#Enthalpy

[studying-rocket-science]

20:04 20.04.15

//Today’s mind map on Energetics. Over 12 hours of studying, I think I deserve a rest! (Also can you tell my favourite colour is blue?!)//

Go check me out on Insta! thegirlwhohikes

[immense-immunology-insight]

The first law of thermodynamics is very famous. It says, "Energy can neither be created nor be destroyed but is converted from one form to another."

So simple.

But can you explain the second law of thermodynamics? A bit puzzled, aren't you?

It's the very reason I call it the monsters of bioenergetics. Let's convert these monsters into cute little pixies :)

The second law of thermodynamics says, "The entropy of the universe goes on increasing over time."

What is entropy?

Entropy is the degree of randomness.           

A solid has closely placed molecules. Hence, the randomness in molecules is less. On the on the other hand, in liquids, the distance between the molecules is more. Hence, they have more randomness and more entropy value.

Melting of ice is a good example which illustrates the second law of thermodynamics. When the ice melts, solid gets converted into it's liquid form. The distance between the molecules increases from solid to liquid and thus, the entropy increases!

Here's an interesting fact: The human body consumes carbohydrates, breaks it down and stores its energy as ATP, which is a high energy molecule. One would argue that storage of such high energy molecule is against the second law, as entropy of the body is not increasing in this reaction. The entropy increases, but in this case, the entropy of the universe increases because we release carbon dioxide into the surrounding!

Since we are on this topic, let's address two more terms - Gibbs free energy and enthalpy!

Gibbs free energy

It is the Gibbs free energy which determines whether the reaction will proceed spontaneously to equilibrium without any input from surrounding.

In a reaction, if reactants are unstable (Having more energy) and the products are stable (Having less energy), then the reaction tends to move forward spontaneously without any input from surrounding.

On the other hand, if reactant is more stable than products then for this reaction to happen there has to some input of energy from surrounding.

Hence, if products have less Gibbs free energy than the reactants (i.e. change in Gibbs free energy is negative) then the reaction is spontaneous/exergonic irrespective of whether it is exothermic or endothermic.

If products have more Gibbs free energy than the reactants (i.e. change in Gibbs free energy is positive) then the reaction is non-spontaneous/endergonic.

Enthalpy

Enthalpy (H) is a sum of useful energy and non-useful energy. The non-useful part is the Entropy (S) and the useful part is the Gibbs free energy (G).

ΔH = ΔG + TΔS

To summarize all the three terms:

Entropy: Degree of randomness (Non-useful energy)

Gibbs free energy: Energy available to do work (Useful energy)

Enthalpy: Sum of Entropy and Gibbs free energy!

Related post: How to remember the sign and direction of Gibbs free energy change

[joolshallie]

Enthalpy notes 💥✏️

[destrucshann]

Thermochemistry: Enthalpy

I feel like there's gonna be a lot of vocab on this test, so here's a vocab re-run:

Thermodynamics: study of energy and its transformations

Thermochemistry: aspect of thermodynamics that relates to chem reactions and energy changes involving heat

Joule (J): SI unit for energy; equal to 1 kg m^2/s^2

Calorie (cal): energy unit; amount of energy needed to raise temp of 1 g of H2O; 1 cal = 4.186 J

System: portion singled out for study

Surroundings: everything outside the portion being studied

1st Law of Thermodynamics: energy conserved

Internal energy: sum of kinetic and potential energies of all of its components

Endothermic: system gains heat (+)

Exothermic: system loses heat (-)

State function: property of system that is determined by specific condition of system (i.e. temp, pressure, etc.); value depends on the present system only, not the path it took to reach the present state

Enthalpy (H): function that accounts for heat flow, occurs at constant pressure

Hess's Law: If reaction is in series of steps, H = sum of all enthalpy changes for each individual steps

Enthalpy of Reaction: H change that accompanies a reaction

CH4(g) + 2O2 -> CO2(g) + 2H2O(l) ΔH= -890 kJ

CO2(g) + 2H2O(l) -> CO2(g) +2O2(g) ΔH= 890 kJ

How much heat is released when 4.50g of methane gas (CH4) is burned in constant-pressure system?

