Search found 53 matches
- Mon Mar 12, 2018 7:36 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: slow step
- Replies: 3
- Views: 536
Re: slow step
In this class it is only possible to have single slow step mechanisms.
- Mon Mar 12, 2018 7:35 pm
- Forum: First Order Reactions
- Topic: Pseudo First Order Reaction
- Replies: 7
- Views: 1795
Re: Pseudo First Order Reaction
You use a pseudo first order reaction when there is more than one reactant by making one of the reactant's concentrations very large so you can test the rate while manipulating the other reactant.
- Mon Mar 12, 2018 7:30 pm
- Forum: General Rate Laws
- Topic: Unique Reaction Rates [ENDORSED]
- Replies: 45
- Views: 170563
Re: Unique Reaction Rates [ENDORSED]
A unique rate is the same for all of the materials in the reaction (products and reactants) because it multiplies the change in substance by one over its coefficient.
- Mon Mar 05, 2018 10:38 am
- Forum: First Order Reactions
- Topic: half life
- Replies: 3
- Views: 592
Re: half life
'n' half lives refer to how many times the concentration has been halved at that point.
- Mon Mar 05, 2018 10:37 am
- Forum: General Rate Laws
- Topic: Rate laws and integrated rate laws
- Replies: 3
- Views: 619
Re: Rate laws and integrated rate laws
The differential rate law is the rate as a function of the concentration and the integrated rate law is the rate as a function of time.
- Mon Mar 05, 2018 10:35 am
- Forum: Balancing Redox Reactions
- Topic: Basic and Acidic conditions [ENDORSED]
- Replies: 11
- Views: 7100
Re: Basic and Acidic conditions [ENDORSED]
In acidic conditions the Hydrogen is balanced by H+ and H20 molecules and in basic conditions the Hydrogen is balanced by H20 and OH- molecules.
- Mon Feb 26, 2018 9:25 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Potential
- Replies: 9
- Views: 3283
Re: Cell Potential
These equations are essentially the same so you can use them interchangeably depending on which information you have.
- Mon Feb 26, 2018 9:22 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reaction Order
- Replies: 9
- Views: 2922
Re: Half Reaction Order
The oxidation half reaction includes the electrons on the right side of the arrow.
- Mon Feb 26, 2018 9:20 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: swapping signs of E values
- Replies: 8
- Views: 3797
Re: swapping signs of E values
You swipe the sign on the anode by using the equation Ecell=Ecathode-Eanode
- Thu Feb 22, 2018 2:38 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode vs Anode
- Replies: 4
- Views: 659
Re: Cathode vs Anode
You put solids on the outside and aqueous solutions on the inside.
- Thu Feb 22, 2018 2:37 pm
- Forum: Balancing Redox Reactions
- Topic: Gibbs free energy of half reactions
- Replies: 4
- Views: 746
Re: Gibbs free energy of half reactions
Yes since G is a state property it is additive.
- Thu Feb 22, 2018 2:37 pm
- Forum: Balancing Redox Reactions
- Topic: Writing and Balancing Half Reactions
- Replies: 6
- Views: 1089
Re: Writing and Balancing Half Reactions
1. Identify which species is being oxidized and which is being reduced. 2. Separate into half reactions. 3. For each one, balance the oxygen by adding H2O to the other side for each O you need. 4. Then balance the hydrogen by adding H+ to the side that needs it. 5. Make sure the reduction and oxidat...
- Mon Feb 12, 2018 9:04 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Pressure
- Replies: 3
- Views: 561
Re: Pressure
Work does affect pressure. W=-PdV
- Mon Feb 12, 2018 9:02 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv vs. Cp [ENDORSED]
- Replies: 13
- Views: 12042
Re: Cv vs. Cp [ENDORSED]
Cv is when the volume is constant and Cp is when the pressure is constant.
- Mon Feb 12, 2018 8:59 pm
- Forum: Phase Changes & Related Calculations
- Topic: Reversible
- Replies: 5
- Views: 1167
Re: Reversible
Reversible expansion does not have a constant pressure so you use w=-nRTln(V2/V1). Irreversible expansion has a constant external pressure so you use w = -(Pex)dV
- Thu Feb 08, 2018 6:09 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity
- Replies: 9
- Views: 1318
Re: Spontaneity
Negative delta G signifies spontaneity while positive delta G reactions are not spontaneous.
- Thu Feb 08, 2018 6:08 pm
- Forum: Van't Hoff Equation
- Topic: Constants
- Replies: 4
- Views: 755
Re: Constants
The change in enthalpy and entropy does not change between different temperatures in this equation so they can be treated as constant.
- Thu Feb 08, 2018 6:07 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Heat transfer
- Replies: 7
- Views: 887
Re: Heat transfer
There is work being done because W=PdeltaV and there is a change in volume therefore there must be a change in work as long as its not free expansion.
