Bunsen Burners

Non-luminous flame

•  when the air hole of the Bunsen Burner is open 
• when the air hole is open, more oxygen can enter the burner; therefore, hotter flame will be produced." 
• its color is transparent or blue 
• Blue flames are its hottest flames 

Luminous flame

•  is produced when the air hole is closed
• if the air hole is closed, oxygen cannot enter the burner; therefore, least hotter because the combustion is not fully complete with least oxygen 
• A luminous flame has an outer of orange color and an inner of blue. 
• Luminous flames emits more light than non-luminous flames.
  

Term 3 Ace

Observations before

The potato in the Salt water solution

                               i.            The slice of the potato was floating near the surface of the water

                             ii.            Its diameter is 4.2 cm

The potato in the Sugar water solution

                               i.            The slice of the potato floated in the middle of the cup

                             ii.            The diameter of the potato is 4.2 cm

The potato in the Plain water

                               i.            The slice of the potato was at the bottom of the cup

                             ii.            The diameter of the potato is 4.2 cm

Observations after an hour

The potato in the Salt water solution

                               i.            After an hour, there were air bubbles form on the surface of the water

                             ii.            The slice of potato sank to the bottom of the cup after an hour

                          iii.            The slice of the potato had turned a little darker

                          iv.            The size of the potato has decreased it shrank by 0.3 cm

                             v.            It turned more flexible and soft

The potato in the Sugar water solution

                               i.            The potato sank to the bottom of the cup after an hour

                             ii.             The potato turned smaller a little

                          iii.            It also became a little softer but not as much as the on in the Salt water solution

                          iv.            The size of the potato remained the same, as it is still 4.2 cm.

The potato in the Plain water

                               i.            The potato remained at the same place it did not sink or float

                             ii.            It turned larger by 0.2cm

                          iii.            It became more rigid than it was at the start

 

	The potato in the Salt water solution	The potato in the Sugar water solution	The potato in the Plain water
BEFORE AFTER	4.2 cm 3.9 cm	4.2 cm 4.2 cm	4.2 cm 4.4 cm

Why did that happen? It has to do with a process called osmosis. The potato is made up of tiny, living units called cells. Each cell is surrounded by a cell membrane which acts much as your skin does. It keeps the cells parts inside and keep other things outside, protecting the cell. While this membrane stops most things, water can pass through it. The water tends to move towards higher concentrations of dissolved chemicals. That means that if the water outside the cell is saltier than the water inside, water will move from the inside of the cell to the outside. That is what happened to the slice of potato in the salt water. As the water left the cell it was much like letting the air out of a balloon. As more and more of the cells lost water, the slice of potato became soft and flexible. The same thing happened for the sugar, but since the cells in the potato contain more sugar than they do salt, the cells did not get as soft.

When you put the potato into the plain water, the reverse happened. Water moved from the outside, where there was no salt or sugar, into the cell where there was some. This caused the cells to swell up, becoming very stiff.

Solution and suspension

When a solute is a substance that dissolves in a solvent. A solvent is a substance that dissolves a solute.
Example of suspension

• Mud or muddy water, is where soil, clay, or silt particles are suspended in water
• Dust particles suspended in air
• Flour suspended in water

Some Examples of Solution

• Commonly encountered solutions involving solid dissolved in a liquid. Solutions in which the solvent is a liquid and the solute is a gas, liquid, or solid are very common.
• The atmosphere is a good example of a solution in which a gaseous solvent (nitrogen) dissolves other gases (such as oxygen, carbon dioxide, water vapor, and neon)
• Solutions of solids in solids are also another example, they are encountered in among various metal alloys 

Separation Techniques 

1. Distillation

Distillation is a unit operation, or a physical separation process, and not a chemical reaction. It can be usedd to separate a mixture of two liquids it involves boiling and condensation.

Magnetic Attraction

It can help to separate mixtures of Magnetic Substances from Non-Magnetic Substances. It uses magnetism. For example, put a mixture in a dish and hold a magnet slightly above the mixture in the dish, and the magnetic substances will be attracted to the Magnet thus separating them.

Evaporation

When a solid dissolves in a liquid, it is known as the solute. The liquid that the solid dissolves in is known as the solvent. Evaporation is used to separate solids from liquids in a solid-liquid mixture.






Chromatography                                               

You can use a filter paper. Firstly draw a starting line with pencil and it should be above the water. Next dot a coloured spot using, e.g. a pen, marker. Then put the paper in alcohol or ethanol but do not submerge it. Then coloured spots will be left in different places.


Filtration

It can be used for solid-solid, solid-liquid and liquid liquid mixture, as it is the size of the partiles that matter. Example you can place apiece of filter paper in a filter funnel, and put a beaker under it. Next pour the mixture into the filter funnel with the filter paper. The liquid passes through, while the insoluble solids does not pass through. Lastly the filtrate will be collected in the beaker, and the residue remains on the filter paper.

Separating funnel

It can separate immiscible liquids. Immiscible liquids are liquids that do not mix with each other, and an example is oil and water.

Crystallization

It is a process by which a dissolved solid(solute) separates from a solution in the form of crystals. It can be use to obtain salts such as copper sulphate. You can set up an apparatus of a beaker of the solution. Next apply heat under the beaker with a bunsen burner, until a hot saturated solution is formed. Lastly let the solution cool, the mixture is filtered. Separation is complete. Crystallization is commonly used by scientists to purify solids.

Sublimation


Sublimation is a process whereby some matters change from the solid state to the gaseous state without going through the liquid state. An example is, place the mixture in an evaporating dish, and position it over a bunsen burner. Now place the inverted funnel just above the dish. The substance with the higher melting point will still be left on the dish. The other substance will vapourise and solidify when it condenses on the surface of the funnel. It involves boiling, evaporation and condensation.