Search found 45 matches
- Sat Mar 14, 2020 8:45 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation
- Replies: 6
- Views: 484
Re: Nernst Equation
That conversion is useful when the system is at room temperature.
- Sat Mar 14, 2020 8:41 pm
- Forum: Van't Hoff Equation
- Topic: ln
- Replies: 34
- Views: 1782
Re: ln
Both sides should be raised to the power of e to get rid of ln and to get the answer.
- Sat Mar 14, 2020 8:38 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Electrolysis
- Replies: 6
- Views: 451
Re: Electrolysis
I think it would be a good idea since it is on the outline.
- Sat Mar 14, 2020 8:36 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: negative sign
- Replies: 12
- Views: 623
Re: negative sign
delta G*= -nFE
w(max)=-nFE
The system is doing work, so energy leaves the system resulting in -w.
w(max)=-nFE
The system is doing work, so energy leaves the system resulting in -w.
- Sat Mar 14, 2020 8:30 pm
- Forum: Balancing Redox Reactions
- Topic: oh
- Replies: 11
- Views: 776
Re: oh
OH- can be added to balance oxygen only if it is a basic solution.
- Sat Mar 14, 2020 8:28 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Delta S
- Replies: 8
- Views: 683
Re: Delta S
delta S(univ)= delta S(sys) + delta S(surr)
- Sat Mar 14, 2020 8:21 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: intensive vs extensive
- Replies: 12
- Views: 771
Re: intensive vs extensive
Extensive properties depend on the amount of substance, while intensive properties do not depend on the amount.
- Sat Mar 14, 2020 8:17 pm
- Forum: General Rate Laws
- Topic: integrals and derivatives
- Replies: 7
- Views: 564
Re: integrals and derivatives
I think the derivatives and integrals were to show how equations are derived.
- Sat Mar 14, 2020 8:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Gibbs free energy
- Replies: 9
- Views: 681
Re: Gibbs free energy
Delta G* is the Gibbs free energy at standard conditions which are 1M, 25 degrees C, and 1 atm.
- Sat Mar 14, 2020 8:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw and other constants
- Replies: 9
- Views: 679
Re: Kw and other constants
The w in Kw represents the equilibrium constant for water. KA x KB= Kw which is equal to [H30+][OH-].
- Sat Mar 14, 2020 8:05 pm
- Forum: Ideal Gases
- Topic: Partial Pressure
- Replies: 13
- Views: 691
Re: Partial Pressure
According to Le Chatelier's principle if there are more moles on the right side then the reaction shifts right creating more products.
- Sun Mar 08, 2020 9:47 pm
- Forum: First Order Reactions
- Topic: Graphing 1st order reaction rates
- Replies: 6
- Views: 375
Re: Graphing 1st order reaction rates
For first order reactions, ln[A] is graphed against time for a linear graph which gives the slope. If just [A] were graphed against time, then the graph would be exponential.
- Sun Mar 08, 2020 9:40 pm
- Forum: Second Order Reactions
- Topic: Termolecular
- Replies: 43
- Views: 2192
Re: Termolecular
Termolecular refers to the simultaneous collision of three species.
- Sun Mar 08, 2020 9:37 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A
- Replies: 8
- Views: 435
Re: A
[A] is the concentration of the reactants and [A]0 is the initial concentration.
- Sun Mar 08, 2020 9:30 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: K
- Replies: 11
- Views: 620
Re: K
The rate constant (k) depends on temperature and activation energy.
- Sun Mar 08, 2020 9:26 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Molecularity
- Replies: 12
- Views: 759
Re: Molecularity
Molecularity is the number of species in an elementary step meaning the number of molecules in a reaction that act as reactants.
- Sun Mar 08, 2020 9:22 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Diagram
- Replies: 21
- Views: 1113
Re: Cell Diagram
I think it is safe to assume that the anode will be on the left while the cathode will be on the right.
- Sun Mar 08, 2020 9:19 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: K < >
- Replies: 8
- Views: 534
Re: K < >
To determine if K is < or > 1 look at the ratio of the concentration of products over reactants. If there are more products than reactants, K>1. If there are more reactants than products, K<1. When K>1 (more products), the E of the cell will be positive.
- Sun Mar 01, 2020 10:03 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: when to use K or Q
- Replies: 18
- Views: 1055
Re: when to use K or Q
If the reaction is at equilibrium, then K is used, but if the reaction is not at equilibrium then Q is used.
- Sun Mar 01, 2020 10:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell potential
- Replies: 15
- Views: 770
Re: cell potential
If the E value is positive, this means that the deltaG value is negative, so the process is spontaneous.
- Sun Mar 01, 2020 9:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 12
- Views: 629
Re: Salt Bridge
A salt bridge allows ion transfer so the two solutions stay neutral. Without the salt bridge, e- transfer would stop due to charge buildup.
- Sun Mar 01, 2020 9:42 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic and Basic Reactions
- Replies: 9
- Views: 475
Re: Acidic and Basic Reactions
When balancing half reactions, H+ is added to balance H and OH- is added to balance O.
- Sun Mar 01, 2020 9:35 pm
- Forum: Balancing Redox Reactions
- Topic: oxidizing agents
- Replies: 11
- Views: 588
Re: oxidizing agents
The oxidizing agent has the ability to oxidize and is itself reduced. The reducing agent reduces and is itself oxidized.
