Search found 106 matches
- Mon Mar 09, 2020 3:36 pm
- Forum: Experimental Details
- Topic: picking a trial
- Replies: 13
- Views: 1558
Re: picking a trial
You should end up with the same result, i guess we just always try to pick out the easiest choice What makes it the easiest choice, like how do you know Sometimes some concentrations are easier to work with than others. For example, say trial 2 is just double trial 1 while the third trial is some r...
- Mon Mar 09, 2020 3:31 pm
- Forum: General Rate Laws
- Topic: molecularity
- Replies: 8
- Views: 563
Re: molecularity
Brian J Cheng 1I wrote:As Naneeta says, they're uncommon. Dr. Lavelle specifically told us to focus on 0, 1, and 2 order reactions (zero order, unimolecular, and bimolecular). Zero order == nonmolecular?
I think a zero order reaction would just have no molecularity at all.
- Mon Mar 09, 2020 3:28 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Slow Step
- Replies: 4
- Views: 323
Re: Slow Step
The problem will usually tell you if it is a fast or slow mechanism:) also hi hailey
- Mon Mar 09, 2020 3:22 pm
- Forum: *Enzyme Kinetics
- Topic: Adsorption
- Replies: 13
- Views: 3105
Re: Adsorption
Adsorption is when gas or solution binds to the surface of a catalyst at active sites, versus absorption which is when solution is basically soaked into a structure.
- Sat Mar 07, 2020 9:39 pm
- Forum: Balancing Redox Reactions
- Topic: Values of Andode and Cathode
- Replies: 8
- Views: 541
Re: Values of Andode and Cathode
You are usually given these values. If it's not explicitly stated which is which, then the positive one is usually the cathode and the negative is the anode.
- Sat Mar 07, 2020 9:38 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: finding n in G=-nFE
- Replies: 15
- Views: 979
Re: finding n in G=-nFE
n is the number of electrons being transferred in the redox equation.
- Sat Mar 07, 2020 9:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Reducing/Oxidizing agents
- Replies: 5
- Views: 356
Re: Reducing/Oxidizing agents
A reducing agent is what is "doing" the reducing in the reaction and ends up being the oxidized element. On the other hand, the oxidizing agent is what "does" the oxidizing and ends up as the reduced element.
- Sat Mar 07, 2020 9:33 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: the intermediate in a reaction
- Replies: 10
- Views: 681
Re: the intermediate in a reaction
Intermediates are produced in a step, then are consumed in a later step. It's kind of like when you are balancing redox reactions and cancel out the electrons from both reactions.
- Sat Mar 07, 2020 9:30 pm
- Forum: General Science Questions
- Topic: Reducing Math Errors
- Replies: 7
- Views: 642
Re: Reducing Math Errors
I usually try to check over my answers, but since I usually never catch mistakes just by looking at my work, I redo the problems I really need to check. I then compare my original work and my later work and make sure it was correct. Also, just double checking your steps as you go is helpful.
- Tue Mar 03, 2020 4:30 pm
- Forum: Balancing Redox Reactions
- Topic: Problem 6K.3
- Replies: 1
- Views: 186
Problem 6K.3
Is part D supposed to say instead? The textbook says is both a reactant and a product.
- Wed Feb 26, 2020 11:10 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potential
- Replies: 4
- Views: 284
Re: Standard Cell Potential
Eº is E at standard conditions.
- Wed Feb 26, 2020 11:10 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M11
- Replies: 2
- Views: 197
Re: 6M11
Cobalt is a solid transition metal.
- Wed Feb 26, 2020 11:07 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electron Transfer
- Replies: 3
- Views: 235
Re: Electron Transfer
Electrons are transferred, so there has to be another to accept or donate that singular one.
- Wed Feb 26, 2020 10:50 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gas constant R
- Replies: 5
- Views: 315
Re: Gas constant R
When Joules and moles are used in the equation, use 8.314 J·K-1·mol-1.
