Organic Chemistry

Organic chemistry is the chemistry of carbon compounds. It is responsible for many of the every day products that are used around the world.
Some examples:

• clothing
• all plastics

Properties of organic compounds

• low melting points
• weak or non-electrolytes
• can form chains of carbon atoms that are linked in a 
• Straight line
• circular pattern
• branched pattern
• can link with other atoms in a

Alkanes (unbranched/straight chain) 

A hydrocarbon is a compound that contains only hydrogen and carbon; there are diff. types of hydrocarbons, and diff. ways to represent them.

Alkanes are saturated hydrocarbons which have carbon atoms bonded by single bonds

-saturate: not possible for another atom to bond to the structure

Naming an alkane is pretty simple. The names of hydrocarbons end in "-ane" because they are alk-ANE-s. 

Here's a video on naming the first 10 alkanes

The First 10 Alkanes

Alkyl Groups

-these are alkanes that have lost one hydrogen atom

if there are more than one of the same kind of alkyl group, use the prefix "di", "tri", "tetra" etc. 

Organic Chemistry

Functional Groups

Functional Groups are organic compounds that can contain elements other than Carbon and Hydrogen.
A functional group may be a single atom (such as F, Cl, Br, or I), or groups of atoms (such as NO2, NH2).
There are 4 types of functional groups.

• Alcohols
• Halides (halogen) or Nitro
• Aldehydes
• Ketones

Halides and Nitro Compounds

Halogen and Nitro compounds can be attached to all alkanes, alkenes, and alkynes. 

The main chain name will receive one of the following prefixes if the appropriate group is attached.

Fluorine -> Fluoro

Chlorine -> Chloro 

Bromine -> Bromo

Iodine -> Iodo

...and so on. As you can see you just replace the "-ine" with "-o". 

Properties of Halogenated Compounds

1. Compounds containing F, Cl, Br, and I are generally insoluble in water.
2. Fluorinated hydrocarbons are unreactive.
3. Compounds containing Cl or Br are more reactive, but only in drastic conditions.
4. Compounds containing I are extremely reactive. 

Properties of Nitro Compounds 

1. Normally insoluble in water.
2. Unreactive to chemical attack, except under drastic conditions.
3. Tend to be explosive.
4. Generally have a pleasant odor. 

Alcohol

Alcohol is an organic compound that contains an -OH (hydroxyl) functional group. 

Alcohols are named by using the longest carbon chain containing the OH group, and replacing the "-E" ending in the parent hydrocarbon chain with the ending "-OL".

Properties of Alcohols

1. Soluble in water, but hydrocarbon chain tends to be insoluble in water.
2. All alcohols are poisonous in some degree. 

What happens if there's more than one OH? 

If a compound has more than one -OH group, number both and add the prefix ending. "-diol", "-triol", etc. 

Check out this video that sort of explains alcohols in a catchy rap.
Alcohol Rap

Aldehydes 

An Aldehyde is a compound that has a double bonded oxygen at the end of a chain. 

Change the parent chain ending to "-al". Be careful! Don't confuse this with alcohol! 

Here's a quick video on aldehydes.

Aldehydes

Ketones

Ketones are hydrocarbon chains with double bonded oxygen that is NOT on either end.

Add "-one" to the parent chain.

Properties of Aldehydes and Ketones

1. Both partially soluble in water.
2. Aldehydes are very reactive.
3. Ketones are relatively unreactive. 

Here's another video, this time on Ketones 

And finally, the last video I'm going to show you is a video on ALL functional groups!

Functional Groups

Bonding

There are 3 types of chemical bonds

Ionic bonds: the transfer between 2 atoms to form a positive and negative ion.
Non-polar covalent bonds: equal sharing of electrons
Polar covalent bonding: unequal sharing of electrons



Ionic bonding uses an electrostatic force. That is the force that exists between particles that are charged as a result of attraction or replusion. (remember, opposites attract? Opposite charges attract and like charges repel). These bonds are very strong and have a high melting temperature.

So, I know you guys have a burning question:

Why do things lose valence electrons? This is explained by electronegativity. Metals have low electronegativity and non-metals have high electronegativity, as we learned in the last chapter. The electronegativity decreases to the right across the periodic table. The difference in the electronegativity will determine the electron sharing and determine if it is equally shared or unequally shared.

