Search found 57 matches
- Thu Mar 15, 2018 12:42 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: emf
- Replies: 3
- Views: 514
emf
I'm a little confused on the concept behind emf. What is the difference between emf and E
- Tue Mar 13, 2018 4:26 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalyst
- Replies: 3
- Views: 455
Re: Catalyst
Yes delta G stays the same, different activation energy
- Tue Mar 13, 2018 4:18 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: HW 15.49
- Replies: 1
- Views: 244
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.
- Mon Mar 12, 2018 5:45 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: problem 15.95
- Replies: 1
- Views: 294
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?
- Mon Mar 12, 2018 5:37 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: slow step
- Replies: 3
- Views: 527
slow step
Is it possible to have multiple slow step in mechanism?
- Sun Mar 11, 2018 11:31 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Problem 15.61
- Replies: 5
- Views: 638
Problem 15.61
Where did the solution manual get the equation ln(k'/k)=Ea/r(1/T-1/T') from?
- Sun Mar 11, 2018 11:16 pm
- Forum: *Enzyme Kinetics
- Topic: Two Paths
- Replies: 5
- Views: 1199
Re: Two Paths
Yes there are multiple paths
- Sun Mar 11, 2018 11:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Organic Chem on Final
- Replies: 9
- Views: 1445
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!
- Sun Mar 11, 2018 11:12 pm
- Forum: Administrative Questions and Class Announcements
- Topic: FINAL
- Replies: 9
- Views: 1446
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!
- Sun Mar 11, 2018 11:06 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate constant
- Replies: 6
- Views: 753
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?
How come increase in concentration doesn't increase rate constant but it does increase rate?
- Fri Mar 02, 2018 12:07 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Interpreting graphs [ENDORSED]
- Replies: 3
- Views: 1109
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
- Fri Mar 02, 2018 12:05 am
- Forum: First Order Reactions
- Topic: First Order Graph
- Replies: 11
- Views: 1966
Re: First Order Graph
The graph would be straight if plotted against InA but it would be curved plotted against A
- Thu Mar 01, 2018 11:59 pm
- Forum: First Order Reactions
- Topic: problem 15.23B
- Replies: 3
- Views: 560
problem 15.23B
For part B,how come we use In(Ainitial/Afinal)=kt? shouldn't it be -kt?
- Sat Feb 24, 2018 1:37 am
- Forum: Balancing Redox Reactions
- Topic: Problem 5 vs 13
- Replies: 2
- Views: 421
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-
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-
- Sun Feb 11, 2018 3:19 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy Equation
- Replies: 4
- Views: 510
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?
- Sun Feb 11, 2018 2:12 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Irreversible Expansion
- Replies: 3
- Views: 577
Irreversible Expansion
why is delta S surrounding for Irreversible expansion zero?
- Sun Feb 11, 2018 2:02 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy Equation
- Replies: 4
- Views: 510
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?
- Fri Feb 09, 2018 4:19 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: delta G=0
- Replies: 6
- Views: 1544
Re: delta G=0
Delta G=equilbrium
- Fri Feb 09, 2018 4:18 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9. 43
- Replies: 5
- Views: 613
Re: 9. 43
its on the formula sheet!
- Fri Feb 09, 2018 2:56 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Question 9.55
- Replies: 2
- Views: 421
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?
- 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: 1520
Re: Perfect Crystal
basically entropy=0 in a perfect crystal because they must be in perfect order
- 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: 802
Re: The sign of the change in Gibb's Free Energy
Negative=spontaneous=no energy need to be added to do work
- Thu Feb 01, 2018 3:06 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: unit of entropy
- Replies: 11
- Views: 1226
- Thu Feb 01, 2018 3:02 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Question 8.13
- Replies: 3
- Views: 412
Question 8.13
whats the significance of saying " compressed suddenly (and irreversibly)". Why must they include irreversibly in the question?
- Thu Feb 01, 2018 3:00 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.13
- Replies: 3
- Views: 396
Re: 9.13
In the solution manual it said to assume ideal behavior and 1 mol of N2 gas
- Wed Jan 24, 2018 2:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Last quarters finals
- Replies: 4
- Views: 354
Re: Last quarters finals
What is considered regular hours?
- Tue Jan 23, 2018 9:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Last quarters finals
- Replies: 4
- Views: 354
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?
- 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: 733
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.
- 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: 288
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...
- 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: 217
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 ...
