Search found 20 matches

by William Chwa 1E
Wed Mar 09, 2016 10:02 pm
Forum: *Haloalkanes
Topic: Priority in numbering vs. double/triple bonds
Replies: 1
Views: 727

Re: Priority in numbering vs. double/triple bonds

Yes, halides are considered subsituents, so numbering of the double bonds takes precedence.
by William Chwa 1E
Tue Mar 01, 2016 11:22 pm
Forum: *Organic Reaction Mechanisms in General
Topic: 1.26
Replies: 1
Views: 304

Re: 1.26

Because the higher priority is given to the element with a higher atomic number. So on the left side, it is a C top and a C on the bottom, but the top has the longer chain so it has the higher priority. On the right side, Br (bottom) has a higher atomic number than C (top), so the bottom has the hig...
by William Chwa 1E
Wed Feb 24, 2016 4:30 pm
Forum: *Alkanes
Topic: Double and Triple Bonds
Replies: 1
Views: 375

Re: Double and Triple Bonds

I surfed a bit online for this and it seems that hydrocarbons containing both a double and and a triple bond actually have a name of their own, called alkenynes. I also read that it is named this way due to the alkyne functional group having priority over the alkene in naming. http://valhalla.chem.u...
by William Chwa 1E
Fri Feb 19, 2016 10:39 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: "reaction profile" & k (quiz 2 preparation)
Replies: 1
Views: 392

Re: "reaction profile" & k (quiz 2 preparation)

If the energy of the products is less than the energy of the reactants, then k (the forward reaction) is favored (k>k'), and K>1. If the energy of the products is greater than the energy of reactants, then k' (the reverse reaction) is favored (k<k'), and K<1. If the energy stays the same, then the r...
by William Chwa 1E
Mon Feb 15, 2016 9:05 pm
Forum: Second Order Reactions
Topic: Book Problem 15.19
Replies: 1
Views: 391

Re: Book Problem 15.19

If you compare experiment 1 with experiment 3, you can get the equation (\frac{1.25}{3.02})^{x} = \frac{8.7}{50.8} , where x will come out to approximately 2. So B will be second order. We choose those two experiments because those two are the only two where every reactant but B stays consta...
by William Chwa 1E
Sat Feb 06, 2016 5:42 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat and Standard Enthalpies
Replies: 1
Views: 434

Re: Specific Heat and Standard Enthalpies

You use standard enthalpy when you are calculating enthalpy of a reaction (whether through Hess' Law, bond enthalpies, or enthalpy of formation), or in entropy or Gibbs free energy problems which could possibly require you trying to find enthalpy in the process. You use specific heat capacity to cal...
by William Chwa 1E
Sat Jan 30, 2016 6:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Voltage
Replies: 1
Views: 371

Re: Voltage

Voltage basically is the difference in potential energy between two points per electrical charge. Thus, "a unit of potential difference" means the work (energy) done per unit of charge.
by William Chwa 1E
Thu Jan 21, 2016 7:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 1
Views: 276

Re: Bond Enthalpies

You just simply multiply the bond enthalpy by the coefficient. If it contains multiple bonds, you can either multiply each one of them or multiply after you have added all of them in the compound.
by William Chwa 1E
Fri Jan 15, 2016 12:20 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: First Law of Thermodynamics
Replies: 1
Views: 309

Re: First Law of Thermodynamics

All it means is that matter nor energy can escape from the universe, simply because there is no other place for that matter or energy to go besides the universe. So the universe itself is considered an isolated system, because it encapsulates every single possible entity, space, etc. and nothing can...
by William Chwa 1E
Mon Jan 11, 2016 10:59 am
Forum: Phase Changes & Related Calculations
Topic: State Properties
Replies: 2
Views: 378

Re: State Properties

Q is not considered a state function because it is path dependent. Enthalpy is determined by the internal energy, pressure, and volume, which are all state functions. Q, however, is a process state that depends on specific transitions between equilibriums.
by William Chwa 1E
Sat Dec 05, 2015 3:51 pm
Forum: Naming
Topic: the difference between bi- and di- prefixes?
Replies: 2
Views: 14531

Re: the difference between bi- and di- prefixes?