Here is how to figure that out! This is the formula:

ENeg Diff.= [ENeg1 - ENeg 2]

If it is a non polar covalent bond, the difference will be <0.5
If it is a polar covalent bond, the difference will be >0.5 and <1.8
If it is an ionic bond, the difference is >1.8


If ENeg Diff <0.5 it's a non polar covalent bond

If ENeg Diff > 0.5 and <1.8 it's a polar covalent bond

If ENeg Diff > 1.8 it's an ionic bond




Lets try an example:

Arsenic and Sulfur
Arsenic is 2.18 and Sulfur is 2.58. |2.18-2.58| = 0.40, therefore it is covalent.

Cobalt and Bromine
Cobalt is 1.88 and Bromine is 2.96 |1.88-2.96| = 1.08, therefore it is a polar covalent bond./

To draw diagrams of the compounds, draw the central atom in the middle and distribute the remaining atoms around it. Draw arrows indicating the direction of the polarity. Draw the partial positive and partial negative charges.

Partial Positive sign is the almost 8 but cut-off sign with a +
Partial Negative sign is the same thing but with a -


What is polarity?
Different Kinds of Bonds

Alkenes and Alkynes

Here are some basic facts:

-Carbon can form double and triple bonds with Carbon atoms
-When multiple bonds from fewer hydrogens are attached to the carbon atom

Alkenes

Alkenes are simply hydrocarbons with one or more double bonds located between carbon atoms leading to an "unsaturated hydrocarbon."

For example: CH2 = CH2 Ethene

CH2 = CH - CH3             1-propene or propene

                                                                            Ethene

Naming Rules:

1) Find the longest chain and place it at the end of the name

2) Number the carbon atoms to get the lowest number for the start of the double bond and place that number before the parent name

3) Assign names and numbers for all side groups and assemble the name alphabetically

Difference between cis and trans:

Cis = both on top or bottom

Trans = one on top and one on bottom



Alkynes

Alkynes are simply hydrocarbons with one or more triple bonds located between carbon atoms leading to an "unsaturated" hydrocarbon

The ending is changed from one of the alkanes and alkene for alkenes to "yne" for alkynes

Same naming/drawing rules apply!

Still feeling confused? Here are some helpful videos:

Naming Alkenes

Naming and Drawing Alkynes

Naming AND drawing Alkenes (25 minutes long!)



Predicting the Number of Valence Electrons

Valence Electrons are the electrons in the outermost (energy level) open electron shell of an atom.
They are the electrons that can take part in chemical reactions, also called the "reactable electrons".
Some things you may need to know:
Open Shell: A shell that contains less than its maximum number of electrons
Closed Shell: A shell that contains exactly its maximum number of electrons.

All Noble Gases have 0 valence electrons, because they all have something called a stable octet.
A stable octet is when the shell has exactly 8 electrons on it.

example: Neon.
Atomic number: 10.
We all think back to grade 10, and remember the order of the number of electrons each shell can hold.
First shell holds 2 electrons.
Second shell holds 8.
Third shell holds 8.
Fourth (and final) shell holds 16.

As you can see, there is a perfect shell - or a stable octet. There is no room for any more electrons.

Valence electrons are all the electrons in an atom except those in the core, or in the filled d- or f- subshells.
A quick way to determine the number of valence electrons for a representative element is to look at which group is it in. 

As you can see in this periodic table, I have drawn on (messily) the group numbers. 

In group 1, there is 1 valence electron for each element. For group 2, there are 2 valence electrons for each element. And so on, until group 8, where there are no valence electrons, because Noble Gases ALWAYS have a stable octet.

The number of valence electrons stays the same as you go up or down a group, but they increase as you go from left to right across the periodic table. 

I'm tired now.

Core Notation

So by this point, we all know how to do electron configuration.

Core Notation is basically just simplifying core notation!

The set of electrons for an atom can be divided into two subsets: core and outer.

The CORE of an atom is the set of electrons with the configuration of the nearest noble gas (He, Ne, Ar, Kr, etc.) that comes before it.

The OUTER electrons consist of all electrons outside the core. These normally take part in chemical reactions.

So, how do you do this "core notation"? 

At first, it made absolutely no sense to me at all.

But as I continued practicing, I found out it's actually pretty simple.

