Search found 53 matches
- Sat Mar 17, 2018 8:23 pm
- Forum: *Ketones
- Topic: Ketones vs Aldehydes
- Replies: 2
- Views: 1242
Ketones vs Aldehydes
When given line structures what should we look for that distinguishes a ketone from an aldehyde since they're pretty similar?
- Sat Mar 17, 2018 12:08 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Q7b Lyndon's Review
- Replies: 6
- Views: 726
Q7b Lyndon's Review
7b) Derive an expression for the rate of formation of the product E using the pre-equilibrium approach.
The unique rate was 1/2 d[E]/dt, why do we put a 1/2?
The unique rate was 1/2 d[E]/dt, why do we put a 1/2?
- Sat Mar 17, 2018 11:47 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic vs Concentration Cell
- Replies: 2
- Views: 410
Galvanic vs Concentration Cell
Is it true that for E values Galvanic should be positive and Concentration should always = 0?
- Thu Mar 15, 2018 12:30 pm
- Forum: General Rate Laws
- Topic: Test #3 Q5
- Replies: 3
- Views: 495
Re: Test #3 Q5
Also Q5 asked the question:
Given the instantaneous rate of rxn is 2.54x10^-2 mol/(Lxs), and intial mass of each reactant is 1.2g confined to a 750mL vessel, what is the rate constant of this reaction?
-What equation are we even using here?
Given the instantaneous rate of rxn is 2.54x10^-2 mol/(Lxs), and intial mass of each reactant is 1.2g confined to a 750mL vessel, what is the rate constant of this reaction?
-What equation are we even using here?
- Thu Mar 15, 2018 12:24 pm
- Forum: General Rate Laws
- Topic: Test #3 Q5
- Replies: 3
- Views: 495
Test #3 Q5
CHCl3(g) + Cl2(g) ---> CCl4(g) + HClg(g)
The rate of the rxn was first order with respect to chlorine and trichloromethane.
What is the rate law?
The rate of the rxn was first order with respect to chlorine and trichloromethane.
What is the rate law?
- Thu Mar 15, 2018 12:14 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta Hc
- Replies: 1
- Views: 1718
Delta Hc
An exam question asked for the value of delta H(c) with given values of 1.000 grams tropinone, heat capacity 25.950kj/C, and a temp increase from 25.262 C to 25.993.
The equations used were q = (Cv)(delta T) and then delta H(c) = q(rxn)/mols burned
What are these two equations?
The equations used were q = (Cv)(delta T) and then delta H(c) = q(rxn)/mols burned
What are these two equations?
- Wed Mar 14, 2018 11:10 am
- Forum: First Order Reactions
- Topic: Negative Orders
- Replies: 5
- Views: 963
Negative Orders
Can a reaction order be negative? If so, how?
- Wed Mar 14, 2018 11:07 am
- Forum: General Rate Laws
- Topic: Test #3 Q3
- Replies: 3
- Views: 995
Test #3 Q3
The rate of AB4 gas consumption in this Rxn is constant throughout and is given as 0.400M/s/ If your rxn vessel starts with 0.15M of B2C, how long will it take to get to 30.00M of B2C? AB4(g) + C2(g)---> AC2(g) + B2C(g) Can someone walk me through this, what do you do after you balance the equation?
- Wed Mar 14, 2018 10:29 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneity in gas equations [ENDORSED]
- Replies: 1
- Views: 289
Spontaneity in gas equations [ENDORSED]
If you're measuring spontaneity in the amount of moles of gas in an equation for example:
2 N2O(g)—> N2(g) + O2(g)
If the amount of moles are equal on both sides what does that tell about delta S?
2 N2O(g)—> N2(g) + O2(g)
If the amount of moles are equal on both sides what does that tell about delta S?
- Tue Mar 13, 2018 4:50 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Value of Q
- Replies: 1
- Views: 304
Value of Q
When solving for Q, [P]/[R] what molecules are not including into equilibrium?
