Search found 43 matches

by Justin Folk 3I
Fri Mar 16, 2018 11:00 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 11
Views: 560

Re: closed vs isolated

Does heat transfer happen when the balloon loses air?
by Justin Folk 3I
Fri Mar 16, 2018 10:59 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 2
Views: 126

Re: Catalysts

They orient the molecules in a way that makes them easier to crash in the correct orientation.
by Justin Folk 3I
Fri Mar 16, 2018 10:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 3
Views: 137

Re: Cell Diagram

Is the salt bridge also connected to, say, Pt(s)? or just metal wire?
by Justin Folk 3I
Thu Mar 15, 2018 6:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 #6
Replies: 3
Views: 166

Re: Test 2 #6

You can tell because of the cell potentials. Overall cell potential has to be positive.
by Justin Folk 3I
Thu Mar 15, 2018 6:35 pm
Forum: *Electrophilic Addition
Topic: Possible Questions
Replies: 1
Views: 379

Re: Possible Questions

Questions like which?
by Justin Folk 3I
Thu Mar 15, 2018 6:34 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.49
Replies: 4
Views: 207

Re: 15.49

Yes rate law is only the slow step
by Justin Folk 3I
Thu Mar 15, 2018 6:33 pm
Forum: Balancing Redox Reactions
Topic: Half-Reactions Sheet
Replies: 5
Views: 227

Re: Half-Reactions Sheet

Yes.
by Justin Folk 3I
Fri Mar 09, 2018 2:20 pm
Forum: Second Order Reactions
Topic: Units [ENDORSED]
Replies: 5
Views: 352

Re: Units [ENDORSED]

What about units for a 1.5 order?
by Justin Folk 3I
Fri Mar 09, 2018 2:19 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Constant Calculations [ENDORSED]
Replies: 3
Views: 272

Re: Rate Constant Calculations [ENDORSED]

You could use the linear equations for the standard rxn numbers to find the constant from initial and time concentrations
by Justin Folk 3I
Fri Mar 09, 2018 2:18 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding n
Replies: 15
Views: 780

Re: Finding n

But if you multiply entire reaction by 2 then why isn’t it using 2 moles?
by Justin Folk 3I
Sat Mar 03, 2018 10:41 pm
Forum: Second Order Reactions
Topic: K in Rate Laws [ENDORSED]
Replies: 2
Views: 133

Re: K in Rate Laws [ENDORSED]

Because for second order reactions the y-axis is 1/[A]. As time progresses the concentration of [A] decreases (assuming A is reactant) and thus 1/A increases, therefore slope of graph >0
by Justin Folk 3I
Sat Mar 03, 2018 10:39 pm
Forum: General Rate Laws
Topic: Multiple Reactants
Replies: 2
Views: 144

Re: Multiple Reactants

1) Double reaction and initial rates are doubled: let's pretend A --> B, [A] = c mol/L and rate = k [A]^1. Your rate would be k*c^1 = kc But let's say [A] = 2c, then rate would be k*(2c)^1 = 2kc So for first order with respect to a reactant, doubling the concentration would give you double the rate
by Justin Folk 3I
Sat Mar 03, 2018 10:37 pm
Forum: First Order Reactions
Topic: Reaction Orders [ENDORSED]
Replies: 2
Views: 120

Re: Reaction Orders [ENDORSED]

They basically mean, in crass terms, "How much does the concentration of reactant affect rate of reaction"
by Justin Folk 3I
Sun Feb 25, 2018 4:24 pm
Forum: Zero Order Reactions
Topic: zero order slopes
Replies: 5
Views: 232

Re: zero order slopes

Yes, slope should be zero. It's the derivative of a constant, which makes it zero.
by Justin Folk 3I
Sun Feb 25, 2018 4:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding n
Replies: 15
Views: 780

Re: Finding n

How do we know it's a mole of reaction?
by Justin Folk 3I
Sun Feb 25, 2018 4:23 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Determining N
Replies: 4
Views: 184

