Search found 61 matches
- Sun Mar 17, 2019 10:04 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: galvanic cells
- Replies: 6
- Views: 1019
Re: galvanic cells
A porous disk is indicated by a single line, and a salt bridge is 2 lines
- Sun Mar 17, 2019 10:01 am
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: n in degeneracy
- Replies: 8
- Views: 2564
Re: n in degeneracy
n is the number of molecules, so n would equal 1
- Sun Mar 17, 2019 9:58 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: adiabatic systems
- Replies: 10
- Views: 991
Re: adiabatic systems
Adiabatic is when q=0, so that would mean that there is no transfer of heat.
- Sun Mar 17, 2019 9:36 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q
- Replies: 6
- Views: 856
Re: Q
When calculating Q, the concentrations do not have to be in standard conditions.
- Sun Mar 17, 2019 9:33 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Endergonic vs. Endothermic
- Replies: 6
- Views: 1937
Re: Endergonic vs. Endothermic
An endergonic reaction is where energy is absorbed, therefore making delta G positive. Exergonic is when energy is released, therefore delta G would be negative.
- Sun Mar 17, 2019 8:48 am
- Forum: Van't Hoff Equation
- Topic: Van't Hoff use
- Replies: 13
- Views: 2154
Re: Van't Hoff use
You would use Van't Hoff equation when there is a temperature change and K
- Sun Mar 17, 2019 8:02 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Isothermal, Isobaric, Adiabatic
- Replies: 2
- Views: 622
Re: Isothermal, Isobaric, Adiabatic
I am not sure, but I think it's better to know just in case. Isothermal is where the temperature stays constant in a system. Isobaric is where the pressure is constant, and adiabatic is where transfers of matter and energy as heat are prohibited.
- Sun Mar 17, 2019 7:57 am
- Forum: Calculating Work of Expansion
- Topic: S=0
- Replies: 12
- Views: 1798
Re: S=0
S is equal to zero when there is no change in the state of entropy and temperature reaches 0 K
- Sun Mar 17, 2019 7:52 am
- Forum: General Rate Laws
- Topic: Exergonic reaction
- Replies: 3
- Views: 590
Re: Exergonic reaction
A reaction is exergonic when it is releasing energy, which would result in a negative delta G since it is losing energy.
- Sun Mar 17, 2019 7:49 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Exothermic vs. Endothermic
- Replies: 10
- Views: 1905
Re: Exothermic vs. Endothermic
Every reaction has activation energy since it is the minimum amount of energy needed to be able to undergo the reaction. Activation energy is the difference in the energy between the transition state and the reactants.
- Sun Mar 17, 2019 5:35 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: ∆G and work
- Replies: 3
- Views: 903
Re: ∆G and work
Delta G is equal to the maximum amount of energy available to do work at constant temperature and pressure.
- Sun Mar 17, 2019 5:26 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pressure Equation
- Replies: 7
- Views: 850
Re: Pressure Equation
You would use that equation when there is a change in pressure.
- Sun Mar 17, 2019 4:53 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work done vs work on system
- Replies: 18
- Views: 3923
Re: Work done vs work on system
When work is being done ON the system, work is positive. When work is being done BY the system, work is negative since it is losing energy.
- Sun Mar 17, 2019 4:47 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Adiabatic and isothermal
- Replies: 6
- Views: 2280
Re: Adiabatic and isothermal
Adiabatic is an isolated system where transfers of matter and energy as heat are prohibited. Isothermal is a process where it is the temperature that stays constant.
- Sun Mar 17, 2019 4:38 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Term Differences (Heat, Enthalpy, Temperature, and Work)
- Replies: 4
- Views: 823
Re: Term Differences (Heat, Enthalpy, Temperature, and Work)
Heat is the transfer of energy due to a difference in temperature. Enthalpy is the heat absorbed or released from a system under constant pressure, where it is affected by factors such as the state of the reactants and products. Temperature is a measure of heat, where temperature can be used to indi...