- Mon Jan 29, 2018 10:09 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Difference between systems? [ENDORSED]
- Replies: 8
- Views: 1112
Re: Difference between systems? [ENDORSED]
Open system - exchange energy and matter
Closed system - exchange only energy not matter
Isolated system - cannot exchange energy nor matter
Closed system - exchange only energy not matter
Isolated system - cannot exchange energy nor matter
- Mon Jan 29, 2018 10:08 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open System
- Replies: 16
- Views: 2388
Re: Open System
The three ways include adding/subtracting matter from a system, adding or removing heat energy from a system, or applying work on or from a system.
- Mon Jan 29, 2018 10:07 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Relationship between entropy and volume in liquids
- Replies: 5
- Views: 641
Re: Relationship between entropy and volume in liquids
If you increase the volume of any substance, the entropy also increases. However the entropy of gas is much larger than that of liquids.
- Sun Jan 28, 2018 8:05 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Energy and matter?
- Replies: 6
- Views: 753
Re: Energy and matter?
Yes in open systems both energy and matter can be transferred. In closed systems only energy, but not matter, can be transferred. In isolated systems neither energy nor matter can be transferred.
- Sun Jan 28, 2018 8:04 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated vs. Adiabatic system
- Replies: 8
- Views: 8675
Re: Isolated vs. Adiabatic system
In isolated systems, no energy is transferred to the surroundings. In an adiabatic system energy is not transferred as heat to surroundings but as work.
- Sun Jan 28, 2018 8:03 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed vs. Isolated
- Replies: 8
- Views: 1154
Re: Closed vs. Isolated
A closed system allows energy to be transferred but not matter. An isolated system allows neither energy or matter to be transferred.
- Sun Jan 21, 2018 10:13 pm
- Forum: Calculating Work of Expansion
- Topic: Types of Work [ENDORSED]
- Replies: 3
- Views: 492
Types of Work [ENDORSED]
Is the only type of work used in this class the expansion work? There are lots of other types of work listed in a table in the textbook
- Sun Jan 21, 2018 10:12 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimeters
- Replies: 2
- Views: 355
Bomb Calorimeters
Can all combustion or burning reactions be treated as if they are in a bomb calorimeter?
- Sun Jan 21, 2018 10:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 7
- Views: 855
Bond Enthalpies
Why when a bond enthalpy for a molecule is greater than that of another one is the the molecule more stable?
- Wed Jan 17, 2018 3:51 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimeters
- Replies: 2
- Views: 558
Bomb Calorimeters
Are all bomb calorimeters isolated systems?
- Wed Jan 17, 2018 3:50 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Temperature
- Replies: 2
- Views: 332
Standard Temperature
Why is 25 degrees C the standard temperature for reactions? Does it matter if the initial temperature is not 25degrees C?
- Wed Jan 17, 2018 3:49 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Extensive vs. Intensive
- Replies: 3
- Views: 501
Extensive vs. Intensive
What is the difference between extensive and intensive properties? Is this difference crucial to know for understanding the concepts?
- Thu Jan 11, 2018 6:30 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Liquids and Solids
- Replies: 3
- Views: 456
Liquids and Solids
If enthalpy change is in terms of gaseous substances, how do you determine the enthalpy change in the dissociation of a liquid or solid?
- Thu Jan 11, 2018 6:29 pm
- Forum: Phase Changes & Related Calculations
- Topic: Superheating
- Replies: 6
- Views: 3388
Superheating
What causes a substance to superheat or supercool? Is this common?
- Thu Jan 11, 2018 6:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar Heat Capacity
- Replies: 1
- Views: 243
Molar Heat Capacity
Why does molar heat capacity increase with molar complexity?
- Fri Dec 08, 2017 12:33 am
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Base Strength
- Replies: 2
- Views: 611
Base Strength
What makes one base stronger than another? I understand the rules for acids but the base rules seemed unclear.
- Fri Dec 08, 2017 12:29 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acid Strength
- Replies: 5
- Views: 3067
Acid Strength
Why is HF a stronger acid then HCl? I thought acid strength in this sense was determined by the electronegativity of the atom bonded to the H+ ion. Cl is more electronegative then F but on the homework it said that HF was stronger than HCl.
- Tue Nov 28, 2017 10:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Reaction Shift
- Replies: 1
- Views: 292
Chemical Reaction Shift
Since the equilibrium constant does not change, when a question asks which way the reaction shifts, is that referring to the value of Q?
- Tue Nov 28, 2017 10:14 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Dentates
- Replies: 1
- Views: 375
Dentates
How do you know what number of dentate a ligand is? Do you have to draw the lewis structure every time?
- Fri Nov 24, 2017 2:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Gases
- Replies: 1
- Views: 355
Gases
Why does adding inert gases not change the pressure of the gas?
- Fri Nov 24, 2017 2:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook Problem 11.47
- Replies: 1
- Views: 311
Textbook Problem 11.47
I am very confused as how to find the percent decomposed of a reactant. When using the ICE table for this problem, I keep getting that PCL3 is 73% decomposed.
