## Search found 60 matches

Wed Mar 13, 2019 10:16 am
Forum: Zero Order Reactions
Topic: General “order” question
Replies: 6
Views: 186

### Re: General “order” question

Another Quick Question: how do we determine the first order reaction/how is it correlated with y=mx+C For a first order reaction, you must look at the graph of ln[A] = -kt + ln[A]o. If this graph is a straight line with slope -k and y intercept ln[A]o, then you have a first order reaction. Typicall...
Wed Mar 13, 2019 10:07 am
Forum: *Enzyme Kinetics
Topic: Catalysts
Replies: 11
Views: 461

### Re: Catalysts

Do catalysts always enter with the reactants of the first elementary step and end with the products in the last elementary step, or can it be the other way around?
Wed Mar 13, 2019 10:03 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Converting
Replies: 2
Views: 42

### Re: Converting

It is especially valid to substitute for k when you have a "bottle neck" effect. This means when the first elementary step of a reaction is fast but the second step is slow. When this happens, you must assume the first elementary reaction is at equilibrium and create an equilibrium constan...
Fri Mar 08, 2019 9:41 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: k values
Replies: 4
Views: 88

### Re: k values

Is k only found experimentally (like order), or do we have to calculate k given reactant concentrations and a rate law?
Fri Mar 08, 2019 9:37 am
Forum: General Rate Laws
Topic: Order of a Reaction
Replies: 3
Views: 57

### Re: Order of a Reaction

To add to the previous answer, if a reaction rate is not dependent on the concentration of a certain reactant, that means it is to the power 0. This, along with the fact that [A] and [B] can be to technically any power, means [A][B] is not necessarily second order.
Fri Mar 08, 2019 9:29 am
Forum: General Rate Laws
Topic: Graph of ln[A] against time
Replies: 4
Views: 63

### Re: Graph of ln[A] against time

Look at it this way: if you were to graph the points without ln, the curve would be exponential. So, in order to make the graph linear, you must take the ln of the data. The ln is changing the curve into a line.
Wed Feb 27, 2019 10:39 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Entropy of Fusion
Replies: 3
Views: 61

### Re: Entropy of Fusion

Just to be sure, S on its own must always be positive, but deltaS can be positive or negative, right?
Wed Feb 27, 2019 10:33 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Value of n
Replies: 7
Views: 100

### Re: Value of n

It is important to keep in mind that n as the number of electrons only applies to the equation deltaG = -nFE, deltaG° = -nFE°, or Wmax = -nFE (these are the only equations from class). When using n in other equation such as the ideal gas law (PV = nRT), n is the number of moles.
Wed Feb 27, 2019 10:28 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Temperature and Gibbs
Replies: 1
Views: 45

### Re: Temperature and Gibbs

Van't Hoff is used when you are given two equilibrium constants and a temperature for one of them or, similarly, two temperatures and an equilibrium constant for one of them. From this information, you can calculate the missing value (which can be K1, K2, T1, or T2). Keep in mind, all of these value...
Wed Feb 20, 2019 10:08 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Units of Gibbs Free Energy
Replies: 5
Views: 83

### Units of Gibbs Free Energy

Since deltaG can be measured in J as well as J/mol, is Gibbs free energy generally considered to be intensive or extensive?
Wed Feb 20, 2019 10:04 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Measurement
Replies: 5
Views: 76

### Re: Gibbs Free Energy Measurement

I believe the most common way to come up with Gibbs free energy is using the methods listed above. In other words, if there is a way to measure Gibbs free energy directly from an experiment, I don't think we need to know it.
Wed Feb 20, 2019 9:58 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs concept
Replies: 7
Views: 117

### Re: Gibbs concept

Can someone explain what is happening on a physical level when deltaG = 0 (the Gibbs free energy is at equilibrium)?
Fri Feb 15, 2019 9:42 am
Forum: Biological Examples (*DNA Structural Transitions, etc.)
Topic: Structures of the Human Body and Systems
Replies: 5
Views: 172

### Structures of the Human Body and Systems

Would individual organs in the human body be considered open, closed, or isolated systems? What about the human body as a whole? Just curious :)
Fri Feb 15, 2019 9:39 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy equations
Replies: 8
Views: 216

