## Search found 26 matches

Sun Mar 05, 2017 9:25 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Self test 4.4A
Replies: 2
Views: 347

### Re: Self test 4.4A

Noting that the y-axis is the potential energy, step 1 requires the most potential energy. Therefore it has the highest activation energy. The difference between TS 1 and the initial value has a greater energy barrier compared to the difference between TS 2 and the local energy minimum.
Sun Feb 26, 2017 8:31 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Boltzmann Distribution and Arrhenius Equation
Replies: 1
Views: 473

### Re: Boltzmann Distribution and Arrhenius Equation

The steric factor, denoted as P, takes into account the relative orientation of the molecules. Molecules have to be oriented in a certain way in order for the collision to break / form the bonds. The steric factor is used to calculate the rate constant, k, where k = (steric factor, P) x (collision f...
Sun Feb 26, 2017 8:18 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm #3b
Replies: 2
Views: 461

### Re: Midterm #3b

Also consider the phase changes from reactants to products.
Sun Feb 26, 2017 8:10 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K constant
Replies: 2
Views: 414

### Re: K constant

The larger the k value, the faster the rate of the reaction. Consider, Rate = k [A] for first order reactions.
Sun Feb 19, 2017 8:38 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Hw 15.35
Replies: 1
Views: 255

### Re: Hw 15.35

The equation, [A]=[A]0/1+[A]0*kt, is a second order integrated rate law and was used to derive its half life, which is t,(1/2) = 1 / (k[A]0). The second order integrated rate law was derived from the rate law, RATE = k[A]^2.
Sun Feb 12, 2017 10:35 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Example on page 50 in Course Reader
Replies: 1
Views: 309

### Re: Example on page 50 in Course Reader

Gold will not dissolve when delta G is positive because it will be a non-spontaneous process.
Sun Feb 12, 2017 10:30 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: When to Use Nernst
Replies: 1
Views: 316

### Re: When to Use Nernst

You would use Nernst Equation when the reaction is not at standard conditions and not at equilibrium.
Sun Feb 05, 2017 8:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Writing Cell Diagram?
Replies: 2
Views: 431

### Re: Writing Cell Diagram?

If you reverse the cell diagram, say from Cathode||Anode and that for the cathode and anode, Products|Reactants, then you have to change the sign of cell potential.
Sun Feb 05, 2017 7:56 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 1
Views: 231

### Re: Cell diagram

A comma represents the reactant and product that are in the same phase whereas a vertical line means they are in different phases.
Sun Feb 05, 2017 7:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework problem #13 (Chapter 14)
Replies: 1
Views: 283

### Re: Homework problem #13 (Chapter 14)

The process for writing a cell diagram is typically arranged, Anode||Cathode where || represents the salt bridge, | represents a change in phase, and a comma represents the same phase. Inert metallic component of an electrode is written on the outside of the cell diagram. Also, Reactant|Product for ...
Sun Feb 05, 2017 7:37 pm
Forum: Balancing Redox Reactions
Topic: Standard Reduction Potential
Replies: 3
Views: 396

### Re: Standard Reduction Potential

The standard reduction potential is an intensive property. Think of this mathematically. If you rearrange the equation to E = -(delta G) / nF, the value of G changes as n changes too so E stays the same.
Sun Jan 29, 2017 8:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.45 Help.
Replies: 1
Views: 279

### Re: 9.45 Help.

The temperature is 111K because that is the boiling point for CH4. The equation for change in entropy for vaporization is equal to the enthalpy of vaporization divided by the boiling point temperature ( delta S = delta H of vaporization / Temp. at boiling point ).
Mon Jan 16, 2017 1:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity: Lead vs. Diamond
Replies: 2
Views: 887

### Heat Capacity: Lead vs. Diamond

Why is the heat capacity of lead greater than that of diamond?
Mon Jan 16, 2017 1:22 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.65
Replies: 1
Views: 252