If liters*atm per moles are used, use 0.0821 L·atm·K-1·mol-1.
If liters*atm per moles are used, use 0.0821 L·atm·K-1·mol-1.
- Wed Feb 26, 2020 10:44 am
- Forum: Balancing Redox Reactions
- Topic: Homework 6M1
- Replies: 5
- Views: 440
Re: Homework 6M1
Cu is the anode since it is losing electrons, and M is the cathode since it is gaining electrons. (I remember this by Red Cat and An Ox: Reduction-Cathode, Anode-Oxidation :)).
Eº=Eº(cathode)-Eº(anode), so you would plug in the voltages to solve for Eº(cathode).
Eº=Eº(cathode)-Eº(anode), so you would plug in the voltages to solve for Eº(cathode).
- Sun Feb 23, 2020 6:25 pm
- Forum: Balancing Redox Reactions
- Topic: spontaneous
- Replies: 15
- Views: 759
Re: spontaneous
When standard reduction potential is positive, it is spontaneous.
- Sun Feb 23, 2020 6:23 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n
- Replies: 13
- Views: 713
Re: n
I think you are referring to R, or the gas constant.
When Joules and moles are used in the equation, use 8.314 J·K-1·mol-1.
If liters*atm per moles are used, use 0.0821 L·atm·K-1·mol-1.
When Joules and moles are used in the equation, use 8.314 J·K-1·mol-1.
If liters*atm per moles are used, use 0.0821 L·atm·K-1·mol-1.
- Sun Feb 23, 2020 6:19 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation Numbers
- Replies: 3
- Views: 284
Re: Oxidation Numbers
Oxidation numbers are the "act" of electrons moving, while formal charge is what the atom "wants" to do with its electrons.
- Sun Feb 23, 2020 6:16 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: ∆G=-nFE
- Replies: 3
- Views: 320
Re: ∆G=-nFE
Reactions at equilibrium usually have a º symbol. So, ∆Gº=-nFEº would be at equilibrium.
- Sun Feb 23, 2020 6:11 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs free energy
- Replies: 5
- Views: 336
Re: Gibbs free energy
Kristina Rizo 2K wrote:What is the numeric value for the faraday constant? I didn't write it down during lecture.
96,485 C·mol-1
- Sun Feb 23, 2020 6:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: voltage
- Replies: 8
- Views: 376
Re: voltage
Voltage is the potential difference between two electrodes and measures the chemical potential for a redox reaction to occur.
- Sun Feb 23, 2020 6:06 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: work
- Replies: 8
- Views: 411
Re: work
When the system does work, it should be negative since energy is leaving the system. If work is done on the system, energy increases so it would be positive.
- Sun Feb 23, 2020 6:03 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: how to get n in equation
- Replies: 8
- Views: 492
Re: how to get n in equation
N refers to the number of electrons being transferred.
- Sun Feb 23, 2020 12:41 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in -nFE
- Replies: 14
- Views: 803
Re: n in -nFE
N signifies the number of electrons are transferred.
- Sun Feb 23, 2020 12:33 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 20
- Views: 1043
Re: Adding Inert Gas
Adding an inert gas does not change the equilibrium constant.
- Mon Feb 03, 2020 10:39 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy
- Replies: 7
- Views: 207
Re: enthalpy
Enthalpy is the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume (H = U + PV)
- Mon Feb 03, 2020 10:31 am
- Forum: General Science Questions
- Topic: Cold and Hot liquids in Freezer
- Replies: 2
- Views: 321
Re: Cold and Hot liquids in Freezer
Warm water evaporates rapidly and since this is an endothermic process, it cools the water and allows it to freeze more readily.
- Mon Feb 03, 2020 10:29 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: residual entropy
- Replies: 4
- Views: 168
Re: residual entropy
How is change in entropy calculated? What are its units? It really depends on the reaction-- whether it is reversible or irreversible, and what kind of transfer is occurring (between two reservoirs, from/to a heat reservoir, etc..). However if given the entropy value of the final and initial states...
