Chapter 7.2 textbook : Oxidation and Reduction by Justin Gunawan 3W

Definitions: Basically oxidation means adding or gaining oxygen and reduction means losing oxygen. You can also say Oxidation means the loss of hydrogen while reduction means gaining it. Oxidation is also a loss of electrons and reduction is gaining it. Oxidation and reduction always takes place together and that means if one substance is oxidised the other one is reduced.

Redox Reaction: Redox reaction is actually means any reaction which involved electrons transfers.












The Expertiment : The Oxidation of Alchohols.

Apparatus and chemicals :

Eye protection

Measuring cylinder (5 or 10 cm³)
Well-plate (24 wells) – eg Sigma ref: M9655.
Glass rod
Plastic dropping pipettes, 6

The Oxidation of alchohol.

a Take approximately 2 cm³ of potassium dichromate(VI) solution in a measuring cylinder and add about 1 cm³ of dilute sulfuric acid. Stir with a glass rod.

b Put 10 drops of the acidified potassium dichromate(VI) solution into each of the wells
A1 – A4 and B2 (see diagram below).

c Practice (over a sink) producing single drops of ethanol from the pipette.

d Add two drops of the alcohols to the wells as follows:

Well No.	Alcohol
A1	Ethanol
A2	Propan-1-ol
A3	Propan-2-ol
A4	2-Methylpropan-2-ol

The following alcohols in dropping pipettes:

Ethanol (Highly flammable) or Industrial denatured alcohol, IDA (Highly flammable, Harmful)
Propan-1-ol (Irritant, Highly flammable)
Propan-2-ol (Irritant, Highly flammable)
2-Methylpropan-2-ol (Harmful, Highly flammable), or other tertiary alcohol

Potassium dichromate(VI) solution, 0.1 mol dm^–3 (Toxic at this concentration), 2 cm³
Sulfuric acid, 1 mol dm^–3 (Irritant at this concentration), 1 cm³

Reference: http://www.practicalchemistry.org/experiments/intermediate/oxidation-and-reduction/the-oxidation-of-alcohols,217,EX.html

Chapter 2.3 from text book: Isotopes and Radioactivity Jeremy Gunawan 3W

Atoms: Atom is the smallest component of an element having the chemical property. Atoms are consisted of a nucleus containing protons and neutrons and one or more electron surrounding the nucleus.

Isotopes: Isotopes is an atom that have the same number of proton and electron but different number of neutron.

Example of Isotopes: We all know that isotopes have the same number of atomic number in that particular atom but different number of mass number that was caused by the changes of the neutron particles.

Example of carbon isotopes:

These are the example of the carbon isotopes. Each of them share the same number of atomic number which is 6 but different number of mass numbers which are 12, 13 and 14.

Some Isotopes are radioactive!!

A carbon - 14 atom behaves in a strange way. It is radioactive and its nucleus is unstable because it have way too many neutron. In some amount of time the nucleus will decays or breakdown, giving out radiation in the form of rays and tiny particles as well as a large amount of energy.

How fast do radioisotopes decay?

Radioisotopes decay at random. We would not know when carbon 14 will decay. But we do know how long for half the radioisotopes in a sample to decay. This is called the half-life. The half-life for carbon-14 is 5730 years. So if you have 100 carbon-14 atoms, 50 of them will have decayed 5730 years from now.

Finding Earth's age using radioisotopes:

We all know that earth had been there for 4.54 billion years. Is it true that earth had been living for 4,54 billion years? or is it only been living for some thousands years. There are some proof that says that earth had been exist for 10000 years or so because the people on that time had wrote their journey or invention. The bible is one of the written example of those old days. But no one had ever wrote or leave any things or invention back in the million years. There are some proof such as the skeleton of dinosaurs that had been decayed. The radioisotopes will help to trace back on how long this bones had been living. Here are some proof on how radioisotopes proof that earth had been living for billion years. The age of the earth had been determine by radiometric age dating of meteorite material and other old stuffs. Using the radioisotopes we could find the half-life of that particular isotope atom. For example like the small zircon in Jack Hills in west Australia had aged for more than 4billion years. The oldest known constituents within the meteorite are 4.567 billion years old. That is how the radioisotopes help to discover how old something is, including us. To find a mummified Egyptian we must first know that our body are made out of a lot of carbon atoms and a tiny percentage of these carbon are carbon-14 which is an isotopes. When a living atoms died the atoms did not take in anymore new carbon atoms but the remnant of the carbon 14 atoms will eventually decays over time and we can measure the faint radiation from them.

Chapter 2: Experimental Techniques(Juan Gunawan)

Reflections(recap):-
Purification:
- Purification is a process of separating a mixture into pure substances.
- Compounds are separated by chemical means while mixture are separated by physical means.
- There are many methods to purify.
- Examples are: Filtration, Decanting, Crystallization, Chromatography, etc.
- Different substances uses different methods of purification.
- For Example: Sublimation is used to purify iodine while Filtration is to purify drinking water.

There are lots of experiments for purification as there are many methods to it. The one i chose is
an uncommon experiment since most of the experiments are water purification. Chromatography
is rarely done in class (I think because we did it only once) and I thought doing chromatography to
candies is quite interesting and fun since i too want to know what is inside our candies.


