Search found 26 matches

by chemstudent_1K
Mon Mar 07, 2016 5:42 pm
Forum: *Cyclopropanes and Cyclobutanes
Topic: bond angle strain
Replies: 1
Views: 404

bond angle strain

In general, does bond angle strain only apply to cyclic structures?
by chemstudent_1K
Sun Mar 06, 2016 2:47 pm
Forum: *Ethers
Topic: Question 2.46
Replies: 1
Views: 477

Question 2.46

Question 2.46 asks to list all the functional groups present in aspartame. The solution lists carboxylic acid, amine, ester, and amide. Why isn't ether also in the list since at the top of the structure, there is an oxygen bonded to two carbons?
by chemstudent_1K
Sat Mar 05, 2016 9:23 pm
Forum: *Ketones
Topic: 2-methyl-5-(prop-1-en-2-yl)cyclohex-2-enone
Replies: 1
Views: 762

2-methyl-5-(prop-1-en-2-yl)cyclohex-2-enone

Instead of writing (prop-1-en-2-yl) in 2-methyl-5-(prop-1-en-2-yl)cyclohex-2-enone, is it wrong to name the structure using (1-methyleth-1-ene) instead (similar to the method described on page 23 in the organic chemistry textbook)? So instead of 2-methyl-5-(prop-1-en-2-yl)cyclohex-2-enone, is it wro...
by chemstudent_1K
Sat Mar 05, 2016 9:58 am
Forum: *Haloalkenes
Topic: Self test 2.2A
Replies: 1
Views: 618

Self test 2.2A

For part b of self test 2.2A is it also correct to call the structure
1,4-diiodocyclohexa-1,3,5-triene?
by chemstudent_1K
Sat Mar 05, 2016 9:43 am
Forum: *Haloalkanes
Topic: Self test 2.1B
Replies: 1
Views: 654

Self test 2.1B

Part B of self test 2.1B asks to give the molecular formula for polytetrafluoroethylene. The solution shows a structure of polytetrafluoroethylene where the two carbons are attached by a single bond. If the polytetrafluoroethylene ends in ene why aren't the carbons attached by a double bond (despite...
by chemstudent_1K
Thu Mar 03, 2016 5:31 pm
Forum: *Electrophilic Addition
Topic: Organic Textbook
Replies: 1
Views: 281

Organic Textbook

On page 152 in the organic textbook there is an electrophilic addition reaction between propene and hydrogen bromide. In the first step, how do you know to add the hydrogen to the carbon on the very right side? Would it be wrong to place the hydrogen on the center carbon and give the carbon on the v...
by chemstudent_1K
Thu Mar 03, 2016 5:11 pm
Forum: *Electrophiles
Topic: common electrophiles
Replies: 1
Views: 391

common electrophiles

In the organic chemistry text book it says that alkyl halides (e.g. CH3Cl) and carbonyls (e.g. (CH3)2CO) are common electrophiles. How are they electrophiles if all atoms in the molecules have an octet of valence electrons and are not positively charged?
by chemstudent_1K
Sun Feb 28, 2016 10:53 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: HW 15.63
Replies: 2
Views: 457

HW 15.63

"The rate constant of the reaction between CO2 an OH- in aqueous solution to give the HCO3- ion is 1.5E10/Ms at 25C. Determine the rate constant at blood temperature (37C) given that the activation energy for the reaction is 38kJ/mol." If A an Ea are independent of temperature why can't yo...
by chemstudent_1K
Mon Feb 15, 2016 8:11 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Elementary Reactions
Replies: 1
Views: 295

Elementary Reactions

Conceptually, for elementary reactions, why are the powers on concentrations for the rate laws simply the number of particles found in the reaction?
by chemstudent_1K
Sun Feb 14, 2016 9:07 pm
Forum: General Rate Laws
Topic: Rate laws
Replies: 1
Views: 317

Rate laws

Are differential rate laws used only for initial reaction rates?
by chemstudent_1K
Sat Feb 06, 2016 9:19 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW 14.85
Replies: 2
Views: 285

HW 14.85

How would Volta have ordered the following metals, if he put the most strongly reducing metal first: Fe, Ag, Au, Zn, Cu, Ni, Co, Al? Is this question asking to order the metals based on how strong they are as reduction agents or is it asking to order them based on the strength with which they are re...
by chemstudent_1K
Fri Feb 05, 2016 10:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 2
Views: 401

Re: Cell Diagrams

So is the opposite true for the anode? The ion with the lowest charge is written before ions with higher charges?
by chemstudent_1K
Fri Feb 05, 2016 9:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 2
Views: 401

Cell Diagrams

For example if there are three ions, H+, MnO4-, and Mn2+ present at the cathode, does it matter what order you write them in a cell diagram? In other words, does it matter whether the ions are placed like ||H+, MnO4-, Mn2+|Pt ,
|| MnO4-, Mn2+, H+|Pt or any other order of the three?
by chemstudent_1K
Fri Feb 05, 2016 4:06 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: HW 14.27
Replies: 2
Views: 451

