Class X Question 1: Chapter 1 – Chemical Reactions and Equations Science Why should a magnesium ribbon be cleaned before burning in air? Answer Magnesium is very reactive metal. When stored it reacts with oxygen to form a layer magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper to remove this layer so that the underlying metal can be exposed into air. Question
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OXIDATION AND REDUCTION Oxygen makes up only about 20% of the air‚ yet is the essential component for so many reactions. Without it fuels would not burn‚ iron would not rust and we would be unable to obtain energy from our food molecules through respiration. Indeed animal life on the planet did not evolve until a certain concentration of oxygen had built up in the atmosphere over 600 million years ago. The term oxidation has been in use for a long time to describe these and other reactions where
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atmospheric condition i.e.‚ moist air‚ carbon dioxide form undesirable compounds on the surface is known as corrosion‚ The compounds formed are usually oxides . Rusting is also a type of corrosion but the term is restricted to iron or products made from it .Iron is easily prone to rusting making its surface rough. Chemically‚ rust is a hydrated ferric oxide Titanic‘s bow exhibiting microbial corrosion damage in the form of ‘rusticles’ Rusting an Electrochemical Mechanism ; Rusting may be explained by an
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hollow block Many people used pure cement hollow block in making buildings but this research aims to make a more durable and fire retardant hollow block in making infrastructures. Background: The glass contains lime‚ magnesium oxide‚ and aluminum oxide that add more durability. Barium also increases the refractive index and low dispersion that make it endure shock. Plastics contain stabilizing additives that include fire retardants to lower the flammability of a material. These 2 combined
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55% S‚ 47.01% O What mass of calcium bromide is needed to prepare 150.0 mL of a 3.50 M solution? (Assume that the molecular weight of CaBr2 is 200.618 g/mol) 105 g Nitrous oxide (N2O)‚ or laughing gas‚ is commonly used as an anesthetic in dentistry and surgery. How many moles are present in 8.4 liters of nitrous oxide at STP? 0.375 moles How many moles of gas molecules will be present in 5000 L of air at STP? 223.2 mol How many molecules are in 1 mol of sucrose (C12H22O11)? |
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on the reaction of magnesium and salt water to produce hydrogen: Mg (s) + 2H2O (l) -> Mg2+ (aq) + H2 (g) ↑ + 2OH- (aq) s: solid; l: liquid; g: gaseous; aq: in solution; the vertical arrow indicates that gas is released. This reaction is very slow‚ due to passivation‚ so to speed it up‚ iron and salt are added. Passivation is the process by which a material is made less reactive‚ usually by the deposition of a layer of oxide on its surface: if you place a strip of magnesium into cold water‚ its
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atmospheric condition i.e.‚ moist air‚ carbon dioxide form undesirable compounds on the surface is known as corrosion. The compounds formed are usually oxides. Rusting is also a type of corrosion but the term is restricted to iron or products made from it. Iron is easily prone to rusting making its surface rough. Chemically‚ rust is a hydrated ferric oxide. Rusting‚ an electrochemical mechanism: Rusting may be explained by an electrochemical mechanism. In the presence of moist air containing dissolved
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CHEMISTRY Guess Paper – 2013 Class – XI Subject - CHEMISTRY MAX MARKS=90 ……………………………………………………………………………………… General instructions: All questions are compulsory. Marks for each question are indicated against it. Questions number 1to 8 are very short –answer questions‚ carrying 1 mark each. Answer these in one word or about one sentence each. Questions number 9 to18 are short –answer questions‚ carrying 2 marks each. Answer these in about 30 words each. Questions number19 to27
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MgO 1. 2. Sodium cloride Magnesium oxide Calcium bromide Aluminum sulphide Nickle (III) chloride (indicates charge) 3. CaBr2 4. Al3+ Ni3+ S2Cl- Al2S3 5. NiCl3 6. Sodium thiosulphate (complex ion) Na2S2O3 7. Aluminum silicate (complex ion) Al2(SiO3)3 (must bracket a complex ion with a subscript) 8. Ammonium phosphate NH4+ PO43- (NH4)3PO4 (bracket comples ion with a subscript) 9. Barium oxide Ba2+ O2- Ba2O2 BaO
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metal + Stem on the nonmetal + the suffix “ide” Formula Name NaCl Sodium chloride CsF Cesium fluoride CaBr2 Calcium bromide MgO Magnesium oxide Li2S Lithium sulfide Al2O3 Aluminum oxide ZnH2 Zinc hydride AgI Silver iodide SrS Strontium sulfide Ca3N2 Calcium nitride K2Te Potassium telluride Na3N Sodium nitride CaC2 Calcium carbide LiH Lithium hydride Mg3P2 Magnesium phosphide Memorize your fixed charge metals!!!! Group 1A‚ 2A‚3A and Al+3‚Zn+2‚ Cd+2 and Ag+1 II. Inorganic Nomenclature Compound
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