Search found 15 matches

by Yuxi Chen 2G
Sat Mar 12, 2016 10:13 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Instability of boat conformation
Replies: 1
Views: 431

Re: Instability of boat conformation

The boat conformation is not stable because there's steric strain between the two highest H atoms (flagpole interactions), and torsional strain between the other four eclipsed C-H bonds.
by Yuxi Chen 2G
Sat Mar 05, 2016 5:38 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Identifying Cis and Trans from Line Structues
Replies: 2
Views: 384

Re: Identifying Cis and Trans from Line Structues

If the groups with higher atomic number are on the same side of double bond, then the structure is considered a cis. If the groups with higher atomic number are on the opposite side of double bond, then the structure is considered trans.
by Yuxi Chen 2G
Sat Feb 27, 2016 11:34 am
Forum: *Cycloalkanes
Topic: numbering question
Replies: 1
Views: 254

Re: numbering question

I think it's because overall 1,2,2 is larger than 2,1,1. So that would fall into the different and non-equivalent numbering category and the name with the lowest number is correct.
by Yuxi Chen 2G
Sat Feb 27, 2016 11:26 am
Forum: *Alkanes
Topic: quiz 3 preparation question 5
Replies: 1
Views: 283

Re: quiz 3 preparation question 5

I am also confused about this question. In the textbook, it says that when two substituents are present in the cycloalkane structure, they are placed alphabetically in the name with the first substituent having the lower number.
by Yuxi Chen 2G
Thu Feb 18, 2016 9:23 pm
Forum: Zero Order Reactions
Topic: Temperature and Rate Constants
Replies: 1
Views: 382

Re: Temperature and Rate Constants

According to p.76 in the course reader, reactants must collide to react. Higher temperature results in more collisions, thus higher k, meaning faster rate.
by Yuxi Chen 2G
Fri Feb 12, 2016 9:38 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetics
Replies: 2
Views: 406

Re: Kinetics

Molecularity is determined by the number of species in an elementary step:

A -> D: unimolecular
A + B -> D: bimolecular
A + A -> D: bimolecular
A + B + C -> D: termolecular
A + B + B -> D: termolecular
by Yuxi Chen 2G
Sat Feb 06, 2016 4:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.37
Replies: 1
Views: 398

Re: 14.37

In the solutions manual, it writes the oxidation reaction in the anode as 2Cl- --> Cl2 + 2e-, which makes sense because the anode/oxidation reaction is typically written on the left of the cell diagram and this reaction loses electrons.
by Yuxi Chen 2G
Sat Feb 06, 2016 4:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Example 14.5
Replies: 1
Views: 244

Re: Example 14.5

Ecathode and Eanode both refer to the standard potential of the electrode, which is a measure of the electron-puling power of a single electrode. The electrodes pull in opposite directions, so the overall cell standard potential is equal to the difference in standard potentials of the two electrodes...
by Yuxi Chen 2G
Thu Jan 28, 2016 9:56 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy of Combustion
Replies: 1
Views: 358

Re: Entropy of Combustion

For the H2O part, I've asked about the phase of water before and Dr. Lavelle responded that
Unless otherwise stated, you should generally assume the water product of combustion to be gas phase. Any combustion necessarily creates high enough temperature and energy to vaporize water.
by Yuxi Chen 2G
Thu Jan 28, 2016 9:49 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Winter 2015 quiz #10 change in entropy
Replies: 1
Views: 408

Re: Winter 2015 quiz #10 change in entropy

I think what the question means is that 200J of energy is reversibly transferred to the bucket of water at 20 degrees C
by Yuxi Chen 2G
Thu Jan 28, 2016 9:44 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Textbook 9.37
Replies: 1
Views: 417

Re: Textbook 9.37

For part a, it asks to calculate the standard reaction entropy for the formation of 1 mol H2O. If the coefficient for H2O is 2, as in 2 H2(g) + O2(g) ---> 2 H2O(l), we would be calculating the standard reaction entropy for the formation of 2 mol H2O. So in order to answer the question, it's easier t...
by Yuxi Chen 2G
Sun Jan 24, 2016 10:15 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: HW9.37(c) interpretation of the entropy change
Replies: 1
Views: 245

HW9.37(c) interpretation of the entropy change

For reaction CaCO3(s) -> CaO(s) + CO2(g), the standard reaction entropy calculated is positive. And the interpretation given in the solutions manual is that the positive change is due to the increase in the number of moles of gas. Could the positive change also be explained as a result of an increas...
by Yuxi Chen 2G
Mon Jan 11, 2016 10:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW 8.93 phase of H2O as the product of combustion reaction?
Replies: 2
Views: 451

HW 8.93 phase of H2O as the product of combustion reaction?

In the solutions manual, the equation given for the combustion of C 6 H 6(l) is: C 6 H 6 (l) + 15/2O 2 (g) -> 6CO 2 (g) + 3H 2 O (l) Since the product H 2 O is in the liquid state, it uses the standard enthalpy of formation of H 2 O (l) when calculatin...
by Yuxi Chen 2G
Sun Jan 10, 2016 3:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW 8.67 atomize C?
Replies: 1
Views: 263

HW 8.67 atomize C?

In part b, it asks to estimate the enthalpy of formation of methanol CH 3 OH in the liquid state by using standard enthalpy of physical changes and bond enthalpies. In the solutions manual for 8.67b, the first step is to include the enthalpy needed to "atomize 1 mol C (gr) ". Since...
by Yuxi Chen 2G
Sun Jan 10, 2016 3:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW 8.65
Replies: 1
Views: 319

Re: HW 8.65

We can write all the involved reactions out first. N 2 + O 2 -> 2NO ∆H1=+90.25 kJ*2 2NO + O 2 -> 2NO 2 ∆H2=-114.1 kJ 2NO 2 + 1/2O 2 -> N 2 O 5 ∆H3=-110.2 kJ/2 N 2 + 5/2O 2 -> N 2 O 5 Thus the relationship between the standard enthalpy of formation of N 2 O 5 and these three separate enthalpies can b...

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