- Sun Mar 17, 2019 3:50 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation Energy
- Replies: 16
- Views: 1521
Re: Activation Energy
Activation energy is the minimum amount of energy required for a certain reaction to occur. In an energy profile diagram, it would be the peak of the graph.
- Sun Mar 17, 2019 3:42 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Equation
- Replies: 9
- Views: 1308
Re: Equation
Yep, usually A=1 unless it was explicitly stated otherwise
- Sun Mar 17, 2019 1:43 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 28
- Views: 1830
Re: Catalysts
A catalyst would lower the peak on a curve since it can speed up the rate of a chemical reaction by providing a faster route.
- Sun Mar 17, 2019 1:31 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Effect of increased concentration on equilibrium
- Replies: 9
- Views: 1497
Re: Effect of increased concentration on equilibrium
the system will favor the forward reaction and produce more products
- Sun Mar 17, 2019 1:28 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: equilibirum expression
- Replies: 3
- Views: 657
Re: equilibirum expression
Pure liquids and solids do not appear in the expression
- Sat Mar 16, 2019 11:09 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ignoring x
- Replies: 16
- Views: 3372
Re: ignoring x
We can ignore x when the 5% rule applies to it, which is when x is less than 5% of the initial concentration.
- Sat Mar 16, 2019 11:03 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Units
- Replies: 6
- Views: 994
Re: Units
There are no units since the units should cancel
- Sat Mar 16, 2019 10:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Temperature and Le Chatlier's Principle
- Replies: 6
- Views: 874
Re: Temperature and Le Chatlier's Principle
For an exothermic reaction, the formation of products is found to be favored by lowering the temperature. For an endothermic reaction, the products are favored by an increase in temperature. So basically, raising the temperature of a reaction mixture at equilibrium will shift the reaction in the end...
- Sat Mar 16, 2019 9:13 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isometric/Isochoric
- Replies: 11
- Views: 1410
Re: Isometric/Isochoric
Isochoric is where the volume stays constant, isobaric is where the pressure stays constant, and adiabatic is where transfers of matter and of energy as heat are prohibited (therefore q=0)
- Sat Mar 16, 2019 9:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Kc
- Replies: 6
- Views: 965
K and Kc
What is the difference between K and Kc, and when do we know to use which one?
- Sat Mar 16, 2019 8:05 pm
- Forum: Ideal Gases
- Topic: units
- Replies: 15
- Views: 1398
Re: units
it's because there shouldn't be any units for K
- Sat Mar 16, 2019 7:40 pm
- Forum: Ideal Gases
- Topic: Ideal gas constant R
- Replies: 10
- Views: 1637
Re: Ideal gas constant R
Yeah, it depends on the question and what units you would need to be able to cancel out
- Thu Mar 14, 2019 4:38 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE
- Replies: 19
- Views: 1515
Re: ICE
E is the equilibrium concentration
- Thu Mar 14, 2019 4:36 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating Equilibrium Composition
- Replies: 2
- Views: 361
Calculating Equilibrium Composition
When using the quadratic equation to calculate the equilibrium composition, how do we know which of the two values is the right one for x?
- Thu Mar 14, 2019 4:32 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibruim Assessment
- Replies: 5
- Views: 574
Re: Equilibruim Assessment
to add on to the x being small, if it is less than 5% of the initial value, then x is negligible when adding or subtracting from a number
- Sun Dec 09, 2018 9:23 pm
- Forum: Sigma & Pi Bonds
- Topic: Amount of sigma bonds
- Replies: 6
- Views: 967
Re: Amount of sigma bonds
There can only be one sigma bond since a single bond has 1 sigma bond.
- Sun Dec 09, 2018 8:41 pm
- Forum: Sigma & Pi Bonds
- Topic: Double Bonds
- Replies: 9
- Views: 1046
Re: Double Bonds
A double bond has 1 sigma bond and 1 pi bond.
