{"id":3942,"date":"2023-10-06T08:17:14","date_gmt":"2023-10-06T08:17:14","guid":{"rendered":"http:\/\/localhost\/ecole9ja\/?p=3942"},"modified":"2023-10-06T08:19:51","modified_gmt":"2023-10-06T08:19:51","slug":"week-5-ss3-second-term-chemistry-notes","status":"publish","type":"post","link":"https:\/\/ecolebooks.com\/nigeria\/posts\/week-5-ss3-second-term-chemistry-notes\/","title":{"rendered":"Week 5 – SS3 Second Term Chemistry Notes"},"content":{"rendered":"

\u00a0WEEK FIVE
\n<\/strong>TOPIC: PRELIMINARY PREPARATION
\n<\/strong>Metals are found mixed with earthy materials as ores. Ores are often<\/p>\n

    \n
  1. concentrated and\n<\/li>\n
  2. converted to oxides before extraction\n<\/li>\n<\/ol>\n

    \u00a0Concentration of the ore <\/strong>can be done by any of the following ways:<\/p>\n

      \n
    1. washing away the earthy materials\n<\/li>\n
    2. Froth- flotation (zinc ore): The ore is agitated (churned up ) with oil and water to form a froth. The froth is removed by blowing air through it\n<\/li>\n
    3. By passing magnetic ores through a magnetic separator. The ore will be deflected while the non-magnetic or partially magnetic part of the ore will move on.\n<\/li>\n<\/ol>\n

      \u00a0Roasting in Air
      \n<\/strong>The ore is roasted in air to convert to an oxide. There is no need to roast if the ore is already an oxide.<\/p>\n

      \u00a0Principle of Extraction of metals
      \n<\/strong>Those metals which are found in a combined state can be extracted through electrolysis or by chemical and thermal methods. The selected method of extraction of any given metal depends on the stability of the ore. The stability of the ore depends on the reactivity of the metal.<\/p>\n

      \n\n\n\n\n\n\n\n\n\n\n
      Metal<\/td>\nReactivity<\/td>\nMost common ore<\/td>\nMethod of extraction <\/td>\n<\/tr>\n
      K
      \nNa
      \nCa
      \nMg\u00a0<\/td>\n      		\n\u00a0
      \n\u00a0Very reactive\u00a0<\/td>\n      		Chlorides\u00a0<\/td>\nElectrolysis of fused hydroxides and chlorides\u00a0<\/td>\n<\/tr>\n
      Chlorides & Trioxocarbonates\u00a0<\/td>\nElectrolysis of fused chlorides\u00a0<\/td>\n<\/tr>\n
      Al
      \nZn
      \nFe
      \nSn
      \nPb\n<\/td>\n      		Moderately reactive<\/td>\nOxides CO32- and Sulphide\u00a0<\/td>\nRoasting of CO32- & sulphides to form oxides reduction of oxides by C of CO\u00a0<\/td>\n<\/tr>\n
      \n\u00a0sulphides\u00a0<\/td>\n<\/tr>\n
      Roasting in air\u00a0<\/td>\n<\/tr>\n
      Heating in air\u00a0<\/td>\n<\/tr>\n
      Cu
      \nHg<\/p>\n

      \u00a0Ag
      \nAu\u00a0<\/td>\n

      		\n\u00a0
      \n\u00a0Least reactive\u00a0<\/td>\n      		\n\u00a0
      \n\u00a0
      \n\u00a0Free element\u00a0<\/td>\n      		\n\u00a0
      \n\u00a0Mined as free elements\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

      \u00a0EVALUATION<\/strong><\/p>\n

        \n
      1. Explain froth floatation\n<\/li>\n
      2. State two ways of concentrating an ore\n<\/li>\n<\/ol>\n

        \u00a0SODIUM
        \n<\/strong>OCCURRENCE
        \n<\/strong>Sodium occurs as NaCl (rock salt), NaNO and Na2<\/sub>CO3<\/sub>.is often known as Chile saltpeter because it is found abundantly in Chile. It also occurs as borax and in complex trioxosilicates (iv) found in clay soil.<\/p>\n

        \u00a0Extraction: <\/strong> It is extracted by electrolysis of fused NaCl using the Downs cell. The cathode is a steel cylinder. Fused NaCl (mp:801o<\/sup>c) is put in the cell where it is heated to keep it molten. CaCl2<\/sub> is often added to lower the melting point of NaCl to about 600oC. Sodium and chloride are the products.
        \nAs the electrolysis progresses, the molten Na collects in the cathode chamber where it gets to the top and is collected through a pipe. A hood guides the gaseous chloride at the anode for collection.<\/p>\n

