Search found 61 matches

by 305174946
Sat Mar 16, 2019 7:18 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Ka stuff
Replies: 2
Views: 188

Ka stuff

Sorry, I wasn't sure where to put this question for chem 14b but for Ka and Kb will we be expected to know the general equations including HA and A?
by 305174946
Sat Mar 16, 2019 6:55 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: lnA
Replies: 2
Views: 62

lnA

Why do you add lnA at the end of the Arrhenius equation? other than to make a linear plot, like other than for graphing purposes?
by 305174946
Sat Mar 16, 2019 6:52 pm
Forum: General Rate Laws
Topic: coefficient of product
Replies: 1
Views: 194

coefficient of product

when finding the rate law and after you solve for the intermediate do you always put the coefficient of the product?
by 305174946
Sun Mar 10, 2019 12:50 pm
Forum: General Rate Laws
Topic: Problem
Replies: 1
Views: 58

Problem

For the first order reaction cyclobutane (g)  2 ethylene(g) at 800K, the half-life
is 0.43 seconds. Calculate the time needed for the concentration of cyclobutane
to fall to 1/64 of its initial value.
by 305174946
Sun Mar 10, 2019 12:49 pm
Forum: General Rate Laws
Topic: Problem
Replies: 1
Views: 41

Problem

Calculate the time required for the concentration of N2O(g) to decrease from
0.75M to 0.33M. The rate constant for the reaction is k= 6.8 x 10-3 /s
by 305174946
Sun Mar 10, 2019 12:47 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order
Replies: 2
Views: 73

Order

What is the most efficient way to determine the order of a reaction and what does that information tell you?
by 305174946
Sun Mar 03, 2019 7:23 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetics and spontaneity
Replies: 2
Views: 62

Kinetics and spontaneity

I know chemical kinetics is used to analyze the speed or rate of a reaction but can it be used to analyze spontaneity?
by 305174946
Sun Mar 03, 2019 7:06 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Porous Disk and Salt Bridge
Replies: 3
Views: 207

Porous Disk and Salt Bridge

So I understand that both the Porous Disk and Salt Bridge are used to transfer ions but is one more efficient than the other? If so, why? Just curious
by 305174946
Sun Mar 03, 2019 7:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Gases and Liquids in Cell Diagrams
Replies: 3
Views: 77

Gases and Liquids in Cell Diagrams

When making a cell diagram do you include gasses and liquids? Especially liquids like H2O, and the reactants are in aqueous form? Like isn't it implied that there is water on both sides on the reaction, so we shouldn't put it?
by 305174946
Fri Feb 22, 2019 2:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: -charge x E = Wmax
Replies: 2
Views: 68

-charge x E = Wmax

Can someone explain why the charge is negative again? Also why is it the maximum work for this equation?
by 305174946
Fri Feb 22, 2019 2:07 pm
Forum: Balancing Redox Reactions
Topic: Standard Oxidation Potentials?
Replies: 1
Views: 42

Standard Oxidation Potentials?

Do standard oxidation potentials exist? If so, why don't we use them? Is it because of the equation? Would things become more complicated?
by 305174946
Fri Feb 22, 2019 2:06 pm
Forum: Balancing Redox Reactions
Topic: Positive E means Favorable
Replies: 2
Views: 218

Positive E means Favorable

Today Lavelle stated that when the standard reduction potential is positive that the reactant is favorable. Did I understand this wrong? Can someone explain please?
by 305174946
Fri Feb 15, 2019 2:14 pm
Forum: Van't Hoff Equation
Topic: Assumptions
Replies: 1
Views: 105

Assumptions

Dr. Lavelle mentioned that when using the ln K2/K1 equation you must assume that entropy and enthalpy are both constant. If these assumptions are not true is there a different equation? or are they always true...?
by 305174946
Fri Feb 15, 2019 2:08 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: At Equilibrium G
Replies: 6
Views: 114

At Equilibrium G

For the equation G=-RTlnK
when K<1 then G is positive which means R>P right? (non-spontaneous?)
and when K>1 then G is negative which means R<P right? (spontaneous?)
by 305174946
Fri Feb 15, 2019 2:06 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equation based on equilibrium
Replies: 5
Views: 92

