Search found 57 matches

by Amy Zheng 2l
Thu Mar 15, 2018 12:42 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: emf
Replies: 3
Views: 164

emf

I'm a little confused on the concept behind emf. What is the difference between emf and E
by Amy Zheng 2l
Tue Mar 13, 2018 4:26 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst
Replies: 3
Views: 132

Re: Catalyst

Yes delta G stays the same, different activation energy
by Amy Zheng 2l
Tue Mar 13, 2018 4:18 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: HW 15.49
Replies: 1
Views: 104

HW 15.49

For part b, how do we know which power to raise each concentration to? I thought that we can't raise concentrations to their respective coefficient in the equation.
by Amy Zheng 2l
Mon Mar 12, 2018 5:45 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: problem 15.95
Replies: 1
Views: 78

problem 15.95

For part e, is it no effect because the activation energy itself is quite low for step 3? If the catalysis was applied to the entire reaction then would the rate increase?
by Amy Zheng 2l
Mon Mar 12, 2018 5:37 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: slow step
Replies: 3
Views: 157

slow step

Is it possible to have multiple slow step in mechanism?
by Amy Zheng 2l
Sun Mar 11, 2018 11:31 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Problem 15.61
Replies: 5
Views: 212

Problem 15.61

Where did the solution manual get the equation ln(k'/k)=Ea/r(1/T-1/T') from?
by Amy Zheng 2l
Sun Mar 11, 2018 11:16 pm
Forum: *Enzyme Kinetics
Topic: Two Paths
Replies: 5
Views: 627

Re: Two Paths

Yes there are multiple paths
by Amy Zheng 2l
Sun Mar 11, 2018 11:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Organic Chem on Final
Replies: 9
Views: 538

Re: Organic Chem on Final

I don't believe any ochem will be covered since he will be finishing all new material on Monday and most likely spend the rest of the week reviewing!
by Amy Zheng 2l
Sun Mar 11, 2018 11:12 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL
Replies: 9
Views: 583

Re: FINAL

I think all of it will be on the final since it is listed on the syllabus and we do not have much more to cover for this chapter!
by Amy Zheng 2l
Sun Mar 11, 2018 11:06 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate constant
Replies: 6
Views: 202

Rate constant

What is the difference between rate constant and reaction rate?
How come increase in concentration doesn't increase rate constant but it does increase rate?
by Amy Zheng 2l
Fri Mar 02, 2018 12:07 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Interpreting graphs [ENDORSED]
Replies: 3
Views: 401

Re: Interpreting graphs [ENDORSED]

Exothermic if energy after is less than energy before. But just because it is exothermic doesn't necessarily mean that it will be spontaneous as explained during thermodynamics. Spontaneity depends on delta G
by Amy Zheng 2l
Fri Mar 02, 2018 12:05 am
Forum: First Order Reactions
Topic: First Order Graph
Replies: 11
Views: 364

Re: First Order Graph

The graph would be straight if plotted against InA but it would be curved plotted against A
by Amy Zheng 2l
Thu Mar 01, 2018 11:59 pm
Forum: First Order Reactions
Topic: problem 15.23B
Replies: 3
Views: 164

problem 15.23B

For part B,how come we use In(Ainitial/Afinal)=kt? shouldn't it be -kt?
by Amy Zheng 2l
Sat Feb 24, 2018 1:37 am
Forum: Balancing Redox Reactions
Topic: Problem 5 vs 13
Replies: 2
Views: 110

Problem 5 vs 13

In problem 5a, the oxidation reaction is: Br-->BrO3-
In problem 13a, the oxidation reaction is: H2->H+

How come for number 13, it's not h2->HCl but in 5 its br->BrO3-
by Amy Zheng 2l
Sun Feb 11, 2018 3:19 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy Equation
Replies: 4
Views: 123

Re: Entropy Equation

If I can only use delta s=q/t for reversible then does than mean that all the other entropy equation (ex: s=nRlnV2/V1) can only be used if the problem states that it is reversible?
by Amy Zheng 2l
Sun Feb 11, 2018 2:12 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible Expansion
Replies: 3
Views: 181

Irreversible Expansion

why is delta S surrounding for Irreversible expansion zero?
by Amy Zheng 2l
Sun Feb 11, 2018 2:02 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy Equation
Replies: 4
Views: 123

Entropy Equation

The equations states that delta s=Qrev/T. If the reaction isn't reversible then does it mean that we can't use this equation to calculate entropy?
by Amy Zheng 2l
Fri Feb 09, 2018 4:19 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G=0
Replies: 6
Views: 243

