Search found 67 matches

by Jack Hewitt 2H
Sat Mar 16, 2019 6:41 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K'
Replies: 4
Views: 32

Re: K'

k' is the reverse reaction constant and can be used in the equation K = k/k'
by Jack Hewitt 2H
Sat Mar 16, 2019 6:38 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exothermic vs Endothermic
Replies: 6
Views: 38

Re: Exothermic vs Endothermic

Ea forward > Ea Reverse: Endothermic
Ea forward < Ea Reverse: Exothermic
by Jack Hewitt 2H
Sat Mar 16, 2019 6:34 pm
Forum: Second Order Reactions
Topic: reaction intermediate
Replies: 4
Views: 31

Re: reaction intermediate

The intermediate is the molecule formed in step 1 that is then used in step 2.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:31 pm
Forum: Second Order Reactions
Topic: 2nd order rates
Replies: 6
Views: 59

Re: 2nd order rates

Yes, because total rate order is found by adding the exponents of the reactants.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:29 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Negative Order
Replies: 4
Views: 40

Re: Negative Order

A negative order signifies that the concentration of the reactant inversely affects the reaction rate.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:27 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: mmol vs mol
Replies: 6
Views: 52

Re: mmol vs mol

As long as the conversion is correct it should not matter. However, the best practice may be to give your answer in the units that were stated in the question.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:25 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: instantaneous and unique rate
Replies: 6
Views: 54

Re: instantaneous and unique rate

Unique Rate: Rate divided by stoichiometric coefficient
Instantaneous: The slope of the tangent line at a specific moment
by Jack Hewitt 2H
Sat Mar 16, 2019 6:23 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Molecularity
Replies: 3
Views: 22

Re: Molecularity

By looking at the number of molecules participating in the rate determining step of the reaction you can determine molecularity.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:20 pm
Forum: First Order Reactions
Topic: Writing First Order Reactions
Replies: 4
Views: 24

Re: Writing First Order Reactions

The one would be implied just as it would be in a math class.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:19 pm
Forum: First Order Reactions
Topic: Half-life Formulas
Replies: 2
Views: 19

Re: Half-life Formulas

It's best to understand how you would get to the half life to help with the conceptual aspects of this section.
by Jack Hewitt 2H
Sat Mar 16, 2019 6:16 pm
Forum: First Order Reactions
Topic: half life
Replies: 3
Views: 24

Re: half life

Because when the first order half-life equation is derived the initial concentration terms will cancel out.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:44 pm
Forum: Van't Hoff Equation
Topic: K value- Temp
Replies: 6
Views: 67

Re: K value- Temp

Temperature is the only thing that can change the value of K.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:42 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Temperature and Equilibrium
Replies: 3
Views: 54

Re: Temperature and Equilibrium

Endothermic Reaction: Increase in temperature will cause the reaction to shift to the right.
Exothermic Reaction: Increase in temperature will cause the reaction to shift to the left.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 6
Views: 101

Re: Systems

Open systems: Exchange both matter and energy with the surroundings
Closed systems: Exchange just energy
Isolated systems: Neither heat nor matter can be exchanged
by Jack Hewitt 2H
Tue Mar 05, 2019 2:32 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Vol.
Replies: 8
Views: 93

Re: Constant Vol.

Yes, when volume does not change work or "w" is equal to 0.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp vs Cv
Replies: 7
Views: 111

Re: Cp vs Cv

The problem should give you enough information to determine which to use.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:29 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ecell
Replies: 13
Views: 137

Re: Ecell

Ecell is calculated by subtracting the reduction potential of the oxidized half reaction (Anode) from the reduction potential of the reduced half reaction (Cathode).
by Jack Hewitt 2H
Tue Mar 05, 2019 2:26 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ideal gases
Replies: 4
Views: 58

Re: Ideal gases

You should use 5/2R if pressure is constant and 3/2R if volume is constant.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Temperature
Replies: 3
Views: 61

Re: Temperature

Try not to round to sig figs until the end of the problem to ensure accurate answers.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 8
Views: 79

Re: Bond Enthalpies

Yes, the bonds broken release energy (reactants) and the bonds formed require energy (products).
by Jack Hewitt 2H
Tue Mar 05, 2019 2:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: equations for q
Replies: 9
Views: 93

Re: equations for q

q=nC(delta)T when given # of moles
q=mCdeltaT when given mass
q=C(delta)T when moles = 1
by Jack Hewitt 2H
Tue Mar 05, 2019 2:16 pm
Forum: Phase Changes & Related Calculations
Topic: Steam vs Boiling Water
Replies: 8
Views: 103

