## Search found 63 matches

Thu Mar 14, 2019 1:40 am
Forum: Zero Order Reactions
Topic: Zero order
Replies: 10
Views: 759

### Re: Zero order

so if I'm understanding this correctly... zero orders are just equal to the constant (k). how would we write them in the k[A][B]^2 thing or would be leave them out?
Thu Mar 14, 2019 1:36 am
Forum: First Order Reactions
Topic: Time Conversions
Replies: 9
Views: 543

### Re: Time Conversions

always use the units that the question initially gives you unless stated otherwise. so yeah convert everything to one type of unit. and don't forget conversions between kJ and J (unrelated sidenote)
Thu Mar 14, 2019 1:33 am
Forum: Second Order Reactions
Topic: Problem 15.35 (half life)
Replies: 1
Views: 101

### Re: Problem 15.35 (half life)

first you solve for k then you use the formula to solve for t and you get t = (1/[A]t - 1/[A]o)/k to solve for t in which [A]t can be replaced by (1/16)[A]o , (1/4)[A]o , and (1/5)[A]o which gives you something like for 1/16th : t = (16/[A]o - 1/[A]o)/k
Thu Mar 14, 2019 1:30 am
Forum: Second Order Reactions
Topic: half-life
Replies: 4
Views: 155

### Re: half-life

you have to get the formula for t from the second rate equation which causes you to get t = (1/[A]t - 1/[A]o)/k and in this case you can replace [A]t with (1/16) x [A]o causing the equation to be t = (16/[A]o - 1/[A]o)/k and you just plug stuff in :)
Thu Mar 14, 2019 1:25 am
Forum: Balancing Redox Reactions
Topic: Balancing basic redox reactions
Replies: 7
Views: 478

### Re: Balancing basic redox reactions

Khan academy has a great video on it but yeah like they said you have to do it as if it were in acidic then you add the HO-
Thu Mar 14, 2019 1:24 am
Forum: Balancing Redox Reactions
Topic: Homework
Replies: 2
Views: 111

### Re: Homework

I generally add the OH- after I balance it using acidic solution then just convert the H+ to OH- (Khan academy has a good video on this) and you only really use H2O to balance oxygen you don't always need to add it.
Thu Mar 14, 2019 1:21 am
Forum: Balancing Redox Reactions
Topic: HW problem
Replies: 2
Views: 125

### Re: HW problem

don't forget that oxygen is always 2- and hydrogen is always 1+ thats usually how you calculate it then its just dependent on if you do the addition/subtraction correctly.
Thu Mar 14, 2019 1:10 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Isothermal
Replies: 5
Views: 235

### Re: Isothermal

deltaU = 0 doesn't mean theres no heat just that theres no difference in the amount of heat in the beginning compared to the end (no change). Just like said above its just a way to tell you to use q = -w since q+w = 0
Thu Mar 14, 2019 12:58 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity of Water
Replies: 6
Views: 415

### Re: Heat Capacity of Water

yea basically if Celsius is changed by 1 decree then so is Kelvin since its just addition
Thu Mar 14, 2019 12:57 am
Forum: Phase Changes & Related Calculations
Topic: steam at 100ºC burn worse
Replies: 7
Views: 434

### Re: steam at 100ºC burn worse

because it holds more energy since it has the heat energy of boiling water + the heat energy required for the phase change
Thu Mar 14, 2019 12:54 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solubility and Equilibrium Constants
Replies: 1
Views: 86

### Re: Solubility and Equilibrium Constants

they're used in those K = [Products]/[Reactants] problems to calculate solubility
Thu Mar 14, 2019 12:51 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibruim Assessment
Replies: 5
Views: 256

### Re: Equilibruim Assessment

don't forget if the x value is very small (i.e. less than 10^-3) you can ignore the x when subtracting it from another value!
Tue Feb 19, 2019 2:49 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterms
Replies: 4
Views: 197

### Re: Midterms

Does anyone know if midterms have ever been graded on a curve?
Tue Feb 19, 2019 2:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Relationship between enthalpy, entropy, and Gibbs
Replies: 4
Views: 201

