specific to a certain value and is fluid depending on the amount of substance there is. Specific heat capacity only refers to the amount of energy needed to raise the temperature of 1 gram of a substance by 1 C. No matter how much substance there is, the specific heat capacity wi...
- Sun Jan 14, 2018 3:15 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 3
- Views: 163
Re: Bond Enthalpies
Resonance shouldn't necessarily affect bond enthalpy, as you can still use the values given to you to determine what you are looking for. For example a single bond between CO has bond enthalpy of 358 kj/mol, while a double bond between CO has bond enthalpy of 799 kj/mol. Either way, you're adding th...
- Sun Jan 14, 2018 3:07 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Infinite Forms of Hess's Law
- Replies: 5
- Views: 137
Re: Infinite Forms of Hess's Law
There can be much more than 2-4 reactions involved with the use of Hess's Law, but it's not necessary to use all of them because it's possible to represent the steps of a chemical reaction with fewer steps.
Re: Test 4
Yes, the oxidation number of Hg would be (III) instead of (I), as the two Fluoride ions make the overall charge -2, which requires a +3 oxidation state from the Hg to make the compound +1.
- Sat Dec 09, 2017 8:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice box question
- Replies: 2
- Views: 324
Re: ice box question
It's not that the equation flips from products becoming the reactants, but more that we are trying to calculate at which concentrations the reaction reaches equilibrium. If you just flip the equilibrium constant to 1/K, you're not changing anything about the concentrations.
- Sat Dec 09, 2017 8:05 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Change in Equilibrium Constant
- Replies: 2
- Views: 245
Re: Change in Equilibrium Constant
The equilibrium constant K only changes when the concentrations of the reactants and products are changed, not when their stoichiometric constants are.
- Thu Dec 07, 2017 11:19 pm
- Forum: Lewis Acids & Bases
- Topic: Identifying Lewis Acid
- Replies: 3
- Views: 213
Re: Identifying Lewis Acid
A simple Pt could be confusing to a reader, and it just makes it easier for everybody if you take the extra measure to write the oxidation number.
- Thu Dec 07, 2017 10:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Pi bond
- Replies: 3
- Views: 217
Re: Pi bond
Essentially if it doesn't matter which atom specifically needs the double bond in the lewis structure, then there is delocalization. For example, benzene, a 6 Carbon ring with three double bonds has delocalized pi bonds because there it doesn't matter which 3 Carbons are double bonded together, so l...
- Thu Dec 07, 2017 10:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE table
- Replies: 7
- Views: 465
Re: ICE table
Basically when the Q and K values in the problem are very close, then the changes in concentration (x) will be extremely small, even negligible in most cases.
- Thu Dec 07, 2017 9:17 pm
- Forum: Amphoteric Compounds
- Topic: Is water both amphoteric and amphiprotic? [ENDORSED]
- Replies: 2
- Views: 466
Re: Is water both amphoteric and amphiprotic? [ENDORSED]
Also I believe any amphiprotic molecule is also amphoteric, but not any amphoteric molecule is amphiprotic.
- Sun Nov 12, 2017 3:53 pm
- Forum: Resonance Structures
- Topic: Understanding Resonance Structures
- Replies: 6
- Views: 395
Re: Understanding Resonance Structures
Resonance is just a term to describe when a molecule has a double bond that can be placed in multiple locations without changing the actual structure of the molecule. A molecule with resonance will always have the same formal charge, that doesn't change. Naturally, the real structure of the molecule...
- Sun Nov 12, 2017 3:06 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond types
- Replies: 2
- Views: 144
Re: Bond types
Also, a general rule of thumb:
Metals typically make ionic bonds with nonmetals, as their electronegativity difference is high
Nonmetals typically make covalent bonds with nonmetals, as their electronegativity difference is low
Metals typically make ionic bonds with nonmetals, as their electronegativity difference is high
Nonmetals typically make covalent bonds with nonmetals, as their electronegativity difference is low
- Sun Nov 05, 2017 5:24 pm
- Forum: Ionic & Covalent Bonds
- Topic: How to easily tell between Ionic and Covalent bonds?
