Chemical Engineering.

I'm gonna try and summarize the stuff I learned while enrolled in the Chemical Engineering program at Western University.

no pressure or nuthin

chem tho

im so hyped for this!

i might have to do one myself. what topics would be sick?
programming?
security?
cryptography?
computability theory?
advanced algebra?
discrete math?

I personally want to see programming, but thats just ME!

programming could be LITTTT

i think i may do that.
except at the same time brandon, tyler, and trent all probably know the basics of programming already lol

but also all doing prog projects together or something just to learn and get better would be so fun

YA I AGREE.

So before I get into university-level stuff, I should make sure that we're all starting off with the same knowledge base, in case anyone has forgotten any fundamentals in the four years since we all graduated from high school (or maybe you never took/cared for high school chemistry).

Lesson 0 - High School Stuff (Part 1: Atoms and Elements)
Chemistry, as opposed to physics or biology, focuses on the differences between different kinds of matter: how they interact with one another and how they form in the first place.

For starters, let's take a gander at the most basic particle with which chemistry concerns itself; the atom.

Pro-tip: every proton is the same. Every electron is the same. Every neutron is the same. Same mass, same charge. They only differ in how many other protons, neutrons and electrons to which they are connected.

Electrons have negative charge, protons have positive positive charge, and neutrons are neutral. Opposite charges bring particles together. Electrons have much less mass than protons and neutrons (the latter two are about equal, being about 2000 times larger than the former), so electrons are neglible when calculating an atom's mass.

Defining an atom relies mainly on the number of protons it has. The numbers of neutrons and electrons in an atom tend to grow with the number of protons. Electrons leave an atom much, much more easily than protons and neutrons do. This leaves the number of protons as the best tool for categorizing atoms.

Take a look at the periodic table:

Each square refers to a different element. An element is a substance which consists of atoms that all contain the same number of protons. The number at the top of each square on a periodic table is the atomic number, the number of protons in each atom. The number at the bottom is the atomic mass, which is pretty much equivalent to the total number of protons and neutrons in the average atom of the element (atoms of the same element differ slightly in the number of neutrons contained).

These elements form the basis for all chemical interaction.

Lesson 0 - High School Stuff (Part 2: Electron Arrangement and Chemical Bonding)
Atoms want to be electrically neutral; they want their protons and electrons to be equal in number. However, atoms also store their electrons in special arrangements, akin to shelves, called electron shells. Spaces within these shells are called orbitals

Atoms prefer to have their orbitals either full or empty. The only shell that tends to be partly full is the outermost (valence) one. This leads an atom to either give away its own electrons or take away electrons from other atoms, whichever is the simpler solution to its partly-full-shell problem. This is what leaves atoms with charges, positive or negative. A charged atom is called an ion.

Ions of opposite charge attract one another and then form chemical bonds to stay together. If two elements are far apart on the periodic table (both horizontally and verticallly), their atoms will form much stronger bonds, ionic bonds. Elements closer together will form covalent bonds.

A collection of atoms bonded covalently is called a molecule. Atoms bonded together ionically don't really form distinct particles, they just create a crystal lattice stricture. A substance whose molecules/crystall lattice are/is the same is called a compound. A compound is a substance of multiple elements bonded together in the same proportions all throughout.

wow i already learned something that i didn't know i didn't know; the difference between a compound and a molecule.

Hey, I've always wondered, what's with Ununseptium and Ununoctium?

Vyzor wrote:Hey, I've always wondered, what's with Ununseptium and Ununoctium?

Synthetic elements (they never occur in nature, too heavy) that have been created (in small amounts) but never named. The names refer to their atomic numbers: un-un-sept-ium is 117, un-un-oct-ium is 118.

Around the 90s, elements are primarily created by mankind. They get named after places and people. Element 111 used to be unununium before being named roentgenium.

Cephalo the Pod wrote:

Vyzor wrote:Hey, I've always wondered, what's with Ununseptium and Ununoctium?

Synthetic elements (they never occur in nature, too heavy) that have been created (in small amounts) but never named. The names refer to their atomic numbers: un-un-sept-ium is 117, un-un-oct-ium is 118.

Around the 90s, elements are primarily created by mankind. They get named after places and people. Element 111 used to be unununium before being named roentgenium.

Oh ok, but how come they have no atomic mass? Is it because not enough have been created to even determine that number?

Heads-up: in this post, I eventually start replacing "grams" with "g".

Lesson 0 - High School Stuff (Part 3: Moles and Molar Concentration)
Chemical reactions take place between individual atoms. It's not about how heavy the substances are, it's about how many particles you have. But counting individual atoms and molecules all the time would be impossible, so what we do is we use a shorthand.

Imagine a typical atom of carbon; 6 protons; 6 neutrons, leading to an atomic mass of 12. We already came up with a standard unit for mass; the gram. So we want a term to refer to how many atoms we need to get us 12 grams of carbon.

You can do the same for any element. Check the bottom of any square on the periodic table. That is the element's average atomic mass. A typical chlorine atom has either 35 or 36 protons+neutrons in its nucleus; how many atoms do you need to get somewhere between 35 and 36 grams of chlorine?

A mole is the number of atoms that gets you x grams of an element (where x is the average of the typical numbers of particles in the atom's nucleus). After some experiments, it turns out that a mole is equal to about 6.02x10^23 particles (imagine about 600 marbles. Multiply that by a thousand. Then multiply it by a billion. Multiply it by a billion again. That is a mole).

Here's where this becomes useful. Say you want to make some sodium chloride (table salt). You have some elemental sodium (a metal) and some chlorine (a poisonous gas). You don't want any leftover sodium or choroine. With a periodic table handy, you know to take 22.99g of sodium and 35.45g of chlorine. That means you have 6.02x10^23 atoms of sodium colliding with 6.02x10^23 atoms of chlorine to make 6.02x10^23 bonds, arranged in a crystal lattice structure. A mole of sodium chloride (NaCl) has a mass of 58.44g.

