Download Study Guide

SMS+TMSC Middle School Science
Chemistry 2016-17
Study Guide
Test on Tue Jan 24, 2017
Grade 8 - Biochemistry & Lab Work
This is only a framework - refer to teachernotes, lab sheets and your own notes!
Vocabulary
ester - a chemical made from combining a carbon-based acid and an alcohol.
acid - a chemical that donates H+ (hydrogen ions or protons).
base - a chemical that donates OH- (hydroxide ions).
alcohol - a hydrocarbon with an added OH group.
prefixes - the first part of a hydrocarbon name that tells you how many carbons are in it:
meth=1 eth=2 prop=3, but=4, pent, hex, hept, oct, etc...
hydrocarbon - a chemical made of linked carbon and hydrogen molecules.
alkane - a hydrocarbon that contains only single bonds
alkene - a hydrocarbon that contains double bonds
alkyne - a hydrocarbon that contains triple bonds
aliphatic - a hydrocarbon with the carbons linked in a chain.
aromatic - a hydrocarbon with the carbons linked in a ring.
Concepts
Carbon (valance 4) can combine with a wide variety of other elements.
It can form chains or rings with other carbon atoms.
This leads to sugars, fatty acids, amino acids and nucleic acids.
Carbons in a chain are termed ALIPHATIC
Carbons in a rings are termed AROMATIC
Hydrocarbons are named for the number of carbon atoms in them and the types of
bonds.
1 carbon with hydrogens on each of the 4 valance sites is called methane: METH=1 and
alkANE = single bonds.
2 carbons with a double bond is ethane: ETH=2, alkENE = double bonds.
See the table in the TeacherNotes.
Each compound has different characteristics. Propane (3 carbons, single bonds) is grill
gas. Polyproplyene (a repeating chain of 3-carbons with double bonds) is the polymer
used in fleece and water bottles.
For a given hydrocarbon, you can add an OH group to it and you have created an
alcohol. Propane can be made into propanol, used as rubbing alcohol.
Aromatics are ring-based, the first important one was benzoic acid, from which benzene
was made. Kekule uncovered the structure of benzene only after a daydream where he
saw the “ouroboros” symbol of a snake eating its tail.
Sugars are single or double ring carbohydrates that taste sweet and provide calories.
Monosaccharides are single ring, disaccharides are double rings and polysaccharides
have three or more sugar rings.
Starches are food starch (amylose) or fiber (cellulose). They have hundreds of
repeating sugar parts. Humans digest amylose as soon as they enter the mouth with an
enzyme in saliva known as amylase.
Fatty Acids add carboxylic acid to a carbon chain. They are the building blocks of fats
and oils.
Amines add NH2 to carbon molecules. These can be changed into amino acids, which
are the building blocks of proteins.
Nucleic acids start with rings containing carbon, hydrogen, oxygen and nitrogen. They
add a sugar and a backbone containing phosphates to form DNA, tRA and mRNA.
DNA is a helical molecule with two strands. mRNA is a messenger molecule that moves
the genetic code from the DNA in the nucleus out to the cell. tRNA transfers the code to
a series of amino acids.
Carbon-based acids can be reacted with alcohols to create a new compound, ester, and
water. Esters are chemicals responsible for many of the food smells you enjoy. By
picking the right acid and alcohol, you can make artificial “flavors” even though you
actually don’t taste them, you smell them.
Labs
Oxidation Lab
We started with steel (iron and carbon, coated with oil) wool. We placed it in water, and
watched... little to nothing happened, as the steel is designed not to react well with other
compounds. We added rubbing alcohol that helped interrupt the protective role of the
oil in the steel. We added salt. We saw limited color change as the iron and salt
promoted the exchange of oxygen into the iron to form iron oxide (rust). We added
hydrogen peroxide, that had more oxygen available than water and saw rapid oxidation
and formation of rust. This reaction also sheds heat, so the temperature odf the mixture
rose.
Iron powder and salt are also in “Hot Hands” hand warmer packets. By opening the
sealed bag you add air and moisture to the mix, allowing for rapid rusting and the
release of heat.