### Re: Entropy equations

Can someone please explain the derivation of deltaS = nRlnV2/V1 ? I do not understand why this can be used.
Fri Feb 15, 2019 9:37 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs and Activation Energy
Replies: 4
Views: 285

### Re: Gibbs and Activation Energy

Is there an SI unit for the change in Gibbs free energy?
Fri Feb 08, 2019 10:05 am
Forum: Calculating Work of Expansion
Topic: Work
Replies: 5
Views: 99

### Re: Work

Is this situation also the case where deltaU = q?
Fri Feb 08, 2019 10:01 am
Forum: Calculating Work of Expansion
Topic: Pressure Units
Replies: 7
Views: 105

### Re: Pressure Units

While the conversion for units of pressure were not included on the last test, four different values for the gas constant (R) were provided: one includes joules, one includes atm, one includes bar, and one includes Torr. So, if your calculation involves the ideal gas law at all, chances are any pres...
Fri Feb 08, 2019 9:55 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Spontaneity
Replies: 2
Views: 51

### Re: Spontaneity

To add a chemistry example for spontaneity, imagine having one of those pumps Lavelle draws out. If the pressure inside the system is different from the pressure outside the system, the pump will move on its own to try to make the outside pressure equal to the system's pressure.
Fri Feb 01, 2019 10:01 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Change in internal energy equation
Replies: 2
Views: 55

### Re: Change in internal energy equation

If you are asking about calculating molar heat capacity at a constant pressure, use q = n(Cp)(deltaT), where n is the number of moles. Similarly, for a constant volume use Cv. Keep in mind that these can only be used for gases.
Fri Feb 01, 2019 9:51 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work Done By vs. On
Replies: 4
Views: 70

### Re: Work Done By vs. On

Just to double check, when work is being done by the system the amount of energy is negative right? Similarly, is the energy positive when work is being done on the system?
Fri Feb 01, 2019 9:49 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy vs Internal energy
Replies: 5
Views: 57

### Re: Enthalpy vs Internal energy

Is there a difference between the SI units of enthalpy and internal energy?
Fri Jan 25, 2019 9:44 am
Forum: Phase Changes & Related Calculations
Topic: Temperature vs. heat vs. energy
Replies: 4
Views: 66

### Re: Temperature vs. heat vs. energy

What are the SI units for each of these (temperature, heat, and energy)?
Fri Jan 25, 2019 9:42 am
Forum: Phase Changes & Related Calculations
Topic: Steam and Boiling water
Replies: 2
Views: 48

### Re: Steam and Boiling water

Simply put, steam transfers more energy to your skin than boiling water because of the excess energy the steam needs to release to turn back into a liquid.
Fri Jan 25, 2019 9:39 am
Forum: Phase Changes & Related Calculations
Topic: Water heating curve
Replies: 7
Views: 101

### Re: Water heating curve

If we were to make a heating curve for some substance other than water, would the general shape of the curve resemble that of water?
Wed Jan 16, 2019 10:19 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Polyprotic Acids
Replies: 2
Views: 39

### Re: Polyprotic Acids

Just to clarify, are all polyprotic acids strong acids then? Since it is assumed the reactions go to completion?
Wed Jan 16, 2019 10:10 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle and Temperature Changes
Replies: 3
Views: 56

### Le Chatelier's Principle and Temperature Changes

Can someone please explain how Le Chatelier's Principle applies to temperature changes when temperature changes affect K value?
Wed Jan 16, 2019 10:05 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw
Replies: 4
Views: 73

### Re: Kw

Also, you must keep in mind that we do not begin with any H3O+ or OH- in the solution. It starts out as 100% H2O. After that, as previously stated, note that H3O+ cannot be created without the formation of OH- in a pure water solution.
Thu Jan 10, 2019 10:35 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Writing Equilibrium Expressions
Replies: 3
Views: 55

### Re: Writing Equilibrium Expressions

Brackets are used when you are calculating Kc and parentheses are used when you are calculating Kp. You also need to include a P next to each reactant and product when calculating Kp to indicate you are using the partial pressures of each compound. Brackets indicate concentrations.
Thu Jan 10, 2019 10:31 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q [ENDORSED]
Replies: 7
Views: 488