Re: Steam vs Boiling Water

Because the steam has more heat and therefore a higher enthalpy.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:14 pm
Forum: Phase Changes & Related Calculations
Topic: Slope of heating curve
Replies: 8
Views: 97

Re: Slope of heating curve

Because the substance can withstand more heat the slope will be much less steep.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:12 pm
Forum: Phase Changes & Related Calculations
Topic: reversible processes and equilibrium
Replies: 4
Views: 63

Re: reversible processes and equilibrium

Yes, the reaction would be in equilibrium if it was reversible.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Delta G rules
Replies: 8
Views: 83

Re: Delta G rules

Delta G > 0 ; Not spontaneous
Delta G < 0 ; Spontaneous
Delta G = 0 ; Equilibrium
by Jack Hewitt 2H
Tue Mar 05, 2019 2:06 pm
Forum: Balancing Redox Reactions
Topic: oxidation states
Replies: 4
Views: 46

Re: oxidation states

Oxidation state is the number of electrons an element needs to gain or lose to reach a neutral state and can be found by using the periodic table.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:04 pm
Forum: Balancing Redox Reactions
Topic: Strength of reducing agent
Replies: 10
Views: 135

Re: Strength of reducing agent

The more negative the value of Ecell is the stronger the reducing agent is.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:03 pm
Forum: Balancing Redox Reactions
Topic: OH-
Replies: 5
Views: 66

Re: OH-

You would use OH- when balancing the hydrogens in a basic solution.
by Jack Hewitt 2H
Tue Mar 05, 2019 2:01 pm
Forum: Balancing Redox Reactions
Topic: Acidic vs basic solutions
Replies: 10
Views: 84

Re: Acidic vs basic solutions

For an acidic solution you would use H20 and H+ to balance the hydrogens and oxygens while in a basic solution you would use H20 and OH- to balance the hydrogens and oxygens.
by Jack Hewitt 2H
Tue Mar 05, 2019 1:59 pm
Forum: Balancing Redox Reactions
Topic: Adding H+ and H2O
Replies: 13
Views: 132

Re: Adding H+ and H2O

Both steps are needed to balance the reaction.
by Jack Hewitt 2H
Tue Mar 05, 2019 1:55 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: K
Replies: 5
Views: 47

Re: K

K = 0 ; delta G = 0
K < 1 ; delta G > 0
K > 1 ; delta G < 0
by Jack Hewitt 2H
Mon Feb 11, 2019 9:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 49
Views: 2313

Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!

I will not be able to make the review session tonight. Can someone post the answers given?
by Jack Hewitt 2H
Thu Dec 06, 2018 6:34 pm
Forum: Einstein Equation
Topic: Numbers to memorize
Replies: 22
Views: 367

Re: Numbers to memorize

Soyoung Park 1H wrote:Do we have to memorize numbers such as c=3.00x10^8 m/s and planck's constant (h=6.63x10^-34Js) for the test?

No you do not we are given a constants and equations sheet. However it may be helpful to memorize them to some extent so you can do problems faster.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:33 pm
Forum: Einstein Equation
Topic: de brogile equation
Replies: 4
Views: 216

Re: de brogile equation

danielruiz1G wrote:in the de Broglie equation why does it state that any moving "particle" , when the examples talk about cars. can any moving object talk have a wavelength?

Yes any moving object has wavelength, but with large objects such as cars the wavelength is irrelevant.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:31 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 14
Views: 271

Re: E=hv

Chase Yonamine 1K wrote:In the equation, E=hv, does E represent the energy of the photon or does it represent the energy required to remove an electron?

e represents the energy of a photon. The works function represents the energy required to remove an electron.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:30 pm
Forum: Photoelectric Effect
Topic: Kinetic energy
Replies: 8
Views: 174

Re: Kinetic energy

Madeline Lequang 1G wrote:Does the formula (1/2)mv^2 only apply to kinetic energy? or can it be used for other types of energy?

It only applies to kinetic energy.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:29 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 13
Views: 154

Re: Speed of light

When doing calculations, should we use 2.99792 × 10 8 m.s -1 or 3.00 × 10 8 m.s -1 for the speed of light? I used the 3.00 × 10 8 m.s -1 on the midterm and got an answer that was two hundredths off and got it marked wrong, so what should be the accurate number to use? Look at the sig figs in the pr...
by Jack Hewitt 2H
Thu Dec 06, 2018 6:27 pm
Forum: Trends in The Periodic Table
Topic: Higher Electron Affinity Nitrogen or Carbon
Replies: 4
Views: 111

Re: Higher Electron Affinity Nitrogen or Carbon

Sarah Bui 4I wrote:Hi! I was just wondering which element has a higher electron affinity nitrogen or carbon and why? I think this is one of the exceptions and I am not sure.

