Search found 37 matches

by Luis De La Cruz 1H
Thu Mar 15, 2018 5:45 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Temperature for an ideal gas
Replies: 2
Views: 205

Temperature for an ideal gas

Is it a fact that a change in temperature will always create a change in either volume or pressure? I'm asking because I can't think of an instance/scenario in which it wouldn't.
by Luis De La Cruz 1H
Thu Mar 15, 2018 5:40 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q under non-constant pressure
Replies: 1
Views: 224

q under non-constant pressure

Will we have to be given delta(U) and the variables to solve for work under non-constant pressure conditions to solve for q at a pressure that isn't constant, or would we just use q=mCvdelta(T) (given the mass and temperatures)? Or does this just depend on the question being asked?
by Luis De La Cruz 1H
Thu Mar 15, 2018 5:22 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Molecularity
Replies: 2
Views: 158

Molecularity

To what extent do we have to know about the molecularity of a reaction for this class?
by Luis De La Cruz 1H
Thu Mar 15, 2018 5:18 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 1
Views: 116

Activation Energy

How can you determine if a reaction is exothermic or endothermic given the activation energy of the forward reaction and the activation energy for the reverse reaction?
by Luis De La Cruz 1H
Sun Mar 11, 2018 9:47 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Transferring of Heat
Replies: 4
Views: 292

Re: Transferring of Heat

In this situation, I believe that the balloon filled with gas is expanding and thus the gas is doing work on the balloon (causing the expansion), but at the same time heat is given off by the balloon, and this is what is maintaining the same temperature. Remember when temperature is kept constant, w...
by Luis De La Cruz 1H
Sun Mar 11, 2018 9:37 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius equation for 2 temperatures
Replies: 2
Views: 129

Re: Arrhenius equation for 2 temperatures

Although it only shows up for one temperature in the equation sheet, I would still memorize the equation for two temperatures or at least know how to derive it, given that we might have a question on the final that pertains to two temperatures..
by Luis De La Cruz 1H
Sun Mar 11, 2018 9:29 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius eq use
Replies: 2
Views: 89

Re: Arrhenius eq use

Basically, whenever you have a problem that deals with activation energy, you will most likely have to use the Arrhenius equation, because that equation relates activation energy and temperature to the rate of a reaction.
by Luis De La Cruz 1H
Sat Mar 10, 2018 6:03 pm
Forum: Calculating Work of Expansion
Topic: 8.27-V needed to calculate n?
Replies: 1
Views: 104

Re: 8.27-V needed to calculate n?

Like the part b states, it is an isothermal process, so by looking at the equation PV=nRT, you see how R and T remain constant so the only thing that changes is the number of moles which you said you are calculating so, by definition the volume has to change,again seen by P(delta V)= (delta n)RT, th...
by Luis De La Cruz 1H
Sat Mar 10, 2018 5:42 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isobaric vs. Isochoric [ENDORSED]
Replies: 2
Views: 364

Re: Isobaric vs. Isochoric [ENDORSED]

The term of Isochoric is also interchangeable with the terms Isovolumetric, or Isometric which all mean the same thing when describing a process, that is that volume during the process remains constant so there is no change in volume essentially.
by Luis De La Cruz 1H
Sat Mar 10, 2018 5:38 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: The First Law
Replies: 6
Views: 393

Re: The First Law

Yes I do believe that the law of conservation of energy is sometimes referred to as the first law of thermodynamics, because from these laws you can see how energy is in fact neither created nor destroyed for an isolated system, and we take our universe to be an isolated system.
by Luis De La Cruz 1H
Sat Mar 10, 2018 5:28 pm
Forum: General Rate Laws
Topic: Fractional Rate Law [ENDORSED]
Replies: 4
Views: 208

Re: Fractional Rate Law [ENDORSED]

Yes, that is exactly how you would be able to calculate the overall order of the reaction, and you should also keep in mind that because [B] is at the bottom, that will affect the units of K as well. This is basically like the first question we got on test 3 for kinetics.
by Luis De La Cruz 1H
Tue Mar 06, 2018 12:08 am
Forum: Balancing Redox Reactions
Topic: Oxidizing Power
Replies: 2
Views: 125

Oxidizing Power

Can anyone explain to me how I would be able to rank say: Mn,Ag, and Ti in terms of increasing oxidizing power? I was really thrown off by this question during test 2.
by Luis De La Cruz 1H
Tue Mar 06, 2018 12:05 am
Forum: First Order Reactions
Topic: Rate of consumption vs concentration
Replies: 2
Views: 141

Re: Rate of consumption vs concentration

When creating the graphs that we've been discussing in chemical kinetics, we use the integrated rate laws, that's because if you look closely, they resemble the familiar y=mx+b format, and this is typically to determine the slope which happens to be k (the equilibrium constant) in these graphs. From...
by Luis De La Cruz 1H
Mon Mar 05, 2018 10:45 am
Forum: Zero Order Reactions
Topic: Slopes
Replies: 3
Views: 151