Apparently the difference between di- and bi- are that di- is Greek, while bi- is Latin. The general trend is that Greek prefixes go with words of Greek words and vice versa. For example, "oxide" is of Greek origin. I've been looking at other examples and looks like bi- is more often used ...
by William Chwa 1E
Sun Nov 29, 2015 6:52 pm
Forum: Identifying Acidic & Basic Salts
Topic: Anions as Acids
Replies: 1
Views: 382

Re: Anions as Acids

It's because HSO4- and H2PO4- are derived from polyprotic acids, which include sulfuric acid and phosphoric acid, respectively. This means they can donate multiple H+ s. So HSO4- and H2PO4- can donate extra H+ s, although they are considered weaker acids and will be harder to lose that extra H+.
by William Chwa 1E
Sat Nov 21, 2015 10:41 pm
Forum: Polyprotic Acids & Bases
Topic: Water
Replies: 1
Views: 472

Re: Water

I personally do not know the answer to this question, but I did some digging online and it looks like theoretically H3O(+) can become H4O (2+), but it would have to involve superacids. But the molecule would be extremely unstable and would almost immediately fall apart into water and a hydrogen mole...
by William Chwa 1E
Sun Nov 15, 2015 6:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Writing endothermic and exothermic reactions
Replies: 1
Views: 3220

Re: Writing endothermic and exothermic reactions

If a reaction is endothermic, then delta H is positive (+heat) on the left side of the equation, with the reactants. If a reaction is exothermic, then delta H is negative on the left side of the equation, thus becoming +heat on the right side of the equation.
by William Chwa 1E
Sat Nov 07, 2015 2:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium Concentrations
Replies: 2
Views: 385

Re: Calculating Equilibrium Concentrations

X is just a variable that you assign which represents the change in molar concentration for the reactant. The reactant will be used up during the reaction, so the change is represented by -X. Then, as you said, depending on the molar ratios of the products, the product(s)' molar concentration will i...
by William Chwa 1E
Sun Nov 01, 2015 2:20 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbitals of 2 Different Elements
Replies: 1
Views: 336

Re: Molecular Orbitals of 2 Different Elements

Yes, we are supposed to know how to draw MO diagrams and calculate bond orders for heteronuclear diatomic molecules as well. The process is largely the same as homonuclear diatomic molecules, except different elements have different energy levels of atomic orbitals. Professor Lavelle did an example ...
by William Chwa 1E
Sat Oct 24, 2015 7:46 pm
Forum: Hybridization
Topic: Hybridization
Replies: 1
Views: 338

Re: Hybridization

It's because the p subshell normally has three orbitals, but a 2sp2 only hybridizes two of those three. The unhybridized p orbital is put on an energy level on its own, above sp2.
by William Chwa 1E
Sun Oct 18, 2015 3:44 pm
Forum: Octet Exceptions
Topic: Exceptions to Octet Rule
Replies: 1
Views: 570

Re: Exceptions to Octet Rule

One exception to the octet rule is when there is an odd number of valence electrons on a compound. In this case, we are unable to reach perfect octets for each element. For instance, NO: -Single bond: 5 valence e- on nitrogen. -Double bond: 7 on nitrogen. -Triple bond: 9 on nitrogen. However, except...
by William Chwa 1E
Fri Oct 09, 2015 7:50 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Elements that have irregular orbitals
Replies: 1
Views: 3129

Re: Elements that have irregular orbitals

On the periodic table, Cr and Cu are one electron short of filling a half full/full 3d orbital (since according to the Aufbau principle, Cr should have 4 electrons in 3d and Cu should have 9). Half full and full subshells bring more stability, so one electron fills the 3d orbital from the 4s. The sa...
by William Chwa 1E
Fri Oct 02, 2015 8:52 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Emission/Line/Atomic Spectrum Equation
Replies: 1
Views: 337

Re: Emission/Line/Atomic Spectrum Equation

The first equation is used for the change in energy of an electron between different quantum levels, while the second equation is to find the potential energy value for the individual quantum levels. Note once you implement E=hv into the first equation you will actually get \Delta E=hR\left \{ \frac...

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