Carbon has a greater affinity for electrons than nitrogen because of its half filled p subshell which makes it more stable than Nitrogen.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:25 pm
Forum: Balancing Chemical Reactions
Topic: Why do we balance chemical equations?
Replies: 8
Views: 167

Re: Why do we balance chemical equations?

Madelyn Cearlock wrote:For the question that asks why do we balance chemical equations, what was the exact answer that was desired? Thank you!

Because of the law of conservation of mass.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:25 pm
Forum: Balancing Chemical Reactions
Topic: Combustion Equation
Replies: 8
Views: 312

Re: Combustion Equation

chrisavalos- 1K wrote:What is the rule for a combustion equation? Do they always produce Carbon Dioxide and Water? I have just never been sure of this. Thank You.

Yes, combustion reactions will always produce CO2 and H2O.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:24 pm
Forum: Significant Figures
Topic: When to round the answers to significant figures
Replies: 11
Views: 268

Re: When to round the answers to significant figures

Do we round the answer in every step of the calculation, or do we just round the final answer to the number of significant figures? Because when I round the answer in every step, my final answers are often different from those given by the textbook. It is best to only round your answers at the very...
by Jack Hewitt 2H
Thu Dec 06, 2018 6:23 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molar Mass
Replies: 8
Views: 309

Re: Molar Mass

Lily Smith 4C wrote:Where do you find the mass of an atom on the periodic table?

It is listed under the element in their box on the periodic table.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 8
Views: 204

Re: Formal Charge

Number of valence electrons - (number of lone electrons + number of lines drawn)
by Jack Hewitt 2H
Thu Dec 06, 2018 6:19 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 4
Views: 88

Re: Electronegativity

chrisdinkel_1K wrote:do we have to determine relative Electronegativites by periodic trends or is it given?

You have to use periodic trends to determine relative electronegativities.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:16 pm
Forum: Lewis Structures
Topic: Elements that break the octet rule
Replies: 6
Views: 81

Re: Elements that break the octet rule

So I know that Br, I, and P can break the octet rule in lewis structures, but I read that there are other elements that can do this too, like Cl occasionally. Which elements are we required to know that break the octet rule for this class? It is better to think of it conceptually that if an element...
by Jack Hewitt 2H
Thu Dec 06, 2018 6:14 pm
Forum: Trends in The Periodic Table
Topic: Bond Lenghts
Replies: 6
Views: 135

Re: Bond Lenghts

How can you tell which molecules have a greater bond length without having its Lewis structure? I know when you have two ions you look for polarizability but what about when you have multiple elements involved? You would need to draw the Lewis structure to determine which molecules have a greater b...
by Jack Hewitt 2H
Thu Dec 06, 2018 6:12 pm
Forum: Properties of Electrons
Topic: Electron Configuration
Replies: 7
Views: 108

Re: Electron Configuration

melissa_dis4F wrote:For the electron configuration of Pd I get [Kr]4d^8 5s^2 but it is [Kr] 4d^10. My question is do we change it to [Kr] 4d^10 because we should fill in the entire d orbital before continuing to the 5s orbital? Is this always?

Yes this is always. It is one of the exceptions to the octet rule.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:11 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 14
Views: 289

Re: Work Function

Melissa Villanueva 3D wrote:How would we solve for the work function? Like what type of information would be given to use in order to find the work function and how would we use the given. Thanks!

You rearrange the formula as you would with an algebraic equation and plug in what is given to solve for the work function.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:08 pm
Forum: Electronegativity
Topic: Trend of Electronegativity
Replies: 9
Views: 211

Re: Trend of Electronegativity

chrisavalos- 1K wrote:I was wondering what the trend for electronegativity was, is it the same as ionization energy?

Yes, the trend for electronegativity is the same as the trend for ionization energy.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:07 pm
Forum: Octet Exceptions
Topic: Exceptions
Replies: 7
Views: 146

Re: Exceptions

jane_ni_3b wrote:How should we know which ones are exceptions?

The most common exceptions we deal with are found in the 3rd period because of an unfilled d-orbital.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:05 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: AXE formula
Replies: 18
Views: 619

Re: AXE formula

Arlene Linares 3A wrote:How do we figure out the AXE formula? I am still having trouble with this.

A is the central atom. X is the number of atoms bonded to the central atom. E is the number of lone pairs on the central atom.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:03 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: AXE formula
Replies: 18
Views: 619

Re: AXE formula

danielruiz1G wrote:is it possible to determine the shape of a molecule if you're only given the AXE formula, if so how do you do it?