        \u00a0\"\"\/At the cathode: Na+ + e- \u00a0\u00a0\u00a0\u00a0 Na(s)<\/sub> (Reduction )
        \n\"\"\/At the anode : Cl- \u00a0\u00a0\u00a0\u00a0Cl + e- (Oxidation)
        \n Cl + Cl \u00a0\u00a0\u00a0\u00a0Cl2 (q)<\/sub>
        \n\t\t\"\"\/
        \n\t\tOverall electrolysis reaction.
        \n\"\"\/2Na+(g) + 2Cl-(i) \u00a0\u00a0\u00a0\u00a02Na(s)<\/sub> + Cl2(g)<\/sub><\/p>\n

        \u00a0Physical Properties
        \n<\/strong><\/p>\n

          \n
        1. Silvery solid with metallic luster\n<\/li>\n
        2. Flaots on water (density of 0.98)\n<\/li>\n
        3. very malleable\n<\/li>\n
        4. melting point of 97o<\/sup>C (Low for a metal)\n<\/li>\n
        5. Good conductor of heat and electricity.\n<\/li>\n<\/ol>\n

          \u00a0EVALUATION
          \n<\/strong><\/p>\n

            \n
          1. Write the cathodic and anodic half cell equations in the electrolysis of fused NaCl\n<\/li>\n
          2. What is the function of CaCl2<\/sub> introduced into the electrolytic cell during the electrolysis above.\n<\/li>\n<\/ol>\n

            \u00a0Chemical Properties
            \n<\/strong><\/p>\n

              \n
            1. \n
              Reaction with air\n<\/div>\n

              \"\"\/4Na (s) + O2<\/sub>(g) 2Na2<\/sub>O(s)
              \n\"\"\/Na2<\/sub>O(s) + H2<\/sub>O(g) 2NaOH (aq)
              \n\"\"\/2NaOH (aq) + CO2<\/sub>(g) Na2<\/sub>CO3(s)<\/sub> + H2<\/sub>O (i)
              \nSodium tarnishes easily when exposed to air due to presence of oxygen.
              \nSodium is stored in paraffin oil, toluene or naphtha to prevent its oxidation by air. In excess air the reaction can be represented as follows:
              \n\"\"\/2Na (g)<\/sub> + O2(g)<\/sub> \u00a0\u00a0\u00a0\u00a0Na2<\/sub>O2(g)<\/sub><\/p>\n

              \u00a02.\u00a0Combination reaction: with H2<\/sub>, Cl2<\/sub>,S,P (with non-metals except Boron,carbon & Nitrogen)
              \n\"\"\/2Na(s)<\/sub> + H2(g)<\/sub> 2NaCl(g)<\/sub>
              \n\t\t\t\t\"\"\/2Na(s)<\/sub> + Cl2(g) <\/sub> 2NaCl(g)<\/sub>
              \n\t\t\t\t\"\"\/2Na(s)<\/sub> + S(g)<\/sub> Na2<\/sub>S(s)<\/sub>
              \n\t\t\t\t\"\"\/3Na(s)<\/sub> + P(g) <\/sub> Na2<\/sub>P(s)<\/sub><\/p>\n

              \u00a0In Hg
              \n\"\"\/ Na(s) + Hg (l) \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Na\/Hg(l)<\/p>\n

              \u00a0With water: it reacts violently with cold water giving out a lot of heat and liberating hydrogen gas.
              \n\"\"\/ 2Na + H2<\/sub>O Na2<\/sub>O + H2<\/sub>
              \n\t\t\t\t\"\"\/ 2Na + 2H2<\/sub>O \u00a0\u00a0\u00a0\u00a0 2NaOH + H2<\/sub><\/p>\n

              \u00a04. With acid:
              \n\"\"\/ 2Na(s)<\/sub> + 2HCl(aq)<\/sub> 2NaCl(aq)<\/sub> + H2<\/sub>O
              \nNB: The reaction is explosive and extremely dangerous<\/p>\n

              \u00a05. with ammonia
              \n\"\"\/ 2Na(s)<\/sub> + 2NH3<\/sub>
              \n\t\t\t\t\t(g)<\/sub> \u00a0\u00a0\u00a0\u00a0 2NaNH2(s) <\/sub> + H2 (g)<\/sub><\/p>\n

