c6-Land and Its Resources

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LAND AND ITS RESOURCES VARIOUS MINERALS IN THE EARTH CRUST 1. Minerals form the Earth crust. 2. Minerals are elements or chemical compounds that are naturally present in the Earth crust. 3. Each type of mineral has its own chemical content. 4. Examples of common minerals are gold, silver, limestone and tin ore. 5. Minerals exist in the form of element or compound. A. Natural mineral elements B. Natural mineral compounds 1. Most elements are active and tend to combine with other elements to form
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  1 LAND AND ITS RESOURCES   VARIOUS MINERALS IN THE EARTH CRUST1. Minerals form the Earth crust.2.Mineralsare elements or chemical compounds that are naturally present in the Earthcrust.3. Each type of mineral has its own chemical content.4. Examples of common minerals are gold, silver, limestone and tin ore.5. Minerals exist in the form of elementorcompound.   A. Natural mineral elementsB. Natural mineral compounds1. Most elements are active and tend to combine with other elements to form compounds.2. Minerals in the form of compounds consist of combinations of a few types of differentelement. Some examples of natural mineral compounds are tin ore, clay and limestone.3. Most minerals in the Earth crust exist in the form of compounds especially oxide,carbonate, sulphide and silicate.   C. Characteristics of minerals   1. Most minerals are still in existence and have not changed in the Earth crust becauseminerals are generally hard and do not dissolve in water.2. The characteristics of a mineral depends on the content and arrangement of atoms in it.3. Characteristics of minerals are divided into:(a)physical characteristicssuch as colour, hardness, luminosity and shape of crystals(b)chemical characteristicssuch as solubility in water, chemical reactions and effect of  heat on it.    2  physical characteristics of mineral    1. Minerals have differentcolours.2.Hardnessof a mineral refers to its resistance against erosion and scratches.3. A hard mineral is able to scratch a mineral that is less hard.4. Generally, all metal oxides, sulphides and carbonates are hard minerals.5. Most minerals exist in the form of crystals. Each crystal has the sameshape.  chemical characteristics of minerals  1. Most mineralsdo not dissolvein water.2. Minerals likemetal oxideandsilicatenormallydo not decomposewhen heated. 3. Some minerals like metal carbonates and sulphides can be easily decomposed byheating.The effect of heat decomposes the compound into its elements or other compounds.4.Effect of heat on metal carbonate(a) Heat decomposes metal carbonate intometal oxideand releasescarbon dioxideas shown in the following equation.   (b) Example,  3 (c) Carbon dioxide that is released can be tested by using lime water. Lime water willturn cloudy in the presence of carbon dioxide.5.Effect of heat on metal sulphide (a) Nearly all metal sulphides decompose when heated to releasesulphur dioxideandformmetal oxideas in the following equation.   (b) Example,(c) Sulphur dioxide is an acidic gas that can be tested with(i) acidic potassium manganate (VII) solution. This gas bleaches the purplecolour of the solution.(ii) acidic potassium dichromate (VI) solution. This gas changes the orange-coloured solution to green.(a) hardness(b) solubility in water(c) effect of heatArrangement of apparatus to study characteristics of minerals    4 1. The hardness of minerals is tested by scratching each mineral with fingernails orknife. The mineral is soft if it can be scratched with fingernails and it is hard if it can onlybe scratched with a knife.2. A little mineral powder is shaken in a test tube that is filled with water.Observations are made on whether the mineral dissolves in water.3. A little mineral powder is put into a test tube and heated. Any gas released is testedwith lime water and acidic potassium manganate(VII) solution as shown in figureabove.4. Observations are recorded in the table provided.
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