Step 1: Locate the atom and note the noble gas at the end of the row ABOVE the element.

As you can (hopefully) see in this picture of the periodic table, I've highlighted the noble gases that can be used in Core Notation.

For example - Chlorine.

The Electron configuration for Chlorine is 1s² 2s² 2p⁶ 3s² 3p⁵

Okay, so what is the noble gas at the end of the row above the element? Locate Chlorine. You will see that at the end, and up one, is Neon. 

The Electron Configuration for Neon is 1s² 2s² 2p⁶

STEP 2: Replace the part of the configuration corresponding to the configuration of the noble gas, with the SYMBOL for the NOBLE GAS in SQUARE BRACKETS. 

So in this case, the CORE NOTATION of Chlorine would be: 

It's simple! This way, you don't have to keep writing out 1s² 2s² 2p⁶ etc.

More of the Periodic Table!

The 1800s was huge for discoveries regarding the periodic table. Here's what you need to know:

Law of Octaves - John Newland
He proposed that elements are arranged according to their atomic weight

Mendeleev:
Discovered that certain features of elements recurred when elements were arranged in order according to mass. Therefore, he decided to organize the elements in periods and families or groups, also known in the general English language as a row or a column. He even left gaps in the table, leaving room for other elements with similar characteristics to be discovered. (Smart cookie!) He is known as the 'father' of the periodic table.

                                                      The smart cookie! (Mendeleev)
Modern Times:
Periodic Law : Elements recur periodically when arranged from lowest to highest atomic number.
-Elements are arranged according to their atomic number. (Got that wrong on the test, damn! But at least you'll know now!)

Here are some fun videos for you!

The Mendeleev Song!
History on Mendeleev
Newland documentary

Now your daily chemistry related lolcat!

Enjoy and I hope everyone did great on the test!

Electron Configuration

For me, electron configurations started out very confusing, but now that I understand, I'll try and show you what works best for me.

First thing to do is to memorize this chart. We aren't given it during quizzes/tests so it is important to know the order.

You also need to know this:
S-types have one orbital (2 electrons or spaces)
P-types have 3 orbitals (6 electrons or spaces)

D-types have 5 orbitals (10 electrons or spaces)

F-types have 7 orbitals (14 electrons or spaces)

Now if I were you, I would be saying spaces? I'm confused!

But here is how it helps!

_    _      _ _ _    _      _ _ _
 
1s  2s    2p         3s    3p

Now, let's start with something easy like a Helium atom. If it is an atom, it has the same number of protons and electrons. Helium's atomic number is 2 therefore it has two protons/electrons. Because it has 2 electrons, fill in one upwards arrow and one downwards arrow. That shell is now full.

Not only is that shell full, we have used up all the electrons!
Therefore the electronic configuration for Helium is 1s2.

Lets use a more complicated one now and test that knowledge!
Lets try a sodium atom. This atom has 11 protons/electrons. Keep going until all those electrons are full.

I would draw it but since its on the computer I can't. So we'll use an astrix to show it.
 
**   **     ** ** **     *    
_     _       _ _ _            _     _ _ _

1s   2s     2p               3s    3p

As you can see we have used all 11 electrons. So let's write it!

In written form it would be 1s2 2s2 2p6 3s1
As you can see the exponents add up to the number of electrons.

If you are still completely confused what I mean when I say arrows, here is a visual example of what I am talking about.

                                                     Orbital diagram for Sodium


Now lets try one with ions!

Electron configuration for N3-

Because it has a charge of -3, there are three extra electrons to deal with. Normally, nitrogen has 7 electrons. But because of its charge, we have to add 3 more.
If it has 10 electrons, write it out until you run out of electrons.

1s2 2s2 2p6
As you can see the exponents add up to 10, the number of electrons for the N3- ion!

The nitride ion, N3­­­ˉ, has an electron arrangement of 1s2, 2s2, 2p6

Without the 3- charge, N would look like this: 1s2 2s2 2p3. The extra 3 electrons fill the 2p orbital and stabilizes the ion, making it similar to a noble gas, which all elements want to be like. (But you will learn more about that later)

What else you need to know:

Ground State: electrons are in their lowest possible level
Excited State: Electrons are in energy levels other than the one that is lowest available.

If the electrons in the excited state, you should try for extra practice to put them in their ground state.


