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الكيمياء لغات Q1-Give the scientific explanation:1-Transition elements are characterized by having variable oxidation states. Because the two sublevels 4S and 3d of nearly equal energy and their electrons are lost in sequence when the atom is oxidized.
2-Iron does not react with conc. nitric acid Due to formation of a thin non – porous layer of oxide which protects iron from further oxidation. (Passivity) 3-Magnetite reacts with conc. acids and gives two salts of iron II and III . Bec.it is a mixed oxide of Fe2O3 , FeO conc Fe3O4 + 4H2SO4 Fe2(SO4)3 + FeSO4 +4H2O
4 - The hydrogen ion does not exist freely in the aqueous solutions of acids. Because the hydrogen ion contains an empty orbital, so it can accept the lone pair of electrons on the oxygen atom in a water molecule by a coordinate bond
forming the hydrated proton or hydronium ion
5- Sodium chloride solution has a neutral effect on litmus. NaCl Na+ + Cl-1 H2O H+ + OH- by addation NaCl + 2H2O + Na+ + OH-
H+ + Cl-
Because NaCl dissociates in water giving hydrochloric acid and sodium hydroxide which are strong electrolytes and completely ionized , so the concentration of H+ ions equals that of OH- ions ,
6- pH Value of pure water = 7 Because the concentration of hydrogen ion equals the concentration of hydroxyl ion = 10-7.
7-Recently we use a mixture of salts of aluminum sodium, calcium, fluorides, rather than carylite when extracting aluminum metal? B. it reduces melting point and has lower density than of the molten which facilitates the separation of aluminum, in the bottom of the electric cell 8-the density of the sulphuric acid in the battery can identify the car battery condition. B. when the battery is completely charged the density of acid equal from 1.28 to 1.30 gm/cm3 but if the acid density decreased to less than 1.2