- Thu Nov 16, 2017 6:49 pm
- Forum: Hybridization
- Topic: Extra P-Orbital
- Replies: 1
- Views: 318
Extra P-Orbital
Why when drawing the hybridized orbitals in Aufbau format is there sometimes an extra P-orbital above the hybridized ones?
- Thu Nov 16, 2017 6:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Radicals
- Replies: 4
- Views: 647
Radicals
How do you know where to put the radical when drawing a lewis structure?
- Wed Nov 08, 2017 11:38 pm
- Forum: Lewis Structures
- Topic: Exceptions
- Replies: 4
- Views: 533
Exceptions
Which two elements are the exceptions in the 3d sub shell?
- Wed Nov 08, 2017 11:37 pm
- Forum: Sigma & Pi Bonds
- Topic: Bonding
- Replies: 2
- Views: 651
Bonding
What is the difference between a sigma and a pi bond?
- Wed Nov 01, 2017 5:34 pm
- Forum: Lewis Structures
- Topic: Electron Configurations
- Replies: 2
- Views: 384
Electron Configurations
Which M3+ ions (where M is a metal) are predicted to have the following ground-state electron configurations:
(a) [Ar]3d6
(b) [Ar]3d5
The answer to
(a) is Co3+
(b) is Fe3+
I am just very confused as to where these answers came from.
(a) [Ar]3d6
(b) [Ar]3d5
The answer to
(a) is Co3+
(b) is Fe3+
I am just very confused as to where these answers came from.
- Wed Nov 01, 2017 5:30 pm
- Forum: Lewis Structures
- Topic: Electron Configurations
- Replies: 2
- Views: 541
Electron Configurations
Which M2+ ions (where M is a metal) are predicted to have the following ground-state electrons:
(a) [Ar]3d7
(b) [Ar]3d6
The answer to
(a) is Co2+
(b) is Fe2+
I am just very confused as to where these answers came from.
(a) [Ar]3d7
(b) [Ar]3d6
The answer to
(a) is Co2+
(b) is Fe2+
I am just very confused as to where these answers came from.
- Wed Oct 25, 2017 9:05 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Subshell Qualities
- Replies: 2
- Views: 564
Subshell Qualities
Why is 'The effect nuclear charge Zeff is independent of the number of electrons present in an atom." false?
- Wed Oct 25, 2017 9:02 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Values of Quantum Numbers
- Replies: 3
- Views: 1955
Values of Quantum Numbers
(a)How many values of the quantum number l are possible when n=7? (b)How many values of ml are allowed for an electron in a 6d-subshell? (c)How many values of ml are allowed for an electron in a 3p-subshell? (d)How many sub shells are there in the shell with n=4?
- Tue Oct 17, 2017 7:51 pm
- Forum: DeBroglie Equation
- Topic: Wavelike Properties
- Replies: 3
- Views: 804
Wavelike Properties
How do you know if a wavelength indicates a particle has wavelike properties or not?
- Tue Oct 17, 2017 7:49 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Formula
- Replies: 2
- Views: 373
Re: Rydberg Formula
I continue to get n=3.2 for this problem.
An excited hydrogen atom emits light with a frequency of 1.14 x 10^14 Hz to reach the energy level n=4. In what principle quantum level did the electron begin?
An excited hydrogen atom emits light with a frequency of 1.14 x 10^14 Hz to reach the energy level n=4. In what principle quantum level did the electron begin?
- Wed Oct 11, 2017 5:12 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Wavelengths of Electromagnetic Radiation
- Replies: 4
- Views: 2340
Wavelengths of Electromagnetic Radiation
What is a good way to remember the categories of electromagnetic radiation?
- Wed Oct 11, 2017 5:11 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Energy Level Series
- Replies: 2
- Views: 374
Energy Level Series
What do the energy levels conceptually mean or apply to (n=1,n=2,etc) when discussing the H-atom. How do the series names (Lymer, Balmer, etc) relate to anything?
- Mon Oct 02, 2017 4:02 pm
- Forum: Balancing Chemical Reactions
- Topic: Example H.1
- Replies: 3
- Views: 905
Re: Example H.1
Allowing for an improper fraction in your balanced equation makes it easier when initially balancing the equation so you don't have to do it in your head. However, a final balanced reaction should contain no fraction stoichiometric coefficients so simply multiply the entire equation by the denominat...
- Mon Oct 02, 2017 4:00 pm
- Forum: Empirical & Molecular Formulas
- Topic: Molarity (Fundamental G, Problem 5b) [ENDORSED]
- Replies: 1
- Views: 489
Molarity (Fundamental G, Problem 5b) [ENDORSED]
A student prepared a solution of sodium carbonate by adding 2.111 g of the solid to a 250.0-mL volumetric flask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a flask to obtain 4.98 mmol CO3^2- ion? I used the ...