### Re: Relationship between enthalpy, entropy, and Gibbs

delta G = delta H - T x delta S

Like someone above said if you plug in numbers to the equation it'll make pretty good sense.
Most of this stuff will be dependent on temperature.
Tue Feb 19, 2019 2:33 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Replies: 35
Views: 1291

are there ever curves?
Tue Feb 19, 2019 2:28 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q=0
Replies: 4
Views: 232

### Re: q=0

They'll usually just say constant temp or isothermal which is pretty much the same thing.
Tue Feb 19, 2019 2:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp vs Cv
Replies: 7
Views: 558

### Re: Cp vs Cv

Cp = Constant Pressure
Cv = Constant Volume
Tue Feb 19, 2019 2:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G a state function?
Replies: 23
Views: 1034

### Re: Delta G a state function?

its defined by state functions which makes it a state function
Tue Feb 19, 2019 12:45 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Test 3
Replies: 10
Views: 412

### Re: Test 3

Gibbs Free energy and electrochemistry for test 2
Wed Feb 13, 2019 11:48 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ideal Gases
Replies: 2
Views: 156

### Ideal Gases

What's the purpose of using Ideal Gases when they are theoretical? And whats the basic difference between ideal gases and real gases?
Wed Feb 13, 2019 11:37 am
Forum: Phase Changes & Related Calculations
Topic: Isothermal
Replies: 9
Views: 544

### Isothermal

On a test or midterm will we be told if the system is Isothermal?
Fri Jan 25, 2019 3:32 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ignoring x
Replies: 10
Views: 350

### Re: ignoring x

everything above^^^ and you can check the 5% rule by taking the value you plug into the -log for pH and dividing it by the original starting concentration of whatever weak acid was used in the problem (usually a given) then you multiply it by 100%
Fri Jan 25, 2019 3:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Favoring
Replies: 4
Views: 283

### Re: Equilibrium Favoring

The post-module assignment just had it that:

K > 1 means that there are more products at equilibrium (lies to the right)
K < 1 means that there are more reactants at equilibrium (lies to the left)
K = 1 means neither are favored.
Fri Jan 25, 2019 3:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What not to count
Replies: 9
Views: 401

### What not to count

I know that when doing the ICE box you don't count Cl, Na, or H2O but are there any other elements that we just inherently disregard?
Fri Jan 25, 2019 3:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th Edition Problem 41
Replies: 3
Views: 131

### Re: 6th Edition Problem 41

I don't have the 6th edition but I don't see how you could have calculated it so that the initial concentration of a reactant = the value of x... reevaluate how you got the x value. (most problems made you do like x^2/some number)
Fri Jan 25, 2019 3:13 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: question 5i.19
Replies: 3
Views: 116

### Re: question 5i.19

Don't forget to use c = n/V and that at equilibrium 40% of hydrogen is left.
Tue Jan 22, 2019 2:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th Edition 6E.3
Replies: 1
Views: 55

### 7th Edition 6E.3

Calculate the pH of 0.15 M H2SO4 (aq) at 25 Celsius (Ka2 = 1.2 x 10^-2)

Could someone explain the concept of Ka2 and why we ignore the second ionization?
Tue Jan 22, 2019 2:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th edition: 6D.15
Replies: 2
Views: 140

### Re: 7th edition: 6D.15

Pretty sure (aq) just means its like surround by water or in water. The problems are also solved basically the same way and there is a chart with values and like info on Al^3+ and how it equals Al(H20)6^3+ (I think that that would be given to us)
Tue Jan 22, 2019 2:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka and Kb
Replies: 2
Views: 89

### Ka and Kb

Will we have to memorize certain Ka/Kb values or will that be given or just not show up at all?
Tue Jan 22, 2019 12:11 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Deprotonation
Replies: 1
Views: 85

### Deprotonation

Can someone give a good/simple explanation of deprotonation is and how to use the percentage in problems?
Fri Dec 07, 2018 9:52 pm
Forum: Dipole Moments
Topic: partial charge
Replies: 2
Views: 334

### Re: partial charge

Its a non polar molecule so I don't think it really matters
Fri Dec 07, 2018 9:51 pm
Forum: Polyprotic Acids & Bases
Topic: Defintion
Replies: 11
Views: 694

### Re: Defintion

Is water then polyprotic?
Fri Dec 07, 2018 9:49 pm
Forum: Naming
Topic: Coordinate #
Replies: 1
Views: 102