- Mon Feb 03, 2020 10:11 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated System Drawing
- Replies: 3
- Views: 192
Re: Isolated System Drawing
He was trying to draw a puffer jacket! Insulation prevents a system from transferring energy or matter with its surroundings. Some examples of an isolated system are a bomb calorimeter and a thermos container.
- Mon Feb 03, 2020 10:08 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: q vs H
- Replies: 9
- Views: 456
Re: q vs H
GFolk_1D wrote:Are deltaH and q interchangeable?
At constant pressure, qp = deltaH. Otherwise, they are not interchangeable.
- Mon Feb 03, 2020 10:07 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: q vs H
- Replies: 9
- Views: 456
Re: q vs H
q refers to heat transfer, while H refers to change in enthalpy (the total potential energy of a system).
- Tue Jan 28, 2020 10:46 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy
- Replies: 3
- Views: 113
Re: Standard Enthalpy
Standard reaction enthalpy is the heat given off or absorbed during reaction, while standard enthalpy of formation is the enthalpy change between the elements in their standard state (reactants) and the compound (product).
- Tue Jan 28, 2020 10:41 am
- Forum: Ideal Gases
- Topic: Ideal Gas
- Replies: 4
- Views: 188
Re: Ideal Gas
A gas is ideal if the molecules do not attract or repel each other, but collide elastically and randomly. Also, ideal gas molecules should take up no volume.
- Tue Jan 28, 2020 10:39 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy of Formation
- Replies: 4
- Views: 277
Re: Standard Enthalpy of Formation
Standard enthalpy of formation equals 0 whenever the element is in its standard state, since they are not formed.
- Tue Jan 28, 2020 10:12 am
- Forum: Phase Changes & Related Calculations
- Topic: State Functions
- Replies: 9
- Views: 425
Re: State Functions
A state function is a property of a system that depends on only the current state, irregardless of what path was taken to get there. Some examples include temperature, pressure, and volume. Enthalpy is considered a state function because it depends on the initial and final states, not the path betwe...
- Tue Jan 28, 2020 10:07 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific heat as an intensive property
- Replies: 2
- Views: 74
Re: Specific heat as an intensive property
Heat capacity is strongly influenced by external factors such as weight, while specific heat measures a substances ability to heat a mole of substance by 1 degree C; since there is a universal weight that is used, the only factors taken into account are the type of substance it is, making it an inte...
- Sat Jan 25, 2020 5:13 pm
- Forum: Ideal Gases
- Topic: Homework problem 5I.11
- Replies: 3
- Views: 273
Re: Homework problem 5I.11
In order to get Qc, you have to us [products]/[reactants. However, in this problem, you have to change mmol to mol, and put that value of moles over 0.5 L to find M, or Molarity. Once you use these conversions, [SO3]^2/[SO2]^2[O2] should give you Qc=6.9.
- Sat Jan 25, 2020 5:10 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka*Kb=Kw
- Replies: 5
- Views: 396
Re: Ka*Kb=Kw
No, in calculation you should get the same thing since 1 times anything is still that value. Just make sure to keep sig. figs. in mind.
- Sat Jan 25, 2020 5:08 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Water Properties
- Replies: 5
- Views: 336
Re: Water Properties
Amphoteric means a substance can act as both and acid and a base, while amphiprotic means a substance can both donate and accept protons.
- Sat Jan 25, 2020 5:07 pm
- Forum: Phase Changes & Related Calculations
- Topic: Standard State
- Replies: 3
- Views: 62
Re: Standard State
I don't think there is an explanation besides the fact that keeping standard conditions makes consistent the results.
The standard state temperature is 298 K.
All gases are at 1 atm pressure and all solutions are at 1M concentration.
The standard state temperature is 298 K.
All gases are at 1 atm pressure and all solutions are at 1M concentration.
