## Search found 41 matches

Thu Mar 10, 2016 9:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Dehydrogenation of cyclohexane to benzene
Replies: 1
Views: 893

### Dehydrogenation of cyclohexane to benzene

For dehydrogenation, is the general thing to do is to add H2(g) to the product side of the reaction?
Thu Mar 10, 2016 3:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Winter Final Exam 2013 4A
Replies: 4
Views: 761

### Re: Winter Final Exam 2013 4A

n represents the number of electrons transferred in the balanced reaction. The reaction shows that Fe(s) is getting oxidized since it's oxidation state changes from 0 as Fe(s) to 2+ in 2 Fe(OH) 2 (s). So for every Fe(OH) 2 formed, 2 electrons are being transferred. Since the reaction states that the...
Thu Mar 10, 2016 3:32 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Hydrolysis of Acetyl phosphate
Replies: 1
Views: 1203

### Hydrolysis of Acetyl phosphate

Winter 2013 Q2B:

Why do we divide the hydrolysis of ATP by the formation of acetyl phosphate to get the amount of moles of ATP?
Thu Mar 10, 2016 2:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Hydrolysis of Acetyl phosphate
Replies: 1
Views: 616

### Hydrolysis of Acetyl phosphate

Winter 2013 Q2B:

Why do we divide the hydrolysis of ATP by the formation of acetyl phosphate to get the amount of moles of ATP?
Sat Feb 27, 2016 5:19 pm
Forum: *Alkanes
Topic: Cycloalkanes
Replies: 2
Views: 335

### Cycloalkanes

What makes an alkane a cycloalkane? For 1.5(a) and 1.6(b) the answer key says that both are cycloalkanes. I understand that because there exists single bonds between C-C and C-H, but when can you say that this type of hydrocarbon is a cycloalkane?
Sat Feb 27, 2016 3:00 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Drawing and labeling reaction profile
Replies: 3
Views: 676

### Re: Drawing and labeling reaction profile

\Delta G_{r} is equal to \Delta G_{products} - \Delta G_{reactants}. If the graph's final point is below the initial point, then that means that \Delta G_{products} < \Delta G_{reactants} and therefore \Delta G_{r} will be negative. If the graph's final point is above the initial point, then that m...
Sat Feb 27, 2016 2:38 pm
Forum: *Alkenes
Replies: 3
Views: 526

What's th best way to figure out this molecular formula? Do we have to draw out the lewis structure first and count how many carbon and hydrogen atoms there are? Or is there a faster and simpler way to figure it out?
Thu Feb 25, 2016 8:33 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Drawing and labeling reaction profile
Replies: 3
Views: 676

### Drawing and labeling reaction profile

4.35 says to draw and label the reaction profile for the reaction: CH 3 Br + - OH \rightleftharpoons CH 3 OH + Br - . For this particular reaction, how do we know that the Gibbs free energy of the reaction between the reactants and products is negative? For other reactions, how will we know whether ...
Sat Feb 20, 2016 4:20 pm
Forum: *Electrophiles
Topic: Carbocations
Replies: 2
Views: 485

### Carbocations

Could someone help explain how to identify reaction intermediates as primary, secondary, or tertiary carbocations? From the reading, I picked up that maybe the number of CH 3 molecules will determine this, but I'm not sure if that is the case. For reference, Self Test 4.2B on page 149 in orange Intr...
Thu Feb 18, 2016 8:49 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Calculating the value of the rate constant
Replies: 1
Views: 442

### Calculating the value of the rate constant

From question 11, Quiz 2 Preparation Winter 2015, it asks us to find the value of the rate constant at 770 K. How would we do that when they give us two rate constants at different temperatures. Are we supposed to find the change in rate constants or what?
Sat Feb 06, 2016 10:14 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Order of Increasing Change in Entropy
Replies: 1
Views: 337

### Order of Increasing Change in Entropy

For the Winter 2011 Midterm Q2B, I just wanted a clearer explanation for how Container A is larger than both Container B or Container C. How do atoms of an ideal monoatomic gas have a larger number of particles?
Tue Feb 02, 2016 6:53 pm
Forum: Balancing Redox Reactions
Topic: 14.1 Book HW
Replies: 3
Views: 501

### Re: 14.1 Book HW

That makes complete sense, but say for question 14.3 where S is technically 2- as well as O, how do you determine that in SO42- that S has to have the oxidation number 6+? Since the total charge of SO 4 is 2-, Oxygen has a charge of 2- but since there are four oxygen atoms present you should multip...
Tue Jan 26, 2016 10:14 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Homework 9.45
Replies: 2
Views: 515

