Search found 53 matches

by Ryan Fang 1D
Wed Mar 14, 2018 10:33 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Initial rate against [A] for first order reaction
Replies: 1
Views: 81

Initial rate against [A] for first order reaction

Why is the plot of initial rate vs [A] for a first order reaction linear?
by Ryan Fang 1D
Wed Mar 14, 2018 10:18 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.85
Replies: 1
Views: 96

15.85

15.85 The following rate laws were each derived from an elementary reaction. In each case, write the chemical equation for the reaction, determine its molecularity, and draw a proposed structure for the activated complex: What does this question mean when it refers to drawing the activated complex? ...
by Ryan Fang 1D
Wed Mar 14, 2018 9:55 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.79 [ENDORSED]
Replies: 2
Views: 181

15.79 [ENDORSED]

15.79 In some reactions, two or more different products can be formed by different pathways. If the product formed by the faster reaction predominates, the reaction is considered to be under kinetic control. If the predominant product is the more thermodynamically stable, the reaction is considered ...
by Ryan Fang 1D
Sun Mar 11, 2018 10:09 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step
Replies: 3
Views: 149

Slow Step

Why does the slow step determine the rate of the reaction?
by Ryan Fang 1D
Sun Mar 11, 2018 10:08 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: What is A?
Replies: 4
Views: 158

What is A?

What is A in the Arrhenius Equation? Will it be given or will we need to calculate it?
by Ryan Fang 1D
Sun Mar 11, 2018 9:17 pm
Forum: General Rate Laws
Topic: Rate Law sign
Replies: 3
Views: 149

Rate Law sign

Can a rate be negative and why?
by Ryan Fang 1D
Sun Mar 04, 2018 2:36 pm
Forum: General Rate Laws
Topic: Rate Law
Replies: 3
Views: 147

Rate Law

Why is the rate law for reactants negative?
by Ryan Fang 1D
Sun Mar 04, 2018 2:33 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Purpose of intermediate?
Replies: 2
Views: 115

Purpose of intermediate?

What is the reason for using an intermediate?
by Ryan Fang 1D
Sun Mar 04, 2018 2:28 pm
Forum: First Order Reactions
Topic: Significance of the order of a reaction?
Replies: 1
Views: 602

Significance of the order of a reaction?

What does the order of a reaction tell us about the reaction?
by Ryan Fang 1D
Mon Feb 26, 2018 11:01 am
Forum: Balancing Redox Reactions
Topic: Textbook 14.1
Replies: 3
Views: 170

Re: Textbook 14.1

I believe this would be a typo
by Ryan Fang 1D
Tue Feb 20, 2018 8:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 3
Views: 124

Cell Diagram

When you do a cell diagram, when do you use commas (,) and when do you use slashes (|)?
by Ryan Fang 1D
Mon Feb 19, 2018 1:24 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.25
Replies: 1
Views: 59

14.25

For question 14.25, when asked which metal is a better reducing agent, how do we know whether to use the Cr2+ or Cr3+ standard reduction potentials. Similarly, how do we know whether to use the Fe2+ or Fe3+ standard reduction potentials?
by Ryan Fang 1D
Tue Feb 13, 2018 9:21 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible Expansion and Total Entropy
Replies: 1
Views: 123

Reversible Expansion and Total Entropy

Why is total entropy = 0 in reversible expansion?

Thanks for the help!
by Ryan Fang 1D
Tue Feb 13, 2018 11:15 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.15
Replies: 2
Views: 151

11.15

(a) Calculate the reaction Gibbs free energy of I2(g) -> 2 I(g) at 1200. K (K =6.8) when the partial pressures of I2 and I are 0.13 bar and 0.98 bar, respectively. (b) What is the spontaneous direction of the reaction? Explain briefly. For this question, why does the solutions manual calculate ∆G° u...
by Ryan Fang 1D
Tue Feb 13, 2018 10:24 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.81
Replies: 1
Views: 99