Thanks for reading, of course I will include a lolcat to thank you for following along!

Periodic Table Trends

This class we did an activity to discover the trends in the periodic table.

We found out the trends by graphing and finding out what we noticed was a trend.
Here is what we found:

Density: the degree of compactness of a substance. As the atomic number increases, so does the density.

Melting Point: The temperature at which a given solid will melt.
Boiling Point: The temperature at which a liquid boils and turns to vapor

Melting points decrease as you move down a group, and increase as you move across a period.

Ionization Energy: The energy required to remove the outermost electron in the atom. It increases as you move across a period, and decreases as you move down a group.

Electronegativity: The tendency of an atom to attract electrons in the formation of anionic bonds. Elements become less electronegative as you move down a group, and more electronegative when you move across a period.

Atomic Radius: Measure of the size of its atoms, usually the mean or typical distance from the nucleus to the boundary of the surrounding electrons. This decreases as you move across a period, and increases as you move down a group.
Next class we focused on elaborating on these trends so stay tuned!

Also, Ms. Chen showed us this great website http://www.ptable.com/ where you can play around with the trends and find out some new trends! I know I will be using it to study!

Atoms

Today you are going to learn how to determine things like isotopes, number of protons, number of neutrons, etc. So lets get started!


REVIEW: Atoms consist of electrons, protons and neutrons.




Proton: Mass = 1, charge = +1, located in the nucleus

Neutron: Mass >1, charge = 0, located in the nucleus

Electron: Charge = -1, located around the nucleus




Atomic Number: Number of protons found in a nucleus


The atomic number = the number of protons which also equals the number of electrons. It's that easy!


Got all that? Time to move on to ions.

Ions are atoms able to gain or lose electrons
The number of protons subtracted by the number of electrons equal the charge of the ion.

Moving on to the mass number. This is the total number of protons and neutrons!
Knowing this, here are some equations to remember:

number of neutrons = mass number - atomic number

mass number = number of protons + number of neutrons

Moving on to atomic mass!

Atomic Mass: the average mass of an isotope

Wondering what an isotope is?

Isotopes: when there is the same number of protons and electrons but a different number of neutrons

Here is a problem that deals with isotopes:

There is an element with 4 naturally occuring isotopes. Their atomic mass and percent is as follows: a = 46 (25%), b = 47 (50%), c = 48 (15%), and d = 49 (10%)

Find the atomic mass for the element.
First, multiply the atomic mass by the percent abundance.

A = 36 x 25 = 11.5
B = 47 x 50% = 23.5

C = 48 x 15% = 7.2

D = 49 x 10% = 4.9

Now add them together to get your answer.

11.5 + 23.5 + 7.2 + 4.9 = 47.1

I just high-fived my cat who is sitting beside me so I felt this picture was necessary.

Thanks for reading!

More of a History Lesson!

Todays class was very different from the rest of the year!
So far we've pretty much done math and then more math that gets super confusing! But now we are starting the history part of chemistry 11.
Today we looked at the Atomic theory and Philosophers ideas of Atoms back in the day!

• The first idea from Greek philosophers of atoms was that they were the smallest particles of matter.
• Aristotle believed that matter was made from different combinations of earth, air, fire and water
• Alchemists tried turning to turn common elements to gold
• These ideas lasted for 2000 years
• In 300BC Democritus; greek philosopher, thought atoms were invisible particles

Next we looked at a few philosophers and talked about their theories on matter!

Lavoisier

1. Lavoisier

• He created the first version of the law of conservation of mass, and the law of definite proportions
• he was the first to recognize and name Oxygen(1778) and Hydrogen(1785)

2.Proust

• He experimentally proved Lavoisier law



Dalton

• he stated that ratio of elements will stay the same before and after.