- Sat Jan 25, 2020 5:04 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic and Exothermic
- Replies: 13
- Views: 515
Re: Endothermic and Exothermic
You can think of heat as either a reactant or a product. When heat is being released, the reaction is exothermic, and heat is product. Conversely, when heat is being absorbed, a reaction is endothermic, and heat is a reactant.
- Wed Jan 15, 2020 5:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5J.5
- Replies: 4
- Views: 140
Re: 5J.5
The problem should state 2HD ⇌ H2 + D2, I think you misplaced a reactant on the product side :)
So with this, there would be no change since there is an equal amount of moles of gas on either side.
So with this, there would be no change since there is an equal amount of moles of gas on either side.
- Wed Jan 15, 2020 5:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Why Ignore Liquid or Solid Volume When Calculating K
- Replies: 7
- Views: 229
Re: Why Ignore Liquid or Solid Volume When Calculating K
Liquids and solids don't necessarily dissolve in solvent, which is a main component of "concentration", which is then the focus of equilibrium calculations.
- Wed Jan 15, 2020 5:03 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K cutoff
- Replies: 5
- Views: 190
Re: K cutoff
If K is less that 10^-3, then x is negligible.
- Wed Jan 15, 2020 4:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sig Figs on HW 5H.1c
- Replies: 4
- Views: 181
Re: Sig Figs on HW 5H.1c
41 is two sig figs, so your answer should also be two sig figs, so 1.7 x 10^3!
- Wed Jan 15, 2020 4:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Significant figures for acid and base calculations
- Replies: 3
- Views: 113
Re: Significant figures for acid and base calculations
I think a rule of thumb in all calculations is to leave the rounding for the end for accuracy.
- Sun Jan 12, 2020 11:28 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: when to use Kc vs Kp
- Replies: 11
- Views: 390
Re: when to use Kc vs Kp
Kc is defined by molar concentrations, while Kp is defined by partial pressures of gases. You typically use brackets for K and Kc, and parentheses for Kp.
- Sun Jan 12, 2020 11:25 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Le Chatelier's Principle
- Replies: 5
- Views: 184
Re: Le Chatelier's Principle
No, solid and liquid concentrations usually do not change during reaction since nothing is dissolving, whereas gaseous and aqueous solutions do.
- Sun Jan 12, 2020 11:22 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids and Liquids
- Replies: 6
- Views: 122
Re: Solids and Liquids
Their concentrations usually do not change during reaction, whereas gaseous and aqueous solutions do. In order for concentration to change, something must dissolve in something else; liquids and solids don't dissolve and therefore aren't taken into account in equilibrium calculations.
- Sun Jan 12, 2020 11:08 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: changing conditions
- Replies: 6
- Views: 236
Re: changing conditions
A reaction tends to favor whatever side needs more or less "substance" to reach equilibrium. If the amount of product decreases, the reaction will favor the product side as to balance the reactants and products again.
- Sat Jan 11, 2020 9:01 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: States of matter [ENDORSED]
- Replies: 4
- Views: 143
Re: States of matter [ENDORSED]
Aqueous solutions dissociate and have a very strong effect on concentration, whereas liquids and solids do not. Since k quantifies the rate of chemical reactions, solids and liquids usually are not taken into account because their concentrations are not strong enough.
- Thu Dec 05, 2019 4:55 pm
- Forum: Bronsted Acids & Bases
- Topic: strong v weak acids
- Replies: 8
- Views: 441
Re: strong v weak acids
I think you really just need to know the 6 strong bases and know those are the ones that completely dissociate. The rest wouldn't completely dissociate, and it is likely that you would be given values for calculations to determine how strong or weak an acid is. Hopefully that made sense! Would thos...
- Mon Dec 02, 2019 10:53 pm
- Forum: Bronsted Acids & Bases
- Topic: strong v weak acids
- Replies: 8
- Views: 441
Re: strong v weak acids
I think you really just need to know the 6 strong bases and know those are the ones that completely dissociate. The rest wouldn't completely dissociate, and it is likely that you would be given values for calculations to determine how strong or weak an acid is. Hopefully that made sense!