11.81

A gaseous mixture consisting of 2.23 mmol N2 and 6.69 mmol H2 in a 500.-mL container was heated to 600. K and allowed to reach equilibrium. Will more ammonia be formed if that equilibrium mixture is then heated to 700. K? For N2(g) + 3 H2(g) -><- 2 NH3(g), K = 1.7 x 10^-3 at 600. K and 7.8 x 10^-5 a...
by Ryan Fang 1D
Sun Feb 11, 2018 1:42 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Total Entropy of the Freezing of Water
Replies: 2
Views: 295

Total Entropy of the Freezing of Water

Can someone explain, using calculations, how the total entropy of the universe increases during the freezing of water at 0 degrees Celsius, thus making it spontaneous? How would you calculate the change in entropy of the surroundings? I don't understand how to get a value other than 0 for the total ...
by Ryan Fang 1D
Sun Feb 11, 2018 1:07 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 9.13
Replies: 2
Views: 114

9.13

For HW question 9.13, why can you assume that there is one mole of nitrogen gas?

Thanks for the help!
by Ryan Fang 1D
Sat Feb 10, 2018 8:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Clausius Inequality [ENDORSED]
Replies: 1
Views: 131

Clausius Inequality [ENDORSED]

I'm confused about how the Clausius inequality does not contradict the idea that entropy is a state function. How can deltaS = qrev/T =qirrev/T due to the fact that it is a state function but then the Clausius Inequality states that deltaS > qirrev/T?

Thanks for the help!
by Ryan Fang 1D
Sun Feb 04, 2018 2:23 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible vs. Irreversible
Replies: 1
Views: 88

Reversible vs. Irreversible

Why can we use qrev in deltaS = qrev/T for irreversible expansion as well?
by Ryan Fang 1D
Sun Feb 04, 2018 1:19 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Entropy Definition
Replies: 1
Views: 112

Entropy Definition

Is there a reason why Dr.Lavelle wants us to avoid the word disorder when describing entropy?
by Ryan Fang 1D
Sun Feb 04, 2018 1:18 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Pulley and Vacuum
Replies: 2
Views: 141

Pulley and Vacuum

I'm slightly confused about the pulley and vacuum system that Dr.Lavelle discussed in lecture. He mentioned that work is done by a system expanding into a vacuum if mass from the pulley is removed or something along those lines. Can someone explain why this is so? Thank you!
by Ryan Fang 1D
Tue Jan 23, 2018 9:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.77 Bond Enthalpy (Benzene)
Replies: 2
Views: 118

Re: 8.77 Bond Enthalpy (Benzene)

While you can add the 6 C-H bonds into both calculations, because you are finding the difference between your two calculations, adding the C-H bonds to both won't make a difference.
by Ryan Fang 1D
Tue Jan 23, 2018 8:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Isothermal expansion
Replies: 3
Views: 127

Re: Isothermal expansion

The equation for deltaU is deltaU = q + w. If deltaU = 0 = q + w, we can subtract w to the other side to get q = -w
by Ryan Fang 1D
Tue Jan 23, 2018 8:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Reaction Enthalpy units
Replies: 1
Views: 88

Standard Reaction Enthalpy units

Are the units for standard reaction enthalpy kj/mol? If so, what are the units if there are two moles of the substance in the standard reaction? Finally, why does the textbook list the standard reaction enthalpies next to the thermochemical equations as only having kj for their units?
by Ryan Fang 1D
Sun Jan 21, 2018 12:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reaction Enthalpy units
Replies: 1
Views: 52

Reaction Enthalpy units

should the units for reaction enthalpies be kj or kj/mol?
by Ryan Fang 1D
Sat Jan 20, 2018 1:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of Formation
Replies: 3
Views: 103

Standard Enthalpy of Formation

How do you tell what is a standard enthalpy of formation?
by Ryan Fang 1D
Sat Jan 13, 2018 12:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Not a State Property
Replies: 6
Views: 180

Heat Not a State Property

Why isn't heat a state property?
by Ryan Fang 1D
Sat Jan 13, 2018 12:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bonds Formed Exothermic
Replies: 2
Views: 106

Bonds Formed Exothermic

Why is energy released when bonds are formed?
by Ryan Fang 1D
Fri Jan 12, 2018 12:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What type of system is a Bomb Calorimeter?
Replies: 4
Views: 508

What type of system is a Bomb Calorimeter?