3. Dalton

• idea that atoms are solid, indestructible spheres
• atoms provide for different elements, based on the law of conservative mass

5 main points of Dalton's Atomic Theory

1. elements are made of tiny particles
2. all atoms of a given elements are identical
3. all atoms of a given element are different from those of any other element
4. Atoms of one element ca combine with atoms of other elements to from chemical compounds
5. atoms can not be created nor destroyed, only changed

4. J.J. Thomson (1850)

planetary model

• blueberry muffin model
• discovered existence of electrons

5. Rutherford (1908)

• discovered the nucleus and that electrons orbit the nucleus
• created planetary model
• claimed atoms were mostly empty space

 Atomic Theory IV

Niels Bohr

6. Niels Bohr (1885-1962)

• observations, electrons surrounding the nucleus had specific "energy levels" or "shells"
• Pictured hydrogen atoms having energy "levels"
• and that they could jump to higher levels
• release light when it comes back down

The Modern Atom

•  atom is the smallest particle of an element
•  all atoms are made up of 3 subatomic particlles

1. electrons
2. protons
3. neutrons

Lastly we got assigned a Timeline to do for April 20
we have to research 12 scientists and construct a time line

1. Aristotle
2. Henri Becquerel
3. Niels Bohr
4. James Chadwick
5. Marie & Pierre Curie
6. John Dalton
7. Democritus
8. Robert Millikan
9. Ernest Rutherford
10. J.J. Thomson
11. Antoine Lavoisier
12. Henry Mosely

A few of these scientists were discussed today in class as shown above!

Percent Yield and Percent Purity

Percent Yield =   actual mass produced (grams)         x 100

              theoretical mass produced (grams)

Percent Yield is found by dividing the actual mass of product formed by the mass of the product expected - aka, the product that is found by using Stoichiometry. 

For example:
If 14g of Sodium is reacted with an excess of Chlorine, then 36.5g of Sodium Chloride is produced. What is the percent yield? 

There are 3 steps.

Step 1: Balance the equation.

Na + Cl2 --> NaCl2 

Luckily for this equation, it's already balanced. So this step is done for you

Step 2: Use Stoichiometry! 

So we know that we have 14g of Sodium (Na), and we're trying to convert from grams to moles to moles to grams. In this case, were converting it from sodium to sodium chloride (NaCl2) 

so:

14g Na x 1 mole/23g x 1 mole NaCl2/1 mole Na x 94g/1 mole = 57.217g NaCl2

Step 3: Find Percent yield.

    36.5g (actual mass produced)        x 100  

57.217g (theoretical mass produced)

= 63.8% 

^ a quick video on Percent yield (in case you don't understand)

Percent Purity=   Mass of pure substance    x 100

               Mass of impure sample

Percent Purity is found by dividing the mass of the pure substance by the mass of the impure sample, and then multiplying by 100. Only the pure part of the sample will react. Before we can use stoichiometry to find out how much of the product will form, we need to know how much of the reactant is pure - and able to react.

For example:

If a 9.2g sample of metal ore contains 3.2g of Copper, what is the percent purity?

So the mass of the pure substance = 3.2g of copper.

The mass of the impure sample = 9.2g of metal ore.

Percent Purity =  3.2g    x 100 = 34.8% pure.

                          9.2g 

unfortunately could not find any you tube videos on percent purity but please enjoy this picture of a polar bear

                         

Stoichiometry Part II

So now it is time to turn up the difficulty! You ready?! Well if you're not too bad.

Let's try some examples! The important thing is to create a map and keep organized.

If 121.5 g of Al are consumed, what volume of hydrogen gas is formed at STP?

Plan: mass Al --> moles Al --> moles H2 ---> volume STP

conversion factor for volume is 22.4 L / 1 mol or 1 mol/22.4 L

also, remember your sig figs or you'll get marks off! bad bad bad you dont want that!

121.5 g Al x 1 mol Al  x   3 mol H2    x   22.4 mol H2 = 151 L H2
                    _______      _______         _________
                    27.0 g Al      2 mol Al          1 mol H2

Lets try more!

3Cu(s) + 8HNO3 (aq) + 3Cu(NO3)2 (aq) + 2NO (g) + 4H20 (l)

How many atoms of copper are required to produce 179.2 L of NO gas at STP?

Let's plan!

volume NO --> mol NO --> mol Cu -->  atoms Cu

6.022 x 10 ^ 23 atoms
--------------------
1 mole

is the conversion factor we need to help us solve this problem!

179.2 L NO gas x 1 mol NO x 3 mol Cu x 6.022 x 10^23 atoms Cu
                              ---------     ---------    --------------------------
                              22.4 L       2 moles NO   1 mol Cu

= 7.22 x 10^24 atoms of Cu

There you go! Now you know how to do stoichiometry with atoms, volume at STP and molecules thrown into the mix. You're invincible!

