Search found 21 matches

by Sophia Eliopulos 2I
Sat Mar 18, 2017 10:05 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Higher Residual Entropy
Replies: 1
Views: 330

Re: Higher Residual Entropy

NO would have a higher residual entropy than BF3 because if you look at it, BF3 can have the fluorine atoms in 3 different places, but essentially they are the same molecule. However, flipping the N and O position across the double bond gives 2 different orientations which is why NO has higher resid...
by Sophia Eliopulos 2I
Sat Mar 11, 2017 11:34 am
Forum: *Alkenes
Topic: Naming alkenes [ENDORSED]
Replies: 2
Views: 398

Re: Naming alkenes [ENDORSED]

I believe the -a- is simply there to make the name easier to say versus having two consonants together.
by Sophia Eliopulos 2I
Thu Mar 02, 2017 2:51 pm
Forum: *Alkanes
Topic: Naming
Replies: 1
Views: 215

Re: Naming

It is 4-ethyl,2,2-Dimethyl-hexane instead of 3-ethyl, 5,5-dimethyl-hexane because you always want the lowest possible number you can have. 2 is lower than 3 and 5 so this is why you would name it this way.
by Sophia Eliopulos 2I
Thu Feb 23, 2017 2:21 pm
Forum: General Rate Laws
Topic: catalyst
Replies: 1
Views: 318

Re: catalyst

Yes, a catalyst can be included in a rate law. That's because, most reactions occur in a series of step and the rate is based on the "rate determining step", which is the slowest step. A catalyst may be a reactant in the rate determining step, and a product in a subsequent step. Therefore,...
by Sophia Eliopulos 2I
Sun Feb 19, 2017 11:38 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Catalyst
Replies: 6
Views: 606

Re: Catalyst

Catalysts work by providing an alternative reaction pathway for the breaking and remaking of bonds. The activation energy for this new pathway is often less than the activation energy of the normal pathway. When a catalyst is present, one of the reactants reacts with the catalyst to form an intermed...
by Sophia Eliopulos 2I
Thu Feb 09, 2017 5:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 4
Views: 498

Re: Cell Diagrams

Many electrode reactions involve only ionic species, which typically consist of aqueous and gas. If neither of the electroactive species is a metal, some other metal must serve as a conduit for the supply or removal of electrons from the system; platinum is commonly used.
by Sophia Eliopulos 2I
Fri Feb 03, 2017 3:24 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Higher Entropy
Replies: 2
Views: 441

Re: Higher Entropy

Hi!
It is also very important to remember the third law of thermodynamics which states that the entropies of all perfect crystals approach zero as the absolute temperature approaches zero (0 Kelvin). So, keeping this in mind, we also should look at the temperature these molecules are at.
by Sophia Eliopulos 2I
Thu Jan 26, 2017 2:20 pm
Forum: Calculating Work of Expansion
Topic: non isothermal processes
Replies: 2
Views: 338

Re: non isothermal processes

If the reaction is isothermal then delta U (change in internal energy) is zero and because delta U= q + w, --> q= w. A reversible process has the same external and internal pressure while in an irreversible process, the internal and external pressure are different.
by Sophia Eliopulos 2I
Thu Jan 19, 2017 2:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cpm vs Cvm [ENDORSED]
Replies: 1
Views: 2842

Re: Cpm vs Cvm [ENDORSED]

Heat capacity increases with molecular complexity because as more atoms are in the molecule, there are more possible bond variations that can absorb the added energy.
by Sophia Eliopulos 2I
Thu Jan 12, 2017 2:20 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7606
Views: 1018138

Re: Post All Chemistry Jokes Here

Getting in the spirit of chem...
by Sophia Eliopulos 2I
Fri Dec 02, 2016 10:22 am
Forum: Student Social/Study Group
Topic: Indicators
Replies: 3
Views: 450

Re: Indicators

It is probably a good idea to remember that indicators are weak acids that give a strong color change with pH. The popular indicator phenolphthalein in acid appears colorless, however in base appears pink. The H+ release results in a structural change so light is absorbed differently. The color chan...
by Sophia Eliopulos 2I
Tue Nov 29, 2016 12:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp and Kc Same?
Replies: 4
Views: 546

Re: Kp and Kc Same?