- Tue Mar 13, 2018 4:20 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Relationship between K and k
- Replies: 2
- Views: 1813
Relationship between K and k
I understand the formula, but what is a more conceptual explanation between big K and little k?
- Mon Mar 12, 2018 10:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Test #1
- Replies: 4
- Views: 644
Test #1
3a) A tank of liquefied propane is punctured, emitting gaseous propane vapors. Is heat being transferred?
-Is this process releasing heat because the substance is undergoing a phase change? (liquid-->gas)
-Is this process releasing heat because the substance is undergoing a phase change? (liquid-->gas)
- Wed Mar 07, 2018 11:10 am
- Forum: Balancing Redox Reactions
- Topic: Test #2
- Replies: 4
- Views: 764
Re: Test #2
Then it asks is the rxn spontaneous?
Is it true that for spontaneity K<1?
Is it true that for spontaneity K<1?
- Wed Mar 07, 2018 11:10 am
- Forum: Balancing Redox Reactions
- Topic: Test #2
- Replies: 4
- Views: 764
Test #2
calculate the K of the following redox rxn:
Ag+(aq) + Cu(s) ---> Ag(s) + Cu2+(aq)
How would you start this problem?
Ag+(aq) + Cu(s) ---> Ag(s) + Cu2+(aq)
How would you start this problem?
- Wed Feb 28, 2018 10:20 am
- Forum: First Order Reactions
- Topic: After Integration [ENDORSED]
- Replies: 3
- Views: 529
After Integration [ENDORSED]
For the formula after we integrate it yields ln[A] = -k x t
Why is the k negative here, and should it be negative for a second order derivation as well?
Why is the k negative here, and should it be negative for a second order derivation as well?
- Mon Feb 26, 2018 3:59 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.25
- Replies: 1
- Views: 273
14.25
What is the reasoning behind why a more negative voltage has more strength? I thought a more positive charge will have more strength?
- Mon Feb 26, 2018 3:49 pm
- Forum: Balancing Redox Reactions
- Topic: Reversing Half-Reactions
- Replies: 2
- Views: 2205
Reversing Half-Reactions
When reversing a Half-Rxn for example
Cu2+(aq) + 2e- ---> Cu(s) E=+0.34V
to Cu(s) ---> Cu2+(aq) + 2e-
why doesn't the value of E switch from positive to negative?
Cu2+(aq) + 2e- ---> Cu(s) E=+0.34V
to Cu(s) ---> Cu2+(aq) + 2e-
why doesn't the value of E switch from positive to negative?
- Mon Feb 26, 2018 3:42 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Standard Potential
- Replies: 4
- Views: 632
Standard Potential
Does a standard potential of a cell occur under certain pH conditions?
Similar to the conditions 25 degrees celsius, 1 bar, etc.
Similar to the conditions 25 degrees celsius, 1 bar, etc.
- Mon Feb 26, 2018 3:32 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: log (Q)
- Replies: 2
- Views: 774
log (Q)
Is it always true that when log[Q]<1 the result will be negative and when log[Q]>1 the result will be positive?
- Tue Feb 13, 2018 5:58 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Equilibrium Equation
- Replies: 1
- Views: 259
Equilibrium Equation
In the equation delta G(r)= -RT ln(k)
what does k represent and is it the same as Q?
what does k represent and is it the same as Q?
- Mon Feb 12, 2018 5:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Extensive vs Intensive
- Replies: 3
- Views: 612
Extensive vs Intensive
For an extensive property the larger the sample, the more heat is required to raise its temperature by a given amount. (Heat capacity)
What exactly is a definition for an intensive property? (Specific heat capacity)
What exactly is a definition for an intensive property? (Specific heat capacity)
- Mon Feb 12, 2018 4:40 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open System
- Replies: 5
- Views: 965
Open System
An open system can exchange both matter and energy with the surrounding - what does it mean by matter is exchanged? Does anyone have an example?
