Search found 55 matches

by MCracchiolo 1C
Sat Mar 17, 2018 11:02 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Standard Gibbs Free Energy for Vaporization of Water
Replies: 2
Views: 431

Standard Gibbs Free Energy for Vaporization of Water

Why is the standard Gibbs Free Energy of the vaporization of water at 100C 0?
by MCracchiolo 1C
Tue Mar 13, 2018 10:37 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.63
Replies: 6
Views: 161

15.63

In question 15.63, why do we need to subtract 0.59 and where does this value come from?
by MCracchiolo 1C
Tue Mar 13, 2018 10:23 pm
Forum: *Enzyme Kinetics
Topic: 15.67
Replies: 2
Views: 189

15.67

Would someone be able to explain why 15.67 uses the ratio of activation energies? i.e. How would I have known to substitute Ea(cat) without looking at the solution manual?
by MCracchiolo 1C
Mon Mar 05, 2018 8:42 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Steps
Replies: 1
Views: 54

Slow Steps

In lecture on Friday (I believe), Lavelle discussed how the reaction between NO2 and CO in a series of steps in order to determine the rate law. The rate law was determined by the slow step of NO2 and NO2 reacting giving the rate law of k[NO2]^2.... if the slow step had been the reaction between NO3...
by MCracchiolo 1C
Mon Mar 05, 2018 8:38 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Overall reaction order
Replies: 3
Views: 118

Re: Overall reaction order

The overall reaction order would be a fraction if changing the concentration of one reactant did not change the rate by a factor of 2 or 4. Similarly, the reaction order can be negative if increasing the concentration of a reactant decreases the rate instead of increasing it.
by MCracchiolo 1C
Mon Mar 05, 2018 8:36 am
Forum: General Rate Laws
Topic: Homework Problem 15.19C
Replies: 5
Views: 137

Re: Homework Problem 15.19C

For part c) you should see that 8.7=(1.25)(1.25)^2(1.25)^2 *k with each concentration being in mol/L if you use experiment 1... thus, k must have the units L^4*mol^-4*s^-1 in order to cancel with (mol/L)*(mol/L)^2*(mol/L)^2
by MCracchiolo 1C
Mon Feb 19, 2018 8:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.17
Replies: 1
Views: 92

14.17

For question 14.17, "Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron (II) chloride" ... How do you know which half reactions you are supposed to be using?
by MCracchiolo 1C
Mon Feb 19, 2018 8:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: OH- ions
Replies: 1
Views: 57

OH- ions

In question 14.15 part C, why is KOH added to the cell diagram?
by MCracchiolo 1C
Mon Feb 19, 2018 7:40 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 6
Views: 163

Re: Oxidation Numbers

Even if the overall charge is neutral?
by MCracchiolo 1C
Mon Feb 19, 2018 7:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.15
Replies: 1
Views: 118

14.15

In question 14.15, in the final cell diagram answer, why aren't Ag(s) and AgBr(s) separated by a comma even though they are in the same state?
by MCracchiolo 1C
Mon Feb 19, 2018 6:01 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 6
Views: 163

Oxidation Numbers

Do elements have oxidation numbers when it's just, for example, O2 or O3?
by MCracchiolo 1C
Mon Feb 12, 2018 9:43 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Example Problem 8.6
Replies: 1
Views: 89

Example Problem 8.6

In example 8.6 in chapter 8, to calculate the internal energy at constant pressure, why do you have to calculate it in two steps - heating to the final temperature at constant volume, followed by isothermal expansion?
by MCracchiolo 1C
Sun Feb 11, 2018 9:53 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Vaporization of Water
Replies: 1
Views: 88

Vaporization of Water

Why is the Gibbs Free Energy at 100 (degrees C) for the vaporization of water, zero?
by MCracchiolo 1C
Sun Feb 11, 2018 9:52 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Problem 9.75 Clarification
Replies: 1
Views: 71

Problem 9.75 Clarification

What is residual entropy and what is a trans-isomer?
by MCracchiolo 1C
Sun Feb 11, 2018 9:50 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Units of S and H
Replies: 4
Views: 322

Units of S and H

When calculating problems that involve DeltaS and DeltaH, if you multiply the standard enthalpies of formation or standard molar entropies by the number of moles in the balanced chemical equation, why are your answers still in kJ/mol and J/(K*mol)?
by MCracchiolo 1C
Mon Feb 05, 2018 10:47 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Intermolecular Forces
Replies: 2
Views: 72

