Search found 50 matches

by SitharaMenon2B
Sat Mar 17, 2018 7:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidation Power
Replies: 3
Views: 99

Re: Oxidation Power

Does this mean high oxidation power is the same as being a strong oxidation agent?
by SitharaMenon2B
Fri Mar 16, 2018 1:41 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Collision model
Replies: 1
Views: 83

Re: Collision model

The collision model assumes the reactants change immediately into products when they collide, while in the activated complex model it first forms an activated complex, and changes into products or reactants based on the amount of energy. I don't think we need to know the models in detail, since the ...
by SitharaMenon2B
Fri Mar 16, 2018 1:36 pm
Forum: General Rate Laws
Topic: Rate Constant Units
Replies: 1
Views: 82

Re: Rate Constant Units

the units of the rate constant are determined by the order of a reaction. they can be determined by using the rate law for that order and the units of rate (mol/L.s) and concentration (mol/L). for example, a first order reaction has rate=k[A], or k=rate/[A], so the units would be the unit of rate di...
by SitharaMenon2B
Sun Mar 11, 2018 3:23 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Elementary Step
Replies: 4
Views: 76

Re: Elementary Step

An elementary step is one part of the reaction mechanism. Each overall reaction is broken up into the individual reactions that occur, and each of these reactions is an elementary step. The rate law of the slow step will match the experimentally determined rate law.
by SitharaMenon2B
Sat Mar 10, 2018 3:26 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Reaction
Replies: 3
Views: 77

Re: Slow Reaction

The slow step is the step with the largest activation energy, and is the rate determining step (so the rate for the slow step will match the experimentally determined rate)
by SitharaMenon2B
Fri Mar 09, 2018 6:58 pm
Forum: Balancing Redox Reactions
Topic: Acidic vs. Basic Solutions [ENDORSED]
Replies: 4
Views: 142

Re: Acidic vs. Basic Solutions [ENDORSED]

For an acidic reaction you balance using H20 and H+ or H30+.
For a basic reaction you balance using H20 and OH-.
by SitharaMenon2B
Thu Mar 01, 2018 7:37 pm
Forum: General Rate Laws
Topic: Reactions higher than the second order [ENDORSED]
Replies: 3
Views: 105

Re: Reactions higher than the second order [ENDORSED]

Reactions higher than the second order are pretty rare, so for chem 14b, we only need to know 0, 1st, and 2nd order reactions
by SitharaMenon2B
Thu Mar 01, 2018 3:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell potential
Replies: 5
Views: 140

Re: Cell potential

Usually the pair with the more positive E° forms the cathode, and the less positive/more negative species forms the anode.
by SitharaMenon2B
Thu Mar 01, 2018 3:26 pm
Forum: First Order Reactions
Topic: Fractional Order Reactions [ENDORSED]
Replies: 3
Views: 148

Re: Fractional Order Reactions [ENDORSED]

It would be possible, but it's not common (since most reactions are 1st or 2nd order), and I don't think the reactions we'll be looking at in class will have a fractional order.
by SitharaMenon2B
Sun Feb 25, 2018 9:55 pm
Forum: General Rate Laws
Topic: Slow Step
Replies: 2
Views: 69

Slow Step

What is the slow step?
by SitharaMenon2B
Sun Feb 25, 2018 9:52 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetics vs Thermodynamics
Replies: 7
Views: 213

Re: Kinetics vs Thermodynamics

thermodynamics only looks at the initial and final state, while kinetics is focused on the path taken. When something is thermodynamically unstable or stable it does not affect whether it will be kinetically stable or unstable. However, the thermodynamic stability and kinetic stability together dete...
by SitharaMenon2B
Tue Feb 20, 2018 10:09 am
Forum: Balancing Redox Reactions
Topic: Balancing REDOX reactions
Replies: 5
Views: 167

Re: Balancing REDOX reactions

E would remain the same, it's not affected by the amount of electrons
by SitharaMenon2B
Mon Feb 12, 2018 9:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units of Delta H
Replies: 2
Views: 108