### Re: Homework 9.45

"9.45 Use the information in Table 8.3 to calculate the changes in entropy f the surroundings and of the system for (a) the vaporization of 1.00 mol CH 4 (l) at its normal boiling point; (b) the melting of 1.00 mol C 2 H 5 OH(s) at its normal melting point; (c) the freezing of 1.00 mol C 2 H 5...
Sat Jan 23, 2016 9:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Equations for 8.27
Replies: 1
Views: 365

### Re: Equations for 8.27

For part (a) it says there is an irreversible expansion against a constant external pressure. So you use w=-P external \Delta V. For part (b) it talks about an isothermal, reversible expansion. You would use the work equation w=-nRTln(v f /v i ). But in order to find how many moles there are, you wo...
Sat Jan 23, 2016 2:33 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Distinguishing forming bonds
Replies: 1
Views: 336

### Distinguishing forming bonds

I'm having trouble understanding 8.75 (a). I understand the bonds that break by is the only bond that forms are 6 moles of N-F bond. Is there no double N-N bond that forms as well?
Thu Jan 21, 2016 4:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Correction for 8.63(c)
Replies: 1
Views: 303

### Correction for 8.63(c)

The solution manual put the enthalpy of formation value for K2S(aq) as -417.5 kJ/mol when Appendix 2A has -471.5 kJ/mol for K2S.
Fri Jan 15, 2016 11:32 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8221
Views: 1434830

### Re: Chemistry Jokes

Who else can relate with this?
Sat Jan 09, 2016 7:09 pm
Forum: Phase Changes & Related Calculations
Topic: Ice Cube added to Water
Replies: 1
Views: 341

### Ice Cube added to Water

I'm having some difficulty getting the right solution for question 8.41 which asks for the final temperature after an ice cube is added to water. The solution manual says to change from grams to moles and then using the table to find the amount of heat lost by ice. I tried using the specific heat ca...
Sat Jan 09, 2016 11:48 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of formation of an element
Replies: 1
Views: 270

### Standard Enthalpy of formation of an element

By definition, the standard enthalpy of formation of an element in its most stable form is zero. In lecture, I found a memory tool quite helpful that Professor Lavelle addressed in class. "If you're at sea level, what is your altitude? The altitude difference is zero." It makes sense becau...
Thu Dec 03, 2015 9:06 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: acetic acid vs trichloroacetic acid vs formic acid
Replies: 1
Views: 2715

### Re: acetic acid vs trichloroacetic acid vs formic acid

How is the -CH3 group in acetic acid less electron withdrawing that the -CCl3 group in trichloroacetic acid? what does electron withdrawing mean? And how is formic acid a stronger acid that trichloroacetic acid? Cl is more electronegative than Hydrogen; thus, when chlorine is attached to the centra...
Tue Dec 01, 2015 8:34 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: O2 Or O2+ - Which has stronger bond explanation
Replies: 5
Views: 6359

### Re: O2 Or O2+ - Which has stronger bond explanation

I already posted my file before but if the system has not recognized it yet, this is my video submission.
Tue Dec 01, 2015 12:25 am
Forum: Bronsted Acids & Bases
Topic: HW 12.9.c is not a proton transfer?
Replies: 2
Views: 437

### Re: HW 12.9.c is not a proton transfer?

A proton transfer would result in a net ionic equation in which an H+ ion is transferred from one species to another. In this case, the reactants could undergo a proton transfer, but this would look like: CH3COOH(aq) + NH3(aq) --> CH3COO-(aq) + NH4+(aq) The way the reaction is written, however, the...
Sun Nov 29, 2015 8:17 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: O2 Or O2+ - Which has stronger bond explanation
Replies: 5
Views: 6359

### Re: O2 Or O2+ - Which has stronger bond explanation

Sun Nov 29, 2015 8:12 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: O2 Or O2+ - Which has stronger bond explanation
Replies: 5
Views: 6359

### Re: O2 Or O2+ - Which has stronger bond explanation

Sun Nov 29, 2015 8:06 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: O2 Or O2+ - Which has stronger bond explanation
Replies: 5
Views: 6359

### Re: O2 Or O2+ - Which has stronger bond explanation

Chem_Mod wrote:Nice Jacob! Just remember to upload the file directly to here also.