Yes because the AXE formula tells you the regions of electron density which is all you need to determine the shape.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:02 pm
Forum: Hybridization
Topic: hybridization
Replies: 13
Views: 164

Re: hybridization

KarlaArevalo4D wrote:Does anyone have an easy way to find the hybridization of the central atom they are able to share? Much appreciated.

The easiest way is to consider the number of regions with electron density. This includes lone pairs.
by Jack Hewitt 2H
Thu Dec 06, 2018 6:00 pm
Forum: Hybridization
Topic: pi vs sigma
Replies: 12
Views: 138

Re: pi vs sigma

Arshia Ramesh 1G wrote:i read on one of the reviews that a pi bond is weaker than a sigma bond but why is that?

It is because a pi bond does not allow for rotation and would break while a sigma bond does allow for rotation.
by Jack Hewitt 2H
Thu Dec 06, 2018 5:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Square Planar
Replies: 12
Views: 139

Re: Square Planar

Phoebe Chen 4I wrote:Are the bond angles in square planar less than or equal to 90?

They are equal to 90.
by Jack Hewitt 2H
Thu Dec 06, 2018 5:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX3E
Replies: 18
Views: 158

Re: AX3E

kevinav wrote:What would be the molecular shape for the general formula AX3E

The molecule would have a trigonal pyramidal molecular shape.
by Jack Hewitt 2H
Thu Dec 06, 2018 5:55 pm
Forum: Hybridization
Topic: lone pairs
Replies: 20
Views: 167

Re: lone pairs

Moryel Yashar 1J wrote:Are lone pairs taken into consideration when determining the hybridization of a central atom?

Yes lone pairs are taken into consideration because they are still areas of electron density.
by Jack Hewitt 2H
Thu Dec 06, 2018 5:54 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Determining Lewis Acids and Bases
Replies: 1
Views: 24

Determining Lewis Acids and Bases

How do I determine which compound is a Lewis Acid and which compound is a Lewis base?
by Jack Hewitt 2H
Fri Nov 02, 2018 7:33 pm
Forum: Lewis Structures
Topic: How to decide central atom?
Replies: 6
Views: 79

Re: How to decide central atom?

Nicholas Le 3A wrote:Is the central atom in the Lewis structures based off of which atom has the lowest electronegativity or which atom has the lowest ionization energy?


It is based off of lowest ionization energy.
by Jack Hewitt 2H
Fri Nov 02, 2018 7:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Scantron
Replies: 6
Views: 86

Re: Scantron

904837647 wrote:So the midterm should be formatted just like the test?


Yes, the midterm should be formatted similarly to the tests.
by Jack Hewitt 2H
Fri Nov 02, 2018 7:29 pm
Forum: Student Social/Study Group
Topic: Midterm
Replies: 15
Views: 294

Re: Midterm

Do we know how many questions from each section will be in the test? Like how many from the fundamentals, quantum, and chemical bonds? I know there’s 8 but how is it going to be divided? My TA said that the amount of questions from each section would correlate to the amount of time we spent on said...
by Jack Hewitt 2H
Fri Oct 26, 2018 2:13 pm
Forum: Properties of Light
Topic: Electromagnetic Spectrum
Replies: 5
Views: 122

Re: Electromagnetic Spectrum

You do not need to fully memorize the spectrum but it will definitely be helpful to be familiar with it for the course.
by Jack Hewitt 2H
Fri Oct 26, 2018 2:10 pm
Forum: DeBroglie Equation
Topic: Measurable wavelength properties
Replies: 5
Views: 149

Re: Measurable wavelength properties

The car was too large to have "measurable wavelike properties".
by Jack Hewitt 2H
Fri Oct 26, 2018 2:07 pm
Forum: Einstein Equation
Topic: Units
Replies: 6
Views: 170

Re: Units

The test required students to know correct units as well as significant figures.
by Jack Hewitt 2H
Fri Oct 05, 2018 9:23 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 73
Views: 1655

Re: How does grading for discussion posts work?

Does anyone actually know when the discussion posts are due?
by Jack Hewitt 2H
Fri Oct 05, 2018 9:22 pm
Forum: Balancing Chemical Reactions
Topic: States of Matter
Replies: 11
Views: 149

Re: States of Matter

Does anyone know if we need to write the different states of matter in each equation?
by Jack Hewitt 2H
Fri Oct 05, 2018 9:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Number of questions on test one [ENDORSED]
Replies: 39
Views: 17156

Re: Number of questions on test one [ENDORSED]

Dr. Lavelle hasn't said how many questions the test will be nor how it will be graded.

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