STUDY QUESTIONS
1. Write short notes on development of
chemistry-a historical perspective.
2. How does chemistry help in the production
of food? 13
3. How can you say chemistry plays a vital role
in the production of cosmetics?
4. (a) Define polymer chemistry.
(b) Write at least three synthetic fibres and
explain their properties and uses.
5. How does chemistry help in medical
applications? Explain properly.
6. (a) Define industrial chemistry.
(b) What do you mean by stain removal?
Write at least three stain removers and
their proper applications in removing the
stain.
7. List at least three notable persons and
mention their contribution to chemistry.
Answers
Explanation:1) Chemistry took its present scientific form in the 18th century, when careful quantitative experiments by Lavoisier, Proust, and Dalton resulted in the law of definite proportions, the law of conservation of mass, and the law of multiple proportions, which laid the groundwork for Dalton's atomic theory of matter.
2)Chemical substances can play an important role in food production and preservation. Food additives can, for example, prolong the shelf life of foods; others, such as colours, can make food more attractive. Flavourings are used to make food tastier. Food supplements are used as sources of nutrition .
4)a-Polymer chemistry is a sub-discipline of chemistry that focuses on the chemical synthesis, structure, and chemical and physical properties of polymers and macromolecules.
b-Following are the uses of some main synthetic fibres .
1. Nylon: It is used to makes stocking , seat belts , ropes , tents , toothbrushes, sleeping bags, curtains and parachutes etc.
2. Rayon: It is used as dress materials mixed with cotton. It is used to makes curtains, bedsheets etc. It is mixed with wool to makes a beautiful carpet.
3. Polyester: PET is also derived from polyester which in terms is used to makes containers, utensils feeling wires etc.4 . Acrylic : It is used to makes sweaters and suit length . It is cheaper than natural wool.
PROPERTIES- 1)Nylons offer extremely good wear resistance, coupled with high tensile strength and modulus of elasticity. They also have high impact resistance, a high heat distortion temperature, and resist wear, abrasion, and vibration 2)Rayon Fiber is comfortable, soft to the skin, and has the moderate dry strength and abrasion resistance. One of the Rayon Fiber's strengths is its versatility and ability to blend easily with many fibers—sometimes to reduce cost, other times for luster, softness, or absorbency and resulting comfort 3)•Polyester is very durable and is resistant to many chemicals.•This is a popular fabric in the fashion industry, as it is resistant to shrining and stretching. ...•The fibres used to create Polyester are very strong yet lightweight.The fibres are easily dyed. 4)Acrylic Characteristics
•Excellent clarity.
•Lightweight
.•Good impact resistance
.•Outstanding thermal insulator.
•UV resistant.
•Easy to heat-form
.5) Chemistry contributes to the preparation and use of materials for surgery (sutures, artificial skin, and sterile materials). The sutures used in many surgeries today do not have to be removed, because they simply dissolve in the body after a period of time.
6) a)Industrial chemistry is concerned with using chemical and physical processes to transform raw materials into products that are beneficial to humanity. This includes the manufacture of basic chemicals to produce products for various industries. Industrial chemistry can be thought of as an industry that generates synthetic replacements for natural products.b) stain removal is the process of removing a mark or spot left by one substance on a specific surface like a fabric.A solvent or detergent is generally used to conduct strain removal and many of these are available over the country.
• strain removal solvents •water-hot,cold,free,fresh and plentiful
•vinegar- is a natural and effective strain removal
• Hydrogen peroxide-peroxide-great for removing blood or rust strain ,hydrogen peroxide has a bleach effect without thedestructive colour change
7) •Amedeo Avogadro (1776 - 1856) Amedeo Avogadro was an Italian scientist who came up with Avogadro's law which states that equal volumes of all gases contain the same number of molecules when under the same conditions of pressure and temperature. The Avogadro constant was named after him.
•Jons Jacob Berzelius (1779 - 1848) Jons Jacob Berzelius was a Swedish chemist who is most famous for helping to develop the notation for writing chemical formulas. He also played a role in discovering and isolating many elements including silicon, thorium, cerium, and selenium. Many chemical terms are credited to Berzelius such as "allotrope" and "catalysis." He is called the father of Swedish chemistry.
•Robert Boyle (1627 - 1691) Robert Boyle is often considered the first modern chemist and one of the founders of chemical science. He also pioneered the scientific method. He developed Boyle's Law which states that, under a closed system with constant pressure, the pressure and volume of a gas are inversely proportional.
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