Here are some videos in case you aren't feeling invincible, but I doubt you're not.
Volume to Volume
mass to volume
mass to mass
                             ---------

Excess and Limiting Reactants

During a chemical reaction, there is not always the correct amount of each reactant present in the ratio in the balanced equation. Obviously, more = excess and less = limiting

These questions take a while to do and require a lot of steps so remember to keep organized. Alright, here is how to do it!

Lets start off with an example:

Fe + S --> FeS

A sample of 111.6 g of Fe is mixed with 96.3 g of S.

First thing to check is that the equation is balanced. After that, you must calculate the moles present.

moles present Fe = 111.6 g Fe x 1 mol Fe/55.8 g Fe = 2.00 mol present Fe

moles present S = 96.3 g S x 1 mol S/32.1 g S = 3.00 mol S present

So now we have our moles present. But how do we know which one is limiting and which one is excess? Well, we must calculate the moles needed.

Use the coefficients in the equation to determine the moles needed.

moles needed S = 2.00 mol Fe x 1 mol S / 1 mol Fe = 2.00 mol S needed

Using moles present and moles needed we can calcullate the excess and limiting reactants.

With 3.00 mols S present, and 2.00 mols S needed, S is the excess reactant. 3.00-2.00=1.00 g in excess

Therefore, if S is the excess reactant than Fe is the limiting reactant!

A question that will typically be asked is:

When this reaction is carried out, what mass of FeS will actually be produced?

To calculate the mass of FeS actually formed in this reaction, we have to start with the limiting reactant (this time Fe). We can't use the limiting reactant since not all of it reacts.
To get the answer, use the stoicheometry we have learned.

Remember to plan first.

mass Fe --> moles Fe ---> moles FeS --> mass FeS

Just write it all out and you are good to go! Lets try another.

4FeS + 7O2 --> 2Fe2O3 + 4SO2


moles present FeS = 439.5 g FeS x 1 mol FeS/87.9 g FeS = 5.00 mol FeS
moles present O2 = 256.0 g O2 x 1 mol O2/32.0 g O2 = 8.00 mol O2

moles needed O2 = 5.00 mol FeS x 7 mol O2/4 mol FeS = 8.75 mol O2

Therefore O2 is the limiting reactant and FeS is the excess reactant.

Hope that helped! Here are some fun videos:

Click!

More!

Stoichiometry

Today we started chapter 6 - stoichiometry.
Stoichi-what?
"stoichio" is Greek for element.
"metry" means measurement.
Stoichiometry is measuring the amounts of chemicals involved in a reaction.

Proportional relationships are the specific amounts of each compound in a reaction.

2Cu + 1O2 -> 2CuO

Suppose you double the amounts of copper and oxygen used.

4Cu + 2O2 -> 4CuO

In a balanced equation, you can continue to increase the amounts of the compounds as long as the proportions are kept the same.
-link to PHET website

This website explains all about proportional relationships and gives you an opportunity to try it out. There's even a game!

The balanced equation describes the ratio in which the substances combine. The ratio is obtained from the coefficients of the balanced equation. This combining ratio is the mole ratio of the combining substances. It can be used to predict what would happen if the amount of one substance is changed.

Now back to stoichiometry. Stoichiometry involves measuring or calculating the amounts of elements or compounds involved in a chemical change.
Coefficients in a balanced equation tell us the numbers of moles reacted or produced. They can also be used as conversion factors.

3X + Y -> 2Z

To find the ratios you just take what you need/what you have OR where you're going/where you started.

Types of Reactions, Predicting Products

This post is about the types of reactions, and predicting products of those reactions!

There are several types of reactions:
Synthesis, Decomposition, Single Replacement, Double Replacement, Combustion, and Neutralization

SYNTHESIS: A + B --> AB

This is just your simple 1+1 = 2. Add two together!

Example: Fe(s) + O2(g) --> Fe2O3

Don't forget to balance!
4Fe(s) + 3O2(g) --> 2FeO3

Don't forget to include the states! If you are confused, check out the solubility table!

DECOMPOSITION: AB --> A + B

When something decomposes, it breaks up. Decomposers break up stuff! So think about breaking up the compound:

Think of that gross pile of worms to remember decomposition.