Hopefully this can help! Kp and Kc are not the same because Kc refers to concentration while Kp refers to partial pressure.
by Sophia Eliopulos 2I
Mon Nov 21, 2016 5:08 pm
Forum: Conjugate Acids & Bases
Topic: pH and pOH
Replies: 4
Views: 631

Re: pH and pOH

pOH = -log[OH-]

the negative log of the hydroxide ion molarity

pKw = -log Kw

the negative log of the water ion product , Kw

pKa = -log Ka

the negative log of the acid dissociation constant, Ka

pKb = -log Kb

the negative log of the base dissociation constant, Kb
by Sophia Eliopulos 2I
Wed Nov 16, 2016 11:03 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Question regarding heteronuclear molecular orbitals
Replies: 2
Views: 329

Re: Question regarding heteronuclear molecular orbitals

I would imagine we need to know how to draw heteronuclear molecular orbitals for the quiz, but we have to know how to draw it for the final anyways. Basically use the same outline for MO as homonuclear molecular orbitals with Z<8, except the more electronegative element has a lower energy level.
by Sophia Eliopulos 2I
Thu Nov 10, 2016 3:36 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7606
Views: 1018138

Re: Post All Chemistry Jokes Here

Saw this one coming...
by Sophia Eliopulos 2I
Thu Nov 03, 2016 3:25 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bonding vs. Anti-bonding
Replies: 2
Views: 1362

Re: Bonding vs. Anti-bonding

Bonding: constructive interference; in-phase; orbital overlap; molecular stability & lower energy. Sigma has head to head overlap while pi bonds along a parallel plane or axis
Anti-Bonding: destructive interference; out-of-phase; no orbital overlap; molecular instability & higher energy.
by Sophia Eliopulos 2I
Fri Oct 28, 2016 12:38 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7606
Views: 1018138

Re: Post All Chemistry Jokes Here

cackled out loud when I saw this
by Sophia Eliopulos 2I
Mon Oct 17, 2016 9:54 am
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds of Octet Outliers
Replies: 3
Views: 454

Re: Ionic Bonds of Octet Outliers

Two exceptions to the octet rule are hydrogen and helium, which both have room for only two electrons in their valence shell. Because they both only have one shell, the first shell has only one s orbital and no p orbital, so it holds only two electrons (which is when helium and hydrogen are most sta...
by Sophia Eliopulos 2I
Thu Oct 13, 2016 10:42 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Building-Up Principle [ENDORSED]
Replies: 3
Views: 2685

Re: Building-Up Principle [ENDORSED]

It helps with practice, but basically you can tell which state it is in by the levels which are filled in an electron configuration. When in an excited state, the electrons "jump" to a higher level, which is not normally found in the ground state configuration of the atom. This jump causes...
by Sophia Eliopulos 2I
Sat Oct 08, 2016 12:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy Level Changes in Orbitals
Replies: 2
Views: 319

Re: Energy Level Changes in Orbitals

I think its more a conceptual aspect. So if an electron is excited to a higher energy level, it can still exist in the same orbital as it was before (1s/2s), but now it also has the possibility of occupying a different orbital (2s/3p).
by Sophia Eliopulos 2I
Sun Oct 02, 2016 10:37 am
Forum: Significant Figures
Topic: Sig Figs in a problem with addition & multiplication [ENDORSED]
Replies: 5
Views: 813

Sig Figs in a problem with addition & multiplication [ENDORSED]

What would we do if we were given a problem that had addition or subtraction and multiplication or division in the same question? Are we supposed to do sig figs at each step as we work through the problem or do we just wait until the end?

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