Search found 60 matches
- Sun Mar 17, 2019 11:58 pm
- Forum: *Enzyme Kinetics
- Topic: How do you tell if something is a catalyst vs an intermediate?
- Replies: 16
- Views: 6013
Re: How do you tell if something is a catalyst vs an intermediate?
Catalyst shows up in products and reactants but intermediated are used during the course of reaction.
- Sun Mar 17, 2019 11:58 pm
- Forum: Calculating Work of Expansion
- Topic: Work in a System
- Replies: 4
- Views: 638
Re: Work in a System
Work is 0 when volume is constant.
- Sun Mar 17, 2019 11:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatlier Principle
- Replies: 10
- Views: 2122
Re: Le Chatlier Principle
Adding a catalysts has no effect on the product or reactant, only speeds up the rate of reaction
- Sun Mar 10, 2019 11:45 pm
- Forum: Zero Order Reactions
- Topic: Zero order reactions
- Replies: 4
- Views: 463
Re: Zero order reactions
It would make sense that the 0 order reaction is most common because it takes place when concentration of reactants is very high.
- Sun Mar 10, 2019 11:44 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 18
- Views: 2065
Re: Final
I think the newer material will be focused on more.
- Sun Mar 10, 2019 11:38 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 12
- Views: 1127
Re: Test 2
Delta G is negative because the reaction is exergonic.
- Sun Mar 03, 2019 9:47 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic vs basic solutions
- Replies: 10
- Views: 1044
Re: Acidic vs basic solutions
For acidic solutions you balance the hyrdrogen by adding H+ and for basic solutions you balance the hydrogen by adding OH-.
- Sun Mar 03, 2019 9:43 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Cell Diagram
- Replies: 4
- Views: 422
Re: Cell Diagram
H+ is needed but H2O isn’t.
- Sun Mar 03, 2019 9:41 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff use
- Replies: 13
- Views: 2144
Re: Van't Hoff use
You use Vant Hoff when you are trying to find how K changes as temperature changes.
- Sun Feb 24, 2019 10:22 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Spontaneous?
- Replies: 13
- Views: 1589
Re: Spontaneous?
You can only know for sure if a process is spontaneous if delta G is negative.
- Sun Feb 24, 2019 10:21 pm
- Forum: Balancing Redox Reactions
- Topic: Reducing and Oxidizing Agents
- Replies: 3
- Views: 408
Re: Reducing and Oxidizing Agents
A reactant can be both a reducing and oxidizing agent when it is used in forming products with different oxidation states.
- Sun Feb 24, 2019 10:19 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Finding n in Delta G = -nFE
- Replies: 3
- Views: 621
Re: Finding n in Delta G = -nFE
N is the number of moles of electrons transferred during the redox reaction. You will usually find it when writing half reactions.
- Sun Feb 17, 2019 6:59 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G=0
- Replies: 1
- Views: 200
Re: Delta G=0
the delta G is usually 0 if the reaction is in a state of equilibrium.
- Sun Feb 17, 2019 6:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibb's Free energy
- Replies: 4
- Views: 485
Re: Gibb's Free energy
delta g represents the spontaneity, so if it is negative it will be spontaneous and if positive it will be non-spontaneous.
- Sun Feb 17, 2019 6:52 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Spontaneous reactions
- Replies: 11
- Views: 4637
Re: Spontaneous reactions
an exothermic reaction is usually spontaneous but if there is a large enough decrease in entropy, the gibb's free energy can be positive, thus making the reaction non-spontaneous.
- Sun Feb 10, 2019 10:24 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Occupying positions
- Replies: 2
- Views: 349
Re: Occupying positions
I think it means that entropy is greater for the liquid form.
- Sun Feb 10, 2019 10:21 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible Expansion
- Replies: 3
- Views: 433
Re: Reversible Expansion
If the system is isolated, then the reversible expansion wil result in a lower internal energy.
- Sun Feb 10, 2019 10:09 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal meaning
- Replies: 4
- Views: 501
Re: Isothermal meaning
Isothermal means that the temperature will remain constant.
- Sun Feb 03, 2019 8:32 pm
- Forum: Calculating Work of Expansion
- Topic: Units for pressure
- Replies: 10
- Views: 791
Re: Units for pressure
You would normally use atm or bar as units in your answer.
- Sun Feb 03, 2019 8:32 pm
- Forum: Calculating Work of Expansion
- Topic: Isolated System
- Replies: 5
- Views: 2885
Re: Isolated System
We do not consider the heat of surroundings in an isolated system because there is no energy exchange.
- Sun Feb 03, 2019 8:30 pm
- Forum: Calculating Work of Expansion
- Topic: work done by vs on a system
- Replies: 5
- Views: 768
Re: work done by vs on a system
Work being done by a system is negative because energy is taken out of the system, while work done on a system is positive because energy is put into the system.
- Mon Jan 28, 2019 12:54 am
- Forum: Ideal Gases
- Topic: pH and pOH
- Replies: 18
- Views: 1969
Re: pH and pOH
The question will tell whether to solve for ph or pOH.