- Mon Dec 02, 2019 10:24 pm
- Forum: Ionic & Covalent Bonds
- Topic: intermolecular vs intramolecular
- Replies: 17
- Views: 1873
Re: intermolecular vs intramolecular
Intermolecular forces exist between surrounding molecules while intramolecular forces are within molecules and hold atoms together.
- Mon Dec 02, 2019 8:24 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Outline topic
- Replies: 2
- Views: 173
Re: Outline topic
If a weak acid was very highly concentrated, as compared to a strong acid at a very low concentration, the pH of the weak acid could be the same or even higher than that of a strong acid.
- Mon Dec 02, 2019 8:21 pm
- Forum: Bronsted Acids & Bases
- Topic: bronsted vs lewis
- Replies: 2
- Views: 78
Re: bronsted vs lewis
Adding on to that, we have been using Bronsted more due to conjugate acid and base pairs which don't exist by the Lewis definition.
- Mon Dec 02, 2019 8:16 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: chelate
- Replies: 5
- Views: 372
Re: chelate
A chelate is a complex that has one or more ligands bonded to it that forms a ring around the central metal atom.
- Mon Dec 02, 2019 8:11 pm
- Forum: Conjugate Acids & Bases
- Topic: 6A.3
- Replies: 2
- Views: 195
Re: 6A.3
You're basically just being asked to write the equation of the dissociation of the acid in water. So you would show the "removal" or dissociation of a proton.
- Mon Dec 02, 2019 8:04 pm
- Forum: Bronsted Acids & Bases
- Topic: Oxoacids
- Replies: 2
- Views: 211
Re: Oxoacids
Any acid that has a bonded oxygen and a hydrogen. HNO3, H2SO4, and H3PO4 are some examples of oxyacids.
- Mon Dec 02, 2019 8:01 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH vs pOH
- Replies: 4
- Views: 156
Re: pH vs pOH
For 6B.5 part d, I first found M2 using M1V1=M2V2, and set M2 as my concentration of OH- ions. Then, I used -log([OH-]) to find pOH, which should give you 3.15. You would then subtract that from 14 because pH+pOH=14, and you should get 10.85.
- Mon Dec 02, 2019 7:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity and electronegativity
- Replies: 2
- Views: 229
Re: Polarity and electronegativity
A polar bond forms when one atom has a greater attraction for electrons than do the other atoms, this pull of electrons is called electronegativity. So, the greater the electronegativity, the greater the polarity of the molecule. In water, for example, oxygen has a greater pull on electrons than the...
- Mon Dec 02, 2019 7:45 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: how to find pH
- Replies: 4
- Views: 277
Re: how to find pH
There are some questions in 6B that ask you to find pH. For example, you can go from the given concentration of an acid to pH by using -log([H3O+]=pH. You could also be given an M1V1=M2V2 type question like 6.B #5.d. The last question form I can think of is being asked to find pOH, and converting th...
- Mon Nov 18, 2019 11:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape vs Electron Geometry
- Replies: 4
- Views: 382
Re: Molecular Shape vs Electron Geometry
Electron geometry considers all electron dense regions, while molecular shapes only consider the present atoms. For example, in NH3, there are 3 bonded atoms, and 1 lone pair. There are 4 electron dense regions, so the electron geometry would be tetrahedral. However, there are only 3 bonded atoms af...
- Mon Nov 18, 2019 11:09 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: pi bond
- Replies: 2
- Views: 203
Re: pi bond
Also, sigma bonds are always found in bonding, they are the first bonds to form, so any single bond will only be a sigma bond. Any bond added after that (double or triple bond) will be a pi bond.
- Mon Nov 18, 2019 11:00 pm
- Forum: Lewis Structures
- Topic: Bent or Angular?
- Replies: 18
- Views: 1050
Re: Bent or Angular?
Technically they are the same thing so I don't think it matters, you would most likely get a problem correct with either name. Lavelle used bent in his lecture though.