Equation based on equilibrium

Can someone please explain the G=G+RTlnQ equation please. Lavelle wrote Q is reaction quotient not K, is he just emphasizing that its not at equilibrium? I thought it was....?
by 305174946
Fri Feb 08, 2019 1:00 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Pressure Problem
Replies: 2
Views: 68

Constant Pressure Problem

In a problem in which there is constant pressure, mols are given as well as the heat of the asks for the change in enthalpy, why would you divide the the heat by the mols?
by 305174946
Fri Feb 08, 2019 12:47 am
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: Residual Entropy
Replies: 5
Views: 120

Residual Entropy

In lecture Lavelle did an example using four carbon monoxide molecules and mentioned that there is no translational/rotational movement and I was wondering what else must be stagnant for this system to have residual entropy?
by 305174946
Fri Feb 08, 2019 12:44 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Spontaneity
Replies: 2
Views: 63

Spontaneity

In lecture, Lavelle said that if the change in internal energy or the change in enthalpy were negative, we could ask if the reaction could be predicted to occur. He also mentioned that we could question if the reaction would be spontaneous and that it was likely to be. How would we know that/figure ...
by 305174946
Sun Feb 03, 2019 8:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 3
Views: 76

Hess's Law

Will we ever have to do Hess's law problems in which we consider the changes in temperature?
by 305174946
Sun Feb 03, 2019 8:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of Formation
Replies: 3
Views: 64

Standard Enthalpy of Formation

The literal definition for enthalpy of formation is that 1 mol of a compound is formed from pure elements in their stable form. My questions are does it always have to be 1 mol of the product, and are we meant to memorize the standard forms of all elements?
by 305174946
Sun Feb 03, 2019 8:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy of Formation
Replies: 2
Views: 52

Enthalpy of Formation

So when calculating bond enthalpies the final answer will be an enthalpy of formation, correct? So I know that bond enthalpies are always positive, but the formation can be pos or neg based on if the number of reactants/products, right?
by 305174946
Fri Jan 25, 2019 11:46 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Solving bond enthalpies
Replies: 3
Views: 56

Solving bond enthalpies

Why is it reactants minus products when solving for the enthalpy of the reaction using bond enthalpies?
by 305174946
Fri Jan 25, 2019 11:45 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpies
Replies: 5
Views: 84

bond enthalpies

Will the values for bond enthalpies between atoms always be positive?
by 305174946
Fri Jan 25, 2019 11:43 am
Forum: Phase Changes & Related Calculations
Topic: Reverse fusion
Replies: 3
Views: 74

Reverse fusion

Can someone please explain how the reversr rxn for fusion is exothermic please.
by 305174946
Fri Jan 18, 2019 12:36 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Kw
Replies: 6
Views: 136

Kw

When are the concentration of hydronium and hydroxide equal? when in pure water?
by 305174946
Fri Jan 18, 2019 12:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding concentration vs amount
Replies: 1
Views: 56

Adding concentration vs amount

If a question asks how the system would be affected after adding a certain concentration (molarity) is that different from adding say grams? please explain difference abnd how you would answer.
by 305174946
Fri Jan 18, 2019 12:29 pm
Forum: Ideal Gases
Topic: Pressure in terms of mols
Replies: 3
Views: 87

Pressure in terms of mols

Is the pressure lower when there are less mols because they are less collisions? or why?
by 305174946
Fri Jan 11, 2019 10:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Charles’s Law
Replies: 4
Views: 61

Charles’s Law

Can someone please explain Charles’s law in depth.
by 305174946
Fri Jan 11, 2019 10:56 am
Forum: Ideal Gases
Topic: Pressure of gasses
Replies: 5
Views: 141

Pressure of gasses

On page 151 of the 6th edition of our textbook there is an equation: P=dhg which solves for the pressure of a gas based on the height of a column of liquid and its density and gravity. I was wondering if we would need to know this calculation, if so can someone please explain it in depth because the...
by 305174946
Fri Jan 11, 2019 10:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Liquids in Chemical Equilibrium
Replies: 1
Views: 38

Liquids in Chemical Equilibrium

We discussed how liquids that were used as solvents were not to be included in solving the chemical equilibrium constant because at the beginning and end of the rxn there was an insignificant change to the volume, what about those liquids in rxn that are not solvents?
by 305174946
Fri Jan 11, 2019 10:48 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Substances
Replies: 2
Views: 50