Example: 1SO2(g) --> 1S(g) + 1O2(g)

SINGLE REPLACEMENT: AB + C --> AC + B

In single replacement, they switch partners. But there are only 3 different elements: A, B and C. Remember to put metals with non-metals. Do not put metals together with metals or vice versa. That would be wrong!

4Al(s) + 3Pb(NO3)4 (aq) --> 4Al(NO3)3 (aq) + 3Pb(s)

Ready to step it up a notch?

DOUBLE REPLACEMENT: AB + CD --> AC + CB

There are four different elements in this reaction, so switch them up! Again, put metals with non-metals.

2Sr(OH)2(aq) + 1Sn(NO3)4(aq) --> 2Sr(NO3)2(aq) + 1Sn(OH)4(s)

Now I have skipped a bit into the next lesson, but more practice for you guys! Moving on!

PREDICTING REACTANTS

When we know the type of reaction, we can predict the products. Just use the ABCD models that are given above.

Let's try it out:

1Al(s) + 3AgNO3(aq) -->

From looking at this, we can see that there are two elements and one compound. What could this be?!
The key word is the compound. Decomposition would have just one compound, and synthesis would have two different elements that would form a compound on the other side of the arrow.

So what could it be? Single replacement, of course!

Trashcat does not like single replacement.

So, if it is single replacement then lets finish it off!

1Al(s) + 3AgNO3(aq) --> 1Al(NO3)3(aq) + 3Ag(s)

That is it for today!

Good luck on the test, make me proud!

Enthalpy and Energy Calculations

It's the RETURN OF THE MOLE! 

ok in all seriousness now, today we learnt about Enthalpy and how to calculate energy to moles.

Enthalpy: the total Kinetic and Potential Energy of a substance - the "heat content" of a substance.

Chemists are interested in the change in enthalpy in a chemical reaction. 

In an exothermic reaction, the enthalpy goes DOWN. It is converted into heat and released. 

In an endothermic reaction, the enthalpy goes UP. It is absorbed. 

/\H = Hproduct - Hreactant 

To find the total change in enthalpy, you just subtract the reactant from the product. 

In this picture, C is in the place where the change in Enthalpy would normally be. 

/\H = Hproduct - Hreactant 

/\H = 300 - 100 

/\H = 200 kJ

As you should already know, the unit for enthalpy is kJ, or kilojoules. 

Energy to moles: 

Here is a mole map.

Here is a mole map, with the calculations for Energy -> moles.

As you can see, to get from moles to energy, you simply multiply by the number of kilojoules/1 mole. To get from energy to moles, you multiply by 1 mole/number of kilojoules.

Wahooooo

Translating Word Equations and Review of Naming Compounds

Super late post. Oops.
This lesson is pretty basic.
here's an example of a word equation:
Sodium sulfate and barium chloride -> ?


All you have to do is translate this into something that you can balance. You need to turn the words into ions.
Sodium = Na+ 
Sulfate = SO4 (2-)
Barium = Ba(2+)
Chlorine = Cl(-)


So to write this as a chemical equation, you just substitute in the ions where the words are.
Make sure to balance it!

Na2SO4 + BaCl2 -> BaSO4 + 2 NaCl

This is a Double Replacement. In a double replacement, the ionic compounds exchange partners, with positive ions going with negative ions.

Naming Compounds: 
This is actually extremely simple. Here's a small picture example of some completed compounds.

Basically all you have to do is name the compounds. We've all done it before, it's not too hard of a concept!

Here are some more examples. 

i) barium chloride and sodium carbonate

ii) ammonium chloride and silver nitrate 

iii) sodium phosphate and calcium chloride

Now try doing some more examples, except this time instead of translating word equations, name the compounds.

iv) Be2As3

v) TiCl4

vi) CoP

ANSWERS: 

i) BaCl2 + 2NaCO3 -> 2NaCl + Ba(CO3)2

ii) NH4Cl + AgNO3 -> AgCl + NH4NO3

iii) 2Na3PO4 + 3CaCl2 -> Ca3(PO4)2 + 6NaCl

iv) Beryllium Arsenide 

v) Titanium (IV) Chloride

vi) Cobalt (III) Phosphide 

Here's a quick and simple video on naming compounds
Naming Compounds

Good luck!