- Sat Feb 10, 2018 1:08 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Total Entropy Change [ENDORSED]
- Replies: 1
- Views: 304
Total Entropy Change [ENDORSED]
The book states
When delta S (total) is positive, it is increasing and spontaneous
When delta S (total) is negative, it is decreasing and only the reverse is spontaneous
- Why is only the reverse spontaneous ?
When delta S (total) is positive, it is increasing and spontaneous
When delta S (total) is negative, it is decreasing and only the reverse is spontaneous
- Why is only the reverse spontaneous ?
- Sat Feb 10, 2018 1:06 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Exothermic/Endothermic [ENDORSED]
- Replies: 3
- Views: 740
Exothermic/Endothermic [ENDORSED]
Do exothermic and endothermic reactions relate to catabolism and anabolism ?
For example, in an exothermic reaction the formation of products is favored by lowering the temperature. Can this be thought as an example of catabolism or anabolism?
For example, in an exothermic reaction the formation of products is favored by lowering the temperature. Can this be thought as an example of catabolism or anabolism?
- Wed Feb 07, 2018 11:33 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Entropy Concept
- Replies: 2
- Views: 394
Entropy Concept
Does an endothermic reaction have the ability to increase spontaneity and entropy in reaction?
- Wed Feb 07, 2018 11:27 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.45
- Replies: 3
- Views: 513
9.45
Find the entropy of the surrounding and the system for:
Freezing of 1.00 lol C2H5OH
Would you use the equation delta H over T, just like if it were melting?
Freezing of 1.00 lol C2H5OH
Would you use the equation delta H over T, just like if it were melting?
- Wed Feb 07, 2018 11:20 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 9.51 [ENDORSED]
- Replies: 3
- Views: 593
9.51 [ENDORSED]
Why are so many exothermic reactions spontaneous?
Using the Gibbs formula is it the negative delta G and delta H values that cause spontaneity?
Using the Gibbs formula is it the negative delta G and delta H values that cause spontaneity?
- Tue Jan 23, 2018 5:23 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Monatomic Gas
- Replies: 5
- Views: 807
Monatomic Gas
For a monatomic gas the value is 3/2R, what is R’s value? Is it a constant or a rate?
- Tue Jan 23, 2018 5:06 pm
- Forum: Calculating Work of Expansion
- Topic: Natural Log
- Replies: 1
- Views: 250
Natural Log
Will there ever be an instance where the natural log of the volumes not be needed? I noticed some notations for irreversible work of expansion as w= -nRT(V2/V1) without the ln, is it just implied?
- Tue Jan 23, 2018 11:36 am
- Forum: Administrative Questions and Class Announcements
- Topic: Formula Sheet
- Replies: 2
- Views: 508
Formula Sheet
Is there a formula sheet that was posted? If so, is it on Chem. Community or the Class Website? Thanks
- Tue Jan 23, 2018 10:31 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Temperature
- Replies: 3
- Views: 313
Temperature
In Gibbs Free Energy, should we always use Kelvin, and is that because we want a positive value?
- Mon Jan 22, 2018 11:07 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: First Law Concept
- Replies: 4
- Views: 437
First Law Concept
I know that it is true for a closed system the internal energy changes as a function of heat & work, however, what about an open or isolated system? How does the first law apply to these two other systems?
- Mon Jan 22, 2018 11:02 am
- Forum: Calculating Work of Expansion
- Topic: Integral Equation
- Replies: 2
- Views: 235
Integral Equation
What do bounds V1 & V2 represent in the equation and also concecptually?
Naming
When would you use “ion” at the end of compound?
- Sat Dec 09, 2017 3:12 pm
- Forum: DeBroglie Equation
- Topic: Wavelike properties
- Replies: 3
- Views: 455
Wavelike properties
How can you tell if something has measurable wavelike properties?