- Thu Jan 18, 2018 10:22 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 8.1 systems
- Replies: 4
- Views: 535
Re: 8.1 systems
Gas is burned into the air
- Thu Jan 18, 2018 10:21 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Q 8.13
- Replies: 9
- Views: 1055
Re: Q 8.13
the system is doing work on the surrounding so its negative
- Thu Jan 18, 2018 10:19 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Homework 8.15
- Replies: 3
- Views: 446
Re: Homework 8.15
No heat is transferred, thus q can't be anything else but zero
- Thu Jan 18, 2018 10:19 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: 8.1 question
- Replies: 8
- Views: 835
Re: 8.1 question
Insulation usually means isolated
- Thu Jan 18, 2018 10:18 pm
- Forum: Phase Changes & Related Calculations
- Topic: 8.5
- Replies: 5
- Views: 489
Re: 8.5
Yes you would add the q and w to get u
- Thu Jan 18, 2018 10:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: HW 8.21
- Replies: 2
- Views: 218
Re: HW 8.21
Yeah, I think 3 sig fig sounds right too
- Sat Dec 09, 2017 2:03 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 2
- Views: 253
Re: Hybridization
areas of electron density gives you the hybridization. so like 2 areas of electron density=sp etc
- Tue Dec 05, 2017 11:56 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strength of Acids and Bases [ENDORSED]
- Replies: 5
- Views: 885
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.
- Tue Dec 05, 2017 11:55 pm
- Forum: Amphoteric Compounds
- Topic: 12.17 part b
- Replies: 3
- Views: 738
Re: 12.17 part b
Because S is a nonmetal
- Mon Nov 27, 2017 11:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equlibrium
- Replies: 2
- Views: 394
Re: Chemical Equlibrium
Concentration as stated by the formula. Brackets=concentration(mol/liter)
- Mon Nov 27, 2017 11:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K value
- Replies: 1
- Views: 161
Re: K value
favors product if K>1 and favors reactant is K<1
- Wed Nov 22, 2017 12:07 pm
- Forum: Hybridization
- Topic: 4.95 composition of the pi bond
- Replies: 2
- Views: 389
Re: 4.95 composition of the pi bond
Extra p orbitals not hybridized form pi forms
- Wed Nov 22, 2017 12:02 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 2
- Views: 255
Re: Coordination Number
Coordination number tells you the number of ions of opposite charge that surround the ion in a crystal.
- Wed Nov 15, 2017 12:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Regions of electron density
- Replies: 4
- Views: 533
Re: Regions of electron density
Yes, lone pair counts as region of e- density
- Wed Nov 15, 2017 12:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole Moment
- Replies: 3
- Views: 290
Re: Dipole Moment
Its from the less electronegative atom to the more electronegative atom. So arrow goes from + ---> -
- Mon Nov 06, 2017 7:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Midterm
- Replies: 8
- Views: 931
Re: Midterm
it will not cover anything from chapter 4
- Mon Nov 06, 2017 7:55 pm
- Forum: Octet Exceptions
- Topic: Noble gas exception
- Replies: 4
- Views: 831
Re: Noble gas exception
d orbitals can fit more electrons
- Tue Oct 31, 2017 6:09 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4016724
Re: Post All Chemistry Jokes Here
what happened to all the chemistry jokes? they're argon(all gone) hahahah
- Tue Oct 31, 2017 6:07 pm
- Forum: Octet Exceptions
- Topic: F orbitals
- Replies: 4
- Views: 755
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
- Sun Oct 29, 2017 3:57 pm
- Forum: Significant Figures
- Topic: 300 vs 300. [ENDORSED]
- Replies: 8
- Views: 4794
Re: 300 vs 300. [ENDORSED]
yep. if there's a period than all number to the left of it is counted as sig figs
- Sun Oct 29, 2017 3:54 pm
- Forum: Trends in The Periodic Table
- Topic: Two Special Elements in Periodic Table
- Replies: 3
- Views: 588
Re: Two Special Elements in Periodic Table
cu, half shell vs full shell
- Thu Oct 19, 2017 12:02 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Question about energy levels [ENDORSED]
- Replies: 8
- Views: 1121
Re: Question about energy levels [ENDORSED]
There is no limit
- Wed Oct 18, 2017 11:59 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra Module Question 44
- Replies: 2
- Views: 571
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
E1=2.1798x10^-18
E1-E4=2.04x10^-18
E=hc/wavelength
wavelength=9.7x10^-8 meters
answer is B
- Wed Oct 11, 2017 9:27 pm
- Forum: Limiting Reactant Calculations
- Topic: Net moles produced (Test question)
- Replies: 3
- Views: 576
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)...
- Wed Oct 11, 2017 9:20 pm
- Forum: Photoelectric Effect
- Topic: Mass of an electron
- Replies: 4
- Views: 547
Re: Mass of an electron
Yes, the standard SI unit for mass is kg
- Fri Oct 06, 2017 1:05 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Coefficients [ENDORSED]
- Replies: 12
- Views: 5858
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.
- Fri Oct 06, 2017 12:59 pm
- Forum: SI Units, Unit Conversions
- Topic: Sig Figs [ENDORSED]
- Replies: 16
- Views: 3302
Re: Sig Figs [ENDORSED]
3 significant figures