Intermolecular Forces

How do the strengths of intermolecular forces affect Gibbs Free Energy?
by MCracchiolo 1C
Mon Feb 05, 2018 10:45 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Net Increases in Amount of Gas
Replies: 3
Views: 109

Net Increases in Amount of Gas

Section 9.8 states that a net increase in the amount of gas usually results in a positive entropy change. Is there ever a situation where that is not the case?
by MCracchiolo 1C
Mon Feb 05, 2018 10:43 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Figure 9.9 in Section 9.6
Replies: 1
Views: 86

Figure 9.9 in Section 9.6

Would someone be able to explain figure 9.9 in section 9.6 that describes a particle in a box?
by MCracchiolo 1C
Tue Jan 30, 2018 12:51 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Homework 9.5 [ENDORSED]
Replies: 11
Views: 349

Re: Homework 9.5 [ENDORSED]

It goes along with the same concept of q(system)=-q(surroundings) where the heat released by one system must be absorbed by something else and vice versa
by MCracchiolo 1C
Tue Jan 30, 2018 12:47 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy and irreversible/reversible reactions
Replies: 1
Views: 84

Re: Entropy and irreversible/reversible reactions

Reversible: (One that can be reversed by an infinitesimally small change in variable; i.e. the example where the internal and external pressure of a gas inside a container are equal and a slight change in either would force the piston in one direction or another) Irreversible: (Work done against a c...
by MCracchiolo 1C
Tue Jan 30, 2018 12:34 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.11 P is inverse of V
Replies: 2
Views: 91

Re: 9.11 P is inverse of V

The concept of P is the inverse of V comes from Boyle's Law, "For a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional."

Meaning, P(1)V(1)=P(2)V(2)
by MCracchiolo 1C
Mon Jan 29, 2018 9:53 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible vs. Reversible Pathways
Replies: 3
Views: 103

Irreversible vs. Reversible Pathways

Chapter 9 states, "This independence means that, if we want to calculate the entropy difference between a pair of states joined by an irreversible path, we can look for a reversible path between the same two states and then use Eq. 1 for that path." What is meant by a reversible path compa...
by MCracchiolo 1C
Mon Jan 22, 2018 3:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Formula Sheet - Molar Heat Capacities of Ideal Gases
Replies: 1
Views: 112

Formula Sheet - Molar Heat Capacities of Ideal Gases

On the Formula Sheet, C(p) and C(v) are listed as (5/2)R and (3/2)R respectively, but in the book, those equations are only for atoms. If we are given an ideal gas such as O2(g)...Do we have to know that linear molecules are C(p)=(7/2)R and C(v)=(5/2)? Or for the tests, is it okay if we use the form...
by MCracchiolo 1C
Sun Jan 21, 2018 1:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sulfur, S(s)
Replies: 1
Views: 84

Sulfur, S(s)

What is the difference between S(s), rhombic and S(s), monoclinic?
by MCracchiolo 1C
Sun Jan 21, 2018 12:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.99 Enthalpies of Formation [ENDORSED]
Replies: 3
Views: 153

8.99 Enthalpies of Formation [ENDORSED]

In the solution manual for 8.99, the calculated reaction enthalpy is found by the equation Delta H (RXN) = -153.89 +2(-167.16)-2(-167.16)-0 = -153.89 kJ/mol ...but the balanced chemical equation is 2HCl(aq)+Zn(s) --> H2(g)+ZnCl2(aq) Shouldn't the standard enthalpy of formation for H2 gas be 0? And w...
by MCracchiolo 1C
Sat Jan 20, 2018 11:18 am
Forum: Calculating Work of Expansion
Topic: 8.13 - Understanding the Solution
Replies: 2
Views: 112

8.13 - Understanding the Solution

For question 8.13, "In a combustion cylinder, the total energy change produced from the burning of a fuel is -2573 kJ. The cooling system that surrounds the cylinder absorbs 947 kJ as heat. How much work can be done by the fuel in the cylinder?" The answer, 1626 kJ...Is that the amount of ...
by MCracchiolo 1C
Thu Jan 18, 2018 9:06 pm
Forum: Calculating Work of Expansion
Topic: Question 8.27 Conversion
Replies: 2
Views: 101