Re: Units of Delta H

For enthalpy of formation, the convention is to use kJ/mol, but for most other types of enthalpy (enthalpy of a reaction, for example) usually just kJ is okay
by SitharaMenon2B
Mon Feb 12, 2018 8:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: work and free energy
Replies: 2
Views: 77

Re: work and free energy

Free energy is the amount of energy that is free to do non-expansion work so delta G = we,max
by SitharaMenon2B
Mon Feb 12, 2018 8:51 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Formula Derivations
Replies: 1
Views: 83

Re: Formula Derivations

We don't have to know how to derive the formulas, just manipulate and combine the already derived formulas. The main derivations we did are on the equation sheet.
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Screen Shot 2018-02-12 at 8.50.14 PM.png (23.85 KiB) Viewed 81 times
by SitharaMenon2B
Sat Feb 10, 2018 2:03 pm
Forum: Calculating Work of Expansion
Topic: irreversible reactions
Replies: 4
Views: 265

Re: irreversible reactions

A reversible reaction occurs at equilibrium, while an irreversible reaction is not at equilibrium. Biological reactions are irreversible because irreversible reactions are usually much quicker.
by SitharaMenon2B
Sat Feb 10, 2018 1:54 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 11
Views: 450

Re: closed vs isolated

No, specifying the system as closed or isolated doesn't mean that the pressure or volume are constant.
by SitharaMenon2B
Sat Feb 10, 2018 1:40 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy being a state function
Replies: 2
Views: 72

Re: Entropy being a state function

Yes, for any state function the answer would be the same for a reversible or irreversible path.
by SitharaMenon2B
Tue Jan 30, 2018 10:15 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 9.27 A
Replies: 5
Views: 159

Re: 9.27 A

The trend is that the more complex a molecule is, the higher the molar entropy is. This is because a more complex molecule with more atoms can be arranged in a lot more configurations.
by SitharaMenon2B
Mon Jan 29, 2018 11:30 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: isothermal
Replies: 3
Views: 117

Re: isothermal

If it is isothermal, then the temperature doesn't change.
by SitharaMenon2B
Mon Jan 29, 2018 11:22 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: unit of entropy
Replies: 11
Views: 277

Re: unit of entropy

The units are usually listed as Joules per Kelvin (J.K-1)
by SitharaMenon2B
Tue Jan 23, 2018 10:23 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.21
Replies: 1
Views: 62

Re: 8.21

It means you don't need to consider the heat capacity of the vessel, and it can be ignored in calculating the solution. Only the copper and the water need to be considered.
by SitharaMenon2B
Tue Jan 23, 2018 10:01 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: mass in q = m(c) delta t
Replies: 5
Views: 347

Re: mass in q = m(c) delta t

Specific heat capacity always uses grams, while molar heat capacity uses moles. So for specific heat capacity you would never need to convert to moles.
by SitharaMenon2B
Tue Jan 23, 2018 9:59 pm
Forum: Calculating Work of Expansion
Topic: reversible and irreversible
Replies: 2
Views: 90

Re: reversible and irreversible

A reversible process means that it can be reversed by a very small change, while an irreversible process cannot be. For reversible expansion, it occurs when the internal and external pressure are equal (the system is at equilibrium)
by SitharaMenon2B
Sat Jan 20, 2018 7:37 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy
Replies: 3
Views: 92

Re: Enthalpy

Enthalpy measures the heat given off or absorbed when a reaction is held at a constant pressure. When it's not constant pressure, it's just heat, not enthalpy.
by SitharaMenon2B
Sat Jan 20, 2018 7:26 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Heating/Cooling A System
Replies: 4
Views: 179

Re: Heating/Cooling A System

You can add energy to an open system by doing work on the system.
by SitharaMenon2B
Sat Jan 20, 2018 7:12 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: When is the change in work or heat = to zero?
Replies: 2
Views: 105

Re: When is the change in work or heat = to zero?