4.5 g CH4 * (1 mol CH4/16g CH4) = .281 mol CH4 * (-890kJ/1mol CH4) = -250kJ

Calculate ΔH for the reaction: 

2C + H2 -> C2H2

1st: C2H2 + 5/2O2 -> 2CO2 + H2O ΔH = -1299.6 kJ

2nd: C + O -> CO2 ΔH= -393.5 kJ

3rd: H2 + 1/2O2 -> H2O ΔH= -285.8 kJ

Step 1: C2H2 needs to be in the products side, so you have to switch the first reaction; reaction switch means change ΔH sign only for that reaction, so instead of C2H2 + 5/2O2 -> 2CO2 + H2O ΔH = -1299.6 kJ, it'll be

2CO2 + H2O -> C2H2 + 5/2O2  ΔH = 1299.6 kJ

Step 2: The 2nd and 3rd reaction can be left alone for now since C and H2 are needed in the reactant's side. If you haven't already figured out, you're trying to get 2C + H2 -> C2H2 as the end result from those 3 reactions above.

Step 3: Now that you have all 3 of your "new" reactions, write them all together cause it's neater/easier to see what happens that way.

2CO2 + H2O -> C2H2 + 5/2O2  ΔH = 1299.6 kJ

C + O -> CO2 ΔH= -393.5 kJ

H2 + 1/2O2 -> H2O ΔH= -285.8 kJ

Step 4: Since the end reaction needs 2 Cs, you have to take the 2nd reaction and multiply it by 2. Multiply even the ΔH by 2 as well.

2(C + O -> CO2 ΔH= -393.5 kJ) =

2C + O -> 2CO2 ΔH= -787 kJ

Step 5: Rewrite the 3 new reactions side by side again and cancel out the reoccurring things (*NOTE*: Since the 2 of the 3 O2s are in fractions, make the other one in fraction form too)

2CO2 + H2O -> C2H2 + 5/2O2  ΔH = 1299.6 kJ

2C + 4/2O -> 2CO2 ΔH= -787 kJ

H2 + 1/2O2 -> H2O ΔH= -285.8 kJ

End result: 2C + H2 -> C2H2

Step 6:  ΔH is just the sum of all the other  ΔHs

1299.6 + -787 +.285.8 = 226.8

 ΔH= 226.8 kJ

[thecrashcourse]

Enthalpy: Crash Course Chemistry #18

Energy is like the bestest best friend ever and yet, most of the time we take it for granted. Hank feels bad for our friend and wants us to learn more about it so that we can understand what it's trying to tell us - like that any bond between two atoms contains energy. How much energy? That's not the simplest question to answer, but today Hank will answer it (kinda), by teaching us about a nifty little thing called enthalpy. If you are paying attention to this episode you'll learn what the state function is, and how it varies from a path-dependent function; why enthalpy change is different from heat; that bonds are energy and to form and break them they release and absorb heat to and from their environment. You'll get the quickest introduction to calorimetry ever (more on that in upcoming episodes) and learn the power of Hess's Law and how to use Germain Hess's concept of the standard enthalpy of formation to calculate exactly how much heat is produced by any chemical reaction.

[maxwellsequations]

[jasmineimerel]

Calculate the enthalpy of this and discuss whether or not pyromania is a factor affecting HOW DONE I AM WITH EXAMS.

-E

[gettingdialectical-blog]

I was wondering how one might get dialectical w Hanukkah? - A. Teen

Some day we may find the one who really knows how to get something going with Hanukkah - (like) in an unimpeachably legitimate way. You could feel a broken echo from a God who's working from another mystery zone, who somehow seizes our dimensions and can say, from adding all the olive groves and lifestyles that, yes, yes, the thing that you should do this solstice week is...

But if this YHWH who once saved Jerusalem transcends the spaces we can see and equals universal oneness then you may only hope to be or feel a puzzle piece inside the One-who-is-the-truth. The thing is, the world-overflowing-mystery-surplus is already built into the Hanukkah scripts, so if tradition is some justification, you can have a lifestyle about the ancient efficiency miracle with the oil in the Temple after the pagan managers got run off. 