The Experiment:-

Chromatography of sweets

This type of experiment goes down well with students since it uses well known material normally used as confectionery. The coloured dye coating the surface is removed from M&M’S® of various colours. A spot of each is put on to a piece of chromatography paper and water is allowed to soak up the paper separating out the component dyes. The results show which dye mixtures are used to produce particular colours for the sweets.

Read our standard health & safety guidance

Lesson organisation

Students should have a good basic understanding of chromatography theory and this practical can be a useful introduction to the method of separation. The experiment can be carried out by groups of two or three and takes about 30-40 minutes. Students must be told that the M&M’S® are not to be eaten under any circumstances.

Apparatus and chemicals

Beaker (250 cm³)
Small soft paint brush
Paper clips (preferably plastic coated), 2
Chromatography paper, approximately 20 cm x 10 cm (see note 1)
Pencil
Ruler
A communal hairdryer (optional) (see note 2)

A supply of M&M’S® of various colours (see notes 3 and 4)

Technical notes

1 Whatman chromatography paper works best for this experiment, but, if unavailable, large sheets of ordinary filter paper can be cut up instead.

2 Ensure that the hairdyer has had an electrical safety check.

3 M&M’S® with a variety of about 6 or 7 different colours are required for each group.

4 If M&M’S® are unavailable this experiment can be carried out with liquid food colouring which is readily available from supermarkets. Chromatography of Smarties® is less successful as they use natural food colourings. Peanut M&M’S® should not be used if there are students with peanut allergies.

Procedure

HEALTH & SAFETY: Students must not attempt to eat the M&M’S® or even lick them. They are for laboratory use only.

a Place the piece of chromatography paper on a clean flat surface, with the longer side horizontal and draw a horizontal line in pencil (not biro) about 1.5 cm from the base of the paper.

b Use the dampened paint brush to remove the colour from one of the M&M’S® and paint this colour on the line about 2 cm from one end. Small spots are best.

c Clean the brush in fresh running water and paint the colour of another M&M® on the line about 2 cm from the first spot.

d Repeat this until all the colours are on the paper or until you have reached the other end.

e Use a pencil (not a biro) to write the name of the colour next to the corresponding spot.

f Roll the paper into a cylinder and hold this in place with the paper clips. Try to avoid any overlapping of the paper when you make the cylinder.

g Put water into the beaker up to depth of about 1 cm.

h Lower the paper cylinder into the beaker of water thus allowing the water to rise up the paper. Ensure that the water is below the level of the spots. Try to avoid moving the paper cylinder about once it is in position.

i When the water approaches the top of the paper cylinder remove it from the water. Mark with a pencil the level of the water at the top of the filter paper.

j Allow the paper cylinder to dry, perhaps by using a hairdryer if available or by clamping it and leaving it to dry overnight.

k Unravel the paper cylinder and examine it carefully.

http://www.practicalchemistry.org/experiments/introductory/mixtures-and-separations/chromatography-of-sweets,194,EX.html


Daily Application of Chromatography:
There are lots of usage of chromatography in real life such as traces of waste oils and pesticides
in the ground or DDTs in groundwater. But, chromatography is widely used in controlling the food quality of the food industry.


http://science.jrank.org/pages/1464/Chromatography-Industrial-applications-chromatography.html

Chapter 1: Particulate Theory of Matter (Shanice)

The Particle Theory of Matter:

1. Matter is made up of tiny particles (Atoms & Molecules)
2. Particles of Matter are in constant motion.
3. Particles of Matter are held together by very strong electric forces
4. There are empty spaces between the particles of matter that are very large compared to the particles themselves.
5. Each substance has unique particles that are different from the particles of other substances
6. Temperature affects the speed of the particles. The higher the temperature, the faster the speed of the particles.


Experiment :

Brownian motion can be demonstrated simply by releasing some smoke particles from burning cord into a small glass container and putting a cover plate to seal the smoke and air into the cell.

To investigate liquid molecular movement place some water with graphite particles suspended in it in the cell.

Now adjust the microscope slightly until you can see very bright specks. The particles of graphite (or smoke) scatter (reflect) the light shining on them and so appear as bright points of light darting about in a random or erratic motion. Note that the graphite (or smoke) particles are much larger than the water (or air) molecules. The particles can be seen by the light they scatter but the molecules themselves are too small to be seen.

The irregular movement of the visible particles of graphite (or smoke) is explained as being due to an uneven bombardment of the particles by the invisible molecules of water (or air). It is due to Brownian motion.

Brownian motion
We can conclude that lighter the particles faster the motion and denser the particles slower the motion.


Dissolving of Crystals in a Liquid due to Diffusion

Place some crystals of potassium permanganate at the bottom of a beaker. Slowly transfer water into the beaker with the help of a pipette. After sometime a dense purple solution is formed at the bottom and you will notice that it gradually spreads with the rest of water. After a few hours, it will be seen that the purple solution of a uniform concentration has formed throughout the solution.

This is because of the random motion of the potassium permanganate crystals in the water and by diffusion a homogeneous solution of potassium permanganate and water is formed.

http://www.tutorvista.com/content/physics/physics-i/matter/brownian-motion.php

:D

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