Is a bomb calorimeter a closed system, because the inner chamber can transfer energy in the form of heat but cannot transfer matter to the water it is surrounded by ? Or is it an insulated system because the bomb calorimeter itself is insulated from the outside environment?
by Ryan Fang 1D
Sat Dec 09, 2017 1:30 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: calculating pH
Replies: 3
Views: 186

Re: calculating pH

He was referring to if you add a small quantity of a weak acid and you calculate the pH/ [H3O+], you'll get what looks like a strong base. He was saying that should make you question it because why would adding a small amount of weak acid result in a strong base? So, he brought of the point that th...
by Ryan Fang 1D
Sat Dec 09, 2017 12:33 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: calculating pH
Replies: 3
Views: 186

calculating pH

I recall in Friday lecture, Dr.Lavelle was talking about how if the concentration of H3O+ is less than 10^-7, the solution then the solution is considered neutral. He brought up numbers like 0.0000001 M H3O+ and 0.0000000001 M H3O+ and he said that if you take the negative log of the smaller number,...
by Ryan Fang 1D
Fri Dec 08, 2017 11:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs Kp
Replies: 3
Views: 130

Kc vs Kp

I noticed that when the textbook refers to K, usually it is referring to Kp. However, I noticed on test 4 and some in lecture examples that sometimes Dr.Lavelle calls the equilibrium constant K when he is referring to Kc. So when K is referenced on the final would we use Kc or Kp?
by Ryan Fang 1D
Tue Dec 05, 2017 7:38 pm
Forum: Bronsted Acids & Bases
Topic: When is does a compound act as an acid or base?
Replies: 1
Views: 110

When is does a compound act as an acid or base?

For example, how would we know if HCO3- loses its H+ proton in water or gains an H+ proton?
by Ryan Fang 1D
Tue Dec 05, 2017 7:02 pm
Forum: Bronsted Acids & Bases
Topic: Chemical equation for dissociation of strong acids
Replies: 2
Views: 191

Chemical equation for dissociation of strong acids

When we write the equation for dissociation of strong acids, should we use an equilibrium arrow like with weak acids or should we use a one direction arrow to represent complete dissociation?
by Ryan Fang 1D
Mon Dec 04, 2017 12:48 pm
Forum: Conjugate Acids & Bases
Topic: No conjugate acid or base? [ENDORSED]
Replies: 1
Views: 139

No conjugate acid or base? [ENDORSED]

Can there ever be a situation where there is no conjugate acid or base?
by Ryan Fang 1D
Mon Dec 04, 2017 12:36 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Difference between pH and pKa?
Replies: 4
Views: 306

Difference between pH and pKa?

Is there a difference between these two values or are they the same?
by Ryan Fang 1D
Fri Nov 24, 2017 9:55 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxalate Ligand Bonding
Replies: 1
Views: 94

Oxalate Ligand Bonding

Which oxygens of the oxalate ligand attach to the central metal atom? Is it two oxygens attached to one carbon or one oxygen from each carbon?
by Ryan Fang 1D
Fri Nov 24, 2017 8:42 pm
Forum: Naming
Topic: Cyano vs Cyanido
Replies: 3
Views: 194

Cyano vs Cyanido

I've heard both of these and I'm not sure which is correct. I've also heard chloro and chlorido. Can someone help please? Thank you!
by Ryan Fang 1D
Sun Nov 19, 2017 10:16 pm
Forum: Hybridization
Topic: Hybridization
Replies: 2
Views: 133

Re: Hybridization

I think that, with practice, the electron geometry of some common molecules becomes intuitive, allowing you to figure out hybridization based off the number of regions of electron density. However, I think it is always best to use the Lewis structure to double check you work. Hope this helps!
by Ryan Fang 1D
Sun Nov 19, 2017 3:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Listing all Bond Angles
Replies: 2
Views: 131

Listing all Bond Angles

Is it important to list every single bond angle of a molecule? For example, SF6 has an octahedral shape and normally, I would say that all the bond angles are 90 degrees. However, there are bond angles in an octahedral shape that are 180 degrees, such as the bond angle between axial F, S atom, and t...
by Ryan Fang 1D
Sun Nov 19, 2017 3:48 pm
Forum: Hybridization
Topic: Hybridization for CH2?
Replies: 1
Views: 458

Hybridization for CH2?