- Mon Jan 28, 2019 12:46 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 8
- Views: 783
Re: Heat Capacity
Heat capacity is an extensive property while specific heat is intensive.
- Mon Jan 28, 2019 12:44 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Units of Kp
- Replies: 9
- Views: 3683
Re: Units of Kp
It is any unit that can measure pressure such as atm or bar.
- Mon Jan 28, 2019 12:41 am
- Forum: Phase Changes & Related Calculations
- Topic: reversible/irreversible
- Replies: 8
- Views: 845
Re: reversible/irreversible
A reversible process is one where the system is always at a point of equilibrium whereas the irreversible process is one where the system is not always at equilibrium. Also, reversible processes tend to do more work.
- Mon Jan 28, 2019 12:39 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pKa vs. pH
- Replies: 15
- Views: 3020
Re: pKa vs. pH
The pKa is the -log(Ka) and pH is -log(H+)
- Mon Jan 28, 2019 12:36 am
- Forum: Phase Changes & Related Calculations
- Topic: Phase changes
- Replies: 14
- Views: 1430
Re: Phase changes
You are correct. Phase changes from vapor to gas will be exothermic and the other way around is endothermic.
- Sun Jan 20, 2019 11:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Is it an acid or a base?
- Replies: 8
- Views: 715
Re: Is it an acid or a base?
Acids usually donate protons (H+) while bases accept protons.
- Sun Jan 20, 2019 11:54 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in Temperature
- Replies: 8
- Views: 1139
Re: Changes in Temperature
If a reaction is endothermic( absorbs energy), a temperature increase will favor the products side. If a reaction is exothermic( gives off energy), a temperature increase will favor the reactants side.
- Sun Jan 20, 2019 11:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice table mols/molarity
- Replies: 3
- Views: 214
Re: ice table mols/molarity
Solving for molarity beforehand will allow you to find the unknown values as opposed to finding moles.
- Fri Dec 07, 2018 9:10 pm
- Forum: Hybridization
- Topic: lone pairs of e-
- Replies: 4
- Views: 449
Re: lone pairs of e-
You would not need to know the hybridization of lone pairs.
- Fri Dec 07, 2018 9:08 pm
- Forum: Bronsted Acids & Bases
- Topic: Oxoacids
- Replies: 2
- Views: 319
Re: Oxoacids
An oxoacid is characterized by at least one hydrogen atom bonded to at least one oxygen and a nonmetal.
- Fri Dec 07, 2018 9:06 pm
- Forum: General Science Questions
- Topic: hydrogen bonding
- Replies: 3
- Views: 573
Re: hydrogen bonding
The hydrogen would have to be attached to F,O, or N.
- Sun Dec 02, 2018 11:49 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric compounds besides water
- Replies: 6
- Views: 547
Re: Amphoteric compounds besides water
An amphoteric compound may be able to add an H+ or remove an H+. Compounds like this include HSO4- and H2PO4-.
- Sun Dec 02, 2018 11:47 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 11
- Views: 1302
Re: Hybridization
Trigonal planar has 3 regions of electron density so it would be sp2
- Sun Dec 02, 2018 11:44 pm
- Forum: Bronsted Acids & Bases
- Topic: Net Ionic Equations
- Replies: 2
- Views: 389
Re: Net Ionic Equations
I think net ionics are useful for identifying bronsted acids and bases in a chemical reaction. You can usually identify the charge on the icon by the oxidation state.
- Sun Nov 25, 2018 11:50 pm
- Forum: Hybridization
- Topic: Questions in Chapter
- Replies: 5
- Views: 503
Re: Questions in Chapter
Knowing the name is not necessary, usually the formula will be given.
- Sun Nov 25, 2018 11:49 pm
- Forum: Hybridization
- Topic: hybridization of BeCl2
- Replies: 4
- Views: 377
Re: hybridization of BeCl2
BeCl2 has a Lewis structure with 2 electron densities. Therefore the the hybridization is sp.
- Sun Nov 25, 2018 11:47 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Bonds
- Replies: 3
- Views: 379
Re: Bonds
Sigma bonds are observed in single bonds but pi bonds are observed in double and triple bonds.
- Mon Nov 19, 2018 12:25 am
- Forum: Resonance Structures
- Topic: Drawing resonance
- Replies: 17
- Views: 1895
Re: Drawing resonance
I think that if a lewis structure has resonance, it would be safe to draw out all possible resonance structures.
- Mon Nov 19, 2018 12:23 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: hydrogen bonding
- Replies: 11
- Views: 1000
Re: hydrogen bonding
Hydrogen bonding is the strongest IMF so the energy needed to separate these molecules is higher. Therefore the melting point would be higher.
- Mon Nov 19, 2018 12:21 am
- Forum: Dipole Moments
- Topic: London Force Times
- Replies: 3
- Views: 395
Re: London Force Times
London forces don’t generally have a set time interval in which the force is active. However, the forces are continuously present between molecules.
- Sun Nov 11, 2018 8:21 pm
- Forum: Hybridization
- Topic: How to Determine
- Replies: 12
- Views: 1159
Re: How to Determine
Hybridization is the result of delocalized electrons from multiple orbitals overlapping to form larger orbitals
- Sun Nov 11, 2018 8:18 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bonds
- Replies: 20
- Views: 1563
Re: Hydrogen Bonds
Hydrogen bonds are the strongest intermolecular force but are still weaker than covalent and ionic bonds.