Question 8.27 Conversion

In question 8.27, I got to the point of 2.23 L*atm for work, but in the solution manual, where does the 101.325 J*L-1*atm-1 come from?
by MCracchiolo 1C
Mon Jan 15, 2018 3:01 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Units
Replies: 2
Views: 132

Units

How do I know when my units should be in kJ or in kJ*mol^-1?
by MCracchiolo 1C
Mon Jan 15, 2018 2:41 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Calculations with Bond Enthalpies (67b)
Replies: 1
Views: 81

Calculations with Bond Enthalpies (67b)

In question 67, part b, the bond enthalpies are listed for O2 and H2, but how do I account for the contribution of carbon as graphite when calculating?
by MCracchiolo 1C
Mon Jan 15, 2018 2:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Standard Enthalpies of Formation
Replies: 1
Views: 89

Standard Enthalpies of Formation

When trying to calculate the standard enthalpy of formation for a compound, I understand you use the reactants in their most stable forms, but how do I know whether the product formed is in the right state?
by MCracchiolo 1C
Mon Jan 15, 2018 11:38 am
Forum: Environment, Fossil Fuels, Alternative Fuels
Topic: Energy Density
Replies: 5
Views: 373

Energy Density

How does energy density affect the efficiency of a fuel and for example, how far a car can drive?
by MCracchiolo 1C
Mon Jan 15, 2018 11:35 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Difference in Standard Enthalpy of Formation and Standard Reaction Enthalpy
Replies: 1
Views: 76

Difference in Standard Enthalpy of Formation and Standard Reaction Enthalpy

What is the difference between the standard enthalpy of formation and the standard reaction enthalpy?
by MCracchiolo 1C
Sat Jan 13, 2018 3:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Nonexpansion Work vs. Expansion Work
Replies: 1
Views: 87

Nonexpansion Work vs. Expansion Work

What is the difference between non expansion work and expansion work, and what does it mean when the book says "at constant volume and no non expansion work" where the change in internal energy is equal to q?
by MCracchiolo 1C
Fri Dec 08, 2017 9:42 pm
Forum: Hybridization
Topic: Bond Angles [ENDORSED]
Replies: 4
Views: 2693

Re: Bond Angles [ENDORSED]

Oh! So 4 regions of electron density or sp^3 for example would still be tetrahedral?
by MCracchiolo 1C
Fri Dec 08, 2017 9:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Space for Additional Complexes [ENDORSED]
Replies: 1
Views: 169

Space for Additional Complexes [ENDORSED]

If we are given a coordination compound with a coordination number less than 6, do we assume we can add complexes to the central metal until we reach a coordination number of 6?
by MCracchiolo 1C
Tue Dec 05, 2017 10:14 pm
Forum: Lewis Acids & Bases
Topic: Identifying Oxides as Acidic or Basic (12.17)
Replies: 1
Views: 112

Identifying Oxides as Acidic or Basic (12.17)

What is the key to knowing if an oxide is acidic or basic?
by MCracchiolo 1C
Tue Dec 05, 2017 9:58 pm
Forum: Bronsted Acids & Bases
Topic: Net Ionic Equations
Replies: 2
Views: 225

Net Ionic Equations

How do I write a net ionic equation?
by MCracchiolo 1C
Wed Nov 29, 2017 4:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook pg. 118 Example [ENDORSED]
Replies: 1
Views: 126

Textbook pg. 118 Example [ENDORSED]

In my textbook on pg. 118, (in Chapter 4), figure 4.7 gives examples of polar vs. non polar molecules based on their VSEPR shapes... BrF3 is listed under AX3 as non polar, but seeing that BrF3 has a total of 28 valence electrons to use for the Lewis Structure, the central Br atom should have two lon...
by MCracchiolo 1C
Tue Nov 28, 2017 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K and Q [ENDORSED]
Replies: 5
Views: 227

Re: Units for K and Q [ENDORSED]

What does K(p) have to be in terms of? bar?
by MCracchiolo 1C
Tue Nov 28, 2017 9:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K and Q [ENDORSED]
Replies: 5
Views: 227

Units for K and Q [ENDORSED]