### Re: Q[ENDORSED]

To expand and clarify, Q and K are calculated the same way. The only difference is the value found for K will be the constant value at equilibrium. Using the same math, you can calculate the reaction quotient (Q) but for any point in the reaction (not necessarily when the reaction is at equilibrium).
Thu Jan 10, 2019 10:24 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K
Replies: 3
Views: 30

### Re: Calculating K

Why do we need to ever convert between Kc and Kp in a problem? In other words, what is converting between Kc and Kp used for?
Fri Dec 07, 2018 10:28 pm
Forum: Biological Examples
Topic: Transition metals
Replies: 3
Views: 151

### Re: Transition metals

Is iron the only transition metal that can be transported using hemoglobin?
Fri Dec 07, 2018 10:25 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 7
Views: 114

### Re: Coordination Number

Can the ligands that count towards coordination number be cations?
Fri Dec 07, 2018 10:22 pm
Forum: Naming
Topic: cyano vs cyanido
Replies: 3
Views: 58

### Re: cyano vs cyanido

What properties of cyanide makes it poisonous to humans?
Sun Dec 02, 2018 9:27 pm
Forum: Conjugate Acids & Bases
Topic: Strong and Weak Acids and Bases in Relations with H2O
Replies: 3
Views: 55

### Re: Strong and Weak Acids and Bases in Relations with H2O

In a strong acid, nearly all molecules of the acid are depronated, and in a strong base, nearly all molecules of the base are pronated. Pronated means having accepted a proton, and depronated means having lost a proton.
Sun Dec 02, 2018 9:23 pm
Forum: Polyprotic Acids & Bases
Topic: oxacids and carboxylic acids
Replies: 5
Views: 255

### Re: oxacids and carboxylic acids

Are any carboxylic acids polyprotic?
Sun Dec 02, 2018 9:20 pm
Forum: Lewis Acids & Bases
Topic: Weak Acid/Base vs. Strong
Replies: 7
Views: 147

### Re: Weak Acid/Base vs. Strong

Can strength be measured by dissociation in a solvent other than water?
Fri Nov 23, 2018 11:18 pm
Forum: Hybridization
Topic: Hybridization Labeling
Replies: 5
Views: 107

### Re: Hybridization Labeling

Can someone please explain the labeling on the lone pairs of electrons? How does that work for the oxygen for example?
Fri Nov 23, 2018 11:15 pm
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 68
Views: 22000

### Re: formula units[ENDORSED]

Are degrees (used to describe bond angles) an SI unit?
Fri Nov 23, 2018 11:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Does formal charge apply to the VSEPR Model?
Replies: 6
Views: 101

### Re: Does formal charge apply to the VSEPR Model?

Also, along with the above answers, keep in mind that the lone pairs usually affect bond angles in the VSEPR model (even if it’s only by a little).
Fri Nov 16, 2018 11:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: tetrahedral vs trigonal planar
Replies: 9
Views: 136

### Re: tetrahedral vs trigonal planar

How many lone pairs are possible when the molecule is in the trigonal planar shape?
Fri Nov 16, 2018 11:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR- Polar vs Nonpolar
Replies: 5
Views: 66

### Re: VSEPR- Polar vs Nonpolar

Also, molecules will be nonpolar if they are diatomic, whether they are VSEPR or not.
Fri Nov 16, 2018 11:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral
Replies: 4
Views: 73

### Re: Octahedral

Do the bond angles of the octahedral shape (90 degrees) ever change (because of things like electron pairs)?
Thu Nov 08, 2018 8:37 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Interaction Potential energy
Replies: 2
Views: 187

### Re: Interaction Potential energy

Why do larger atoms with some bond to another atom not follow the same rule as larger size atoms using VDW forces (with regards to attraction and strength)?
Thu Nov 08, 2018 8:29 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Van Der Waal forces
Replies: 3
Views: 549

### Re: Van Der Waal forces

Do Van Der Waals forces act differently in different physical states (solid vs. liquid vs. gas)?
Thu Nov 08, 2018 8:26 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Wednesay - 11/7 Notes
Replies: 2
Views: 108

