## Search found 53 matches

- Sat Mar 17, 2018 8:23 pm
- Forum: *Ketones
- Topic: Ketones vs Aldehydes
- Replies:
**2** - Views:
**482**

### 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:
**349**

### 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:
**182**

### 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:
**238**

### 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:
**238**

### 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:
**836**

### 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:
**411**

### 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:
**619**

### 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:
**134**

### 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:
**151**

### 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:
**519**

### 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:
**363**

### 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:
**326**

### 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:
**326**

### 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:
**265**

### 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:
**125**

### 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:
**440**

### 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:
**320**

### 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:
**273**

### 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:
**108**

### 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:
**251**

### 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:
**494**

### 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:
**125**

### 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:
**349**

### 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:
**206**

### 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:
**219**

### 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:
**352**

### 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:
**360**

### 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:
**107**

### 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:
**232**

### 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:
**156**

### 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:
**246**

### 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:
**143**

### 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:
**260**

### 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:
**209**

### 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:
**432**

### 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:
**290**

### 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:
**331**

### 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:
**418**

### 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:
**361**

### 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:
**250**

### 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:
**250**

### 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:
**185**

### 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:
**192**

### 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:
**406**

### 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:
**406**

### 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:
**406**

### 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:
**102**

### 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:
**102**

### 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:
**497**

### 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:
**497**

### 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:
**1033**

### 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.?