Search found 26 matches

by Yunna Gu
Sat Mar 12, 2016 8:50 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Quiz 3 Question1
Replies: 1
Views: 392

Quiz 3 Question1

Why is it true that when rate constant decreases, Ea stays the same?
by Yunna Gu
Sat Mar 12, 2016 6:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for delta H of formation
Replies: 1
Views: 974

Units for delta H of formation

Are units for delta h of formation suppose to be kj or kj/mol because in the course reader it only had kj, and yet I got points marked off on quiz 1 for not including per mol. What is the right units?
by Yunna Gu
Tue Mar 08, 2016 4:23 am
Forum: *Alcohols
Topic: Naming with 2 substituents?
Replies: 1
Views: 334

Re: Naming with 2 substituents?

Yes, you need to know which function group gets priority over another. In this case, carboxyl group has priority over the hydroxide. You can look up the priority list of functional group easily on google.
by Yunna Gu
Tue Mar 08, 2016 4:20 am
Forum: *Alkanes
Topic: Condensed Formula/2D Structural Formula Final 2011 Q.6
Replies: 1
Views: 458

Re: Condensed Formula/2D Structural Formula Final 2011 Q.6

You would need to actually draw out the molecule and make sure every atoms is satisfied with the octet rule, then you can start counting the longest parent chain.
by Yunna Gu
Mon Feb 22, 2016 2:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating Cell Potential
Replies: 2
Views: 370

Re: Calculating Cell Potential

You always flip the anode's sign, and you always subtract anode from cathode after you flip the sign.
by Yunna Gu
Tue Feb 09, 2016 1:43 am
Forum: Balancing Redox Reactions
Topic: Midterm 2015 #8C
Replies: 1
Views: 436

Midterm 2015 #8C

For this problem, why do you only count the number of electrons of CO2?
by Yunna Gu
Sun Feb 07, 2016 9:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.9
Replies: 1
Views: 241

14.9

How do you know the moles of electron for part a is 2, and the moles of electron for part b is 6?
by Yunna Gu
Sat Feb 06, 2016 9:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.35 Typo?
Replies: 2
Views: 517

Re: 14.35 Typo?

You have to balance out the electrons between the reduction and oxidation side, so they cancel out.
by Yunna Gu
Sat Feb 06, 2016 9:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode in Galvanic Cell
Replies: 2
Views: 389

Re: Electrode in Galvanic Cell

You use platinum, graphite, and liquid mercury because they don't interfere with the reaction.
by Yunna Gu
Mon Feb 01, 2016 11:57 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Drawing Diagrams
Replies: 1
Views: 251

Re: Drawing Diagrams

There's no scientific reasoning behind it. You can have the cathode on the left and anode on the right if you want. Just make sure when you indicate the electron flow, it's from right to left now.
by Yunna Gu
Mon Feb 01, 2016 11:56 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Conductor Solids in Salt Bridges
Replies: 1
Views: 221

Re: Conductor Solids in Salt Bridges

The solid metal is there to give off electrons or gain electrons. Remember how Dr. Lavelle said in class that the metal will eventually become thinner on the anode side, and there will be a metal build up on the cathode side.
by Yunna Gu
Mon Feb 01, 2016 11:52 am
Forum: Balancing Redox Reactions
Topic: 2 Half Reactions
Replies: 2
Views: 362

Re: 2 Half Reactions

Remember that electrons don't always flow from left to right. You can always switch the oxidation and reduction side. It's better to say that electrons flow from the reduction side to the oxidation side.
by Yunna Gu
Mon Feb 01, 2016 11:48 am
Forum: Balancing Redox Reactions
Topic: Basic or acidic solution?
Replies: 5
Views: 631

Re: Basic or acid solution?