Sun Nov 29, 2015 8:04 pm
Forum: Conjugate Acids & Bases
Topic: Increasing Acidity
Replies: 3
Views: 804

### Increasing Acidity

When asked to list HClO3; HCLO; HCLO2; HClO4 from least acidic to most acidic, why does adding more negatively charged Oxygen atoms increase the acidity? I know that a strong acid completely dissociates in water. In these Bronsted acids, what is the conjugate base?
Tue Nov 24, 2015 7:13 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: O2 Or O2+ - Which has stronger bond explanation
Replies: 5
Views: 6359

### O2 Or O2+ - Which has stronger bond explanation

Tue Nov 24, 2015 12:48 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg's Indeterminacy Equation
Replies: 4
Views: 956

### Re: Heisenberg's Indeterminacy Equation

The question could also ask the minimum uncertainty in velocity. For Heisenberg's uncertainty principle, be careful to notice what information is given. For cases where they give the radius size of an certain metal atom, make sure to double the length of the radius to get the diameter, which represe...
Sat Nov 14, 2015 12:15 pm
Forum: Ideal Gases
Topic: Dissociation of X2 Molecule
Replies: 1
Views: 549

### Dissociation of X2 Molecule

Could someone help me clarify how to tell from the 4 flasks given in 11.7 which one is at equilibrium? What am I supposed to notice?
Wed Nov 11, 2015 11:15 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Complexes
Replies: 5
Views: 762

### Re: Chelating Complexes

Chem_Mod wrote:What does the problem state?
Wed Nov 11, 2015 11:04 am
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 3
Views: 455

### Naming Coordination Compounds

How would we write the name for the following coordination compounds?

[Cr(NH3)3(OH2)3]3+

Na2[PtCl2(ox)2]
Sun Oct 25, 2015 6:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW 4.19 (c)
Replies: 1
Views: 285

### HW 4.19 (c)

For BH2-, could someone please explain to me how the solution manual got a bond angle that is slightly less than 120 degrees?
Sat Oct 24, 2015 5:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of IF5
Replies: 1
Views: 1433

### Shape of IF5

Could someone please explain to me why the shape of IF5 is square pyramidal?
Thu Oct 22, 2015 10:02 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Ethyne (Acetylene)
Replies: 1
Views: 417

### Ethyne (Acetylene)

Predict the shape of an ethyne (acetylene) molecule, HCΩCH.

Please provide explanation to why it is linear.
Tue Oct 20, 2015 11:33 pm
Forum: Bond Lengths & Energies
Topic: Chemical Bond Length
Replies: 1
Views: 328

### Re: Chemical Bond Length

In addition, what is the correct method for finding the experimental chemical bond length?
Tue Oct 20, 2015 11:30 pm
Forum: Lewis Structures
Topic: HW 3.39 part (b) and (c)
Replies: 2
Views: 448

### Re: HW 3.39 part (b) and (c)

Hi! The potassium ions aren't bonded to the phosphorus atom because these are ionic compounds, not molecules(where electrons are shared). Ionic compounds don't usually have paired electrons because the anion usually takes electrons from the cation. In this case, the phosphorus(anion) takes electron...
Tue Oct 20, 2015 11:25 pm
Forum: Bond Lengths & Energies
Topic: Chemical Bond Length
Replies: 1
Views: 328

### Chemical Bond Length

For chemical bond lengths, are we expected to memorize the covalent radii of each oxygen or will that be provided? And for question 89 part (c), I can't seem to figure out where they found the bond length for Oxygen from Figure 3.21
Thu Oct 15, 2015 10:04 pm
Forum: Lewis Structures
Topic: HW 3.39 part (b) and (c)
Replies: 2
Views: 448

### HW 3.39 part (b) and (c)

Write the complete Lewis structure for each of the following compounds: (b) potassium phosphide Hi, could someone please explain why the Lewis structures appear the way they are in the solutions manual. For part (b), why are the Potassium ions not bonding with Phosphorus but rather floating around it?
Thu Oct 15, 2015 1:46 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Chlorine and Oxidation States
Replies: 5
Views: 2895

### Re: Chlorine and Oxidation States

So basically, to find two different oxidation states, do you have to either add or subtract electrons to go toward the closest noble gases?
Tue Oct 13, 2015 10:20 am
Forum: Empirical & Molecular Formulas
Topic: Hydrocarbons in Combustion
Replies: 5
Views: 875

### Re: Hydrocarbons in Combustion

For Question 2, this was my work to get the correct solution.
Sat Oct 03, 2015 10:56 am
Forum: Administrative Questions and Class Announcements
Topic: Independent Study
Replies: 1
Views: 298

### Independent Study

The syllabus talks about doing at least 8 hours of independent study per week. What is the best way to divide our time among doing the hw problems, reading the assigned chapter, and going through the course reader?

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