- Sat Dec 09, 2017 3:08 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Solutions
- Replies: 1
- Views: 371
Solutions
Practice Problem
How many grams of NaOH do you need to prepare a 3.00x10^2 mL stock solution of 2.00M NaOH?
---> 24.0g
So in the next set: How many milliliters of the stock solution would you need to make a 250 mL of 0.650M NaOH solution?
how would you do this problem?
How many grams of NaOH do you need to prepare a 3.00x10^2 mL stock solution of 2.00M NaOH?
---> 24.0g
So in the next set: How many milliliters of the stock solution would you need to make a 250 mL of 0.650M NaOH solution?
how would you do this problem?
- Sat Dec 09, 2017 3:02 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Paramagnetism
- Replies: 3
- Views: 717
Paramagnetism
What is the concept behind Paramagnetism?
- Sat Dec 09, 2017 12:01 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 3
- Views: 490
Bond Angles
Does a tetrahedral shape always have 109.5 degree angles?
For what shapes are the angles >109.5 and <109.5 ?
For what shapes are the angles >109.5 and <109.5 ?
- Fri Dec 08, 2017 11:37 pm
- Forum: Electronegativity
- Topic: Electronegativity of atoms
- Replies: 3
- Views: 580
Electronegativity of atoms
Does electronegativity refer to the value associated with atoms?
For example Group 1 is 1+, Group 2 is 2+, Group 13 is 3+, Group 15 3-, etc.
For example Group 1 is 1+, Group 2 is 2+, Group 13 is 3+, Group 15 3-, etc.
- Fri Dec 08, 2017 11:32 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Amount of Electrons [ENDORSED]
- Replies: 6
- Views: 1082
Amount of Electrons [ENDORSED]
How many electrons in an atom can have the quantum numbers:
n=4, l=2, ml=+1, ms=+1/2
These quantum numbers represent the subshell 4d, so would it be 10 electrons ?
n=4, l=2, ml=+1, ms=+1/2
These quantum numbers represent the subshell 4d, so would it be 10 electrons ?
- Fri Dec 08, 2017 5:46 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma Bonds
- Replies: 4
- Views: 606
Re: Sigma Bonds
A Sigma bond is present in all single, double, and triple bonds.
Double and triple bonds are distinguished because they contain pi bonds.
Double and triple bonds are distinguished because they contain pi bonds.
- Fri Dec 08, 2017 5:40 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Ground State Configuration
- Replies: 3
- Views: 530
Re: Ground State Configuration
Practice Problem
What is the full electron configuration for carbon in the ground state? How many unpaired electrons?
For the ground state would it be 1s^2 2s^2 2p^2 ?
And the for unpaired electrons are there 4?
What is the full electron configuration for carbon in the ground state? How many unpaired electrons?
For the ground state would it be 1s^2 2s^2 2p^2 ?
And the for unpaired electrons are there 4?
- Fri Dec 08, 2017 5:39 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Ground State Configuration
- Replies: 3
- Views: 530
Ground State Configuration
Ground State Configuration
Fe^2+
I thought the ground state would be [Ar]3d^4 4s^2 because of its 2+ state?
Fe^2+
I thought the ground state would be [Ar]3d^4 4s^2 because of its 2+ state?
- Fri Dec 08, 2017 5:24 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming of Ligands
- Replies: 2
- Views: 252
Naming of Ligands
What are the definitions of monodentate, bidentate, and tridentate?
In that case what makes NH2CH2CH2NH2 a bidentate?
In that case what makes NH2CH2CH2NH2 a bidentate?
- Fri Dec 08, 2017 5:15 pm
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 2
- Views: 306
Lewis Structures
Octet Rule
Why does the molecule NO2 not obey the octet rule?
Is it because of the lone pair that is placed on the central figure N?
Why does the molecule NO2 not obey the octet rule?
Is it because of the lone pair that is placed on the central figure N?
- Fri Dec 08, 2017 2:49 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Solutions
- Replies: 5
- Views: 806
Re: Solutions
Practice Question (pt.3)
How many milliliters of the stock solution would you need to make 250mL 0.650M NaOH solution?