I don't think you would need to know the pH of the solution for redox reaction. It usually does not matter.
by Yunna Gu
Mon Jan 18, 2016 2:30 pm
Forum: Phase Changes & Related Calculations
Topic: Molar Heat Capacity
Replies: 3
Views: 471

Re: Molar Heat Capacity

The reason why NO2 has a higher molar heat capacity than NO is because NO2 is a non-linear molecule while NO is a linear molecule.
by Yunna Gu
Mon Jan 11, 2016 1:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 3
Views: 496

Re: Hess's Law

Remember that when you flip the sides you have to multiply the delta H by a negative sign. And when you multiply the equation, you also have to multiply the delta H by the same number!
by Yunna Gu
Tue Nov 24, 2015 10:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VIDEO: VSPER Theory
Replies: 1
Views: 358

VIDEO: VSPER Theory

Video By:

Yunna Gu UID: 704 610 862 (3F)
Erina Baudat UID: 504 595 749 (1L)
by Yunna Gu
Mon Nov 16, 2015 2:26 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: chemical equilibrium expressions
Replies: 1
Views: 330

Re: chemical equilibrium expressions

When the molecules are aqueous, it is [___], which means the molarity (mol/L) of the molecule. When the molecules are in a gas state, then it is P(__) because you can not measure gas in molarity but you can measure it in pressure.
by Yunna Gu
Mon Nov 09, 2015 7:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant and cubic equations
Replies: 1
Views: 413

Re: Equilibrium constant and cubic equations

It will usually be small or you probably don't have to solve it because Dr. Lavelle doesn't expect us to know how to solve for it.
by Yunna Gu
Sun Nov 01, 2015 5:37 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbitals with 2 Different Elements
Replies: 2
Views: 265

Re: Molecular Orbitals with 2 Different Elements

The sigma-2p orbitals will be above the pi-2p orbitals. You always go with the element with the lower atomic number as Dr. Lavelle said during the review session on Friday.
by Yunna Gu
Sun Nov 01, 2015 5:35 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Diagrams
Replies: 1
Views: 319

Re: Molecular Orbital Diagrams

Elements like B, C, and N have the abnormal molecular orbitals, when the anti-bonding sigma orbital has a higher energy than the bonding pi orbitals, because they have less than 8 electrons. You can compare the difference between the normal and abnormal MO diagram and by looking at page 17 (normal) ...
by Yunna Gu
Sun Oct 25, 2015 9:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electronegativity and bond strength
Replies: 1
Views: 395

Re: Electronegativity and bond strength

Because F is the most electron negative element in the periodic table, and it being on the outside of the structure will attract other electrons, so rather be more attracted to C, it is more attracted to outside electrons, thus making the bond between C and F weak.
by Yunna Gu
Sun Oct 25, 2015 9:28 pm
Forum: Resonance Structures
Topic: Expanded Octets
Replies: 1
Views: 484

Re: Expanded Octets

That is the reason why they can have expanded octets. Because they have d orbitals, the extra electrons can be added to the d orbitals. "For atoms in the fourth period and beyond, higher d orbitals can be used to accommodate additional shared pairs beyond the octet. The relative energies of the...
by Yunna Gu
Sun Oct 18, 2015 9:26 pm
Forum: Lewis Structures
Topic: unpaired electrons for 02
Replies: 2
Views: 398

Re: unpaired electrons for 02

If you draw out the Lewis structure of O2, you will see each O has 2 lone pairs, and parametric means that the element has unpaired electrons.
by Yunna Gu
Fri Oct 16, 2015 9:51 pm
Forum: Resonance Structures
Topic: 3.57 part B
Replies: 1
Views: 425

Re: 3.57 part B

Because hydrogen is usually attached to an oxygen like in organic compounds
by Yunna Gu
Fri Oct 16, 2015 9:48 pm
Forum: Resonance Structures
Topic: Determining the number of resonance structures
Replies: 1
Views: 375

Re: Determining the number of resonance structures

There's no way of knowing until you draw out the Lewis structure and look at the possibilities.
by Yunna Gu
Sun Oct 11, 2015 5:29 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Shielding Effect
Replies: 5
Views: 898

Re: Shielding Effect

If you are more of a math person, here's the equation that explains why E gets closer to 0 as n increases: En=-hR/n^2

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