What triggers a chemical reaction? - Kareem Jarrah

Šta pokreće hemijsku reakciju? - Karim Džara (Kareem Jarrah)

Prevodilac: Mile Živković Lektor: Anja Saric

You know how sometimes you go to bake a cake

Znate kako nekada krenete da napravite tortu

but your bananas have all gone rotten,

ali su vam sve banane istrulile,

your utensils have rusted,

escajg je zarđao,

you trip and pour all of your baking soda into the vinegar jug,

sapletete se i prospete svu sodu bikarbonu u posudu sa sirćetom

and then your oven explodes?

i onda vam eksplodira rerna?

My friend, you and your chemical reactions have fallen victim to enthalpy and entropy

Prijatelju, ti i tvoje hemijske reakcije žrtve ste entalpije i entropije

and, boy, are they forces to be reckoned with.

i druže moj, to su sile na koje treba računati.

Now, your reactants are all products.

Svi tvoji reaktanti su proizvodi.

So, what are these "E" words, and what's their big idea?

Šta su onda te reči na slovo "e" i šta one znače?

Let's start with enthalpy,

Počnimo s entalpijom,

an increase or decrease of energy during a chemical reaction.

to je povećanje ili smanjenje energije tokom hemijske reakcije.

Every molecule has a certain amount of chemical potential energy

Svaki molekul ima određenu količinu potencijalne hemijske energije

stored within the bonds between its atoms.

koja se skladišti unutar veza Između njegovih atoma.

Chemicals with more energy are less stable,

Hemikalije sa više energije su manje stabilne

and thus, more likely to react.

i stoga manje sklone reakcijama.

Let's visualize the energy flow in a reaction,

Prikažimo tok energije u reakciji,

the combustion of hydrogen and oxygen, by playing a round of crazy golf.

sagorevanje vodonika i kiseonika, uz partiju ludog golfa.

Our goal is to get a ball, the reactant, up a small rise

Naš cilj je da reaktankt, loptu, dovedemo do malog uzvišenja

and down the other much steeper slope.

i spustimo niz dosta strmiju liticu.

Where the hill goes up, we need to add energy to the ball,

Tamo gde brdo ide nagore, moramo lopti da dodamo energije

and where it goes down, the ball releases energy into its surroundings.

a tamo gde se brdo spušta, lopta ispušta energiju u svoje okruženje.

The hole represents the product, or result of the reaction.

Rupa predstavlja proizvod, ili rezultat reakcije.

When the reaction period ends, the ball is inside the hole,

Kada se završi period reakcije, lopta je unutar rupe

and we have our product: water.

li imamo svoj proizvod - vodu.

This, like when our oven exploded, is an exothermic reaction,

Kao kod naše rerne koja je eksplodirala, ovo je egzotermička reakcija,

meaning that the chemical's final energy is less than its starting energy,

što znači da je finalna energija hemikalije manja od početne

and the difference has been added to the surrounding environment

a razlika je dodata u okruženje

as light and heat.

u obliku svetlosti i toplote.

We can also play out the opposite type of reaction,

Takođe možemo prikazati suprotan tip reakcije,

an endothermic reaction,

endotermičku reakciju,

where the final energy is greater than the starting energy.

gde je finalna energija veća od početne.

That's what we were trying to achieve by baking our cake.

To smo pokušali da postignemo pečenjem naše torte.

The added heat from the oven would change the chemical structure

Dodatna toplota iz rerne bi izmenila hemijsku strukturu

of the proteins in the eggs and various compounds in the butter.

proteina i jaja i raznih jedinjenja u puteru.

So that's enthalpy.

To je entalpija.

As you might suspect,

Kao što biste pretpostavili,

exothermic reactions are more likely to happen than endothermic ones

egzotermičke reakcije se lakše dešavaju od endotermičkih

because they require less energy to occur.

jer je za njihovo dešavanje potrebno manje energije.

But there's another independent factor that can make reactions happen:

Ali postoji još jedan nezavisni faktor od kojeg se dešavaju reakcije:

entropy.

entropija.

Entropy measures a chemical's randomness.

Entropija meri nasumičnost hemikalije.

Here's an enormous pyramid of golf balls.

Evo ogromne piramide od loptica za golf.

Its ordered structure means it has low entropy.

Njena uređena struktura znači da ima nisku entropiju.

However, when it collapses, we have chaos everywhere,

Ipak, kada se sruši, svuda imamo haos,

balls bouncing high and wide.

loptice lete na sve strane.

So much so that some even go over the hill.

Čak toliko da neke od njih pređu preko brda.

This shift to instability, or higher entropy,

Prelaz na ovu nestabilnost, ili višu entropiju,

can allow reactions to happen.

dozvoljava da se dese reakcije.

As with the golf balls, in actual chemicals

Kao i kod loptica za golf, kod pravih hemikalija

this transition from structure to disorder gets some reactants past the hump

ovaj prelaz od strukture do nereda prebaci neke reaktante preko brda

and lets them start a reaction.

i dozvoljava im da pokrenu reakciju.

You can see both enthalpy and entropy at play

Možete videti i entalpiju i entropiju na delu

when you go to light a campfire to cook dinner.

kada krenete da upalite logorsku vatru da biste napravili večeru.

Your match adds enough energy

Vaša šibica daje dovoljno energije

to activate the exothermic reaction of combustion,

da aktivira egzotermičku reakciju sagorevanja

converting the high-energy combustible material in the wood

i prebaci zapaljivi, visokoenergetski materijal u drvetu

to lower energy carbon dioxide and water.

na ugljen-dioksid i vodu sa manje energije.

Entropy also increases and helps the reaction along

Entropija takođe uvećava reakciju i pomaže joj da se dešava

because the neat, organized log of wood

jer je zgodno, organizovano parče drveta

is now converted into randomly moving water vapor and carbon dioxide.

sada pretvoreno u isparenje vode i ugljen-dioksida koji se kreću nasumično.

The energy shed by this exothermic reaction

Energija koja se ispušta u ovoj egzotermičkoj reakciji

powers the endothermic reaction of cooking your dinner.

napaja endotermičku reakciju s kojom se kuva večera.

Bon appétit!

Prijatno!