- Mon Nov 18, 2019 10:58 pm
- Forum: Lewis Structures
- Topic: Organic Compounds
- Replies: 2
- Views: 180
Re: Organic Compounds
Usually Carbons are attached to each other, and Hydrogens are attached to carbons, so you end up with a long chain of Carbons with single bonded Hydrogens, or whatever atom you're given, to fulfill octet rules.
- Mon Nov 18, 2019 10:50 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma Bonds
- Replies: 2
- Views: 149
Re: Sigma Bonds
Each single bond a central atom has attaches to it is a sigma bond, every additional bond added to the initial single bond (double or triple bond) is a pi bond. So in the case of SF6, S has 6 single bonded F's, so it has 6 sigma bonds and no pi bonds. NO3- on the other hand has 2 single bonds and 1 ...
- Mon Nov 18, 2019 10:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Worksheet for 1D/1F 10/16
- Replies: 24
- Views: 2018
Re: Worksheet for 1D/1F 10/16
For number #2, X I understand why the pairs (CH3CH2CH2CH3 & CH(CH)3, H2S & H2O, KI & KCl) are stronger than each other, but how do you know that H2S and H2O have stronger interactions than the hydrocarbons, and that KI and KCl have stronger interactions than the others?
- Sat Nov 16, 2019 10:51 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Deciding Between Trigonal Planar vs Trigonal Pyramidal
- Replies: 4
- Views: 174
Re: Deciding Between Trigonal Planar vs Trigonal Pyramidal
The trigonal planar notation would look like AX3, which means there are three bonding atoms and no lone pairs. Trigonal pyramidal would look like AX3E, which means there are three bonding atoms and one lone pair, or 4 electron dense regions.
- Sat Nov 16, 2019 10:38 am
- Forum: DeBroglie Equation
- Topic: De Broglie Wavelength
- Replies: 23
- Views: 3329
Re: De Broglie Wavelength
You would use de Broglie whenever you're dealing with a particle that is not light, and has mass.
- Sat Nov 16, 2019 10:21 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle with Lone Pairs
- Replies: 3
- Views: 117
Re: Bond Angle with Lone Pairs
The lone pairs repel the bonded molecules more, thus pushing them together and lessening the bond angles.
- Thu Nov 14, 2019 9:35 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 5
- Views: 455
Re: Polarizability
I'm pretty sure you would either use the electronegativity chart, or look a the molecule itself. If the molecule is asymmetrical, it will be polar, but if it is symmetrical then it will be nonpolar.
- Thu Nov 14, 2019 9:28 pm
- Forum: Electronegativity
- Topic: water solubility
- Replies: 4
- Views: 233
Re: water solubility
You would use the rule, "like dissolves like", and the fact that water is a polar molecule. The more electronegative a molecule is, the more polar it is, so as polarity increases the more likely a molecule is to dissolve in water.
- Tue Nov 05, 2019 10:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6536
Re: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
Could someone please explain 8b please? I used the photoelectric effect equation relating kinetic energy, energy of the photon, and the work function, but for some reason I'm not getting the correct answer. What answer did you get? I'm having the same trouble and wondering if maybe we made the same...
- Tue Nov 05, 2019 10:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6536
Re: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
Can someone explain to me the concepts behind 10a? I am confused on why it is Aluminum. Thanks Aluminum is larger than Silicon because the effective nuclear charge is stronger in Silicon, which means that the electrons are pulled more strongly towards the nucleus mostly because there are more of th...
- Tue Nov 05, 2019 9:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6536
Re: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
Could someone please explain 8b please? I used the photoelectric effect equation relating kinetic energy, energy of the photon, and the work function, but for some reason I'm not getting the correct answer.
- Tue Nov 05, 2019 8:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6536
Re: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
For Dino Nuggets 6a, what equation do we need to use ? ive been trying to use different one (because theres a lot for E) and that molar mass is messing me up. I used de Broglie's since light isn't involved. Also, make sure you convert the molar mass to mass using Avogadro's... that also might be me...