HW 14.27

Using data in appendix 2B calculate the standard potential for the half-reaction U4+ + 4e- -> U. Why can't you just stop after adding the standard potentials for the two half reaction U4+ + e- -> U3+ and U3+ + 3e- ->U? Why isn't this sum the answer and why do you have to go onto adding the delta G v...
by chemstudent_1K
Fri Feb 05, 2016 12:26 am
Forum: Balancing Redox Reactions
Topic: HW 14.13d
Replies: 3
Views: 532

HW 14.13d

Part of HW question 14.13d asks to write the half reactions for Au+->Au + Au+3

One of the half reactions is Au+ + e- -> Au, but how do we know to use Au+3 + 3e- -> Au for the other half reaction instead of Au+3 + 2e- -> Au+?
by chemstudent_1K
Wed Feb 03, 2016 6:31 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: HW 14.33a
Replies: 1
Views: 517

HW 14.33a

The standard Gibbs free energy of formation of Tl3+(aq) is +215kJ/mol at 25C. Calculate the standard potential of the Tl3+/Tl couple. The solution manual uses the deltaG=-nFE formula and solves for E to get the answer, but isn't this answer the standard potential of the entire cell, not the standard...
by chemstudent_1K
Tue Feb 02, 2016 10:55 am
Forum: Van't Hoff Equation
Topic: HW 11.83
Replies: 4
Views: 657

HW 11.83

Calculate the equilibrium constant at 25C and at 150C for each of the following reactions, using data available in appendix 2A: A. NH4Cl(s)<->NH3(g)+HCl(g) Does it matter whether we use deltaG=sum of deltaG(products)-deltaG(reactants) or deltaG=deltaH-TdeltaS to find the standard free energy? And do...
by chemstudent_1K
Thu Jan 28, 2016 6:59 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Units
Replies: 1
Views: 285

Units

When calculating standard reaction enthalpy, entropy, and Gibbs free energy from formation values, why do the answers have units with /mol? Shouldn't /mol cancel out since you multiply by the coefficient in the calculation?
by chemstudent_1K
Tue Jan 26, 2016 11:55 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Change in entropy
Replies: 1
Views: 241

Change in entropy

To use the two formulas, deltaS=nRln(V2/V1) and deltaS=nCln(T2/T1), does it matter whether a reaction occurs reversibly or not?
by chemstudent_1K
Tue Jan 26, 2016 9:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molar Kinetic Energy
Replies: 1
Views: 255

Molar Kinetic Energy

Is the molar kinetic energy of an ideal gas the same as the internal energy of an ideal gas?
by chemstudent_1K
Tue Jan 26, 2016 8:51 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: HW 8.49
Replies: 1
Views: 316

HW 8.49

Oxygen difluoride is a colorless, very poisonous gas that reacts rapidly with water vapor to produce O2,HF, and heat:

OF2(g)+H20(g)->O2(g)+2HF(g) delta H=-318kJ

What is the change in internal energy for the action of 1.00 mol OF2?


Are we just supposed to assume that the reaction occurs at 298K?
by chemstudent_1K
Sun Jan 24, 2016 5:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Residual entropy
Replies: 1
Views: 231

Residual entropy

Conceptually, what occurs in a molecule that leads it to have residual entropy?
by chemstudent_1K
Fri Jan 15, 2016 3:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: State function
Replies: 2
Views: 358

State function

Why does heat need to be under constant pressure in order to be a state function? Conceptually, why is heat not a state function?
by chemstudent_1K
Sun Jan 10, 2016 8:30 pm
Forum: Phase Changes & Related Calculations
Topic: HW 8.43
Replies: 1
Views: 303

HW 8.43

Hw 8.43 pg 310: The following data were collected for a new compound used in cosmetics: delta Hfus=10.0kJmol-1, delta Hvap=20.0kJmol-1; heat capacities: 30Jmol-1 for the solid; 60Jmol-1 for the liquid; 30Jmol-1 for the gas. Which heating curve below best matches the data for the compound? Why does t...
by chemstudent_1K
Sun Jan 10, 2016 8:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Problem 8.13
Replies: 2
Views: 324

Re: Problem 8.13

When the question states "The cooling system that surrounds the cylinder absorbs 947 kJ as heat," it means that the surroundings has gained that 947 kJ as heat and warms up because the system has given off the 947 kJ of heat, making q (heat given off by system) in the equation, delta U=q+w...
by chemstudent_1K
Sat Jan 09, 2016 11:14 pm
Forum: Phase Changes & Related Calculations
Topic: phase change
Replies: 3
Views: 440

Re: phase change

Temperature remains constant during the solid to liquid transition because the heat must first be used to separate the (ice) water molecules apart to form liquid water before heat can be used to raise the temperature of the liquid. The same is true for the liquid to vapor transition.

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