- Sun Dec 09, 2018 8:38 pm
- Forum: Sigma & Pi Bonds
- Topic: Triple bond?
- Replies: 18
- Views: 1783
Re: Triple bond?
A triple bond means that there are 2 pi bonds and 1 sigma bond.
- Sun Dec 09, 2018 8:37 pm
- Forum: Sigma & Pi Bonds
- Topic: Number of sigma and pi bonds
- Replies: 5
- Views: 1078
Re: Number of sigma and pi bonds
To count the number of sigma and pi bonds there are, a single bond would be sigma, a double bound would be a pi bond and sigma bond and a triple bond would be one sigma bond and 2 pi bonds.
- Sun Dec 09, 2018 8:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX3E
- Replies: 18
- Views: 3303
Re: AX3E
It would be trigonal pyramidal.
- Sun Dec 09, 2018 8:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 7
- Views: 711
Re: Polarity
To have a polar bond, it means that the electrons forming that bond are unequally distributed.
- Sun Dec 09, 2018 8:01 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VESPR Shapes
- Replies: 3
- Views: 541
Re: VESPR Shapes
Thank you, that was actually really helpful!
- Sun Dec 09, 2018 7:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shaped structures
- Replies: 3
- Views: 516
Re: T-shaped structures
Yeah, the bond angle for a t-shape would be 90.
- Sun Dec 09, 2018 7:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 2
- Views: 340
Re: Polarity
Not necessarily, the lone pairs just means that there's more of a repulsion and the shape changes.
- Sun Dec 09, 2018 7:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw
- Replies: 13
- Views: 2099
Re: Seesaw
The angles for a seesaw shape are less than 90 and 120.
- Sun Nov 18, 2018 4:08 pm
- Forum: Hybridization
- Topic: Sigma and Pi Bonds [ENDORSED]
- Replies: 12
- Views: 1098
Sigma and Pi Bonds [ENDORSED]
Can someone please explain sigma and pi bonds and how they are formed?
- Sun Nov 18, 2018 3:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: cis and trans dichloroethene
- Replies: 3
- Views: 535
cis and trans dichloroethene
Can someone please explain cis-dichloroethene and trans-dichloroethene and what the difference between the two is?
- Sun Nov 18, 2018 3:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polyatomic Molecules
- Replies: 1
- Views: 196
Polyatomic Molecules
How can a polyatomic molecule be nonpolar if its bonds are polar?
- Sat Nov 10, 2018 3:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Strengths of Repulsion
- Replies: 2
- Views: 268
Strengths of Repulsion
Why do lone pairs have a more strongly repelling effect then electrons in bonds?
- Fri Nov 09, 2018 1:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Formula
- Replies: 2
- Views: 352
Re: VSEPR Formula
The VSEPR formula is AXnEm, where A represents a central atom, X represents an attached atom, and E represents a lone pair.
- Fri Nov 09, 2018 1:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming the molecular shape
- Replies: 4
- Views: 586
Naming the molecular shape
When naming the molecular shape, do we also consider any lone pairs that are present? Or do we only take into consideration the positions of the atoms?
- Sun Nov 04, 2018 4:04 pm
- Forum: Resonance Structures
- Topic: resonance structures for the test
- Replies: 2
- Views: 326
Re: resonance structures for the test
Yeah, I think we would have to draw all the resonance structures with a double headed arrow connecting them.
- Sun Nov 04, 2018 4:00 pm
- Forum: Electronegativity
- Topic: Electron Affinity vs. Ionization Energy
- Replies: 8
- Views: 847
Re: Electron Affinity vs. Ionization Energy
Ionization energy increases across a period and decreases down a group, while electron affinity is also the same where it increase across a period and decreases down a group.
- Sun Nov 04, 2018 3:33 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 4
- Views: 380
Re: Drawing Lewis Structures
Yeah I think you would need to draw the resonance hybrid, where you draw the two resonance structures connected with a double headed arrow.
