チタンの化学的性質

チタンは高温で多くの元素や化合物と反応することができます。 さまざまな元素は、チタンとのさまざまな反応に応じて 4 つのカテゴリに分類できます。

最初のカテゴリー：共有結合およびイオン結合化合物を生成するハロゲンおよび酸素グループ元素およびチタン。

2 番目のカテゴリー: 遷移元素、水素、ベリリウム、ホウ素、炭素、窒素元素、チタン。金属間化合物と限定された固溶体を生成します。

カテゴリ III: 無限固溶体を生成するジルコニウム、ハフニウム、バナジウム、クロム、スカンジウム元素およびチタン。

Category IV: noble gases, alkali metals, alkaline earth metals, rare earth elements (except scandium), actinium, thorium, etc. do not react with titanium or basically do not react. With the compound HF and fluoride hydrogen fluoride gas reacts with titanium when heated to generate TiF4, the reaction formula is (1); water-free hydrogen fluoride liquid can generate a layer of dense titanium tetrafluoride film on the surface of titanium, which prevents HF from leaching into the interior of titanium. Hydrofluoric acid is the strongest solvent for titanium. Even hydrofluoric acid with a concentration of 1% can react violently with titanium, see equation (2); anhydrous fluoride and its aqueous solution do not react with titanium at low temperatures, and only molten fluoride reacts significantly with titanium at high temperatures. Ti + 4HF = TiF4 + 2H₂ + 135.0 kcal (1) 2Ti + 6HF = 2TiF₃ + 3H₂ (2) HCl and chloride hydrogen chloride gas can corrode titanium metal, dry hydrogen chloride reacts with titanium to form TiCl4 at >300 度、式 (3) を参照。 濃度の塩酸<5% does not react with titanium at room temperature, and hydrochloric acid with 20% hydrochloric acid reacts with titanium at room temperature to generate purple TiCl3, see formula (4); when the temperature is long and high, even dilute hydrochloric acid will corrode titanium. Various anhydrous chlorides, such as magnesium, manganese, iron, nickel, copper, zinc, mercury, tin, calcium, sodium, barium and NH4 ions and their aqueous solutions, do not react with titanium, titanium in these chlorides have good stability. Ti + 4HCl = TiCl4 + 2H2 + 94.75 kcal (3) 2Ti + 6HCl = TiCl₃ + 3H2 (4) Sulfuric acid and hydrogen sulfide titanium with 5% sulfuric acid has a significant reaction, at room temperature, about 40% of sulfuric acid corrosion of titanium is the fastest, when the concentration is greater than 40% and reaches 60% corrosion instead of slower, and 80% and then reach the fastest. Heated dilute acid or 50% concentrated sulfuric acid can react with titanium to generate titanium sulfate, see formula (5), (6), heated concentrated sulfuric acid can be titanium reduction, generate SO2, see formula (7). At room temperature titanium reacts with hydrogen sulfide, generating a protective film on its surface, which prevents further reaction between hydrogen sulfide and titanium. However, at high temperatures, hydrogen sulfide reacts with titanium to precipitate hydrogen, see equation (8), powdered titanium at 600 ° C began to react with hydrogen sulfide to generate titanium sulfide, at 900 ° C the reaction product is mainly TiS, 1200 ° C when Ti2S3. Ti+H2SO4=TiSO4+H2 (5) 2Ti+3H2SO4=Ti2(SO4)3+3H2 (6) 2Ti+6H2SO4= Ti2(SO4)3+3SO2+6H2O+202 kcal (7) Ti+H2S=TiS+H2+70 kcal (8) Nitric acid and aqua regia Dense, smooth-surfaced titanium has good stability to nitric acid due to the fact that nitric acid rapidly generates a strong oxide film on the surface of titanium, but rough surfaces, especially sponge or powdered titanium, can react with secondary, hot dilute nitric acid, see equation (9), (10), higher than 70 ℃ concentrated nitric acid can also react with titanium, see formula (11); room temperature, titanium does not react with aqua regia. When the temperature is high, titanium can react with aqua regia to generate TiCl2. 3Ti+4HNO3+4H2O=3H4TiO4+4NO (9) 3Ti+4HNO3+H2O=3H2TiO3+4NO (10) Ti+8HNO3=Ti(NO3)4+4NO2+4H2O (11) To sum up, titanium's nature and temperature and its existence of morphology, purity has an extremely close The relationship is extremely close to the temperature and its existence form and purity. Dense metallic titanium is quite stable in nature, but powdered titanium can cause spontaneous combustion in air. The presence of impurities in titanium significantly affects the physical and chemical properties, mechanical properties and corrosion resistance of titanium. Especially some interstitial impurities, they can make titanium lattice distortion, and affect the various properties of titanium. The chemical activity of titanium at room temperature is very small, and can react with a few substances such as hydrofluoric acid, but the activity of titanium increases rapidly when the temperature increases, especially at high temperatures, titanium can react violently with many substances. The smelting process of titanium is generally carried out at high temperatures above 800℃, so it must be operated in a vacuum or under the protection of an inert atmosphere. Physical properties of titanium metal titanium metal (Ti), gray metal. Atomic number 22, relative atomic mass 47.87. The arrangement of electrons outside the nucleus in the sublayer 1S2 2S2 2P6 3S2 3P6 3d2 4S2. metal activity in the magnesium, aluminum, room temperature is not stable, so in nature only to the existence of the state of the chemical compound, common titanium compounds are ilmenite (FeTiO3), rutile (TiO2) and so on. Titanium has a high content in the earth's crust, ranking ninth at 5,600 ppm, which translates into a percentage of 0.56%. The density of pure titanium is 4.54×103kg/m3, the molar volume is 10.54cm³/mol, the hardness is poor, Mohs hardness is only about 4, so the ductility is good. Titanium's thermal stability is very good, melting point of 1660 ± 10 ℃, boiling point of 3287 ℃. Chemical Properties of Titanium Metal Titanium metal is extremely reductive in high-temperature environments, chemically combining with oxygen, carbon, nitrogen, and many other elements, as well as seizing oxygen from some metal oxides (e.g., aluminum oxide). At room temperature, titanium and oxygen are combined to form a very thin and dense oxide film, which does not react with most strong acids and bases at room temperature, including the king of acids - aqua regia. It only reacts with hydrofluoric acid, hot concentrated hydrochloric acid and concentrated sulfuric acid, so titanium embodies corrosion resistance.