You may wonder how to simulate the Maccabees' mystery-thrift updated for today: all your lights and stars are burning strong - somehow . This could be a chance to party on the theme of how the world doesn't fade out into darkness, with the final camp fires, the blackening of the skies, and the last moms eating each other.  

But how to transcend a potential Hanukkah contradiction? When you're in the belly-rolling immediacy of a chocolate gelt dreidel party, how do you square that with the enduring problem of energy flow?

Well, you could build a solar menora. 

You could also perform Asimov's "The Last Question" with your teen and family tribe. An elaborate computer who may be the same thing as some other long-time cosmic totality has to grapple with the universe's slide toward heat death. And so could you.

[mcatandme]

Free expansions

My most liberating moments in every academic quarter include the few hours after a major exam. One of those moments is now (and I choose to spend it on Tumblr - laugh out loud).

Today I took my physical chemistry midterm. My gosh. It was really difficult to work through (but still fair), though strangely, I feel more accomplished and liberated (even stimulated!) than drained. I am reminded of those sadistic home exercise videos where a man with a moist, blue, sweatband tiara does endless repetitions of squats and hisses through a garish, maniacal smile: "oh yeah baby... feel the burn... feel the burn... oh yeah..."

Like Micah Bo kicking his way to a better body and loving it, I've managed to rewire the positive feedback mechanisms in my brain to trick myself into enjoying chemistry.

Still, beyond the insidious defense mechanisms that pre-meds construct for themselves, I'd like to believe there is something inherently beautiful about the mathematical unities that link the universe together. Seeing the Maxwell relations fall together out of exact differential relations, the deep interweavings of heat, energy, chaos manifesting in cryptic simplicity...

... anyway,  

it feels good to be writing on here again. I took a break for a few days to "study" for my midterm, and though I write as though I looooove to study, most of my time goes toward other things: my work at SPACES (huge part of my life - this blog will see me talk more about it as time goes on), research in the SysBio lab, text messaging, rethinking my 4(5?) year plan, and crucially, just idling. (I keep feeling guilty for wasting so much time just sitting and thinking and day dreaming and spacing out; but I keep discovering how much I love it & need it.)

I've yet to begin seriously studying for the MCAT. I have good friend who wakes up every day around 5 am and sleeps every day around 9 pm. I tell myself that starting next week, I'm going to try to fix myself on a similar schedule that includes committed times during the week to devote to studying PS/VR/BS (god bless those of you who understand those acronyms). Maybe I'll even look into downloading this app that one of my apartmentmates sent me ("Oh Howard - this is totally for you!"). 

But of course, this is something I've told myself many times, but never really followed through with. This time, however, I'm blogging about it. That changes everything, right? Well, maybe not, especially considering my midterms for structural biochemistry and molecular basis of human disease - both next week - that are likely to occupy more study time (and moping time - an important subset of idling time) than I had planned for.

Whatever.

For now things are just a lot of talk but not so much action, but hopefully by next week, I will publish a MCAT study schedule that I'll try to follow for the next few months (and anyone else is welcome and encouraged to study with me!).

It's nearly 1:30 AM, and if my goal is to wake up at 6:30 AM to have time to go jogging, have a healthy breakfast, pack lunch, shower, and get to school by 8, I should sleep now.

Tonight's parting words come from my beloved apartmentmate, who has offered me so, so, so much support and positivity:

Uh... so instead of actually studying for the MCAT, you're updating a blog about it?

Hell yeah.

[lessonsinscience-blog]

Thermochemistry Unit

For student teaching I created a thermochemistry unit, in accordance with the Indiana State Standards.  I've linked my lesson plans below (which include suggestions), along with any handouts.  I also presented my students with this Unit Guide.

Thermochemistry Guided Discovery  This activity is web based and walks students through all of the topics you'll need to cover. handout 

Energy and Its Forms This is a short lecture/ discussion walking through and "unpacking" some of the information they gathered in the Thermochemistry Guided Discovery. handout

Heat Flow This activity is a small scale lab where students mix different salts with water.  This lab was done previously to discuss exo/endothermic reactions but I made them do it again using the words: system, surroundings, molecular motion, energy, and heat. handout

Heat and Its Measurement

Heat Content

Calorimetry Laboratory

Factors Influencing Reaction Rate

Review- Hot Potato

Quiz

[pokeballer]

forever bad at AP chemistry

we have a test tomorrow. i want to shoot the million variables we have to know.