- Sun Feb 23, 2020 6:39 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: standard conditions
- Replies: 8
- Views: 514
Re: standard conditions
Solutes with a concentration of 1M and gases of 1 atm at 273.15K are in standard condition.
- Sun Feb 23, 2020 6:31 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: work
- Replies: 8
- Views: 411
Re: work
If a system is doing work on its surroundings, then work is being lost and work is negative. If the surroundings are doing work on the system, then work is being gained and work is positive. In the case of a battery, the system is doing work so the amount of energy that leaves the system is negative.
- Sun Feb 23, 2020 6:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 4
- Views: 245
Re: Platinum
The left side of the cell diagram has a solid (copper), while the right side only has iron in aqueous states, so because of this a solid such as platinum is added to the right. The platinum is an inert conductor which acts as an electrode to transfer electrons.
- Thu Feb 20, 2020 5:33 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Adiabatic systems
- Replies: 14
- Views: 775
Re: Adiabatic systems
q will always equal 0 in adiabatic systems because there is no heat flow.
- Thu Feb 20, 2020 5:29 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 20
- Views: 1036
Re: Adding Inert Gas
When an inert gas is added, the pressure does increase, but there is no change in the concentrations of the products and the reactants. Because of this there is no effect on the reaction.
- Mon Feb 10, 2020 10:44 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs. extensive, state vs. non state
- Replies: 6
- Views: 230
Re: Intensive vs. extensive, state vs. non state
Heat capacity is an extensive property that depends on the amount of a substance, if the heat capacity is divided by the amount of substance then you have an intensive property known as specific heat capacities.
- Mon Feb 10, 2020 10:36 pm
- Forum: Calculating Work of Expansion
- Topic: calculating work of a reversible reaction
- Replies: 5
- Views: 363
Re: calculating work of a reversible reaction
If a system is doing work on the surroundings in the instance of expansion, then work is being lost so work will be negative.
- Mon Feb 10, 2020 10:27 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy Change due to Changes in Temperature
- Replies: 2
- Views: 128
Re: Entropy Change due to Changes in Temperature
I think that temperature would have to be in Kelvin. In this class, whenever temperature is brought up it is almost always converted to kelvin.
- Mon Feb 10, 2020 10:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Molar Concentration Direction.
- Replies: 2
- Views: 156
Re: Molar Concentration Direction.
It is always assumed that the concentration of the reactants decreases by x, so in this example the reactants N2 changes by -2x (because of the coefficient when you balance the chemical equation) and O2 changes by -x.
- Mon Feb 10, 2020 9:56 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE BOX
- Replies: 27
- Views: 753
Re: ICE BOX
X will be too small if it is less than 5% of the initial and if K<10^-3.
- Mon Feb 10, 2020 9:53 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: X is to small
- Replies: 8
- Views: 467
Re: X is to small
When Kc< 10^-3 and x is less than 5% of the initial concentration then it is okay to approximate.
- Fri Jan 31, 2020 4:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume and Pressure
- Replies: 8
- Views: 245
Re: Volume and Pressure
They are inversely related, meaning if the pressure increases then volume will decrease and vice versa.
- Fri Jan 31, 2020 4:26 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess' Law
- Replies: 7
- Views: 220
Re: Hess' Law
Enthalpy changes can be added and subtracted because enthalpy is a state property.
- Thu Jan 30, 2020 5:27 pm
- Forum: Calculating Work of Expansion
- Topic: Application
- Replies: 1
- Views: 106
Re: Application
I don't think we will be asked to show how the equation for work: w=-P(deltaV) is derived.
- Thu Jan 30, 2020 5:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Constant Pressure
- Replies: 7
- Views: 353
Re: Constant Pressure
If pressure or volume are constant, there is no change between the final and initial values.
- Thu Jan 30, 2020 5:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units for work
- Replies: 3
- Views: 120
Re: Units for work
The textbook converts L x atm to J or kJ.
- Thu Jan 30, 2020 4:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Functions
- Replies: 9
- Views: 418
Re: State Functions
Enthalpy would be considered a state function, meaning it must be able to be added. Change in enthalpy can be added to give the total enthalpy change.
- Mon Jan 20, 2020 10:39 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: pKa and pKb
- Replies: 17
- Views: 838
Re: pKa and pKb
pKa and pKb are acidity and basicity constants which are given as their negative log:
pKa=-log(ka)
pKb=-log(kb)
pKa=-log(ka)
pKb=-log(kb)
- Mon Jan 20, 2020 10:33 pm
- Forum: Ideal Gases
- Topic: Acid and Bases
- Replies: 16
- Views: 498
Re: Acid and Bases
So if a reaction produces more H30+ ions it is more acidic, does this means that the more OH- ions a reaction produces the more basic it is?
- Mon Jan 20, 2020 10:29 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: 5% Rule
- Replies: 6
- Views: 323
Re: 5% Rule
Yes, the 5% rule is used to get a valid approximation without having to use the quadratic formula when calculating for both acid base and chemical equilibria.
- Mon Jan 20, 2020 10:25 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure changes
- Replies: 7
- Views: 182
Re: Pressure changes
If the partial pressure of a reactant was increased, the volume will decrease and there will be more moles of gas on the right, so the reaction shifts left.
- Mon Jan 20, 2020 10:19 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: X was ignored
- Replies: 27
- Views: 989
Re: X was ignored
The -x can be ignored because it was small relative to the initial concentration.