Search found 25 matches

by Hannah_Chao_1D
Mon Mar 13, 2017 10:24 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram and Pt(s)
Replies: 4
Views: 600

Re: Cell Diagram and Pt(s)

You add Pt(s) when at least one side of the cell does not have solid reactants. The Pt(s) functions as a nonreactive electrode when the reactants are all in solution
by Hannah_Chao_1D
Mon Mar 13, 2017 10:17 am
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Confusion about Z and E naming
Replies: 1
Views: 342

Re: Confusion about Z and E naming

The priority naming for the EZ system is written on page 16 of the Introduction to Organic Chemistry book (the green one that came with the course reader): 1. The priority is determined by the atoms or atom groups bonded to each of the C's in the double bond. 2. It is based on the atomic number of t...
by Hannah_Chao_1D
Sun Mar 12, 2017 4:05 pm
Forum: *Cyclopropanes and Cyclobutanes
Topic: Ch 3 in Intro to Organic Chemistry
Replies: 1
Views: 647

Re: Ch 3 in Intro to Organic Chemistry

Number three is an eclipsed conformation. If you draw the Newman projection, the CH3's are overlapping at the top and the H's are overlapping at the bottom.
by Hannah_Chao_1D
Mon Mar 06, 2017 4:35 pm
Forum: *Ketones
Topic: Naming
Replies: 2
Views: 736

Re: Naming

I think that for more complicated alkenes and alkynes, it's acceptable to write the number before the infix. For example in the book, 2-pentyne can also be named pent-2-yne. Since 2-propanone doesn't have double or triple bonds and is a fairly simple molecule, I don't think it should be named pronan...
by Hannah_Chao_1D
Mon Mar 06, 2017 4:27 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Lewis Structure question
Replies: 1
Views: 650

Re: Lewis Structure question

When drawing Lewis structures, you want the formal charge to be as close to zero as possible. formal charge= (valence electrons of atom) - 1/2(number electrons in bonds) - (electrons in lone pairs) Since O has 6 valence electrons, it wants 2 bonds and 2 lone pairs for a formal charge of zero. That i...
by Hannah_Chao_1D
Thu Mar 02, 2017 9:27 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Substituent Naming
Replies: 3
Views: 420

Re: Substituent Naming

You number the carbons to make the longest possible C chain (the parent chain). This means that the longest possible chain doesn't need to be the one that's written linearly. The number before the substituent is the lowest one. Keep in mind that if there are multiple substituents, you want the sum o...
by Hannah_Chao_1D
Thu Mar 02, 2017 9:21 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Mechanisms
Replies: 2
Views: 374

Re: Mechanisms

Since those are the only ones we covered in class, I assume that those are the only ones we'll be expected to know.
by Hannah_Chao_1D
Thu Mar 02, 2017 9:20 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Exergonic Reaction
Replies: 2
Views: 412

Re: Exergonic Reaction

Exergonic means that the energy of the products is less than the energy of the reactants. The reaction releases energy into the surroundings. Thus the energy of the surroundings increases and energy of the system decreases.
by Hannah_Chao_1D
Sun Feb 19, 2017 10:49 pm
Forum: First Order Reactions
Topic: Second Order Reaction Question
Replies: 1
Views: 333

Re: Second Order Reaction Question

The half life of a second order reaction is inversely proportional to the reactant's concentration because the 2nd order integrated rate law depends on the inverse on the reactant's initial concentration. All the graphs are supposed to have a slope of -k but the graphs all have different axes. In a ...
by Hannah_Chao_1D
Sat Feb 11, 2017 7:12 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Midterm 2013 Q7
Replies: 1
Views: 254

Re: Midterm 2013 Q7

I did the same problem and got the same answer as you. I think there is an error in the course reader's answer.
by Hannah_Chao_1D
Mon Feb 06, 2017 5:11 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: ion-selective electrodes
Replies: 1
Views: 320

Re: ion-selective electrodes

Yes, it can be used like that.
Eº is for standard conditions and before the reaction occurs.
The Nernst equation with numbers is at 25ºC for the sake of using constants for 25ºC instead of variables.
by Hannah_Chao_1D
Sat Feb 04, 2017 3:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode Disintegration in Silver Concentration Cell Diagram [ENDORSED]
Replies: 1
Views: 220

Re: Anode Disintegration in Silver Concentration Cell Diagram [ENDORSED]

The oxidation reaction Ag(s) --> Ag+(aq) + 1 e- occurs at the anode. Since the silver is coming from the anode, the anode is dissolving and the concentration of silver ions is increasing.
by Hannah_Chao_1D
Fri Jan 27, 2017 2:21 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Definition of Gibbs free energy
Replies: 1
Views: 344