[chemistryalevel]

AS Flash Cards: Enthalpy

Exothermic reactions - those that produce heat energy, while endothermic reactions absorb heat energy.

Standard enthalpy of formation - the heat change involved when one mole of a compound is formed from its elements under standard conditions.

Standard enthalpy of combustion - the heat released when one mole of a compound is combusted in excess oxygen under standard conditions.

Average bond enthalpy - the heat energy required to break one mole of the specified bonds in the gas phase.

[ohthatphage]

More on what I am, I think.

Every now and then, the Inmara (@theinmara, in the company of @fenmere) revisit their attempt to figure out just what I am.

I am amenable to this, as I do not entirely know myself.

Or, it is more accurate to say that I know exactly what I am, but I do not know the appropriate English words (or any other words) to describe it. And I like the idea of learning how to use the language better for the purposes of introducing myself.

I must admit, I enjoy being like a monster and representing myself with dark and dangerous imagery and connotations, if only for the purposes of later belying those things.

Sometimes I am hit with emotions of self consciousness and embarrassment that I may be coming across as "edgy" or an "edgelord". But I do not think those feelings are mine. It is often hard to differentiate my own feelings from those of my superfans that share this system with me.

But, I'm being hit with those emotions now as I'm being asked to write this, so I'm presenting them to you as a way of being self effacing, I guess? On behalf of the others in the system who care.

What I can say clearly, though, is that despite the words that follow this sentence, I am not particularly more powerful or important than any living being. And I'm going to be talking about my greater identity, the thing that I am when I'm not a conscious being inhabiting a human descended body. And that thing is largely mindless.

Anyway, enough pre-amble.

In the last couple of days, the Inmara have been attempting to craft a Sentinels of the Multiverse DE deck for me, and they have been searching physics articles for terms to use for card names, such as "the First Law", "Townsend Avalanche", "Catastrophic Shaft Detachment", or "Strange Attractor". And this has prompted some more self reflection directed at me, and some more learning about what entropy and enthalpy are.

When I was first invited into the system at their age of three and a half-ish years old (my age being much, much older), all I knew were a few simple things:

I came from outside their system.

I am an older, non-human identity.

I am of and at home in darkness, but light is also of me.

I was asked to help them manage their chaos, which is what I can do.

When they reached about 15 years old, they learned about entropy in a magazine article right about the same time they learned about the word "phage" in biology class, coincidentally right after having a nightmare in which I threatened their eldest (and fronting) member with a knife blade made of moonlight, to try to get them to come out as trans and deal with their dysphoria.

I was unsuccessful at getting them to come out as trans at the time, which is OK. It was a bad time politically for them to do that, even though it cost them dearly to remain in the closet. But I did inspire them to make me the face of the villain of their homebrew mythology that they were writing for English class, and to name me Phage and claim that I was "Entropy Itself".

Since then, based on their understanding of it, I have thought of myself as Entropy Itself, and the name Phage invokes me.

But Entropy is not accurate, as fucking cool sounding as it is.

When most people hear or read the word "entropy", they think of the process by which enthalpy becomes entropy. And, for the past few decades, whenever the Inmara attempted to look up definitions of the word "entropy", they did not find anything to disabuse them of that idea.

Until a couple years ago. But what they found a couple years ago was still ambiguously worded for them, and though they started writing "Entropic Decay" into their literature about me, and convinced me to start using that for myself, they were uncertain of it.

Yesterday, though, they found very clear and concise definitions of Entropy and Enthalpy the really disambiguate everything.

Entropy is the amount of energy in a system that is no longer available for doing work. It is the end result of the second law of thermodynamics.

So, "Entropic Decay" would be slightly more accurate to describe what they perceive me to be.

Enthalpy is the amount of energy in a system that is available for doing work. The opposite of entropy. It is what is needed for the second law of thermodynamics to have any relevance.