Even though K and Q do not have units, do the values you use to calculate K and Q need to be in specific units, say, (mol*L^-1)?
by MCracchiolo 1C
Tue Nov 28, 2017 8:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Mole Ratios in ICE Tables
Replies: 2
Views: 511

Mole Ratios in ICE Tables

When using ICE tables to calculate concentrations, do we have to factor in the number of moles of each species. If so, when do those coefficients factor into the calculations?
by MCracchiolo 1C
Tue Nov 28, 2017 5:37 pm
Forum: Hybridization
Topic: Ch 4 Question 75
Replies: 3
Views: 215

Ch 4 Question 75

After deducing that CH4O is sp^3 tetrahedral, how do I know whether or not the compound is polar?
by MCracchiolo 1C
Tue Nov 28, 2017 5:35 pm
Forum: Hybridization
Topic: Ch 4 Question 95
Replies: 1
Views: 134

Ch 4 Question 95

When looking at the sigma and pi bonds of CH2=CHCHO, how do you know which orbitals are hybridized and which aren't such as in the case of the C-H bond where the sigma bond is (C2sp^2, H1s)?
by MCracchiolo 1C
Tue Nov 28, 2017 5:33 pm
Forum: Hybridization
Topic: Bond Angles [ENDORSED]
Replies: 4
Views: 2693

Bond Angles [ENDORSED]

How do I measure the bond angles of hybridized orbitals?
by MCracchiolo 1C
Tue Nov 28, 2017 5:28 pm
Forum: Naming
Topic: (EDTA) and (en) Q17.37
Replies: 1
Views: 117

(EDTA) and (en) Q17.37

On Question 17.37, parts (c) and (d) contain the symbols (edta) and (en) within the chemical formula. What do these mean and how do I know that edta is hexadentate and en is bidentate?
by MCracchiolo 1C
Mon Nov 27, 2017 3:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Net Ionic Equations
Replies: 1
Views: 120

Net Ionic Equations

When writing the equilibrium expressions for fully dissociated ionic compounds, the book says to use the net ionic equation...Would someone be able to write the steps to finding the net ionic equation as a refresher from high school chem?
by MCracchiolo 1C
Mon Nov 27, 2017 3:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Section 11.2 Terminology -"Activities"
Replies: 1
Views: 104

Section 11.2 Terminology -"Activities"

In Section 11.2 of the book, when calculating the equilibrium constant, K, the authors use the terminology "activities" to describe the general expression for the equilibrium constant. Can we ignore this fact because we are assuming our gases are ideal gases and not real gases? Are "a...
by MCracchiolo 1C
Wed Nov 22, 2017 11:45 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 2
Views: 125

Coordination Number

What information can you deduce from knowing the coordination number? Why is it important?
by MCracchiolo 1C
Wed Nov 22, 2017 10:17 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Localization and Delocalization [ENDORSED]
Replies: 1
Views: 240

Localization and Delocalization [ENDORSED]

What is the difference between talking about localized bonds with regard to Valence-Bond Theory and delocalized bonds in Molecular Orbital Theory?
by MCracchiolo 1C
Fri Nov 17, 2017 12:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: General Understanding of Coordination Sphere
Replies: 2
Views: 210

General Understanding of Coordination Sphere

What is the general definition and significance of the coordination sphere with transition metals?
by MCracchiolo 1C
Tue Nov 14, 2017 3:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Radicals and Their Shape
Replies: 4
Views: 200

Radicals and Their Shape

When using VSEPR and Lewis structures to describe radicals, is a lone electron treated as its own region of electron density? How does a lone electron affect the shape?
by MCracchiolo 1C
Tue Nov 07, 2017 4:31 pm
Forum: Lewis Structures
Topic: Resonance Structures
Replies: 1
Views: 111

Resonance Structures

Do structures such as that for ONF have resonance even though the atoms bonded to the central atom (N) are not the same?
by MCracchiolo 1C
Tue Nov 07, 2017 4:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Ions
Replies: 2
Views: 136

Electron Configuration of Ions

For group 13, would someone be able to explain the reasoning behind the elements forming 3+ ions in the context of their electron configurations? Thank you!
by MCracchiolo 1C
Thu Oct 05, 2017 11:23 pm
Forum: Limiting Reactant Calculations
Topic: M19
Replies: 3
Views: 224

M19

Looking for an explanation for the steps in problem M19 as you go from the grams of product to the formula of the reactant. Thank you!

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