Search found 16 matches
- Fri Mar 11, 2016 2:56 pm
- Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
- Topic: Drawing arrows
- Replies: 1
- Views: 295
Re: Drawing arrows
Half arrows are used when one electron is moving from the source to the end. The arrow indicates electron flow, so you would draw the arrow starting from the electron rich source to the electron deficient end. Therefore, the arrow indicates where the electrons are going.
- Sun Mar 06, 2016 7:53 pm
- Forum: *Alkanes
- Topic: Atomic number and organic molecule
- Replies: 2
- Views: 339
Re: Atomic number and organic molecule
The use of atomic numbers is to determine the priority of the groups bonded to sp2 carbons which would then indicate if the molecule is trans (E) or cis (Z).
Re: Numbering
That is correct. You want to use the lowest number possible, and not necessarily the sum. Sometimes, the nonexistent "sum rule" does work out, like in the case you have described.
- Fri Feb 19, 2016 11:51 am
- Forum: General Science Questions
- Topic: sig figs if problem uses ln
- Replies: 2
- Views: 987
Re: sig figs if problem uses ln
The natural log of a number should have the same number of decimal places as there are sig figs in the original number.
- Sat Feb 13, 2016 7:25 pm
- Forum: General Rate Laws
- Topic: Catalyst versus Reaction Intermediate
- Replies: 1
- Views: 348
Re: Catalyst versus Reaction Intermediate
I don't think it is correct to say that a catalyst is the opposite of a reaction intermediate. A catalyst is a substance that increases the rate of reaction by lowering the activation energy. It is not a part of the reaction, meaning it is neither a product or reactant. Therefore, a catalyst is not ...
- Sat Feb 06, 2016 2:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Notation of cell diagrams
- Replies: 1
- Views: 316
Re: Notation of cell diagrams
You use a vertical line to separate the electrode from the aqueous or gas species, and you use a comma to list the species of the same phase.
- Fri Jan 29, 2016 6:33 pm
- Forum: Calculating Work of Expansion
- Topic: Types of Systems
- Replies: 3
- Views: 672
Re: Types of Systems
During the process of reversible expansion, the pressure from both sides of the system, external and internal, are equal. However, an irreversible expansion demonstrates a difference in external and internal pressures.
- Fri Jan 22, 2016 5:22 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: liquid and gas phases coexisting?
- Replies: 2
- Views: 370
Re: liquid and gas phases coexisting?
Liquid and gas coexist within a range of temperatures during phase transition, meaning that both liquid and gas are present until it reaches a certain temperature.
- Sat Jan 16, 2016 2:09 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q=Csp(delta T)
- Replies: 1
- Views: 818
Re: q=Csp(delta T)
You use q=cΔT when you calculate the heat energy lost or gained using a calorimeter. The c in this equation is the heat capacity of the calorimeter. You use q=mcΔT to calculate the heat energy lost or gained in open air. The c in this equation is the specific heat of the substance you are heating. I...
- Fri Jan 08, 2016 4:57 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: How do you know if something is in its standard state?
- Replies: 2
- Views: 6096
Re: How do you know if something is in its standard state?
A standard state of a substance is its phase at 1 atm and 25°C. Most reactions are given in their standard state. Regarding elements, liquid is the standard state for mercury and bromine, gas is the standard state for noble gases, halogen, flourine, chlorine, hydrogen, oxygen, and nitrogen, and all ...
- Wed Nov 25, 2015 2:30 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: MO Theory Video
- Replies: 2
- Views: 464
MO Theory Video
We have prepared a review of the molecular orbital theory, including a diagram, bond order, diamagnetism or paramagnetism, and LUMO and HOMO.
- Sun Nov 08, 2015 8:08 pm
- Forum: Lewis Structures
- Topic: Unpaired Electrons
- Replies: 1
- Views: 377
Unpaired Electrons
Why does the unpaired electron in the lewis structure of NO2 go to N and not O?
- Fri Oct 30, 2015 9:44 am
- Forum: Hybridization
- Topic: Hybridization
- Replies: 2
- Views: 503
Re: Hybridization
Sigma bonds are formed from end to end overlap, while pi bonds are formed from side to side overlap of p orbitals.
- Fri Oct 30, 2015 9:24 am
- Forum: Lewis Structures
- Topic: exceptions to octets
- Replies: 2
- Views: 451
Re: exceptions to octets
Another one to remember is chlorine. It can hold more than 8 valence electrons.
- Fri Oct 23, 2015 10:14 am
- Forum: Hybridization
- Topic: Energy Levels and Orbitals
- Replies: 2
- Views: 439
Re: Energy Levels and Orbitals
Different energy levels represent the distance of electrons from the nucleus. Larger numbers of the energy level mean that it is further away from the nucleus. Orbitals, however, are the space within the energy levels where the electrons are located. The orbitals come in different shapes (s, p, d, f)
- Sun Oct 04, 2015 10:28 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: How to approach this problem?
- Replies: 1
- Views: 468
Re: How to approach this problem?
This problem is asking you to find the sulfide of M. M is an unknown metal so you have to start by finding out what that is. You can do so by subtracting the mass of the oxygen and hydrogen from the molar mass. 74.10 g/mol - (2 x 15.999 + 2 x 1.008) = 40.086 The closest element with that mass is cal...