Search found 21 matches

by Chloe 3D
Wed Mar 09, 2016 10:34 pm
Forum: *Cycloalkenes
Topic: Final 2012 Question 5
Replies: 2
Views: 546

Re: Final 2012 Question 5

If I'm having trouble deciding between cis and trans from a line structure, it always helps me to draw the Lewis Structure of the compound (or at least the portion surrounding the double bond). In this case, on either side of the C=C bond, each carbon atom is bonded to both an additional carbon atom...
by Chloe 3D
Thu Mar 03, 2016 11:46 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts in relation to Graph Peaks
Replies: 2
Views: 355

Re: Catalysts in relation to Graph Peaks

In an reaction profile diagram, the presence of a catalyst is typically indicated by the addition of a dotted line of the lower activation energy barrier. The original Ea peak should still be drawn.
by Chloe 3D
Wed Feb 24, 2016 9:58 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Symbols
Replies: 2
Views: 1110

Re: Symbols

The ‡ symbol is used to denote an activated complex of the transition state. This complex is highly unstable and persists only while bonds are breaking and new bonds are forming. The symbol can be attached to variables to represent the properties of the transition state. For example, G°‡ is the stan...
by Chloe 3D
Mon Feb 22, 2016 5:19 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: 4.30
Replies: 4
Views: 568

Re: 4.30

I'm not sure about using that equation, but I found a general rule from the Chapter 4 reading. It said only reactions with activation energies at or below roughly 80 kJ.mol-1 will occur at room temperature.
by Chloe 3D
Mon Feb 22, 2016 5:14 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Psuedo-thermodynamics
Replies: 2
Views: 459

Re: Psuedo-thermodynamics

I'm not sure if this is what you mean, but I believe your question refers to page 89 in the course reader. It considers the reaction A + B ⇄ AB‡ ⇄ C in which reactants A and B are in pseudo-equilibrium with the activated complex of A and B, AB‡. The constant, K1‡ = [AB‡]/[A][B]. To understand why th...
by Chloe 3D
Tue Feb 09, 2016 7:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding or Subtracting the E values
Replies: 2
Views: 2756

Re: Adding or Subtracting the E values

I believe there are two different methods to compute the E knot value. For a given redox reaction, you can first write the associated half-reactions and given standard reduction potentials. When you flip one half-reaction to become an oxidation, the sign of its E knot value will change. In this case...
by Chloe 3D
Thu Jan 28, 2016 3:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 4
Views: 1043

Re: Bond Enthalpies

To determine which bonds are broken and which are formed, it helps me to draw the lewis structures for the reaction. Then you can interpret the result visually. For example, consider the reaction 2H2(g) + O2(g) --> 2H2O(g). After drawing the lewis structure, you see that the bonds of the reactants (...
by Chloe 3D
Thu Jan 21, 2016 8:21 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy and Spontaneous Reactions
Replies: 3
Views: 402

Re: Entropy and Spontaneous Reactions

A spontaneous reaction, by definition, increases entropy. As a gas expands from V1 to V2, the larger volume provides a greater range of locations for the molecules. We can therefore expect the positional disorder of the gas to increase, subsequently increasing its entropy. The reverse process, compr...
by Chloe 3D
Thu Jan 14, 2016 7:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.53- Knowing which eqn to use to find q
Replies: 1
Views: 366

Re: Question 8.53- Knowing which eqn to use to find q

Hello, The specific heat capacity (calculated by q=mCΔT) and molar heat capacity (calculated by q=nCΔT) wouldn't work in this problem because they refer to the heat capacity divided by the mass of the sample (in the first case) and the number of moles of the sample (in the second case). Their units ...
by Chloe 3D
Fri Jan 08, 2016 11:12 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Characteristics that give higher heat capacities?
Replies: 3
Views: 1137

Re: Characteristics that give higher heat capacities?