Re: Slopes

Most of the UAs have mentioned that this information becomes more relevant for 14BL where you actually conduct a chemical kinetics experiment, where you are taking the experimental data derived from the conducted experiment and you plot it on a graph ([ln a] vs time, [a] vs time, or 1/[a] vs time). ...
by Luis De La Cruz 1H
Mon Mar 05, 2018 10:34 am
Forum: Second Order Reactions
Topic: Half-life of second order reactions
Replies: 2
Views: 297

Re: Half-life of second order reactions

This is probably due to the fact that there is a different half life formula for second order reactions, and therefore you have to switch up your methodology for solving half life problems that pertain to second order reactions.
by Luis De La Cruz 1H
Sun Mar 04, 2018 9:14 pm
Forum: First Order Reactions
Topic: Order Reactions
Replies: 3
Views: 171

Re: Order Reactions

No, but obviously know which differential rate law and integrated rate law is associated with each order that we've learned about, respectively.
by Luis De La Cruz 1H
Sun Mar 04, 2018 9:06 pm
Forum: Zero Order Reactions
Topic: Will we need to know how to derive equations? [ENDORSED]
Replies: 9
Views: 376

Re: Will we need to know how to derive equations? [ENDORSED]

Dr. Lavelle has stated multiple times that he won't ever ask straight up derivation of equation questions on exams, however do review how and where each equation comes from because a combination of equations might need to be used to come up with the equation you would need for a particular test ques...
by Luis De La Cruz 1H
Sun Mar 04, 2018 9:02 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Constant K
Replies: 4
Views: 216

Re: Rate Constant K

One thing that helps me when trying to figure out the units of K, is the fact that the rate will always end up having to be in (M/s) or Molarity/s, therefore you essentially are manipulating the units of K which as stated above can change depending on the order of the reaction in order to end up wit...
by Luis De La Cruz 1H
Sun Mar 04, 2018 8:50 pm
Forum: General Rate Laws
Topic: Half Life
Replies: 6
Views: 228

Re: Half Life

Another important and perhaps real life application for the half life would be for pharmacists and doctors that are prescribing drugs, since they need to know how long that drug will stay in your system, which is something the half life of a reaction would be able to tell you.
by Luis De La Cruz 1H
Sun Mar 04, 2018 8:46 pm
Forum: Second Order Reactions
Topic: Half life constant and Rate reaction constant
Replies: 4
Views: 212

Re: Half life constant and Rate reaction constant

Like stated above, each K constant that you derive will be different, depending on the order of the reaction (0,1, or 2) because each order has its own half life formula associated with it.
by Luis De La Cruz 1H
Fri Mar 02, 2018 10:00 pm
Forum: Balancing Redox Reactions
Topic: Inert Conductors [ENDORSED]
Replies: 2
Views: 143

Inert Conductors [ENDORSED]

Are there other inert conductors, other than platinum that we should familiarize ourselves with for this class?
by Luis De La Cruz 1H
Fri Mar 02, 2018 9:50 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Factors Affecting Entropy
Replies: 4
Views: 1104

Re: Factors Affecting Entropy

Given that a gas just has that many more possible micro states (the particles that make up the gas) that it can be in due to the very nature of gases (particles that are essentially free flowing), it will basically always have a higher entropy than liquids, because the particles in a liquid will sti...
by Luis De La Cruz 1H
Fri Mar 02, 2018 9:45 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Using Kelvin [ENDORSED]
Replies: 3
Views: 161

Re: Using Kelvin [ENDORSED]

I would say to always stick to what you are given on the tests, that way there is no discrepancy/controversy to your final answer. Also during intermediate solving use the exact values you are getting and only round until the final answer using the minimum number of sig figs given in the initial pro...
by Luis De La Cruz 1H
Fri Mar 02, 2018 9:41 pm
Forum: Calculating Work of Expansion
Topic: w in a calorimeter
Replies: 2
Views: 156

Re: w in a calorimeter

It all depends on the calorimeter that you are dealing with, but for the most part in this class we talked about bomb calorimeters (isolated system) so there is no change in volume and therefore why w=0.
by Luis De La Cruz 1H
Fri Mar 02, 2018 9:18 pm
Forum: Phase Changes & Related Calculations
Topic: U = 3/2 nRT
Replies: 3
Views: 937

Re: U = 3/2 nRT

As stated above, I don't think we will use this equation too often for this class, but it is present on the equation sheet, because you can get some useful information. From the relationship the equation describes, you can see that U, which is internal energy depends solely on T, which is temperatur...
by Luis De La Cruz 1H
Sun Feb 18, 2018 11:26 pm
Forum: Balancing Redox Reactions
Topic: Basic and Acidic conditions [ENDORSED]
Replies: 11
Views: 3371

