Organics External 2.5

Best resources/ past papers can be found on the NZQA website: https://www.nzqa.govt.nz/ncea/assessment/view-detailed.do?standardNumber=91165

External Exam

Thursday 17h November, 2:00pm

4 literacy Credits

Google meet recordings

23/4/20 Alkane tutorial (pg 135-152)

Level 2 chem tutorial (2020-04-23 at 18:04 GMT-7)

Polymers Tutorial 8/5/20 (pg 168-179)

L2 chem tutorial (2020-05-07 at 18:02 GMT-7)

30/4/20 Alkene tutorial (pg 158-167)

Level 2 chem tutorial (2020-04-30 at 18:00 GMT-7)

Alcohols Tutorial 15/5/20 (pg 187-197)

L2 Chem Tutorial (2020-05-14 at 18:03 GMT-7)

Timeline

Week 1: Alkanes and their properties, SciPad pgs 134-147

Week 2: Haloalkanes and Alkenes, SciPad pgs 148-165

Week 3: Markovnikov's Rule, Polymers, and Alkynes, SciPad pgs 166-179

Week 4: Alcohols, SciPad pgs 187-198

Week 5: Elimination Reactions, Amines and Carboxylic Acids, SciPad pgs 199-212

Week 6: Carboxylic Acids, SciPad pgs 213-214

Week 7: Revision and mock exam

Learn

Organic chemistry is looking at compounds that have carbon atoms in them. They can have other atoms attached as well, but they must ALWAYS have carbon in them. Carbon has 4 electrons in their outer shell so must ALWAYS have 4 bonds attached to it.

Alkanes- straight chain

(pg135-138)

Alkanes are the most basic molecule as they only contain carbons and hydrogen atoms.

meth-
eth-
prop-
but-
pent-
hex-
hept-
oct-

A chain of 1 carbon atom is called methane.

A chain of 2 carbon atoms is called ethane, and so on.

Alkanes- branched chains

(pg139- 142)

Follow these steps:

Find the longest straight chain and name it as previously stated.
Then name the branches coming off it.
- A 1 carbon branch is called methyl
- A 2 carbon branch is called ethyl
- Hopefully you can see the same pattern as before!

Naming branched alkanes.webm

Don't forget...

di, tri, tetra
number , number
number - letter

Structural Isomers of Alkanes

(pg143)

Isomers are molecules which have the same molecular formula (they are made of the same number of atoms) but these atoms are arranged and hence named differently.

Don't move on to this if you aren't comfortable naming alkanes

Melting and Boiling Points of Alkanes

(pg145, 146)

A high boiling points means the intermolecular forces of attraction between molecules is strong. As the length of the carbon chain increases so does the strength between the bonds, hence the melting and boiling points gets higher.

Haloalkanes

(pg148-151)

Elements from group 17 are called halogens and readily bond to carbon to form haloalkanes.

F- fluro
Cl- Chloro
Br- Bromo
I- Iodo

Don't forget...

di, tri, tetra
number , number
number - letter

Classifying haloalkanes

(pg152)

If the carbon atom the halogen is attached to has 3 hydrogens attached it is classes as primary

Alkenes

(158-160)

These molecules still only contain carbons and Hydrogens but now there is a double bond between two carbons. This changes the ending of the name to an -ene

For example a 2 carbon chain with a double bond is called ethene.

A 5 carbon chain with a double bond between the 2nd and 3rd carbon is called pent-2-ene

START NUMBERING CARBONS TO GET THE LOWEST NUMBER FOR YOUR DOUBLE BOND - DO NOT THEN START COUNTING FROM THE OTHER END TO GET A LOWER BRANCH NUMBER!!!! ALWAYS NUMBER IN ONE DIRECTION

Geometric Isomers of Alkenes

(pg161, 162)

Geometric isomers can exist if:

The molecule has a double bond to prevent rotation.
There must be different groups on the same carbons of the double bond.

Addition Reactions

(pg163-167)

Addition reaction occur to alkenes. This is where the double bond breaks and two smaller molecules are added in.

Markovnikov's Rule

Is when you are adding a non-symmetrical reagent like H-Cl.

The carbon atom in the double bond with the most hydrogen atoms already attached will get another hydrogen atom.
The rich get richer.

Markovnikov's rule.webm

Just watch the first 2mins of this one or else it may confuse you!

Polymerisation

(pg168-174)

This is an addition reaction. When you have lots and lots of an alkene (monomer) you can break the double bond and they will form a long chain of repeating units (polymer).

Making slime Experiment!

Elimination Reactions

(pg 175-177)

The reverse of an addition reaction. We remove a small molecule and form an alkene.

Saytzeff's Rule (pg201)

Is when you eliminate an asymmetrical molecule like H-Cl.

Normally, the halogen is eliminated "removed" and that means a double bond will form with the next carbon.

But that means the next Carbon needs to lose a Hydrogen. So which Carbon loses their Hydrogen?

The poor get poorer!

Alkynes

(pg 178, 179)

Another type of molecule here where you have a triple bond between two carbon atoms. Process for naming them is the exact same as for alkenes.

Alcohols

(pg 187-191)

Alcohols have an (OH) and are named using the -ol ending.

Eg a 3 carbon molecule with an OH attached to the 2nd carbon--> propan-2-ol

Classification

Either primary, secondary or tertiary. Same process as classifying the haloalkanes.

M/p, B/P and Solubility

Generally same trend as alkanes. As you increase the carbon chain length, you increase the strength of bond between molecules. Hence increasing the boiling point.

Small alcohols are very soluble as the polar OH has a bigger impact on the molecules ability to dissolve. As you increase the carbon chain the impact this OH can have significantly decreases and the solubility goes down.

Alcohol Reactions

(pg 192- 201)

I hope you all appreciate my artistic abilities here!

Amines

(pg 207, 208)

The have a carbon chain but with an NH2 group attached. The naming is relatively straight forward:
M/P and B/P follow the same trend in that as the carbon chain gets longer, the bond strength between molecules increases, thus increases the M/P and B/P.
Solubility is similar to alcohols in that the NH2 end of the molecule is polar so wants to dissolve in water but as the non-polar carbon chain increases in length it has more power and the solubility will decrease.

For instance this will be named propan-2-amine

Amine Reactions

(pg209)

Amines are formed from reacting a haloalkane with alcoholic ammonia. This is a substitution reaction and it is a straight swap, the NH2 group for the halogen.

Amines are BASIC because when in water the Nitrogen takes an H off water to leave the basic hydroxide (OH-) molecule.

Carboxylic Acids

(pg210, 211)

The end carbon is double bonded to an oxygen and also single bonded to an OH group.
The naming involves -oic acid as the ending.
Formed from the oxidation of alcohols.
Same trend is M/P and B/P and solubility as alcohols and amines.
They are ACIDIC because in water they donate a hydrogen from the OH group to water to form the acidic H3O+ molecule.

Carboxylic Acid Reactions

(pg 212-2114)

The first 3 reactions you should recall from last year. It's just instead of a very basic acid like HCl we have a more complicated acid, but the reactions are the same.

Acid + carbonate ---> Salt + water + carbon dioxide gas
Acid + base --> Salt + water
Acid + metal --> Salt + Hydrogen gas
- - - - Expected observations of bubbling when a gas in produced

The final reaction is a carboxylic acid reacting with an amine to form an alkylammonium salt. See if you can understand it from the book otherwise we will go through this in class.

Revision

Once you have finished the chapter then complete any End of Chapter Review Questions and the practice exam in the SciPad. I will also get you to create an A3 revision poster which has all the reactions you need on it and the main concepts.

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