A bomb-calorimeter always has a constant volume, and any time volume is constant, then work = 0. This is because work is force x distance, and at a constant volume distance is 0.
by SitharaMenon2B
Mon Jan 15, 2018 11:21 am
Forum: Phase Changes & Related Calculations
Topic: Questions about Heat
Replies: 3
Views: 116

Re: Questions about Heat

Heat refers to energy that is transferred. The type of energy would not be heat, but thermal energy.
by SitharaMenon2B
Fri Jan 12, 2018 11:17 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Example 8.13
Replies: 2
Views: 105

Re: Example 8.13

You can figure out which bonds need to be broken and which ones need to be formed by drawing out the lewis structures of the reactants and products.
by SitharaMenon2B
Thu Jan 11, 2018 4:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies vs. Standard Enthalpies of Formation
Replies: 2
Views: 81

Re: Bond Enthalpies vs. Standard Enthalpies of Formation

Bond enthalpy is the amount of energy needed to break a bond, while the standard enthalpy of formation is the amount of energy needed to form a compound, or to create the bond.
by SitharaMenon2B
Mon Dec 04, 2017 11:14 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate Acid and Base
Replies: 5
Views: 221

Re: Conjugate Acid and Base

You can find the conjugate acid by adding an H+, since when a base accepts a proton it it becomes the conjugate acid. When an acid donates a proton it would become a conjugate base, so you would fine the conjugate base by removing an H+.
by SitharaMenon2B
Mon Dec 04, 2017 11:10 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 12.17
Replies: 3
Views: 138

Re: 12.17

I don't think it would work to only consider the Bronsted definitions, but for the Lewis definition, you could draw out the lewis structure of each and see if it can accept a lone pair of electrons (which would make it a Lewis acid) or if it can donate a lone pair of electrons (which would make it a...
by SitharaMenon2B
Wed Nov 29, 2017 9:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.35 Chelating Complexes
Replies: 4
Views: 214

Re: 17.35 Chelating Complexes

Chelating complexes are when the ligands form a ring that includes the central metal, and form with polydentate ligands. For 17.35, only isomer b can bind both amine groups to the same transition metal centers. A and c wouldn't work because the amine groups would have to bind to two different transi...
by SitharaMenon2B
Tue Nov 28, 2017 8:28 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination compounds
Replies: 1
Views: 108

Re: coordination compounds

You can look at the chemical formula to see how many ligands are attached. For example, [Fe(CN)6]4- has 6 CN- ligands, so it would have 6 bonds.
by SitharaMenon2B
Sun Nov 26, 2017 7:55 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: #4.29? Determining which isomer has the largest dipole moment?
Replies: 2
Views: 158

Re: #4.29? Determining which isomer has the largest dipole moment?

The strength of the dipole is based on the angles of the polar bonds. Since polar bonds in opposite directions cancel out, the bonds that cancel the least will be the strongest. The polar Cl bonds for isomer 1 are closer to going in the same direction than the bonds for isomer 2, therefore the bonds...
by SitharaMenon2B
Sun Nov 26, 2017 7:49 pm
Forum: Naming
Topic: Roman numeral placement
Replies: 4
Views: 175

Re: Roman numeral placement

Often if the roman numeral is in the middle, it's because the part after is outside the coordination sphere, and would be listed after the metal.
by SitharaMenon2B
Sun Nov 26, 2017 7:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How to predict bond angles?
Replies: 3
Views: 157

Re: How to predict bond angles?

Bond angles are based on the shape and lone pairs of a molecule. For example, all molecules with AX4 (4 atoms bonded to the central atom) will be tetrahedral and will have bond angles of 109.5. When there are lone pairs, the angles are decreased, but the exact angle is specific to the molecule. Two ...
by SitharaMenon2B
Sun Nov 26, 2017 7:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sigma and Pi bonds
Replies: 2
Views: 137

Re: Sigma and Pi bonds

Sigma bonds are formed when orbitals are end to end, and pi bonds are formed when orbitals are side by side. Hybridization explains the shape and orientation of the orbitals, which is needed to see if they overlap end to end or side by side. If one bond is formed end to end ( a sigma bond), it's imp...
by SitharaMenon2B
Wed Nov 08, 2017 5:21 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Principal Energy Level Change Sig Figs
Replies: 2
Views: 135