- Tue Nov 05, 2019 8:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6536
Re: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
Can someone explain how to do #5 from this problem set? First, you want to find your initial molarity since it isn't given to you. You would use the first set of information to do so. You would have one flask with 5.00 grams of KMnO4 (which you would convert to moles). To find the molarity of this ...
- Tue Nov 05, 2019 8:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6536
Re: dino nuggets #1 [ENDORSED]
Isopropyl alcohol, used in rubbing alcohol, is a compound containing only C, H, and O. What is the empirical formula of isopropyl alcohol if you find that 0.255 g of the compound gives 0.561 g of CO2 and 0.306 g of H2O when burned completely in excess oxygen? Can someone please help get started on ...
- Tue Nov 05, 2019 6:18 pm
- Forum: SI Units, Unit Conversions
- Topic: When to use scientific notation
- Replies: 4
- Views: 281
Re: When to use scientific notation
I agree^. I also tend to use scientific notation when numbers become larger than the hundreds. Once in the thousands, I usually use scientific notation to keep myself from losing track of 0's. It definitely needs to be used to satisfy sig fig requirements sometimes.
- Tue Nov 05, 2019 6:10 pm
- Forum: Empirical & Molecular Formulas
- Topic: percent composition
- Replies: 3
- Views: 433
Re: percent composition
The total mass of the relative parts of the compound will have to add up to 1 or 100%, since you're given all components of the compound. The percentages should always add up to 100.
- Tue Oct 29, 2019 1:22 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Configurations
- Replies: 3
- Views: 152
Re: Electron Configurations
Any electron configuration can be written in shorthand, so you can write ground-state or excited-state configurations using shorthand. Thank you! This helps, what are the differences between ground-state and excited-state configurations? In ground-state, atoms have the least possible amount of ener...
- Tue Oct 29, 2019 1:16 pm
- Forum: Bond Lengths & Energies
- Topic: Lattice Energy
- Replies: 9
- Views: 408
Re: Lattice Energy
Lattice energy is the energy given off when oppositely charged ions in the gas phase come together to form a solid.
- Tue Oct 29, 2019 1:05 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Configurations
- Replies: 3
- Views: 152
Re: Electron Configurations
Any electron configuration can be written in shorthand, so you can write ground-state or excited-state configurations using shorthand.
- Mon Oct 28, 2019 8:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: e- configuration of Pd and Ni
- Replies: 2
- Views: 192
Re: e- configuration of Pd and Ni
There are several elements that are anomalies when it comes to electron configuration, such as Copper, Silver, Gold, Palladium, Chromium, and Molybdenum. These elements designate more electrons to their d-subshells from the s-subshells for more stability. Unfortunately, you just have to know which o...
- Mon Oct 28, 2019 8:12 pm
- Forum: Ionic & Covalent Bonds
- Topic: Homework 2A15
- Replies: 3
- Views: 201
Re: Homework 2A15
I think question 2A15 is asking what is the likely charge formed by the given elements, rather than what elements it would form ions with based on its charge. The answer is +3 because Ga is "willing" to give away 3 electrons. Hopefully I'm understanding your question correctly!
- Mon Oct 21, 2019 9:51 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radii
- Replies: 10
- Views: 528
Re: Atomic Radii
The more protons that are located in the nucleus, the stronger the pull is for the electrons, so the electrons are "geographically" much closer to the center of the atom.
- Mon Oct 21, 2019 9:48 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 6
- Views: 294
Re: Electron Affinity
In high school, I learned to think of electron affinity as the "love an atom or molecule has for an electron". Usually, elements with electron shells that are almost filled tend to have greater electron affinities, or, they want to fill their shells more readily than other elements. For ex...