Re: Determining N

Determined by the balanced equation or no?
by Justin Folk 3I
Tue Feb 20, 2018 10:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.27
Replies: 1
Views: 95

Re: 14.27

Yes i believe so. Thanks for the tip. Got stuck on this one
by Justin Folk 3I
Fri Feb 16, 2018 5:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode/ Cathode
Replies: 6
Views: 245

Re: Anode/ Cathode

Red Cat-- reduction at cathode
An Ox-- anode oxidation
by Justin Folk 3I
Fri Feb 16, 2018 5:17 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: s vs. delta s
Replies: 7
Views: 301

Re: s vs. delta s

I thought we can only measure change in entropy?
by Justin Folk 3I
Fri Feb 16, 2018 5:16 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What does R stand for?
Replies: 13
Views: 769

Re: What does R stand for?

Yes, you're right sorry. THere's multiple R. You need to look at the units, on the third row of equation sheet. THanks
by Justin Folk 3I
Sat Feb 10, 2018 3:08 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 11
Views: 560

Re: closed vs isolated

No, closed is just where matter can't escape. isolated is where neither matter nor internal energy can escape
by Justin Folk 3I
Sat Feb 10, 2018 3:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: finding heat capacity using q=cΔT
Replies: 3
Views: 233

Re: finding heat capacity using q=cΔT

The heat capacity is defined as ENERGY per TEMPERATURE
by Justin Folk 3I
Sat Feb 10, 2018 3:04 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: When to use + sign
Replies: 11
Views: 402

Re: When to use + sign

So since it's for a change its always used?
by Justin Folk 3I
Sat Jan 27, 2018 8:33 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Examples of work being done
Replies: 7
Views: 316

Re: Examples of work being done

For example pushing a cart is work being done. You use some energy (instead of to heat up) to push the cart.
by Justin Folk 3I
Sat Jan 27, 2018 8:31 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy of gas vs liquid vs solid
Replies: 7
Views: 1602

Re: Entropy of gas vs liquid vs solid

Because gas has more "randomness" by intuition. THere is inherently order in a liquid and solid-- they are all contained and there is only a set place that they can go. Gravity dictates this in a liquid and the lattice of a solid dictates this
by Justin Folk 3I
Sat Jan 27, 2018 8:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: units for delta H
Replies: 4
Views: 206

Re: units for delta H

KJ, or KJ per mole. depends on the context.
by Justin Folk 3I
Sat Jan 20, 2018 10:54 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What does R stand for?
Replies: 13
Views: 769

Re: What does R stand for?

Heat constant. When do you use 8.314 and when do you use 0.00821?
by Justin Folk 3I
Sat Jan 20, 2018 10:54 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter
Replies: 10
Views: 455

Re: Calorimeter

The calorimeter is usually calibrated well so that there is little heat lost that is not absorbed by the substance you are measuring heat. Thus you can measure the heat of a reaction, and thus you can also measure the heat per mole (by measuring the amt. of substance consumed)
by Justin Folk 3I
Sat Jan 20, 2018 10:52 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 4
Views: 105

Re: Enthalpy

Bond enthalpy is equal to enthalpy of formation in a diatomic molecule; for the others it is the sum of the bond enthalpies i believe. Correct me if wrong
by Justin Folk 3I
Fri Jan 12, 2018 10:29 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Change Signs
Replies: 5
Views: 205

Re: Enthalpy Change Signs

Think of it as enthalpy of formation being the same for each substance no matter whether it is on reactant or product side. Thus, if reactants - products = H, products - reactants = -H
by Justin Folk 3I
Fri Jan 12, 2018 10:26 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Why is fusion another name for melting?
Replies: 4
Views: 218

Re: Why is fusion another name for melting?