### Re: 8.65

The second equation is halved because we want to find the enthalpy of one mole of dinitrogen pentaoxide.
Sun Dec 04, 2016 10:27 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8505
Views: 1470430

### Re: Post All Chemistry Jokes Here

Students fear O-chem so much because they go through alkynes of trouble.
Sun Nov 27, 2016 8:48 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: HW 11-117
Replies: 1
Views: 344

### Re: HW 11-117

Because the glucose solution is considered very dilute, the change in solvent concentration due to water would be so insignificant that it can be ignored.
Sun Nov 27, 2016 8:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chapter 11 #89
Replies: 1
Views: 335

### Re: Chapter 11 #89

It is divided by 100 because the graph is given in kPa. You have to convert kPa to bar. 1 kPa equals 0.01 bar.
Sun Nov 20, 2016 8:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework Problem 11.41
Replies: 3
Views: 1326

### Re: Homework Problem 11.41

Start with the ICE chart and and convert the grams of CO2 to moles. Then knowing that there are 2 moles of NH3 for every one mole of CO2, moles of CO2 will be doubled for NH3. Be aware that NH4(NH2CO2) is a solid!
Sun Nov 20, 2016 8:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework Problem Chapter 11 #25
Replies: 5
Views: 654

### Re: Homework Problem Chapter 11 #25

The question asks you to refer to the chart from Table 11.2
Sun Nov 13, 2016 10:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 11.41
Replies: 1
Views: 287

### Re: HW 11.41

Subtracting 17.4g of CO2 from 25.0g of ammonium carbonate does not work. 25.0g of ammonium carbonate is present initially (before any reaction happened) but only 17.4g CO2 are present in equilibrium . Because 17.4g of CO2 are present in equilibrium, there are still still some amount of ammonium carb...
Sun Nov 06, 2016 7:14 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Problem 4.67
Replies: 1
Views: 351

### Re: Problem 4.67

The molecular orbital diagram is based on the atom's atomic number, not the number of their valence electrons. Therefore for atoms Z<8, the order should be pi then sigma, and for atoms Z greater than or equal 8, the order would be sigma the pi.
Sun Oct 30, 2016 5:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis structure and molecular shapes [ENDORSED]
Replies: 1
Views: 400

### Re: Lewis structure and molecular shapes[ENDORSED]

They are both technically the same, except that the structure on the right is more specific because the right represents the see-saw shape according to the VSEPR Model
Sun Oct 23, 2016 4:16 pm
Forum: Dipole Moments
Topic: Do Dipole Moments affect Bond Strength?
Replies: 2
Views: 2642

### Re: Do Dipole Moments affect Bond Strength?

The difference in electronegativity is also described as the average of the ionization energy and the electron affinity. Therefore the higher the ionization energy, the larger electronegativity difference is and hence, the more electronegative, the more ionic the bond is. The strength of the bond is...
Sun Oct 09, 2016 9:27 pm
Forum: Photoelectric Effect
Topic: problem 1.69
Replies: 1
Views: 301

### Re: problem 1.69

First, you need to convert 2.93 eV to joules because work function should be in joules. 1eV is 1.602x10^-19 J.
And to set this up, you need to compare which laser provides the most energy.
Fri Sep 30, 2016 9:34 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.19 Solutions Manual Explanation
Replies: 1
Views: 447

### Re: G.19 Solutions Manual Explanation

You have to divide the total volume again because the equation is M (initial) x V (initial) = M (final) x V (final), where the diluted solution is the final phase.
Fri Sep 30, 2016 9:28 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Question
Replies: 2
Views: 1929

### Re: Limiting Reactant Question

A) To find the limiting reagant for the formation of P4O10, you would use stoichiometry to compare the usage of oxygen by P4 in both reactions. Given that 5.77g of oxygen is in the vessel, determine if there is enough oxygen present for the following reaction. B) Knowing that you have 5.77g of oxyge...