- Sun Nov 11, 2018 8:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: molecular shapes
- Replies: 13
- Views: 978
Re: molecular shapes
I’m pretty sure we will have to know most of the molecular geometry up to 6 bonds. So that includes bond angle and name.
- Fri Nov 02, 2018 11:25 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: degeneracy of the a 4p orbital
- Replies: 9
- Views: 2169
Re: degeneracy of the a 4p orbital
The degeneracy would be 3 because there are 3 possible orientations for electrons in the p orbital.
- Fri Nov 02, 2018 11:21 pm
- Forum: Properties of Electrons
- Topic: Isoelectronicity
- Replies: 3
- Views: 1039
Re: Isoelectronicity
Isoelectronicity is defined by two or more elements or ions having the same electronic configuration.
- Fri Nov 02, 2018 11:19 pm
- Forum: Photoelectric Effect
- Topic: Test #2 Question #2b
- Replies: 4
- Views: 780
Re: Test #2 Question #2b
The speed of an ejected electron is not dependent on the intensity of the photon because, as we know, the photoelectric effect theorized that the light is not thought of as a wave propagating through space but instead thought of as quantized packets of energy. Because of this, the energy is dependen...
- Fri Oct 26, 2018 11:26 pm
- Forum: Resonance Structures
- Topic: Resonance Structures
- Replies: 5
- Views: 452
Re: Resonance Structures
A resonance structure comes into play when there are 2 or more ways of writing out a Lewis structure for a molecule. We lost all structures because we can’t specifically pinpoint one correct structure.
- Fri Oct 26, 2018 11:22 pm
- Forum: General Science Questions
- Topic: Periodic Table
- Replies: 16
- Views: 1676
Re: Periodic Table
I typically try to round to as many decimal places that would allow for an accurate answer but also allows for the limiting significant figure to determine the answer.
- Fri Oct 26, 2018 11:20 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma v. Pi
- Replies: 6
- Views: 900
Re: Sigma v. Pi
A sigma bond is a basic covalent bond whereas a public bond whereas a pi bond is a covalent bond between 2 perpendicular orbitals.
- Sat Oct 20, 2018 1:44 am
- Forum: Properties of Light
- Topic: Rydberg formula
- Replies: 8
- Views: 820
Re: Rydberg formula
It's also important to note that N1 is going to be 1 because the element used is hydrogen. That should clear up any confusion as to missing variables.
- Sat Oct 20, 2018 1:09 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodes of F Orbital
- Replies: 1
- Views: 200
Re: Nodes of F Orbital
I believe that the angular nodes number is equal to the angular quantum number
- Sat Oct 20, 2018 12:58 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Combustion Problem
- Replies: 1
- Views: 558
Re: Combustion Problem
To start the problem, you would first calculate how many grams of salicylic acid is contained in the pill. You would do this by multiplying the 1.35g by 0.15. Keep in mind that because this is a percent, the number of significant figures would still be 3. You would then convert the grams of salicyli...
- Fri Oct 12, 2018 1:24 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical & Molecular Formulas
- Replies: 11
- Views: 1569
Re: Empirical & Molecular Formulas
Yes they can. If the molar mass of the empirical formula is the same or relatively similar to that of the molecular formula, then the empirical formula is the molecular formula.
- Fri Oct 12, 2018 1:23 pm
- Forum: Empirical & Molecular Formulas
- Topic: Order of Molecules
- Replies: 4
- Views: 1018
Re: Order of Molecules
Usually, if the problem gives the order of the elements, I would just follow that.
- Fri Oct 12, 2018 1:19 pm
- Forum: Photoelectric Effect
- Topic: Variable for frequency
- Replies: 6
- Views: 570
Re: Variable for frequency
To my knowledge, there aren’t any other variable you could use to differentiate frequency and velocity. You could just curve the v to differentiate it from a normal V.
- Fri Oct 05, 2018 2:00 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: MOLARITY
- Replies: 17
- Views: 2147
Re: MOLARITY
Molarity is essentially a quantity used to define the concentration of a substance in solution. It can be used as a conversion factor to determine the moles of a substance or volume of a substance.
- Fri Oct 05, 2018 1:57 pm
- Forum: Limiting Reactant Calculations
- Topic: M15 problem (6th edition)
- Replies: 2
- Views: 171
Re: M15 problem (6th edition)
For this problem, you are given the grams of both reactants. You would find the limiting reactant by converting the grams of each substance to the theoretical grams of aluminum chloride. Whichever substance produces the least amount of aluminum chloride would be the limiting reactant. This would als...
- Thu Oct 04, 2018 8:37 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting reactants [ENDORSED]
- Replies: 3
- Views: 371
Re: Limiting reactants [ENDORSED]
I wouldn't necessarily say that you can assume that the one reactant would be the limiting reactant because there could be additional details in the problem that would say otherwise. However, you could assume that if all other reactants were in "excess", then the one reactant would be cons...