- Mon Oct 21, 2019 9:44 pm
- Forum: DeBroglie Equation
- Topic: Protons and Electrons
- Replies: 4
- Views: 247
Re: Protons and Electrons
If the protons and electrons are moving at the same velocity, it would mean that the protons have a shorter wavelength. However, if they are moving at the same momentum it would mean they have the same wavelength.
- Mon Oct 21, 2019 4:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shell vs. Orbital
- Replies: 3
- Views: 131
Re: Shell vs. Orbital
Electrons that have the same value of n (principle quantum number) are in the same shell. Period 2 (for example) elements are all in the same shell. Electrons with the same l value (orbital shape) are in the same sub-shell. These would be the s-block, p-block, d-block, and f-blocks. An orbital is ma...
- Mon Oct 21, 2019 4:13 pm
- Forum: Trends in The Periodic Table
- Topic: Neon
- Replies: 3
- Views: 124
Re: Neon
He could have used any element, not just Neon, as an example. Neon is a noble gas and has a full electron shell so it is stable without any charge. I think it was just easiest to show that the listed ions are isoelectronic with Neon because it is already stable. But you could say the same for Cl- an...
- Tue Oct 15, 2019 9:49 pm
- Forum: Photoelectric Effect
- Topic: Speed of Light
- Replies: 29
- Views: 1468
Re: Speed of Light
Yes, speed of light (c) is a constant and will always be 2.998 x 10^8.
- Tue Oct 15, 2019 9:47 pm
- Forum: Properties of Light
- Topic: Variables and what they mean
- Replies: 9
- Views: 452
Re: Variables and what they mean
Lambda is the Greek letter used for wavelength, and "v" is frequency.
- Tue Oct 15, 2019 9:40 pm
- Forum: Einstein Equation
- Topic: Einstein Equation [ENDORSED]
- Replies: 5
- Views: 384
Re: Einstein Equation [ENDORSED]
Yes, you use E=hv to find the energy of a singular photon.
- Tue Oct 15, 2019 9:37 pm
- Forum: Properties of Light
- Topic: 1A.15
- Replies: 4
- Views: 341
Re: 1A.15
R is the symbol for the Rydberg constant, which is 3.28984*10^15 Hz.
- Tue Oct 15, 2019 9:35 pm
- Forum: Properties of Electrons
- Topic: atomic spectroscopy
- Replies: 5
- Views: 362
Re: atomic spectroscopy
Yes, when an atom absorbs energy, its electrons jump to higher energy levels, and jump back down again. Each jump releases a certain amount of energy that corresponds to a specific wavelength of light. Since each element has its own emission spectrum, you can use the wavelengths of light to compare ...
- Tue Oct 08, 2019 11:41 pm
- Forum: Limiting Reactant Calculations
- Topic: M 19.
- Replies: 4
- Views: 187
Re: M 19.
You first have to find both grams and moles of each given atom- C, H, and N. Then, find the mass of O by subtracting the total mass of C, H, and N from the given amount of grams of caffeine (0.376 g). You convert that mass to moles. Divide all of the molar amounts by the smallest and find the empiri...
- Tue Oct 08, 2019 11:34 pm
- Forum: Balancing Chemical Reactions
- Topic: state of acids
- Replies: 3
- Views: 150
Re: state of acids
According to the Arrhenius definitions, acids "release" their H+ ions in water so they are considered aqueous.
- Tue Oct 08, 2019 11:32 pm
- Forum: Significant Figures
- Topic: Do we use molar mass ?
- Replies: 8
- Views: 239
Re: Do we use molar mass ?
Usually you would only use the values given in the problem to decide how many sig figs to use. There are usually way less than eight sig figs on given values so it shouldn't matter in your answer anyways.
- Tue Oct 08, 2019 11:27 pm
- Forum: SI Units, Unit Conversions
- Topic: Accuracy vs Precision
- Replies: 11
- Views: 739
Re: Accuracy vs Precision
I liked the dartboard example that Dr. Lavelle used- in that higher accuracy would mean that the darts would hit the bullseye, and higher precision would mean that darts would hit the same spot (regardless of position) again and again.