Abeka Chemistry Chapter 11 fully solved exam study guide (100% accurate expert solutions)download to pass

What is metallurgy? the science of extracting metals from their naturally occurring materials and preparing them for use What is an ore? naturally occurring material containing a metal in sufficient concentration to make its extraction profitable Brainpower Read More Previous Play Next Rewind 10 seconds Move forward 10 seconds Unmute 0:00 / 0:00 Full screen List the four general steps in the production of a useful metal from an ore. concentration, reduction, refining, shaping What process of ore separation involves mixing crushed rock with oil, water, and detergent and agitating it? floatation Explain why the reactivity of the alkali metals increases with atomic number. Answers will vary. The valence electron becomes farther away from the nucleus as atomic number increases. The electron is therefore more easily lost, making the element more prone to undergo chemical reactions. How are alkali metals generally prepared? Write a balanced equation for the preparation of K by this method. electrolysis of their molten chloride salts; 2 KCl (l) →electrolysis→2 K(l) + Cl₂(g) Differentiate between the causes of temporary hard water and permanent hard water. Answers will vary. Permanent hard water contains the fulfate of calcium, magnesium, or iron (II), whereas temporary hard water contains the bicarbonate. Show by an equation one cause of boiler scale. Ca(HCO₃)₂(aq) →∆→ CaCO₃(s) + CO₂(g) + H₂O(l) Explain how a cation-exchange resin softens water. Positively charged ions such as Ca²⁺, Fe²⁺, and Mg²⁺ in water are exchanged on the resin for Na⁺ or H⁺ ions. Give one use for each of the following alkaline earth metals Beryllium Magnesium Calcium Strontium Answers should include some of the following ideas: ∙beryllium - x-ray tubes; structural materials, alloys used in aircraft, springs, and nonsparking tools; corrosion-resistant ship parts (also nuclear weapons - chl. 17) ∙magnesium - incendiary bombs; fireworks; old-fashioned flashbulbs, lightweight alloys (used in wheels, ladders, metal furniture, aircraft, and spacecraft) ∙calcium - important nutrient (bones, teeth; nerve excitation, vision, muscle contration); compounds used in building materials (limestone, cement, concrete, gypsum) ∙strontium - compounds used in signal flares and fireworks Give the chemical formula for lime CaO Give the chemical formula for slaked lime Ca(OH)₂ Give the chemical formula for limestone CaCO₃ Give the chemical formula for milk of magnesia Mg(OH)₂ Give the chemical formula for Epsom salts MgSO₄∙7H₂O Give the chemical formula for magnesia MgO Give one compound of each alkaline earth metal and its use. Answers will vary; the following are some compounds mentioned in the text: ∙beryllium-no compounds mentioned; but alloys have many uses ∙CaO (lime), Ca(OH)₂ (slaked lime) - many industrial uses ∙Mg(OH)₂ (milk of magnesia) - antacids; laxatives ∙MgSo₄∙7H₂O (Epsom salts) - treatment of bruises and sprains; laxatives and cathartics ∙MgO (magnesia) - the heat-resistant brick; insulators ∙Sr(NO₃)₂ - signal flares; fireworks ∙BaSO₄ - x-rays of GI tract; white paints ∙Ba(NO₃)₂ - pyrotechnics (fireworks) List two uses for slag. any 2 of the following: ∙manufacture of cinder block, concrete, and asphalt ∙support material for railroad ties ∙mineral wool (insulation, ceiling tiles) How does direct iron reduction differ from blast-furnace reduction? Direct iron reduction does not require the use of coke for the reduction process but uses natural gas instead; the iron is also produced in solid form (sponge iron) rather than as a liquid. Describe the basic oxygen process for iron refining. Answers will vary. In a high-temperature furnace, a supersonic blast of pure oxygen is blown against the surface of teh molten iron, oxidizing the impurities; no external heat source is necessary. Lime and other fluxes are added to convert oxidized silicon impurities to slag; alloying metals or carbon may also be added. How does the electric-arc process differ from the basic oxygen process? The electric-arc process uses an electric arc betwen giant carbon electrodes to provide heat to melt the charge, whereas the basic oxygen process uses a powerful blast of oxygen to oxidize impurities. Use of the electric-arc process results in greater purity of the metal due to the higher temperatures. Name three ways to increase the hardness of a piece of steel. cold working, quenching, case hardening What process can be used to make a piece of quenched steel less brittle? tempering List the three primary precious metals. gold, silver, platinum What property of gold allows it to be separated from sand or crushed ore by panning or sluicing? high density What chemical process is used today to extract gold from low-grade ores? cyanide process What percentage gold is in 10K gold? (Use three sig figs) (10 parts Au/24 parts metal) x 100% = 41.7% Au What is sterling silver? silver-copper alloy (92.5% Ag, 7.5% Cu) Give three uses for gold, three uses for silver and two uses for platinum. ∙gold - jewelry; dentistry (i.e., crowns) and medicien; microcircuitry; investment/financial reserve ∙silver - coins; jewelry; dental fillings ∙platinum - catalyst in pollution-control devices and petroleum production; electronic devices; spark plugs; surgical tools; dental work; investment (bullion); compounds used as anticancer drugs Give the formula for alumina. Al₂O₃ Give the formula for bauxite. Al₂O₃∙n H₂O Give the formula for cryolite. Na₃AlF₆ What is the role of cryolite in aluminum purification? In its molten form, it dissolves the bauxite, allowing aluminum to be produced electrolytically at reasonable temperatures. Write the balanced equation for a thermite reaction. Fe₂O₃(s) + 2 Al(s) →∆→2 Fe(l) + Al₂O₃(s) + heat What is meant by the term semiconductors? substance having electrical conductivity that is intermediate between insulators and conductors How is silicon prepared and purified? Silicon is prepared by heating silica in an electric furnace with coke. To further purify the element, it is reacted with HCl(g) to form trichlorosilane, which can be further purified by fractional distillation.