Re: Basic and Acidic conditions [ENDORSED]

For questions pertaining to acidic conditions you use H+, not H3O+, but yes for basic conditions you use OH- and you use water for both as well.
by Luis De La Cruz 1H
Sun Feb 11, 2018 11:50 pm
Forum: Calculating Work of Expansion
Topic: different ways to calculate w
Replies: 4
Views: 182

Re: different ways to calculate w

Indeed, you would use the first equation for instances in which pressure is constant, since the equation itself seems to tell you there is no change in pressure, only a change in volume, hence the missing delta before pressure. While the second equation is a derived equation (which you don't need to...
by Luis De La Cruz 1H
Sun Feb 04, 2018 1:59 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Temperature and Δ U
Replies: 2
Views: 159

Re: Temperature and Δ U

The important thing to realize is that when Temperature is constant as is the case in isothermal processes, q\neq 0 , q=0 only in the instance of an adiabatic process, in which no heat is exchanged between the system and its surroundings. To relate work to temperature in the instance of an isotherma...
by Luis De La Cruz 1H
Mon Jan 29, 2018 10:31 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Second Law of Thermodynamics [ENDORSED]
Replies: 5
Views: 319

Second Law of Thermodynamics [ENDORSED]

Why is it that humans (being the system), who seemingly grow more "ordered" over time, don't violate the second law of thermodynamics which states that things will always tend to increase in more "disorder" until reaching equilibrium?
by Luis De La Cruz 1H
Sun Jan 21, 2018 11:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Entropy of an Isolated System
Replies: 4
Views: 196

Entropy of an Isolated System

Why is it that the entropy of an isolated system either increases or remains constant? Why is it that it never decreases?
by Luis De La Cruz 1H
Mon Jan 15, 2018 10:47 am
Forum: Phase Changes & Related Calculations
Topic: Questions about Heat
Replies: 3
Views: 134

Questions about Heat

I'm still confused about the topic of heat. Is heat a type of energy, or is heat the term we use to describe a transfer of energy?
by Luis De La Cruz 1H
Wed Jul 27, 2016 12:58 am
Forum: Naming
Topic: Naming to Formula
Replies: 1
Views: 211

Naming to Formula

Why is it that the formula for triamminetrichloronickel(IV) sulfate is [NiCl3(NH3)3]2 SO4 I would expect it to be [NiCl3(NH3)3]^+1 SO4 Sulfate contributes -2 while 3 chlorides contributes -3 for a total of -5 The oxidation state of Nickel is +4 So there must be a +1 total charge on the formula to co...
by Luis De La Cruz 1H
Tue Jul 26, 2016 10:32 pm
Forum: *Titrations & Titration Calculations
Topic: Switching Ka to Kb [ENDORSED]
Replies: 5
Views: 571

Re: Switching Ka to Kb [ENDORSED]

The question about calculating a "new volume or "V-total" is rather vague, however when I calculate V-total in a titration problem I first have to find the amount of volume of titrant (strong acid or strong base) that is needed to get to the stoichiometric point, then I add that volum...
by Luis De La Cruz 1H
Mon Jul 18, 2016 10:21 am
Forum: Naming
Topic: Bonding areas
Replies: 2
Views: 298

Re: Bonding areas

No, the charge of the anionic anion does not correlate with the number of bonding areas, or to be more specific bonding regions the ligand has.
A clear counterexample would be the anionic ligand carbonato: CO3^2-
Carbonato has 3 bonding areas/regions and the yet the charge on it is still 2-
by Luis De La Cruz 1H
Sun Jul 10, 2016 9:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double bonds and regions of electron density
Replies: 2
Views: 688

Double bonds and regions of electron density

Why is it that double bonds are considered only as one region of high electron density given that within that double bond there are two pairs of shared electrons? For example in a carbonate ion, CO32-?
by Luis De La Cruz 1H
Mon Jul 04, 2016 8:42 am
Forum: Ionic & Covalent Bonds
Topic: Covalent vs ionic character
Replies: 2
Views: 404

Re: Covalent vs ionic character

I would say go with covalent bonding due to the fact that covalent bonding is the bonding that is most common within atoms. The type of element the atom is from, would also be relevant as a clue to what bonding it might have. For example, metal on metal atom bonding will most likely be a covalent bo...
by Luis De La Cruz 1H
Sun Jun 26, 2016 4:54 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital Shape for Larger Quantum Numbers [ENDORSED]
Replies: 2
Views: 343

Re: Orbital Shape for Larger Quantum Numbers [ENDORSED]

I believe there is an orbital higher than f which would be the g orbital, however this orbital corresponds to a block of elements on the periodic table that have not been discovered yet possibly with elements that have electrons that could reside within the g-orbital.

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