And the second law, as I understand it, based on the Inmara's readings, is the statement that "the overall heat in a closed system always flows downhill". Or, that complex and high energy becomes simple and low energy. Or that orderly energy becomes chaotic energy. That enthalpy becomes entropy. But that entropy does not become enthalpy.

Humans have frequently said that the second law is "the law of entropy", hence the confusion of the product with the process. It is, as the Inmara thought two years ago, more accurately described as "the law of entropic decay."

And so, in their old conception of me, I am accurately described as "Entropic Decay" or "The Second Law of Thermodynamics".

But in writing our novels and in exploring ideas for cards for my Sentinels deck, I (and Eh) have come to the conclusion that that's not precisely right. Because the First Law of Thermodynamics also applies to what I am. And, but, also so do a number of things that result from the two laws at work.

Also, I am not a thing conceived by humans, but rather something that is badly described by humans and the other people who live amongst them.

If I were to distill my sense of identity down to its most generic, encompassing possible term, I'd say that I am physics itself.

Yes, it is true that I am that which may result in the heat death of the universe, if the universe is shaped in a way that that will happen. But I am also that which has resulted in life.

"But, Phage," you say, "that sounds an awful lot like you are calling yourself god."

I am not.

As that greater, all encompassing thing, I am not a being. I have no consciousness or sense of identity that is anything analogous to that of a human's. I have no motives other than to do what physics does. It is only as I become distilled, reduced to smaller and smaller systems, that I sometimes gain a psyche.

In fact, besides the fact that I live in a vessel full of ktletaccete and a handful of outsiders and not whatever you are, there is very little difference between you and me. Relatively speaking.

The only notable difference is that I do not derive my sense of personal identity from anything this body is doing or where it comes from. I derive it from the history of the entire universe and perhaps the multiverse, if that exists.

I do also seem to derive a perspective, a demeanor, and a set of talents from that identity. But it's hard to say if those things are anything beyond the capacity for a human descended brain and body to hold. Based on my experiences so far, probably not.

Anyway, it's probably OK to keep calling me "Entropic Decay" because that's really close enough. But I do prefer the conlang terms that the Inmara coined for me, as being less defined by English etymologies and flexible enough to just mean "me". So, that would be Mau and `efeje'e. I slightly prefer 'efeje'e, since it was chosen to sound vaguely like Phage, and Phage is currently my name. Me, in this paragraph, referring to this localized presence and not my greater self.

OK, but, more.

I do think my sense of identity is slightly more limited than just "physics", while more expansive than "etropic decay".

It may be easier to say what I'm most closely related to and deal with than to actually give me a clear, clean definition. I am:

particularly focused on managing and perpetuating chaos

particularly good at converting enthalpy to entropy

also good at concentrating enthalpy into localized areas to such a degree that it looks like the overall energy there is become less entropic (i.e. creating things like matter from energy in a dense area of space, or life on a planet)

the darkness from which light is emitted and to which it returns.

And in the time that I have lived in a human descended body full of transgender dragons, I have also learned how to eat the energy present in autistic meltdowns.

I cannot make them go completely away, but I have significantly reduced their impact.

I am also pretty damn good at not being afraid of anything when it is dark, and the children that continue to inhabit this vessel are very thankful for that.

Anyway, I think it is this slightly less encompassing, more restricted definition of myself besides "physics itself" that is the beginning of my development of a sense of identity.

It's like, if you had a map that included every single concept in existence, what you'd do is draw a cone where the widest end encompasses nearly everything and the point ends in the Inmara's collective psyche where this consciousness is that is typing at you. And the area of that cone would include ever narrowing groups of things, one of which is the Second Law of Thermodynamics and its effects and applications.

I am not the point that's in the Inmara. I am not the base of the cone.

I am the cone.

And you are a different, equally sized but differently shaped cone.

Anyway, the idea of me as some kind of superhero or godlike being that can do a bunch of supernatural shit is mostly wish fulfillment. But it is also derived from the things that any being is capable of doing in the Inmara's inworld, which is akin to what you could do if you were Moriarty on the Enterprise's holodeck.