Pure Substances

In lecture we discussed how liquids and solids were not included in the chemical equilibrium equation because they were pure substances. Can someone please explain why gases are not pure substances.
by 305174946
Wed Nov 28, 2018 10:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Radicals
Replies: 2
Views: 87

Radicals

In the VSEPR formula, would you apply a radical as a "lone pair"
by 305174946
Wed Nov 28, 2018 8:37 pm
Forum: Hybridization
Topic: Radicals
Replies: 3
Views: 86

Radicals

When determining hybridization, do radicals count as regions of electron density?
by 305174946
Thu Nov 22, 2018 10:28 pm
Forum: Dipole Moments
Topic: Canceling?
Replies: 3
Views: 80

Canceling?

When dipole moments cancel that means that the molecule is nonpolar correct? Also, since dipole moments have the same magnitude (right?) the only way to cancel them is by direction, right? Is there any other way for them to cancel?
by 305174946
Thu Nov 22, 2018 10:27 pm
Forum: Sigma & Pi Bonds
Topic: Drawing bonds
Replies: 3
Views: 107

Drawing bonds

Will we learn how to draw the sigma and pi bonds? Will this be on the test? Can someone explain how they intersect and what it means?
by 305174946
Thu Nov 22, 2018 10:25 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: on test? [ENDORSED]
Replies: 3
Views: 146

on test? [ENDORSED]

This subject won't be on the test, correct? Also when will we learn molecular orbital theory?
by 305174946
Thu Nov 22, 2018 10:24 pm
Forum: Hybridization
Topic: determining shape from given information
Replies: 3
Views: 63

determining shape from given information

could you determine the geometry of a molecule (VSEPR) if given only its hybridization? if given its hybridization and another aspect? if so what aspect?
by 305174946
Thu Nov 22, 2018 10:19 pm
Forum: Hybridization
Topic: reason for hybridization
Replies: 9
Views: 234

reason for hybridization

why does hybridization exist?
by 305174946
Thu Nov 22, 2018 10:18 pm
Forum: Hybridization
Topic: d-block
Replies: 3
Views: 69

d-block

In hybridization, when combing the s, p and d block where does that hybridization fall in terms of energy compared to the regular electron configuration ?
by 305174946
Thu Nov 22, 2018 9:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Transition Metals
Replies: 1
Views: 57

Transition Metals

How does VSEPR work for the transition metals? Does it still apply?
by 305174946
Thu Nov 22, 2018 9:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Isoelectric species
Replies: 2
Views: 63

Isoelectric species

How does VSEPR work for isoelectric species? Does it still apply?
by 305174946
Thu Nov 22, 2018 9:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing Structures on Test
Replies: 11
Views: 190

Drawing Structures on Test

When drawing the lewis structures on the test and using the wedges, if we "misplace" an axial or equatorial atom will that be a major mistake?
by 305174946
Thu Nov 08, 2018 5:50 pm
Forum: Lewis Acids & Bases
Topic: Lewis acids and bases
Replies: 1
Views: 129

Lewis acids and bases

This may be the wrong section to ask this question... However, in my discussion section, we were learning about Lewis acid and bases and my TA did an example with Al+3 and H20. He was saying that for the structure you would need 6H20 molecules and then he drew it and it was very confusing. If anyone...
by 305174946
Thu Nov 08, 2018 5:21 pm
Forum: Dipole Moments
Topic: Permanent Dipole Moments
Replies: 4
Views: 241

Permanent Dipole Moments

Can someone explain permanent dipole moments to me please? As well as their importance
by 305174946
Thu Nov 08, 2018 5:17 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 2
Views: 134

Polarizability

In discussion section, we went over how charge and volume are the factors that determine the "polarizing power" or a cation or the "polarizability" or an anion. In this list of ions, which would have the greater "polarizing power"? Please explain :)

Rb+, Sr+2, Be+2
by 305174946
Tue Oct 30, 2018 12:48 am
Forum: Resonance Structures
Topic: Drawing Resonance Structures
Replies: 1
Views: 102

Drawing Resonance Structures

Just curious, but when Lavelle says that resonance is the average of the arrangement of atoms with different arrangements of electrons, how would this be shown? Is it only with the double-sided arrows? Or with line structures like he showed with Benzene?
by 305174946
Tue Oct 30, 2018 12:43 am
Forum: Sigma & Pi Bonds
Topic: What each bond refers to
Replies: 3
Views: 133

