CHAPTER 9

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THE CONVERSION OF PHYSICAL PROPERTY AND CHEMICAL

PROPERTY

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PHYSICS FOR JUNIOR HIGH SCHOOL VII

MATERIAL CONVERSION

Physical conversionPhysical conversion is a conversion that does not produce new material and temporal only. Chemical conversionChemical conversion is a conversion that produces new material and goes permanently, not returning to original material. New material is the material that its properties are different from its original material and can not change to its original property.

Material conversion

Physical conversionChemical

conversion

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PHYSICS FOR JUNIOR HIGH SCHOOL VII

PERUBAHAN FISIKA & KIMIA

PERBEDAAN PERUBAHAN FISIKA DAN KIMIA

Physical conversion Chemical conversion

Not forming any new

substance

Reversible

No chemical reaction

Forming some new

substances

Irreversible

There is a chemical

reaction, it is proven by

the formation of gas,

precipation, colour, and

energy conversion.

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PHYSICS FOR JUNIOR HIGH SCHOOL VII

PHYSICAL CONVERSION

PHYSICAL CONVERSION IN OUR DAILY LIFE1. Physical conversion caused by form change

Conversion Example

Melting The melting of Candle, iron, and

aluminum.

Evaporation The evaporation of sea-water, ether,

and eucalyptus oil.

Liquation The liquation of ice, and snow.

Dewing Aqueous vapor dews

Freezing The freezing of water, oil, and gel.

Sublimating Dry ice becomes gas, solid menthol

sublimates becoming steam, and

camphor sublimates.

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PHYSICAL CONVERSION

2. Physical conversion caused by resolvabilitySugar property that is melted in the water like sweetness still can appear If the solution evaporates. There will be both the same sugar and taste. The process of making syrup, acetate, and alcohol of 70 % are the kinds of physical conversion.

3. Physical conversion caused by the form changeThe material conversion and wood becomes a chair is the kind of physical conversion. It is because the wood only change in its shape, but the property does not change. The chair property is same with wood. It is the same case in the change of raw wood becomes wood pieces, bamboo becomes angklung, paper becomes paper-toys, and cloth becomes clothes.

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PHYSICAL CONVERSION

4. Physical conversion caused by energy currentfor bulb, the wolfram wire does not change. The bulb only converts the electric energy to the light energy, The electric bell coil only converts the electric energy to moving energy so that it makes a voice. The element of electrical iron only converts electric energy to heat energy. So, it is a physical conversion because in this case the material only acts as energy current conductor.

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CHEMICAL CONVERSION

CHEMICAL CONVERSION IN DAILY LIFE1. Physical conversion caused by burning

burning is a chemical reaction between the burned material and oxygen. The process of burning caused by fire, burning does not only produce ash and gas, but also energy. Example, the candle burning produces light energy, and the gasoline or diesel oil burning produces moving energy.

In our daily life, there are so many burning chemical reactions, such as burning wood, paper, candle, gasoline, or diesel fuel, or bomb explosion.

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PHYSICS FOR JUNIOR HIGH SCHOOL VII

CHEMICAL CONVERSION

2. Chemical conversion caused by decompositionDecomposition is the chemical reaction caused by micro-organism. For food, it gets odor, rotten, and coming out gas. For instance, rotten rice or moldy bread. The both decomposed foods can not be as their first form.

3. Chemical conversion caused by fermentationFermentation is a kind of chemical conversion because the fermented food will be softer, more aromatic, and taste differently. E.g. in the process of making sticky-tapai and cassava-tapai. The sticky-tapai is made of sticky-rice, while the cassava-tapai made of cassava. By fermentation, sticky-rice and cassava become tapai. Tapai has different characteristic from its ingredients. Moreover, it can be turned neither to be sticky-rice nor cassava.

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PHYSICS FOR JUNIOR HIGH SCHOOL VII

CHEMICAL CONVERSION

4. physical conversion caused by heatingThe solution of salt that is heated will produce salt. That is why the salt solution considered as a physical conversion. And cooking rice is a kind of chemical conversion. It is because the hulled-rice becoming cooked-rice. The cooked-rice can not be turned to be hulled-rice anymore. Like the other processes, the heating process like poaching corn and cassava, frying egg, or making soft-cake, those foods become softer so that easy to be digested.

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PHYSICS FOR JUNIOR HIGH SCHOOL VII

CHEMICAL CONVERSION

5. Chemical conversion caused by photosynthetic

Photosynthetic is a reaction of constructing a compound that occurs at greenery. Photosynthetic process is a chemical conversion because the greenery processes water and carbon dioxide by the help of sun so that it can produce carbohydrate and oxygen.

6. Chemical conversion caused by corrosion

Corrosion is a chemical reaction between iron, oxygen, and water. This reaction produces corrosion that is generally metal oxide. Corrosion is a chemical conversion because it does not produce a new substance.

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