Endothermic/Exothermic Reactions

All chemical reactions involve changes in energy. Some reactions release energy (exothermic) and others absorb it (endothermic).

Here are some points to remember:

• If a reaction takes less energy to break bonds than it gives off to form bonds, it is exothermic.
• Enthalpy, represented by H, is the heat contained in the system

Okay, now lets get down to the good stuff! Energy diagrams! Now I am a proud graph hater, but it can be straightforward if you pay attention to all the different names. First, lets learn them:

• Energy of reactants = total potential energy of all reactants in the reaction
• Energy of products = total potential energy of all products in the reaction
• Energy of the activated complex = potential energy of the "transition state" between reactants and products.
• Activation energy = the energy that must be added to get the reaction to progress (reactants to activated complex)
• Delta H (there is no delta sign on this computer, sorry!) = change in potential energy during the reaction.

And what is chemistry without formulas? Here are some to keep in mind:

Delta H: Energy of products - energy of the reactants
Energy of activated complex = energy of reactions + activation energy

If the change in enthalpy is negative, it is exothermic. If it is positive, it is endothermic.

Now, onto the graph.
Label the x axis as the reaction progress. (some unit of time)
Label the y axis Potential Energy in kJs.

Want to see what it all looks like?

From this diagram, you can see everything I just talked about! Notice the labels and try to draw your own!

Here are some videos to help you out!

Endothermic Reactions

Exothermic Reactions

Animation on activation energy

Balancing Equations!!

sorry for the late post :S
but YAY for a change we got something easy to do! Balancing Chemical Equations :)
this is review from grade 9 and 10! if you forgot... heres how it goes.

What is a Chemical Equation?

When a chemical reation occurs it can be described as a equation. It shows the chemical that react, called the reactants which are located on the left hand side. Also the chemicals that they produce, called products which are located on the right hand side of the equation. These two sides are seperated by an arrow that indicated the reactants form the product.

The Concept:

Take a look at this chemical word equation:

Ethane + Oxygen  Carbon Dioxide + Steam

This is the writen equation, now you have to translate it to the chemical equation:

C₂H₆ + O₂ CO₂ + H₂O

In this equation notice how neither the Carbon, Hydrogen or Oxygen atoms match from the left hand side to the right hand side? 

Left has: 2 Carbon, 6 Hydrogen, 2 Oxygen

Right has: 1 Carbon, 2 Hydrogen, 3 Oxygen  

This is why we must balance the equation!

Since there are two carbon atoms on the left side, but only one on the right, so we need to put a 2 in front of the carbon dioxide molecule to give two carbons on each side:

C₂H₆ + O₂  2CO₂ + H₂O

Now we will look at the hydrogen atoms. There are six hydrogen atoms on the left side and two on the right side, so now we have to put a 3 on the right hand side so it is equal to the number of hydrogen atoms on the left hand side:

C₂H₆ + O₂  2CO₂ + 3H₂O

Now there are two carbon atoms on each side, and six hydrogen atoms on each side, but the oxygen atoms don't match. There are 2 of them on the left side and 7 on the right side. This is easily solved by multiplying the oxygen molecule on the left side by 3.5 (as 2 x 3.5 = 7):

 

C₂H₆ + 3.5O₂  2CO₂ + 3H₂O

This gives 2 carbons, 6 hydrogens and 7 oxygens on each side of the equation. The equation is balanced, but rather than a decimal just double all the figures in the equation:

2C₂H₆ + 7O₂  4CO₂ + 6H₂O

YAY! now it is balanced :)

As you go on balancing those quations you may come across molecules as being a unit such as:

SO₄ Dont even worry about it, just go on about your business. Treat them the same way!

Also a note:

Watch out for Diatomic Elements which are specific elements that go around in pairs (atom of 2).

they include: Hydrogen(H2), Oxygen(O2), Flourine(F2), Bromine(Br2), Iodide(I2), Nitrogen(N2), and Clorine(Cl2)

So whenever you are writing a chemical equation, always remember, if u come across these elements alone, they come in pairs of 2!

To help you remember these elements just think: HOFBrINCl

 

HERE ARE SOME SEMI HELPFUL VIDEOS! 

http://www.youtube.com/watch?v=RnGu3xO2h74

http://www.youtube.com/watch?v=BVEvvqMGMSc