weapons and transport. They produced bronze by heating copper and tin with charcoal. * Iron Age (1000 BCE – 1 CE) – iron steel and lead was used for tools‚ weapons and pipes. Iron is much harder than bronze. * Modern Age (1 CE – Present) – main metals are iron‚ aluminium and steel‚ which were used for pipes‚ buildings‚ transport and electrical cables. This is the age where technology of iron and steel improved. Around the 1880’s‚ there was a significant move towards new alloys and metals
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HKDSE Chemistry – A Modern View 1 (SAMPLE) Suggested Answers (Coursebook) |Chapter 1 The fundamentals of chemistry | |Class Practice |1 | |Chapter Exercises |3 | |Chapter 2 The atmosphere
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WOODS Is organic and will decay over time. In wetter conditions with decay will be quicker. It is also subject to conditions such as dry rot‚ or pests. The greater the density of wood‚ the greater its mechanical strength. Knots also contained‚ formed where branches grew from main trunk‚ or where a bud was formed. Can generate weaknesses‚ or be aesthetic. HARDWOODS o o Deciduous (leaf-losing) trees. Slower growing‚ making them denser. Some take up to 100 years to reach full maturity
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Suggest ONE safety precaution for handling rubidium in the laboratory. (5 marks) 1 2. HKCEE 1995 Q6b The table below gives some information about five metals. Metal Abundance in the Price per kg ($) Relative resistance of earth’s corrosion crust (%) (1 = least resistant Relative strength of metal (1 = lowest 3 = highest) 4 = most resistant) Al 170 3 1 Cu 0.0055 140 3 3 Au 0.0000004 1100000 4 2 Fe 5.0 20 1 3 Zn
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Quantum Numbers [13] Electron Configuration [14] Periodic Table [15] Periodic Trends KSev [16] Chemical Bonding [17] Formal Charge [18] Resonance Structure [19] Bonds [20] VSEPR [22] Valence Bond Theory [22] Molecular Orbital Theory [B]Lab [1] Corrosion [2] Oxidation Reduction Reactions [3] Calorimetry [4] Qualitative Analysis [5] Flame Test [6] Molecular Model *(Ctrl + F the roman numeral to skip to that part. Ex: [B.3]) KSev [A.1] Thermodynamics Thermodynamics “thermo” = heat “dynamics”
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What causes corrosion What is CP and how does it work? Galvanic vs. impressed current Electrolytes (or where can I use CP) Marine applications Condition assessments _____________________________CORRTECH What is Corrosion? Corrosion is defined as the degradation of a material due to a reaction with it’s environment. Metals require energy to process them from their native state to a usable material. Nature wants to reverse this. _____________________________CORRTECH Corrosion Process
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It contains 18% chromium and 8% nickel. It has corrosion resistance to mild-atmospheric and fresh water‚ industrial atmospheric‚ marine atmospheric‚ mild chemical and oxidizing chemical environments. Type 302 is also highly resistant to gasoline. 303 AISI 303 is an austenitic steel in the chromium-nickel group‚ which is hardenable by cold work and used for chemical resistance. It has added silicon for easier machinability. It has corrosion resistance to mild-atmospheric and fresh water‚ industrial
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Chapter 1 Chemical Reactions and Equations Q.1. Why should magnesium ribbon be cleaned before burning in air ? Ans: Magnesium ribbon is a very reactive metal. When stored it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide being a stable compound prevents further reaction of magnesium with oxygen. The magnesium is cleaned before burning in air to remove this layer so that the metal can be exposed to air properly. Q.2. Write the balanced
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CORROSION LAB REPORT THE CHANGE IN MASS(±0.005g) OF VARIOUS TYPES OF CORROSIVE METALS WHEN PLACED IN A SOLUTION OF 1 MOLAR CONCENTRATION OF HYDROCHLORIC ACID OVER A PERIOD OF 8 DAYS AT AN AVERGAE ROOM TEMPERATUR OF 24 DEGRESS CELCIUS. Research Question: Does the mass(±0.005g) of various types of corrosive metals (iron‚ nickel‚ zinc‚ copper and tin) change when placed in a solution of 1 molar hydrochloric acid over a period of 8 days at an average room temperature of 24 degrees Celsius? Aim:
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Stainless Steels: must have at least 10% chromium A. Ferritic Stainless Steels: Iron‚ chromium + low carbon a. Magnetic b. Lowest cost c. Non-hardenable i. Can be annealed d. BCC structure e. Low carbon ii. Less than .2% f. Chromium content iii. 16-20% g. B. Martensitic Stainless Steel: iron‚ chromium + higher carbon h. Magnetic i. Martensitic Structure j. Hardenable k. High Carbon
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