You might also be able to think of it as fusion being the heat it takes to put together, which is the reverse and equal in absolute value to the heat it takes to break apart?
by Justin Folk 3I
Fri Jan 12, 2018 10:24 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies vs. Standard Enthalpies of Formation
Replies: 2
Views: 104

Re: Bond Enthalpies vs. Standard Enthalpies of Formation

Is standard enthalpy of formation based on forming from the gaseous state as well?
by Justin Folk 3I
Wed Nov 30, 2016 1:24 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH of a weak acid and its salt
Replies: 1
Views: 297

Re: Calculating pH of a weak acid and its salt

KNO2 has NO2- when it dissociates, which it will because any compound with K+ will dissociate (generally).

Therefore, we have an initial concentration of NO2- to plug into ICE box
by Justin Folk 3I
Wed Nov 30, 2016 1:23 pm
Forum: *Titrations & Titration Calculations
Topic: Titrations
Replies: 1
Views: 240

Re: Titrations

Why do we want strong base/strong acid to be the titrant?
by Justin Folk 3I
Wed Nov 30, 2016 1:22 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.57, pH/pOH v. pKa/pKb
Replies: 1
Views: 295

Re: 12.57, pH/pOH v. pKa/pKb

No, pH is the measure of the [H+], while pKa is the measure of basically how much of a given acid HA dissociates. They are related, though. While Ka value doesn't tell too much about H+ concentration (due to other things like diprotonations, 2 H+ / mol acid), if everything else is held constant, suc...
by Justin Folk 3I
Sat Nov 26, 2016 6:01 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Can you classify acids as strong or weak from their formulas alone? [ENDORSED]
Replies: 7
Views: 899

Re: Can you classify acids as strong or weak from their formulas alone? [ENDORSED]

No, usually not. The only strong acids are the ones that are listed as "strong acids," and we know this because a Ka value doesn't exist-- everything dissociates so [HA] == 0, and Ka becomes undefined. Theoretically, you could deduce based on electronegativity its ionic vs covalent charact...
by Justin Folk 3I
Mon Nov 14, 2016 1:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Concentration Units [ENDORSED]
Replies: 3
Views: 741

Re: Equilibrium Concentration Units [ENDORSED]

Just molarity, since all units are the same, and some have varying degrees, so it wouldnt make sense to have units.
by Justin Folk 3I
Thu Oct 27, 2016 3:07 pm
Forum: Ionic & Covalent Bonds
Topic: Determining Which Has A Stronger Bond
Replies: 2
Views: 343

Re: Determining Which Has A Stronger Bond

Bonds work because of a balance of attraction between electrons and protons, and that they're not so close that the protons in the nucleus repel each other. Therefore, shorter bonds are better because the protons can easier "grab" the electrons.
by Justin Folk 3I
Fri Oct 21, 2016 11:47 am
Forum: Trends in The Periodic Table
Topic: What is the difference between electron affinity and electronegativity?
Replies: 3
Views: 642

Re: What is the difference between electron affinity and electronegativity?

They are inversely related-- electron affinity is the energy required to eject an electron, while electronegativity is the tendency to gain an electron
by Justin Folk 3I
Fri Oct 14, 2016 1:27 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation [ENDORSED]
Replies: 4
Views: 556

Re: Rydberg Equation [ENDORSED]

Will we be given that it is a hydrogen atom? This only works for hydrogen, but the problem 8 in the practice quiz 2 didn't list it as a hydrogen atom.
by Justin Folk 3I
Thu Oct 06, 2016 8:32 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Boundary Surface of Orbitals [ENDORSED]
Replies: 2
Views: 871

Re: Boundary Surface of Orbitals [ENDORSED]

Those shapes are right, but important to note that it's not the "boundary," but rather the probability region-- where an electron is most likely to be-- if I understand correctly!
by Justin Folk 3I
Thu Sep 29, 2016 2:11 am
Forum: Trends in The Periodic Table
Topic: Electron Affinity [ENDORSED]
Replies: 3
Views: 399

Re: Electron Affinity [ENDORSED]

I believe nitrogen has an electron affinity so much lower because it has (relatively) much fewer protons than oxygen and fluorine. Also what Alexis said about stability and all orbitals being half-filled: most stable when either all half-filled or all filled

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