Does CH2 require hybridization? It seems like the two hydrogen atoms would bond with the unpaired electrons in the 2p orbital of carbon without the need for hybridization. If this is so, why doesn't CH2 form instead of CH4?
by Ryan Fang 1D
Fri Nov 17, 2017 5:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for Seesaw?
Replies: 1
Views: 695

Bond Angles for Seesaw?

What would be the bond angles of a Seesaw molecular geometry? The lone pair should affect the equatorial bond angles by making them less than 120, but does the lone pair affect the axial bond angle?
by Ryan Fang 1D
Tue Nov 14, 2017 11:44 pm
Forum: Hybridization
Topic: Does hybridization only occur when bonding?
Replies: 3
Views: 153

Does hybridization only occur when bonding?

Can an atom have hybridized orbitals when not bonded or in the process of bonding?
by Ryan Fang 1D
Tue Nov 14, 2017 11:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2 Lone Pairs and 2 Bonding Pairs vs 1 Lone Pair and 2 Bonding Pairs
Replies: 2
Views: 141

2 Lone Pairs and 2 Bonding Pairs vs 1 Lone Pair and 2 Bonding Pairs

How would the angles of a molecule with trigonal planar electron geometry and bent molecular shape (ClO2+) differ from a molecule with tetrahedral electron geometry and a bent molecular shape (H2O)?
by Ryan Fang 1D
Mon Nov 13, 2017 10:20 am
Forum: Ionic & Covalent Bonds
Topic: What type of bond is stronger? [ENDORSED]
Replies: 2
Views: 166

What type of bond is stronger? [ENDORSED]

What type of bond is stronger and what would we use to determine the bond strength?
by Ryan Fang 1D
Sat Nov 04, 2017 3:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Why does the Cu2+ ion form?
Replies: 1
Views: 219

Why does the Cu2+ ion form?

Cu+ has the electron configuration of [Ar]3d10. Cu2+ has the electron configuration of [Ar]3d9. Why does Cu2+ form? It doesn't seem like there is a reason for this ion.
by Ryan Fang 1D
Sat Nov 04, 2017 11:47 am
Forum: Lewis Structures
Topic: Expanded Octet
Replies: 1
Views: 132

Expanded Octet

Can an atom with an expanded octet ever not be the central atom? If so, how what would this look like?
by Ryan Fang 1D
Sat Nov 04, 2017 11:23 am
Forum: Lewis Structures
Topic: Boron and Beryllium
Replies: 1
Views: 142

Boron and Beryllium

Can someone explain why the elements Boron and Beryllium do not need to satisfy the octet rule?
by Ryan Fang 1D
Sat Oct 14, 2017 9:03 pm
Forum: Properties of Light
Topic: Halmiltonian of Schrodinger's Equation
Replies: 1
Views: 138

Halmiltonian of Schrodinger's Equation

Can someone explain in simpler terms what exactly each part of the hamiltonian for Schrodinger's equation means?
by Ryan Fang 1D
Sat Oct 14, 2017 8:39 pm
Forum: Properties of Light
Topic: How to use the Rydberg Formula? [ENDORSED]
Replies: 6
Views: 398

How to use the Rydberg Formula? [ENDORSED]

In a Rydberg equation problem, you are given two n values. The Rydberg formula is: frequency = R(1/n1^2 - 1/n2^2). How do I know which n comes first in the Rydberg formula? How do I know which one is n1 and which one is n2?
by Ryan Fang 1D
Thu Oct 05, 2017 9:06 pm
Forum: Significant Figures
Topic: 3 Sig Figs 1795.507? [ENDORSED]
Replies: 5
Views: 391

3 Sig Figs 1795.507? [ENDORSED]

How do you round this to 3 significant figures? 1800 only has two and 1796 has four significant figures. Thanks for the help!
by Ryan Fang 1D
Thu Oct 05, 2017 11:22 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Unit [ENDORSED]
Replies: 2
Views: 223

Formula Unit [ENDORSED]

What exactly is a formula unit? How does it differ from moles and molecules?

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