Re: Definition of Gibbs free energy

Gibbs free energy is the maximum nonexpansion work (inc. electrical and mechanical work) that the system can do at constant temperature and pressure. In other words, it is the measure of energy that is free to do the maximum nonexpansion work.
by Hannah_Chao_1D
Tue Jan 17, 2017 10:41 am
Forum: Phase Changes & Related Calculations
Topic: Enthalpy
Replies: 8
Views: 954

Re: Enthalpy

Since no temperature is given, assume standard conditions. The standard condition for temperature is 298K or 25ºC.
by Hannah_Chao_1D
Sat Jan 14, 2017 1:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Heat Capacity
Replies: 3
Views: 356

Re: Heat Capacity

Heat capacity is the heat needed to increase an OBJECT's temperature by 1ºC and is an extensive property. Specific heat capacity is the heat needed to increase 1g of the object's temperature by 1ºC and is an intensive property. In other words, the specific heat capacity depends on the AMOUNT of the ...
by Hannah_Chao_1D
Tue Nov 29, 2016 1:56 pm
Forum: Conjugate Acids & Bases
Topic: Strong Bases
Replies: 1
Views: 362

Re: Strong Bases

All alkaline earth metal oxide and hyrdoxides are strong bases.
by Hannah_Chao_1D
Sun Nov 27, 2016 11:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Increasing Pressure
Replies: 1
Views: 305

Re: Increasing Pressure

The pressure can be increased by decreasing the volume or by adding moles of (inert) gas (Ideal Gas Law: PV=nRT). The greater the number of moles of gas, the greater the pressure. Thus, when the pressure is increased, the reaction will try to reduce the pressure created by the moles of gas by favori...
by Hannah_Chao_1D
Mon Nov 14, 2016 9:48 am
Forum: Naming
Topic: Anionic Ligands
Replies: 1
Views: 348

Re: Anionic Ligands

The difference between the names shows tells you which atom in the ligand is bonding to the central atom. The ligand has the same structure for both names. Nitro and nitrito are both nitrite ions (NO 2 - ). Nitro means that the N is bonding to the central atom, and nitrito means that the double-bond...
by Hannah_Chao_1D
Sun Nov 13, 2016 1:53 pm
Forum: Naming
Topic: What is the difference between "Hydrate" and "Aqua"
Replies: 2
Views: 532

Re: What is the difference between "Hydrate" and "Aqua"

"Aqua" denotes a coordinate covalent bond between water and the central atom in the coordination sphere, while a hydrate is a water molecule outside of the coordination sphere that is attracted to a ion or polar compound via hydrogen bonds.
by Hannah_Chao_1D
Mon Oct 31, 2016 7:42 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: M.O. when out of phase
Replies: 1
Views: 252

Re: M.O. when out of phase

When the orbitals are out of phase, there is a node (probability of finding an electron is zero) and yes it is possible to have that.
by Hannah_Chao_1D
Tue Oct 25, 2016 3:12 pm
Forum: Lewis Structures
Topic: Lewis Structure (Octet Rule)
Replies: 2
Views: 414

Re: Lewis Structure (Octet Rule)

Elements with an atomic number greater than 20 can have more than 8 valence electrons because they can use the d orbitals.
by Hannah_Chao_1D
Thu Oct 20, 2016 9:06 pm
Forum: Lewis Structures
Topic: Homework Question 3.27 Parts A&C [ENDORSED]
Replies: 1
Views: 321

Re: Homework Question 3.27 Parts A&C [ENDORSED]

The roman numerals give you the ionic charge of the ion. The net ionic charges in the compound should equal zero, so the the numeral helps you determine how many of each ion and charge you need. For example in part a, Tl has a charge of 3+ so you need a charge of 3- to have a neutral compound. Since...
by Hannah_Chao_1D
Sun Oct 16, 2016 3:28 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds of Octet Outliers
Replies: 3
Views: 513

Re: Ionic Bonds of Octet Outliers

He, Li, and Be follow the duet or duplet rule. They all want 2 electrons because the highest subshell they can have is ns^2 and the s orbital can only have 2 electrons.
by Hannah_Chao_1D
Sun Oct 09, 2016 6:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Confusion [ENDORSED]
Replies: 3
Views: 673

Electron Configuration Confusion [ENDORSED]

According to the Aufbau Principle, electrons fill up lower energy orbitals first. For example the electrons fill the 4s orbital then the 3d orbital since the 3d orbital has more energy than the 4s orbital. However, the course reader says that after the 4s orbital state/orbital occupies and electrons...
by Hannah_Chao_1D
Sat Oct 01, 2016 4:02 pm
Forum: Student Social/Study Group
Topic: CHEM JOKES
Replies: 29
Views: 4176

Re: CHEM JOKES

Watson: Sherlock want to hear a joke about sodium?
Sherlock: Na
Watson: How did you know I was going to say that?
Sherlock: Elementary, my dear Watson, elementary.

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