Re: delta G=0

Delta G=equilbrium
by Amy Zheng 2l
Fri Feb 09, 2018 4:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9. 43
Replies: 5
Views: 209

Re: 9. 43

its on the formula sheet!
by Amy Zheng 2l
Fri Feb 09, 2018 2:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Question 9.55
Replies: 2
Views: 116

Question 9.55

How come we dont have to do sum of Hproduct- sum of Hreactant to get H? While for S we do need to do product-reactant?
by Amy Zheng 2l
Sun Feb 04, 2018 6:09 pm
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: Perfect Crystal
Replies: 9
Views: 317

Re: Perfect Crystal

basically entropy=0 in a perfect crystal because they must be in perfect order
by Amy Zheng 2l
Sun Feb 04, 2018 6:07 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: The sign of the change in Gibb's Free Energy
Replies: 6
Views: 200

Re: The sign of the change in Gibb's Free Energy

Negative=spontaneous=no energy need to be added to do work
by Amy Zheng 2l
Thu Feb 01, 2018 3:02 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Question 8.13
Replies: 3
Views: 107

Question 8.13

whats the significance of saying " compressed suddenly (and irreversibly)". Why must they include irreversibly in the question?
by Amy Zheng 2l
Thu Feb 01, 2018 3:00 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13
Replies: 3
Views: 161

Re: 9.13

In the solution manual it said to assume ideal behavior and 1 mol of N2 gas
by Amy Zheng 2l
Wed Jan 24, 2018 2:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Last quarters finals
Replies: 4
Views: 229

Re: Last quarters finals

What is considered regular hours?
by Amy Zheng 2l
Tue Jan 23, 2018 9:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Last quarters finals
Replies: 4
Views: 229

Last quarters finals

I remember Lavelle emailed us about getting back our finals during week 3. I was wondering where and when can I go get my test?
by Amy Zheng 2l
Tue Jan 23, 2018 9:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.99
Replies: 6
Views: 208

Re: 8.99

I think the manual got 800 gram from the idea that 1L of water is approx 1000g. So 800ml of solution would equate to 800 gram. In the question it states to treat it as the same density as water.
by Amy Zheng 2l
Fri Jan 19, 2018 5:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: relationship between q and w
Replies: 2
Views: 143

relationship between q and w

Is there a set rule for the relationship between q and w? I was thinking that if a reaction is negative q then the system is exothermic so work must be negative since you're loosing energy. If a reaction is positive q then the system is endothermic so work must be positive since you need to input en...
by Amy Zheng 2l
Fri Jan 19, 2018 5:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.49
Replies: 2
Views: 91

Question 8.49

In the question it states that the reaction produces heat but then delta H is negative. And I'm not sure if this is right, but I thought that heat would be negative since delta h is negative. BUT since the reaction produces heat that also leads me to think that heat would be positive. Basically I'm ...
by Amy Zheng 2l
Thu Jan 18, 2018 10:22 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.1 systems
Replies: 4
Views: 189

Re: 8.1 systems

Gas is burned into the air
by Amy Zheng 2l
Thu Jan 18, 2018 10:21 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q 8.13
Replies: 9
Views: 363

Re: Q 8.13

the system is doing work on the surrounding so its negative
by Amy Zheng 2l
Thu Jan 18, 2018 10:19 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Homework 8.15
Replies: 3
Views: 173

Re: Homework 8.15

No heat is transferred, thus q can't be anything else but zero
by Amy Zheng 2l
Thu Jan 18, 2018 10:19 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 8.1 question
Replies: 8
Views: 286

Re: 8.1 question

Insulation usually means isolated
by Amy Zheng 2l
Thu Jan 18, 2018 10:18 pm
Forum: Phase Changes & Related Calculations
Topic: 8.5
Replies: 5
Views: 189

Re: 8.5

Yes you would add the q and w to get u
by Amy Zheng 2l
Thu Jan 18, 2018 10:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 8.21
Replies: 2
Views: 116

Re: HW 8.21

Yeah, I think 3 sig fig sounds right too
by Amy Zheng 2l
Sat Dec 09, 2017 2:03 pm
Forum: Hybridization
Topic: Hybridization
Replies: 2
Views: 167

Re: Hybridization

areas of electron density gives you the hybridization. so like 2 areas of electron density=sp etc
by Amy Zheng 2l
Tue Dec 05, 2017 11:56 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of Acids and Bases [ENDORSED]
Replies: 5
Views: 377

Re: Strength of Acids and Bases [ENDORSED]

more O causes the electrons to be further away from the H, thus making it easier to break off from the compound.
by Amy Zheng 2l
Tue Dec 05, 2017 11:55 pm
Forum: Amphoteric Compounds
Topic: 12.17 part b
Replies: 3
Views: 345

