Search found 15 matches

by Jiangyuan Luo 1K
Sun Mar 13, 2016 10:00 am
Forum: *Ethers
Topic: Priority of Ethers
Replies: 4
Views: 1593

Re: Priority of Ethers

That's incorrect. Dr. Lavelle revised it.
by Jiangyuan Luo 1K
Sun Mar 13, 2016 9:41 am
Forum: *Electrophiles
Topic: CO2
Replies: 5
Views: 1314

Re: CO2

A easy to way to think about it. CO2 can react with OH-, which is obviously a nucleophile, so CO2 must be a electrophile.
by Jiangyuan Luo 1K
Sun Mar 06, 2016 1:14 am
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Stability
Replies: 1
Views: 398

Re: Stability

The staggered conformation maximizes the distance between certain atoms in a molecule. As a result, this conformation minimizes the repulsion between electrons around the atoms and thus minimizes the energy of the molecule, causing it to be more stable.
by Jiangyuan Luo 1K
Mon Feb 29, 2016 4:19 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Geometric Isomers with multiple double bonds
Replies: 1
Views: 1167

Re: Geometric Isomers with multiple double bonds

We consider the C=C between the third and the fourth carbon atoms. When we are talking about geometric isomers due to C=C, for each of the carbon atom on both sides of the double bonds, it has to be connected by two different chain. For example, the first carbon atom is connected to two hydrogen ato...
by Jiangyuan Luo 1K
Mon Feb 29, 2016 4:10 pm
Forum: *Alkenes
Topic: Isomers of C4H8 (workbook p46)
Replies: 1
Views: 392

Re: Isomers of C4H8 (workbook p46)

They are the same. Since the C=C is on the first and second carbon atoms, two atoms connecting with the first carbon atom are both Hydrogen, and thus there is no geometric isomer. The angle between the second C-C bond and the third C-C bond is always 109.5 degrees no matter how you draw it.
by Jiangyuan Luo 1K
Fri Feb 19, 2016 6:51 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reverse reactions
Replies: 1
Views: 339

Re: Reverse reactions

Are you referring to a question in today's quiz? I think you can not find the K (equilibrium constant) if only the concentrations are provided because you do not know if the reaction is at equilibrium. Instead you can calculate the Q, which equals to k(forward)/k(backward) at that instant moment. Ho...
by Jiangyuan Luo 1K
Fri Feb 19, 2016 6:34 pm
Forum: *Electrophiles
Topic: Electrophiles and lone pairs
Replies: 1
Views: 400

Re: Electrophiles and lone pairs

I think electron deficient refers to when an element has less electrons than it should have according to its atomic number. For example, in HBr, since Br is more electronegative than H, it attracts the electron of H and make that electron closer to Br, and thus we consider their is no electron aroun...
by Jiangyuan Luo 1K
Mon Feb 08, 2016 10:59 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs Free Energy and Work
Replies: 2
Views: 553

Re: Gibbs Free Energy and Work

The change of Gibbs Free Energy measures the maximum non-expansion work that a system does under constant P and V. In the battery, this non-expansion work is electric work done by the transfer of electrons under voltage difference between cathode and anode.
by Jiangyuan Luo 1K
Mon Feb 01, 2016 7:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reducing Agent Strength
Replies: 1
Views: 365

Re: Reducing Agent Strength

In a Redox reaction, the reducing property of reducing agent is always stronger than the reducing property of the reduced product. For example, in Zn + Cu 2+ = Cu + Zn 2+, Zn is the reducing agent and Cu is the reduced product. Thus, Zn is stronger than Cu in terms of reducing agent.
by Jiangyuan Luo 1K
Sun Jan 24, 2016 9:16 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Reaction Entropy vs. Standard Entropy of Formation
Replies: 1
Views: 325

Re: Standard Reaction Entropy vs. Standard Entropy of Format

Hi, Standard entropy of formation is often measured in laboratory and can be look up in reference form or book. The standard entropy of formation of a compound under certain temperature is the entropy change when elements react to form 1 mol of this compound under this temperature. For example, the ...
by Jiangyuan Luo 1K
Sun Jan 24, 2016 8:59 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: About spontaneity and boiling point
Replies: 2
Views: 1256

About spontaneity and boiling point

Dr. Lavelle mentioned that boiling point is the temperature that the vaporization is spontaneous at 1 atmosphere. However, water, which has a boiling point of 100℃, vaporizes constantly in room temperature. Is the vaporization of water spontaneous? If not, how to explain the relationship between spo...
by Jiangyuan Luo 1K
Sun Jan 17, 2016 10:18 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated Systems
Replies: 2
Views: 486

Re: Isolated Systems

I think the isolated system is an ideal model. It cannot even exist in lab setting, but can only be used in calculation.
by Jiangyuan Luo 1K
Sun Jan 10, 2016 4:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Kekulé Structures
Replies: 2
Views: 429

Re: Kekulé Structures

There are two versions of the structure of Benzene. A Kekulé structure is the alternative of single bond and double bond. Another one is that the bond between two carbon atoms is neither single bond or double bond, but it is a bond between single bond and double bond (a sigma bond with a big pi bond...
by Jiangyuan Luo 1K
Sun Jan 10, 2016 3:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: The delta H calculation in addition reaction
Replies: 1
Views: 419

The delta H calculation in addition reaction

When we calculate the enthalpy change of the addition reaction: ethylene reacts with hydrogen to form ethane, we consider that the "C=C" in ethylene completely breaks and a new "C—C" in ethane forms, so we subtract the heat released when "C—C" forms from the heat absorb...

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