### Coordinate #

Can someone explain how to find Coordinate numbers? They're just the bonds right?
Sun Dec 02, 2018 10:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Bipyramidal
Replies: 6
Views: 297

### Re: Trigonal Bipyramidal

Maybe I'm just reading this wrong but are you referring to see saw?
Sun Dec 02, 2018 9:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Notation
Replies: 10
Views: 391

### Re: VSEPR Notation

Is VSEPR Notation also referred to as VSEPR Formula?
Sun Dec 02, 2018 9:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole moment
Replies: 7
Views: 377

### Re: Dipole moment

Knowing the polarity of the element also helps show its ability to form dipole dipole (idk how relevant that is but hey just trying to contribute)
Sun Dec 02, 2018 9:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape in relation to polarity and boiling point
Replies: 5
Views: 710

### Re: Molecular shape in relation to polarity and boiling point

Ion bond > H bond > dipole dipole > dipole induced > induced induced
Sun Dec 02, 2018 9:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Ozone and polarity
Replies: 3
Views: 2210

### Re: Ozone and polarity

Yea its because of the lone pairs and I'm pretty sure the formal charge equation proves that.
Sun Dec 02, 2018 9:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.95 6th ed
Replies: 3
Views: 191

### Re: 4.95 6th ed

Just use formal charge formula FC = Valence - [lone pair electrons - (shared electrons/2)]
Tue Nov 13, 2018 2:20 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Hybrid vs. Molecular Orbitals
Replies: 3
Views: 569

### Re: Hybrid vs. Molecular Orbitals

Hybrid orbitals are interactions of orbitals in the same atom while molecular orbitals are between two different atoms.
Tue Nov 13, 2018 2:18 am
Forum: Ionic & Covalent Bonds
Topic: London Van Der Waals Force?
Replies: 5
Views: 256

### Re: London Van Der Waals Force?

They are caused by relative EN due to the fact that electrons move and it is also how Geckos walk on walls and stuff! (Fun fact)
Tue Nov 13, 2018 2:16 am
Forum: Bond Lengths & Energies
Replies: 2
Views: 156

Actually thats incorrect. Covalent radii is half the distance between the two nuclei. It isn't the sum of the two radii at all. When the two atoms bond the like kinda mesh together so yea its just half the distance between not the sum.
Tue Nov 13, 2018 2:12 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral versus Trigonal Pyramidal
Replies: 3
Views: 185

### Re: Tetrahedral versus Trigonal Pyramidal

Also it's important to know that lone pairs have stronger repelling forces than bond pairs.
Tue Nov 13, 2018 2:09 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial vs. Equatorial Lone Pairs
Replies: 2
Views: 130

### Re: Axial vs. Equatorial Lone Pairs

Tue Nov 13, 2018 2:08 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: Interaction potential energy equation
Replies: 3
Views: 168

### Re: Interaction potential energy equation

Sorry didn't mean to repost question. As a note to any moderators: the site would work better if we could still see what we are replying to while we are replying.
Tue Nov 13, 2018 2:07 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: Interaction potential energy equation
Replies: 3
Views: 168

### Re: Interaction potential energy equation

What is the interaction potential energy telling us? What do we use it to determine? Does it have anything to do with whether their is a dipole moment and how strong that dipole moment is? I thought it meant just the energy that is added to the total energy during a reaction. I'm also pretty sure it...
Tue Nov 13, 2018 1:59 am
Forum: Resonance Structures
Topic: Drawing resonance
Replies: 17
Views: 1061

### Re: Drawing resonance

If the bond can go anywhere then might as well draw the arrows I don't think it would ever hurt you.
Tue Nov 13, 2018 1:57 am
Forum: Octet Exceptions
Topic: Octet exceptions
Replies: 8
Views: 485

### Re: Octet exceptions

In all honesty, the octet rule is pretty worthless after the few elements in the 2nd row that it applies to. We just pretend that it continues but hardly anyone knows anything about any element after the 3rd row.
Tue Nov 13, 2018 1:56 am
Forum: Lewis Structures
Topic: VSEPR Model
Replies: 6
Views: 485

### Re: VSEPR Model

It also shows where electrons are and how they interact.
Tue Nov 13, 2018 1:54 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Modules
Replies: 2
Views: 382