Re: 12.17 part b

Because S is a nonmetal
by Amy Zheng 2l
Mon Nov 27, 2017 11:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equlibrium
Replies: 2
Views: 150

Re: Chemical Equlibrium

Concentration as stated by the formula. Brackets=concentration(mol/liter)
by Amy Zheng 2l
Mon Nov 27, 2017 11:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K value
Replies: 1
Views: 98

Re: K value

favors product if K>1 and favors reactant is K<1
by Amy Zheng 2l
Wed Nov 22, 2017 12:07 pm
Forum: Hybridization
Topic: 4.95 composition of the pi bond
Replies: 2
Views: 139

Re: 4.95 composition of the pi bond

Extra p orbitals not hybridized form pi forms
by Amy Zheng 2l
Wed Nov 22, 2017 12:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 2
Views: 139

Re: Coordination Number

Coordination number tells you the number of ions of opposite charge that surround the ion in a crystal.
by Amy Zheng 2l
Wed Nov 15, 2017 12:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Regions of electron density
Replies: 4
Views: 238

Re: Regions of electron density

Yes, lone pair counts as region of e- density
by Amy Zheng 2l
Wed Nov 15, 2017 12:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole Moment
Replies: 3
Views: 151

Re: Dipole Moment

Its from the less electronegative atom to the more electronegative atom. So arrow goes from + ---> -
by Amy Zheng 2l
Mon Nov 06, 2017 7:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Midterm
Replies: 8
Views: 379

Re: Midterm

it will not cover anything from chapter 4
by Amy Zheng 2l
Mon Nov 06, 2017 7:55 pm
Forum: Octet Exceptions
Topic: Noble gas exception
Replies: 4
Views: 382

Re: Noble gas exception

d orbitals can fit more electrons
by Amy Zheng 2l
Tue Oct 31, 2017 6:09 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019391

Re: Post All Chemistry Jokes Here

what happened to all the chemistry jokes? they're argon(all gone) hahahah
by Amy Zheng 2l
Tue Oct 31, 2017 6:07 pm
Forum: Octet Exceptions
Topic: F orbitals
Replies: 4
Views: 267

Re: F orbitals

yes as you move down the periodic table f ortibals come in. f sub shell has 7 orbitals so it can fit 14 electrons
by Amy Zheng 2l
Sun Oct 29, 2017 3:57 pm
Forum: Significant Figures
Topic: 300 vs 300. [ENDORSED]
Replies: 8
Views: 555

Re: 300 vs 300. [ENDORSED]

yep. if there's a period than all number to the left of it is counted as sig figs
by Amy Zheng 2l
Sun Oct 29, 2017 3:54 pm
Forum: Trends in The Periodic Table
Topic: Two Special Elements in Periodic Table
Replies: 3
Views: 230

Re: Two Special Elements in Periodic Table

cu, half shell vs full shell
by Amy Zheng 2l
Wed Oct 18, 2017 11:59 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Module Question 44
Replies: 2
Views: 195

Re: Atomic Spectra Module Question 44

E4=1.36x10^-19
E1=2.1798x10^-18
E1-E4=2.04x10^-18
E=hc/wavelength
wavelength=9.7x10^-8 meters
answer is B
by Amy Zheng 2l
Wed Oct 11, 2017 9:27 pm
Forum: Limiting Reactant Calculations
Topic: Net moles produced (Test question)
Replies: 3
Views: 261

Re: Net moles produced (Test question)

Since it's a combustion question, the products and reactants for this equation are all in the gas state. You're burning Butane gas with the O2 in the air, creating h20(water vapor=gas) and Co2(gas). Add up all the coefficients on the product side(36) and all the coefficients on the reactant side(30)...
by Amy Zheng 2l
Wed Oct 11, 2017 9:20 pm
Forum: Photoelectric Effect
Topic: Mass of an electron
Replies: 4
Views: 254

Re: Mass of an electron

Yes, the standard SI unit for mass is kg
by Amy Zheng 2l
Fri Oct 06, 2017 1:05 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Coefficients [ENDORSED]
Replies: 12
Views: 863

Re: Empirical Coefficients [ENDORSED]

Generally I would round to the nearest whole number if its +/- 0.1 from a whole number. Often times numbers are off a little due to rounding errors.
by Amy Zheng 2l
Fri Oct 06, 2017 12:59 pm
Forum: SI Units, Unit Conversions
Topic: Sig Figs [ENDORSED]
Replies: 16
Views: 1889

Re: Sig Figs [ENDORSED]

3 significant figures

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