Im not sure how to go about this problem? Any advice?
How many milliliters of the stock solution would you need to make 250mL 0.650M NaOH solution?
Im not sure how to go about this problem? Any advice?
- Fri Dec 08, 2017 2:40 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Solutions
- Replies: 5
- Views: 806
Re: Solutions
Practice Question (pt.2)
How many grams of NaOH do you need to prepare a 3.00 x 10^2 mL stock solution of 2.00M NaOH?
so first 2.00M x 3L which gives 0.6.
Why do you multiply this value by NaOH Molecular Weight (40.069)? Shouldn't you divide because of the formula MI VI = MF VF?
How many grams of NaOH do you need to prepare a 3.00 x 10^2 mL stock solution of 2.00M NaOH?
so first 2.00M x 3L which gives 0.6.
Why do you multiply this value by NaOH Molecular Weight (40.069)? Shouldn't you divide because of the formula MI VI = MF VF?
- Fri Dec 08, 2017 2:34 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Solutions
- Replies: 5
- Views: 806
Solutions
Practice Question: SOLUTIONS You need to make a stock solution of 0.0800M of sodium carbonate-Na2CO3 How much sodium carbonate would you add to a 250ml volumetric flask before filling to 250ml with water to make a 0.0800M aqueous solution of sodium carbonate? I know you should multiply 0.0800M x 25...
- Sat Nov 11, 2017 11:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Book Exercises
- Replies: 3
- Views: 269
Re: Book Exercises
4.22
Also unsure of the molecule IO6^5- shape I am getting an incorrect answer, any help?
Also unsure of the molecule IO6^5- shape I am getting an incorrect answer, any help?
- Sat Nov 11, 2017 11:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Book Exercises
- Replies: 3
- Views: 269
Book Exercises
4.26
Write the Lewis Structure and determine whether the molecule is polar or nonpolar.
SiO2
I got the Lewis Structure but am unsure what property makes it polar/nonpolar?
Write the Lewis Structure and determine whether the molecule is polar or nonpolar.
SiO2
I got the Lewis Structure but am unsure what property makes it polar/nonpolar?
- Sun Oct 29, 2017 10:40 pm
- Forum: DeBroglie Equation
- Topic: Test 2, Question #7 [ENDORSED]
- Replies: 5
- Views: 788
Re: Test 2, Question #7 [ENDORSED]
Regarding the work posted above for part b of question #7-
So did you take (4.0*10^18) divided by 1/2(9.11*10^-31), then once you get that value square root it because velocity is V^2? I tried that and was unable to get 3.03*10^6
So did you take (4.0*10^18) divided by 1/2(9.11*10^-31), then once you get that value square root it because velocity is V^2? I tried that and was unable to get 3.03*10^6
- Sun Oct 29, 2017 10:26 pm
- Forum: DeBroglie Equation
- Topic: Test 2, Question #7 [ENDORSED]
- Replies: 5
- Views: 788
Re: Test 2, Question #7 [ENDORSED]
Test 2, Question #5 Determine the frequency of the emitted photon when an electron in a hydrogen atom drops from the quantum state of n=3 to n=1. I used the formula -hR/n^2 and calculated: n=3... -1/9hR = -2.42x10^-19 n=1... -1hR = -2.18x10^-18 Using these two values I then used N(final)-N(intial),...
- Sat Oct 07, 2017 9:13 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: E.15 [ENDORSED]
- Replies: 10
- Views: 1644
Re: E.15 [ENDORSED]
An example from section "E"
What mass of NaHSO4 should you weigh out to obtain .20 mol NaHSO4?
How would you start this problem off? Im confused would this be Mass Percentage Comp.?
What mass of NaHSO4 should you weigh out to obtain .20 mol NaHSO4?
How would you start this problem off? Im confused would this be Mass Percentage Comp.?