Re: Principal Energy Level Change Sig Figs

I think you can use the lowest number of sig figs that the constants are given in. For example, Planck's constant and Rydberg's constant are both given with 6 sig figs, so I think you would use 6 sig figs in your answer.
by SitharaMenon2B
Wed Nov 08, 2017 5:18 pm
Forum: Lewis Structures
Topic: Lewis Structure of N2O
Replies: 2
Views: 190

Re: Lewis Structure of N2O

The structure with the -1 formal charge on oxygen would be more stable since oxygen is more electronegative than nitrogen, and the structure is most stable with the negative formal charge on the most electronegative atom.
by SitharaMenon2B
Thu Nov 02, 2017 9:24 pm
Forum: Trends in The Periodic Table
Topic: first and second ionization energies [ENDORSED]
Replies: 3
Views: 233

Re: first and second ionization energies [ENDORSED]

It would be harder to remove the 2nd electron than the first because once the first electron is removed the atom becomes a cation, and the positive charge will have a much stronger pull on the electrons. Also, I think having a full s orbital would not make it harder to remove an electron, having a f...
by SitharaMenon2B
Thu Nov 02, 2017 9:14 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1.45
Replies: 2
Views: 153

Re: 1.45

It's because the + or - 5 is the uncertainty, and since it can be 5m/s in each direction, the total uncertainty is 2x5=10m/s.
by SitharaMenon2B
Thu Oct 26, 2017 3:43 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 148

Re: Electron Affinity

A high positive electron affinity means that it is easy to add an electron, since electron affinity is the energy released when an electron is added. If the electron affinity is a very large negative number it will be difficult to add an electron , since energy would be required instead of released.
by SitharaMenon2B
Thu Oct 26, 2017 3:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuraiton
Replies: 2
Views: 171

Re: Electron Configuraiton

The convention is to only use a noble gas, since the electron configurations for noble gases have a full valence shell and are stable.
by SitharaMenon2B
Sun Oct 22, 2017 9:26 pm
Forum: DeBroglie Equation
Topic: units for mass
Replies: 6
Views: 311

Re: units for mass

The De Broglie equation and the equation for kinetic energy both require mass (m) to be in kilograms
by SitharaMenon2B
Sun Oct 22, 2017 9:17 pm
Forum: Photoelectric Effect
Topic: Work Function [ENDORSED]
Replies: 5
Views: 237

Re: Work Function [ENDORSED]

For your second question, yes. If the energy of the photon is exactly equal to the work function, the electron would still be emitted, but it would not have any kinetic energy.
by SitharaMenon2B
Sun Oct 15, 2017 12:29 pm
Forum: Properties of Light
Topic: Excitation of electrons
Replies: 5
Views: 216

Re: Excitation of electrons

1 million electrons is correct because each photon interacts with one electron, and a photon will only be absorbed if it has enough energy to excite an electron, so for every photon that is absorbed, one electron is excited.
by SitharaMenon2B
Sun Oct 15, 2017 12:19 pm
Forum: Properties of Electrons
Topic: Speed/Energy of Electrons
Replies: 4
Views: 212

Re: Speed/Energy of Electrons

The frequency refers to the number of waves per second that pass a point in space , but the speed of light (in a vacuum) stays constant for every wave of light (it doesn't change for different frequencies).
by SitharaMenon2B
Sat Oct 07, 2017 4:44 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity unit [ENDORSED]
Replies: 11
Views: 638

Re: Molarity unit [ENDORSED]

Molarity as an SI unit is usually defined by moles per liter so I would say you probably should not use moles per mL
by SitharaMenon2B
Mon Oct 02, 2017 4:20 pm
Forum: Empirical & Molecular Formulas
Topic: Molarity (Fundamental G, Problem 5b) [ENDORSED]
Replies: 1
Views: 188

Re: Molarity (Fundamental G, Problem 5b) [ENDORSED]

If you don't round the molarity (I used 0.07967 M) then you get 0.0625 L, or 62.5 mL, which appears to be the right answer

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