If you want 1000g of NaCl, you divide your desired mass by the molar mass of NaCl (calculations are approximate).
(1000g)/(58.44g/mol)=17.11mol
(17.11mol)*(22.99g/mol)=393.4g (you need about 393.4g of sodium).
(17.11mol)*(35.45g/mol)=606.6g (you need about 606.6g of chlorine).

The chlorine is heavier than the sodium, but it is completely used up in the reaction. This is why moles and molar mass are important.

Oh, and in addition: a lot of reactions take place when substances are dissolved in water. This makes molar concentration (moles/volume) another important measurement.

Vyzor wrote:

Cephalo the Pod wrote:

Vyzor wrote:Hey, I've always wondered, what's with Ununseptium and Ununoctium?

Synthetic elements (they never occur in nature, too heavy) that have been created (in small amounts) but never named. The names refer to their atomic numbers: un-un-sept-ium is 117, un-un-oct-ium is 118.

Around the 90s, elements are primarily created by mankind. They get named after places and people. Element 111 used to be unununium before being named roentgenium.

Oh ok, but how come they have no atomic mass? Is it because not enough have been created to even determine that number?

I guess they haven't. Or maybe didn't, when this version of the table was made. It's possible that elements 117 and 118 were merely theoretical at the time.

good stuff. allan wants to know what type of chem eng you're in

lostboi_626 wrote:good stuff. allan wants to know what type of chem eng you're in

General Chemical. As opposed to Biochemical (the split happens starting 3rd year). Biochemical students don't get as many technical electives as General Chemical, instead getting several biochemical courses. Other than that, we take the same stuff.

word, lovin these updates too

Lesson 0 - High School Stuff (Part 4: Ideal Gas Law)
There are four important variables that must be observed when describing the state of a gas:

• Pressure
  
• Volume
  
• Temperature
  
• Amount
  

These variables change in proportion to one another. Temperature increases (or decreases) as pressure increases (or decreases); and does the same with volume (when the container can stretch). Volume increases when pressure decreases, and vice versa.

Here's that paragraph in equations:

• (P1)/(T1)=(P2)/(T2)
  
• (V1)/(T1)=(V2)/(T2)
  
• (P1)*(V1)=(P2)*(V2)
  

In addition, when you add gas particles to a container, either pressure or volume increases. If you involve all four variables, you don't even need a second set of variables. You can just use one equation to compare pressure and volume to temperature and amount.

Here's the Ideal Gas Equation:
P*V=n*R*T
n is the number of moles of gas. R is an experimentally derived constant that matches the right side of the equation with the left in terms of both number and units. R is equal to about 8.314J/(mol*K). You can check the spoiler tag for an explanation in case you're confused by the units.

Spoiler:

Now, this is called ideal for a reason. This equation doesn't account for internal attraction between gas molecules. In reality, the right side of the equation is typically multiplied by another dimensionless constant). We'll get to that when Thermodynamics II rolls around. Eventually. Very eventually.

is there a reason it's called 'ideal'?
does it not always hold?

lostboi_626 wrote:is there a reason it's called 'ideal'?
does it not always hold?

See the last paragraph.
The Ideal equation does not account for attraction and repulsion between molecules. This alters the volume of the gas.

ahh okay sick

Lesson 0 - High School Stuff (Part 5: Quantum Chemistry)
This part isn't too integral to Chemical Engineering, just helps you understand why certain atoms form certain numbers of bonds. For instance, a carbon atom forms four carbon bonds, an oxygen atom forms two, etc.

I've spoiler'd most of this post to emphasis my main point at the bottom.

Spoiler:

Atoms don't want partially full electron shells. Atoms want them either full or empty. It's what pushes a lithium atom to give away an electron, and a fluorine atom to take one. Some atoms hybridize their orbitals.

For instance, a carbon atom will mix it's second shell's orbitals together to form four sp3 orbitals. The four electrons in the atom's second shell get distributed evenly. These four orbitals are what let the carbon atom form its four atomic bonds. This is what forms the basis of organic chemistry, and will be observed later.

cool i've never heard pauli exclusion principle explained in such simple terms

Lesson 0 - High School Stuff (Part 6: Derivatives)
Chemical Engineering frequently involves equations that includes calculus. Nothing too complex, but it really helps to understand exactly what this stuff is.

You all remember the slope of a line, right? The ratio between the rise (change in y-value between two points) and the run (change in x-value between those same points)? Good.

Well lots of equations have non-straight graphs. The instantaneous slope at a specific point changes from point to point. We need to develop a method to find the derivative of a function. A derivative is an equation that can be used to find the instantaneous slope of another equation at any point.

So, here's what you do. You have two points for an equation. The first point has an x-value of, well, let's call it x, and a y-value of f(x). The second point has an x-value of (x+h) and a y-value of f(x+h). What you do, when you want to find the derivative, is you make h equal a number infinitely close to 0, so that you'll have two points infinitely close together.

The derivative is equal to
f(x+h)-f(x)
------------
 (x+h)-x

Let's look at a specific example: x^2. The second y-value is (x+h)^2.

(x+h)^2-x^2                
----------------   
  (x+h)-x                                    

x^2+2*x*h+h^2-x^2
--------------------------
               h

You end up with 2*x+h. But h practically equals 0. So you can simplify it to 2*x. Notation for generic derivative is dy/dx, or d[f(x)]/dx, or f'(x).

Try it with other equations. Here's a quick guide to some handy derivatives. If you have questions about these, I'll be happy to clarify.

Spoiler: