Introduction to Chemistry

Chemistry is defined as the branch of science that deals with the structure composition, properties and behavior of matter.

The Role of Chemistry in Society

(i) Washing/cleaning with soap
(ii) Understanding chemicals of life
(iii) Baking
(iv) Medicine
(v) Fractional distillation of crude oil
(vi) Manufacture of synthetic compounds/substances
(vii) Diagnosis/test for abnormal body functions.
(viii) Careers such as; chemical engineering, veterinary medicine, chemistry teacher among others

Phases of Matter

Matter is anything that has weight/mass and occupies space/volume.
States of Matter:
(i) Solid – e.g. soil
(ii) Liquid – e.g. water
(iii) Gas – e.g. Nitrogen

– solid is made up of particles which are very closely packed. Hence has a definite/fixed shape and fixed/definite volume /occupies definite space. It has a very high density.
– liquid is made up of particles which have some degree of freedom. It thus has no definite/fixed shape. It takes the shape of the container it is put. A liquid has fixed/definite volume/occupies definite space.
– gas is made up of particles free from each other. It thus has no definite/fixed shape. It takes the shape of the container it is put. It has no fixed/definite volume/occupies every space in a container.

Methods for Separation of Mixtures

A mixture is a combination of two or more substances that can be separated by physical means
Some of the simple methods that can be used to separate mixtures include;

i) Sorting/picking – the method involves physically picking one pure substance from a mixture with another such as sorting maize from maize-beans mixture
ii) Decantation – a method that involves pouring out a liquid from a solid that has settled /sinking solid in it. e. g. Decanting water from sand.
iii) Filtration – this involves sieving/passing particles of a mixture through a filter containing small holes that allow smaller particle to pass through but do not allow bigger particle to pass through.
iv) Skimming – this involves scooping floating particles. E.g. leaves from water

Rules of the School Chemistry Laboratory

(i) Enter the laboratory with permission in an orderly manner without rushing/pushing/scrabbling
(ii) Do not try unauthorized experiments because they could be harmful
(iii) Do not taste any chemical in the laboratory. They may be poisonous.
(iv) Waft gas fumes to your nose with your palm. Do not inhale/smell gases directly. They may be highly poisonous/toxic.
(v) Boil substances with mouth of the test tube facing away from others and yourself. Products of heating solids may be a highly poisonous/toxic gas.
(vi) Wash with lots of water any skin contact with chemicals immediately
(vii) Read and follow safety instruction.
(viii) Clean your laboratory work station after use
(ix) In case of fire, remain calm, switch of the source of fuel-gas tap. Leave the laboratory through the emergency door
(x) Do not carry unauthorized item from a chemistry laboratory
(xi) All experiments that evolve/produce poisonous gases should be done in the open or in a fume chamber.
(xii) Report immediately to teacher/laboratory technician any irritation, cut, burn, bruise or feelings arising from laboratory work.
(xiii) Use fire extinguishers near the chemistry laboratory to put of medium fires. Leave strong fires wholly to professional fire fighters

Chemistry Laboratory Apparatus

Apparatus are scientific tools/equipment used in performing scientific experiments. They are classified into different categories as follows;

Apparatus for Measuring Volume

1. Measuring cylinder

Measuring cylinders are apparatus used to measure volume of liquid/ solutions. They are calibrated/ graduated to measure any volume required to the maximum. Measuring cylinders are named according to the maximum calibrated/graduated volume.
An example is the 50ml-measuring cylinder can hold maximum calibrated/graduated volume of 50 milliliters or 50 cubic centimetres

2. Burette

A burette is a long and narrow/thin apparatus used to measure small accurate and exact volumes of a liquid solution. It must be clamped first on a stand before being used. It has a tap to run out the required amount out.

3. Pipette and pipette filler

Pipette is a long and narrow/thin apparatus that widens at the middle used to measure and transfer small very accurate/exact volumes of a liquid solution
Pipette filler is used to suck in a liquid solution into a pipette instead of using the mouth. It has a suck, adjust and eject button for ensuring the exact volume is attained

4. Volumetric flask

A volumetric flask is thin /narrow but widens at the base/bottom. It is used to measure very accurate/exact volumes of a liquid solution
The maximum calibration / graduation mark is a visible ring, and are named according to their calibrated volume

In order to adjust the volume to the calibration, a dropper or a teat pipette can be used.

Apparatus for Measuring Mass

1. Beam balance

A beam balance has a pan where a substance of unknown mass is placed. The scales on the opposite end are adjusted to “balance” with the mass of the unknown substance using grams

2. Electronic/electric balance

An electronic/electric balance has a pan where a substance of unknown mass is placed. The mass of the unknown substance in grams is available immediately on the screen.

Apparatus for Measuring Time

1. The stop watch/clock
A standard apparatus for measuring time using hours, minutes and seconds.

Apparatus for Scooping

1. Spatula

A spatula is used to scoop solids which do not require accurate measurement

2. Deflagrating spoon

It is used to scoop solids which do not require accurate measurement mainly for heating, and is longer than the spatula.

Apparatus Used in Heating

1. Test Tube

It is a narrow/thin glass apparatus open on one side

2. Boiling tube

It is a wide glass apparatus, bigger than a test tube and open on one side

3. Beaker

A beaker is a wide calibrated/graduated lipped glass/plastic apparatus used for transferring liquid solution which do not normally require very accurate measurements

4. Conical flask

A conical flask is a moderately narrow glass apparatus with a wide base and no calibration/graduation. The narrow mouth ensures no spillage

5. Round bottomed flask

A moderately narrow glass apparatus with a wide round base and no calibration/graduation. It must be held/ clamped when in use because of its wide narrow base.

6. Flat bottomed flask

It is a moderately narrow glass apparatus with a wide round base with a small flat bottom.

7. Tripod Stand and Wire gauze

A tripod stand is a three legged metallic apparatus which unstable apparatus are placed on during heating. Wire gauze is a metallic/iron plate of wires crossings. It is placed on top of a tripod stand.

8. Clamp stand

It is a metallic apparatus which tightly hold apparatus at their “neck” firmly, it has a wide base that increases stability

9. Test tube holder

It is a hand held metallic apparatus which tightly holds a test/boiling/ignition tube firmly during heating.