### Re: Wednesay - 11/7 Notes

The subjects we went over in the 10 am lecture were:
1. Strengths and lengths of bonds.
2. Interactions between ions and molecules (the attractive forces such as ion-ion, ion-dipole, etc.).
3. Polarizability
4. Van der Waals forces/London dispersion forces.
Fri Nov 02, 2018 11:49 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 9
Views: 351

### Re: Bond Length

Is there any sort of calculation/equation where we will have to use specific values of bond length?
Fri Nov 02, 2018 11:46 pm
Forum: Lewis Structures
Topic: Formal Charges
Replies: 2
Views: 70

### Re: Formal Charges

I believe it does not matter. However, it will matter when we start focusing on the geometric structure of atoms rather than their formal charges.
Fri Nov 02, 2018 11:42 pm
Forum: Ionic & Covalent Bonds
Topic: Dipole
Replies: 4
Views: 59

### Re: Dipole

Do dipole moments have characteristics of ionic bonds too?
Sun Oct 28, 2018 11:23 pm
Forum: Ionic & Covalent Bonds
Topic: the Octet rule
Replies: 21
Views: 334

### Re: the Octet rule

No, there are exceptions. For example, a hydrogen atom has only 1 electron, therefore the maximum number of electrons it can have is two (to fill the orbital).
Sun Oct 28, 2018 11:01 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 13
Views: 111

### Re: Lewis Structures

Can every atom have potentially 8 electrons in the Lewis Structure besides H and He?
Sun Oct 28, 2018 10:59 pm
Forum: Ionic & Covalent Bonds
Topic: Topic 2A.1 (valence electrons) 7th edition
Replies: 3
Views: 111

### Re: Topic 2A.1 (valence electrons) 7th edition

Why is removing a second electron from an atom in the gaseous state harder than removing the first electron?
Fri Oct 19, 2018 9:08 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Geometric Representations of Orbitals
Replies: 1
Views: 40

### Geometric Representations of Orbitals

Do we need to know the geometric shapes of the 5 d-orbitals, or just of the s and p - orbitals?
Fri Oct 19, 2018 9:06 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: orbitals
Replies: 6
Views: 96

### Re: orbitals

Can "l" be any number less than "n-1," or must it be n-1?
Fri Oct 19, 2018 9:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: d- orbitals
Replies: 2
Views: 94

### Re: d- orbitals

The five names for the d-orbital are dxy, dyz, dzx, dz^2, and dx2-y2.
Fri Oct 12, 2018 3:00 pm
Forum: DeBroglie Equation
Topic: Wavelike properties vs classical model
Replies: 1
Views: 51

### Re: Wavelike properties vs classical model

The equation you are asking about is the classical mechanics description of light. So in a general sense it is tied to quantum mechanics.
Fri Oct 12, 2018 2:48 pm
Forum: Properties of Light
Topic: How light behaves
Replies: 8
Views: 194

### Re: How light behaves

Our issue is we cannot see what light is really made up of. However, it displays properties that compare to those of waves in some instances and photons (packets of energy) in others. The struggle comes when trying to decide when it acts like a wave and when it acts like a photon.
Fri Oct 12, 2018 2:37 pm
Forum: Properties of Light
Topic: Quantum World Topics
Replies: 3
Views: 32

### Re: Quantum World Topics

While I do not know any other specific resources to help you with the topic, I do know forming study groups will work wonders for your understanding of the subject. Discussing what you don't understand with students who have a clearer understanding of the material can sometimes be better than findin...
Thu Oct 04, 2018 10:27 pm
Forum: SI Units, Unit Conversions
Topic: Converting units in problems
Replies: 3
Views: 86

### Re: Converting units in problems

Must we always show our work when converting units in problems, or can it be assumed by the grader?
Thu Oct 04, 2018 10:21 pm
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 68
Views: 22000

### Re: formula units[ENDORSED]

What was the unit of measurement only used by chemists, also known as 10 to the -10 power?
Thu Oct 04, 2018 10:17 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 73
Views: 2195

### Re: How does grading for discussion posts work?

If we were to post four times in one week, would the extra post roll over to next week's grading?