- Sun Oct 28, 2018 5:19 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bonds
- Replies: 5
- Views: 502
Re: Hydrogen Bonds
Hydrogen bonds are weaker because it involves the attraction between hydrogen and another molecule, whereas covalent and ionic bonds are a sharing or transfer of electrons which is stronger.
- Sun Oct 28, 2018 4:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic Bonds vs Covalent Bonds
- Replies: 7
- Views: 734
Re: Ionic Bonds vs Covalent Bonds
To add on, basically covalent bonds are stronger than ionic bonds in aqueous solutions, whereas ionic bonds are stronger in non-aqueous solutions.
- Sun Oct 28, 2018 4:31 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent Bonds
- Replies: 7
- Views: 708
Re: Covalent Bonds
Nonmetals form anions because they gain electrons due to their high charge, which results in the formation of negatively charged ions.
- Sun Oct 21, 2018 6:26 pm
- Forum: DeBroglie Equation
- Topic: Smallest Detectable Wavelength
- Replies: 2
- Views: 197
Re: Smallest Detectable Wavelength
I think he said it was 10^-18
- Sun Oct 21, 2018 6:00 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shape of Orbitals
- Replies: 3
- Views: 380
Shape of Orbitals
What are the different shapes of each orbital and an easy way to memorize the difference? Will we need to draw them on the test?
- Sun Oct 21, 2018 4:08 pm
- Forum: *Shrodinger Equation
- Topic: Application of Schrodinger's Equation
- Replies: 2
- Views: 364
Re: Application of Schrodinger's Equation
If I remember correctly, Schrodinger's equation is a wave equation that precisely predicts the probability of behavior of a system.
- Sun Oct 14, 2018 12:07 am
- Forum: Einstein Equation
- Topic: Numbers to memorize [ENDORSED]
- Replies: 37
- Views: 4231
Re: Numbers to memorize [ENDORSED]
Yeah, before the test we're given an equation sheet that has those numbers. So luckily, we don't need to memorize them!
- Sat Oct 13, 2018 11:49 pm
- Forum: Properties of Light
- Topic: Units for a Joule [ENDORSED]
- Replies: 3
- Views: 572
Re: Units for a Joule [ENDORSED]
This is because joule is a unit of work, and the equation for work is: work = force x displacement. When you expand this, you get work = mass x acceleration x displacement. The units for mass is kg, for acceleration is m/s^2, and for displacement is m. As a result, when you times them all together, ...
- Sat Oct 13, 2018 11:26 pm
- Forum: DeBroglie Equation
- Topic: explain debroglie equation?
- Replies: 3
- Views: 232
Re: explain debroglie equation?
The De Broglie equation is λ = h/mv, where λ is the wavelength, h is Planck's constant (6.626 x 10^-34), m is the mass of the particle, and v is the velocity of the particle. You use this equation to find the wavelength of a moving particle.
- Fri Oct 05, 2018 5:44 pm
- Forum: Significant Figures
- Topic: Determining Sig Figs
- Replies: 6
- Views: 460
Re: Determining Sig Figs
When you are multiplying or dividing, the number of sig figs in your answer is determined by the number with the least amount of sig figs. However, when you are adding or subtracting, the number of decimal places in the answer is determined by the smallest number of decimal places in the problem.
- Fri Oct 05, 2018 5:00 pm
- Forum: SI Units, Unit Conversions
- Topic: HW E.9
- Replies: 3
- Views: 399
Re: HW E.9
Yeah, Lavelle said that he would give us the formula, and it won't be until later on when we learn how to write formulas that he will expect us to do it by ourselves.
- Fri Oct 05, 2018 4:33 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical formula set up
- Replies: 9
- Views: 676
Re: Empirical formula set up
If I remember correctly, Lavelle said it was just easier to answer the problem since it makes it simpler and the numbers are easier to work with.