What each bond refers to

In class Lavelle referred to pi and sigma bonds when discussing resonance but never really went into much detail. Can anyone explain what each refers to?
by 305174946
Tue Oct 30, 2018 12:42 am
Forum: Formal Charge and Oxidation Numbers
Topic: Stable Structure in SO4^-2
Replies: 1
Views: 77

Stable Structure in SO4^-2

In class, Lavelle said that the most stable structure for a sulfate ion is with two double bonds because the formal charge matched the given charge of the ion. If this is so, why wasn't the first structure we created (with only single bonds) as stable? Is it because the FC values for the two double ...
by 305174946
Sun Oct 28, 2018 1:10 pm
Forum: Trends in The Periodic Table
Topic: Smallest ionic radius [ENDORSED]
Replies: 6
Views: 183

Smallest ionic radius [ENDORSED]

If you're comparing P^-3, Cl^-, S^-2, which would have the smallest ionic radius? Would you have to compare their protons at this point?
by 305174946
Sun Oct 28, 2018 1:08 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: D Block
Replies: 1
Views: 28

D Block

In the D-block, when we write the 3d before the 4s, that means that electrons come from the 4s orbital when ions are formed right?
by 305174946
Sun Oct 28, 2018 1:03 pm
Forum: Ionic & Covalent Bonds
Topic: Determining the number of electrons in a compound [ENDORSED]
Replies: 2
Views: 86

Determining the number of electrons in a compound [ENDORSED]

Can someone explain to me again how to add up the electrons in a compound like Lavelle did in class with SO4^-2 please
by 305174946
Sat Oct 20, 2018 4:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Superscript
Replies: 3
Views: 47

Superscript

Does the superscript in configurations (2s^2) correlate to how many electrons can be in that orbital?
by 305174946
Sat Oct 20, 2018 4:05 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: P orbital
Replies: 2
Views: 78

P orbital

How do you know which value (-1,0,1) corresponds to the axes px,py,pz? Will these be on the test: determining which axes.
by 305174946
Sat Oct 20, 2018 4:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Realistic Values
Replies: 1
Views: 57

Realistic Values

How does one determine whether or not values calculated for uncertainty of velocity or position are realistic? How does one know they are realistic?
by 305174946
Tue Oct 09, 2018 1:07 am
Forum: Properties of Light
Topic: Wavelength vs Frequency
Replies: 7
Views: 112

Re: Wavelength vs Frequency

Also in an experiment, how would one alter the wavelength and frequency of light?
by 305174946
Tue Oct 09, 2018 1:05 am
Forum: Photoelectric Effect
Topic: Other Sources of energy
Replies: 1
Views: 64

Other Sources of energy

In the photoelectric experiment shown to us in class the source of energy was light. Could another source of energy be used and produce the same or similar outcomes (a similar amount of electrons emitted)?
by 305174946
Tue Oct 09, 2018 1:02 am
Forum: Properties of Electrons
Topic: Energy per photon equation
Replies: 3
Views: 79

Energy per photon equation

Just to clarify, in the equation: E=hv
as well as in the photoelectric experiment, the energy of per photon is reliant solely on the frequency?
by 305174946
Fri Oct 05, 2018 12:06 pm
Forum: SI Units, Unit Conversions
Topic: SI Units on tests
Replies: 5
Views: 159

SI Units on tests

In high school, for tests we were told to make sure that all our answers were in MKS (meters, kilograms and seconds) or just in SI units in general. For Lavelle’s exams are there specific units that he expects all answers to be converted to?
by 305174946
Fri Oct 05, 2018 12:02 pm
Forum: Properties of Light
Topic: Energy Function
Replies: 1
Views: 46

Energy Function

In the equation: E= -hR/n^2 (solves for the energy of electrons as a function of n)
What are the variables and how do they contribute to finding the energy of the electron?
by 305174946
Fri Oct 05, 2018 11:45 am
Forum: Empirical & Molecular Formulas
Topic: When finding empirical formula
Replies: 4
Views: 134

When finding empirical formula

When beginning to find the empirical formula, do you always start with the mass percentage composition if it is not given?

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