### Re: Modules

How does it come with the textbook? I didn't see it.
Tue Nov 13, 2018 1:53 am
Forum: Ionic & Covalent Bonds
Topic: Replacement for Modules
Replies: 7
Views: 354

### Re: Replacement for Modules

Does anyone know the name of the site he keeps saying to use?
Sat Oct 27, 2018 10:44 am
Forum: Ionic & Covalent Bonds
Topic: Ground State
Replies: 6
Views: 308

### Re: Ground State

So would the answer be [Ar]3d6?
Sat Oct 27, 2018 10:18 am
Forum: Ionic & Covalent Bonds
Topic: Replacement for Modules
Replies: 7
Views: 354

### Replacement for Modules

Hey so I was wondering if there are any studying resources that are similar to the modules since there are no more of those to use. Thank you! (Also I am not sure where to post this question)
Thu Oct 25, 2018 4:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Why is there a negative?
Replies: 4
Views: 277

### Why is there a negative?

Why is there a negative in the equation (En = -hR/n^2) when we just put the positive value whenever a questions asks us to find the frequency or wavelength? Is there any scenario in which we would put the negative value as the answer?
Fri Oct 19, 2018 12:40 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Modules
Replies: 2
Views: 382

### Modules

Does anyone know when more models will be uploaded to the Chem14A website? I felt this is the best place to ask since I am "uncertain" and Heisenberg Indeterminacy is the last module topic.
Thu Oct 18, 2018 11:47 pm
Forum: Quantum Numbers and The H-Atom
Topic: Lyman, Balmer, etc.
Replies: 1
Views: 128

### Lyman, Balmer, etc.

So as we know the Lyman series is n=1, the Balmer series is n=2, and so on and so on. My question is whether or not we will need to know all the series after these two or will we just be given n = 4?
Thu Oct 18, 2018 11:41 pm
Forum: Properties of Light
Topic: Microwaves vs. Actual Microwaves
Replies: 1
Views: 161

### Microwaves vs. Actual Microwaves

How come on the EM spectrum "Microwaves" are said to have wavelengths between 1mm and 10cm but actual physical Microwaves can have wavelengths up to 1m? Do Microwaves not use "Microwaves"?
Fri Oct 12, 2018 9:34 pm
Forum: Properties of Light
Topic: Question related to Light and Rainbows
Replies: 1
Views: 72

### Re: Question related to Light and Rainbows

Well the formation of rainbows required pretty specific stuff like there has to be rain and sun and the sunshine needs to be going through at a certain angle in respect to whoever is looking at it and obviously there has to be water droplets in the air and again no clouds. Its more common to see rai...
Fri Oct 12, 2018 9:25 pm
Forum: Properties of Light
Topic: question from class today
Replies: 3
Views: 108

### Re: question from class today

I think you should write out the entire question haha I don't remember that happening but maybe I'm in a different lecture or missed it or something haha
Fri Oct 12, 2018 9:17 pm
Forum: Properties of Light
Replies: 2
Views: 53

Well a black body is an object that "absorbs all radiation falling on it, at all wavelengths," and you can calculate the emissions with Planck's Law but I don't think we're really doing many of those calculations. I hope that kinda helped haha
Fri Oct 05, 2018 12:02 am
Forum: Empirical & Molecular Formulas
Topic: HW 1 Problem F.9
Replies: 7
Views: 232

### Re: HW 1 Problem F.9

yeah I was confused too but I guess since avogradro is a constant the ratios for the moles are the same as the ratios for the atoms since they're all being multiplied by the same thing.
Thu Oct 04, 2018 11:58 pm
Forum: Empirical & Molecular Formulas
Topic: Compound Names
Replies: 9
Views: 539

### Re: Compound Names

No we don't need to know them yet but its good practice to figure out the meaning of compound names because they'll be needed in the future
Thu Oct 04, 2018 11:53 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding in Mole Ratios for Empirical Formulas
Replies: 2
Views: 236

### Re: Rounding in Mole Ratios for Empirical Formulas

I would instead treat 9.77 as 9.75 and multiply the ratio by 4 so you end up with C 5 : H 39 : O 22 (its more accurate this way). Just look to see if decimals can be rounded to .25 .5 or .75 cuz those are easy numbers to work with.