- Replies: 8
- Views: 473
Re: How to easily tell between Ionic and Covalent bonds?
I really doubt he expects us to memorize all values of electronegativity, so they'll probably be given to us.
- Sun Nov 05, 2017 5:19 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Lower in Energy? [ENDORSED]
- Replies: 6
- Views: 295
Re: Lower in Energy? [ENDORSED]
Typically we look at the principal quantum number to determine which orbital is lower in energy, but in the case of 3d and 4s, 4s is lower.
- Sat Oct 28, 2017 4:58 pm
- Forum: Lewis Structures
- Topic: S and P blocks and Lewis structures [ENDORSED]
- Replies: 4
- Views: 220
Re: S and P blocks and Lewis structures [ENDORSED]
You know whether a molecule uses a double or triple bond if you use all the available electrons in the covalent bond. For example, Carbonate (CO 3 2- ) has 24 valence electrons in total (4 from Carbon, 18 from three Oxygens, 2 from the 2- charge). The Carbon atom needs to double bond to one of the O...
- Sat Oct 28, 2017 4:01 pm
- Forum: Hybridization
- Topic: Principle Quantum Number in D-Block [ENDORSED]
- Replies: 4
- Views: 301
Re: Principle Quantum Number in D-Block [ENDORSED]
You start filling the 3d orbital after 4s because the 4s orbital generally has lower energy than the 3d orbital.
- Sun Oct 22, 2017 9:18 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Quantum Number l exception [ENDORSED]
- Replies: 4
- Views: 284
Re: Quantum Number l exception [ENDORSED]
The value of l is also not just (n-1), but can also include the negatives numbers too. For s: l can only be 0, while for p: l can be -1, 0, and 1.
- Sun Oct 22, 2017 8:58 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: XYZ [ENDORSED]
- Replies: 4
- Views: 278
Re: XYZ [ENDORSED]
You don't necessarily have to think of the p-orbital as XYZ, it's just a label for each of the three orbital subsets. You can simply call them subset 1, subset 2, and subset 3 if you want. It's the same as you learned in high school.
- Sat Oct 14, 2017 4:28 pm
- Forum: Properties of Electrons
- Topic: 1.3 Atomic Spectra [ENDORSED]
- Replies: 1
- Views: 159
Re: 1.3 Atomic Spectra [ENDORSED]
The energy levels don't have to have a specific interval of change. The Balmer series just refers to whenever electrons transition to the principal quantum number 2. It can be from both n=3 to n=2 and n=4 to n=2.
- Sat Oct 14, 2017 4:21 pm
- Forum: Properties of Light
- Topic: Photoelectric Experiments:Light [ENDORSED]
- Replies: 4
- Views: 273
Re: Photoelectric Experiments:Light [ENDORSED]
I'm pretty sure ultraviolet light is typically used for photoelectric experiments.
- Sat Oct 14, 2017 4:16 pm
- Forum: Photoelectric Effect
- Topic: Post-Module Question #29 [ENDORSED]
- Replies: 1
- Views: 152
Re: Post-Module Question #29 [ENDORSED]
You're right to be using the work function, but the units are wrong. The question asks for how much energy is required to remove an electron from one sodium atom.
This means that you need to divide 1.506 x 10^5 J.mol-1 by avogadro's number (6.022 x 10^23).
It should give you 2.501 x 10^-19 J.
This means that you need to divide 1.506 x 10^5 J.mol-1 by avogadro's number (6.022 x 10^23).
It should give you 2.501 x 10^-19 J.
- Sat Oct 14, 2017 2:53 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect Doubt [ENDORSED]
- Replies: 4
- Views: 233
Re: Photoelectric Effect Doubt [ENDORSED]
Is it the number of photons or the energy of the photons that causes electrons to be ejected from the metal?