I'm not sure whether the effect would be a higher or lower molar heat capacity, but I believe that the phase of a substance (solid, liquid, or gas) affects its heat capacity.
by Chloe 3D
Tue Dec 01, 2015 4:32 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: percentage protonated vs ionized
Replies: 1
Views: 1298

Re: percentage protonated vs ionized

The percentage deprotonated would be calculated in solutions of weak acids. This is a measure of the concentration of A- (acid molecules that have donated a proton) as compared to the initial concentration of the acid HA. A small percentage of deprotonated molecules would indicate that the acid HA i...
by Chloe 3D
Tue Nov 24, 2015 4:01 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.67 Calculating pH from Molarity and Formula
Replies: 1
Views: 479

Re: 12.67 Calculating pH from Molarity and Formula

I think you use the molecular formula to determine whether each compound is an acid or a base. From there, you can take the negative log of the molarities to find the pH (if the compound is an acid) or the pOH (if the compound is a base). Once you have the pOH, subtract this value from 14.00 to find...
by Chloe 3D
Thu Nov 19, 2015 5:57 pm
Forum: Bronsted Acids & Bases
Topic: Amphiprotic Acids & Bases
Replies: 1
Views: 2985

Re: Amphiprotic Acids & Bases

Yes, there are many amphiprotic substances. Some examples include the hydrogen carbonate ion (HCO3-), the hydrogen sulfate ion (HSO4-), the hydrogen phosphate ion (HPO4-), and the hydrogen sulfide ion (HS-). Consider, for example, HCO3-. In the equation HCO3- + H20 --> H3O+ + CO3 2-, HCO3- acts as a...
by Chloe 3D
Thu Nov 12, 2015 11:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Molecular shape
Replies: 4
Views: 543

Re: Determining Molecular shape

From the lewis structure, you can determine molecular shape by determining the number of regions of electron density surrounding the central atom. Regions of electron density include both bonded atoms and lone pairs. Remember that lone pairs, however, experience a stronger repulsion; they therefore ...
by Chloe 3D
Thu Nov 05, 2015 9:17 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond Order
Replies: 5
Views: 1748

Re: Bond Order

While a fractional bond order is an indication of resonance in most cases, I believe there are some exceptions. Consider the molecule NO, for example. It has a bond order of 2.5. However, because the molecule is composed of only two atoms, there is no possible resonance structure.
by Chloe 3D
Wed Oct 28, 2015 2:57 pm
Forum: Lewis Structures
Topic: Process of drawing Lewis Structure for Ionic bonds
Replies: 1
Views: 406

Re: Process of drawing Lewis Structure for Ionic bonds

To draw a Lewis Structure for an ionic compound, I believe you need to draw the lewis structure of each individual ion and place the structure in brackets indicating the charge of the ion. So for ammonium chloride, you'd draw the structure for a NH4+ ion and then, in separate brackets, the structure...
by Chloe 3D
Thu Oct 22, 2015 3:12 pm
Forum: Lewis Structures
Topic: Lewis Structures (Conceptual)
Replies: 2
Views: 269

Re: Lewis Structures (Conceptual)

Lewis structures are a crucial step in determining the shape of a molecule because they tell you how many regions of electron density the molecule has. Without this information, you could not name the shape.
by Chloe 3D
Thu Oct 15, 2015 9:57 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons
Replies: 2
Views: 2637

Re: Valence Electrons

Hello, You're correct. The number of valence electrons is the number of electrons in the outer shell of an atom. To determine the valence electron configuration of an element, you first select select the nearest noble gas preceding the element. For nickel, this would be argon. The electron configura...
by Chloe 3D
Thu Oct 08, 2015 10:52 pm
Forum: Limiting Reactant Calculations
Topic: Ratio between Products and Reactant
Replies: 1
Views: 422

Re: Ratio between Products and Reactant

I believe determining the molar ratio of reactants to products takes the same form regardless of the relative number of reactants and products. Your equation, 2NBr3 + 3NaOH ---> N2 + 3NaBr + 3HOBr is already balanced, so we can evaluate it from here. For every 2 moles of NBr3 that are reacted, you'l...
by Chloe 3D
Thu Oct 08, 2015 10:42 pm
Forum: Einstein Equation
Topic: Work Function
Replies: 1
Views: 533

Re: Work Function

The work function gives the minimum energy required to remove an electron from the metal surface. If the problem gives an energy of the photon which is higher than the work function, you will know that the electron has kinetic energy. If the problem gives an energy of the photon equal to the work fu...
by Chloe 3D
Sat Oct 03, 2015 5:36 pm
Forum: Photoelectric Effect
Topic: Light Intensity
Replies: 2
Views: 374

Re: Light Intensity

First it is important to note that intensity of radiation is an indication of the number of photons present, whereas E=hv is a measure of the energy of each individual photon. The way I tend to think about this is in terms of the work function. An electron can be driven out of the metal only if it r...

Go to advanced search