              \u00a0Test for sodium ions
              \n<\/strong>Flame test: Na compounds give a golden yellow colour for non-luminous flame.
              \nNote: Potassium gives a lilac (pale purple) flame which looks common (deep red) when viewed through a blue gas.<\/p>\n

              \u00a0USES OF SODIUM
              \n<\/strong><\/p>\n

                \n
              1. It is used in manufacturing important compounds such as tetraethyl lead (Iv) .(Pb(C2<\/sub>H5<\/sub>)4<\/sub>\n\t\t\t\t\t<\/li>\n
              2. Sodium vapour lamps (orange-yellow light) are used to light high ways and airports\n<\/li>\n
              3. it is used in liquid form as a coolant in nuclear reactors\n<\/li>\n
              4. Can be used as a reducing agent in combination with ethanol or sodium amalgam.\n<\/li>\n
              5. Can be sued in the extraction of titanium to reduce titanium tetrachloride to the metal.\n<\/li>\n<\/ol>\n

                \u00a0Compound of Sodium <\/strong>The following are compounds of sodium: Na2<\/sub>O, Na2<\/sub>O2<\/sub>, NaOH, NaCl, Na2<\/sub>SO4<\/sub>, NaNO3<\/sub>, NaCO3<\/sub>.<\/p>\n

                \u00a0SODIUM TRIOXOCARBONATE (Na2<\/sub>CO3<\/sub>)
                \n<\/strong>Na2<\/sub>CO3<\/sub> exists.<\/p>\n

                  \n
                1. As soda ash in the anhydrous state\n<\/li>\n
                2. As a monohydrate, Na2<\/sub>CO3<\/sub>.H2<\/sub>O.\n<\/li>\n
                3. As a decahydrate (more often) Na2<\/sub>CO3<\/sub>.10H2<\/sub>O called washing soda\n<\/li>\n<\/ol>\n

                  \u00a0The laboratory preparation follows the three equations below:
                  \n\"\"\/a.\u00a0\u00a0\u00a0\u00a02NaOH(aq)<\/sub> + CO2(g)<\/sub> \u00a0\u00a0\u00a0\u00a0 Na2<\/sub>CO3<\/sub>. + H2<\/sub>O(l)<\/sub>
                  \n\t\t\t\t\"\"\/b.\u00a0\u00a0\u00a0\u00a0Na2<\/sub>CO3(aq)<\/sub> + H2<\/sub>O + CO2(g)<\/sub> 2NaHCO3 (s)<\/sub>
                  \n\t\t\t\t\"\"\/c.\u00a0\u00a0\u00a0\u00a02NaHCO3(s)<\/sub> NagCO3<\/sub> + H2<\/sub>O(g)<\/sub> + CO2(g)<\/sub><\/p>\n

                  \u00a0The NaHCO formed as a white ppt is filtered off, washed and heated to give he anhydrous Na2<\/sub>CO3<\/sub>. Na2<\/sub>CO3<\/sub> is prepared industrially using the Solvay process.<\/p>\n

                  \u00a0SOLVAY PROCESS \u2013 INDUSTRIAL PREPARATION<\/strong>A concentrated sodium chloride solution is saturated with NH3<\/sub> gas to produce ammoniacal brine this is allowed to fall into the top of a large tower. As the solution passes through a series of baffle-plates (baffles) it react with CO2 which is forced up the tower under pressure.<\/p>\n

                    \n
                  1. \"\"\/NH3<\/sub>(aq) + CO2(g)<\/sub> + H2<\/sub>O NH4<\/sub>HCO3(aq)<\/sub>\n\t\t\t\t\t<\/li>\n
                  2. \"\"\/NH4<\/sub>HCO3(aq)<\/sub> + NaCl(aq) <\/sub> NaHCO3<\/sub>(s) + NH4<\/sub>Cl (aq)<\/sub>\n\t\t\t\t\t<\/li>\n<\/ol>\n

                    The NaHCO3(aq)<\/sub> is filtered, washed and heated to yield anhydrous NaCO3<\/sub>, steam and CO2<\/sub>. the CO2<\/sub> is used again in the tower.<\/p>\n

                      \n
                    1. \"\"\/2NaHCO3<\/sub>(s) heat<\/sup> Na2<\/sub>CO3(s)<\/sub> + H2<\/sub>O + CO2 <\/sub>(g)\n<\/li>\n<\/ol>\n

                      \u00a0The soda ash (anh. Na2<\/sub>CO3<\/sub>) can be dissolved in hot H2<\/sub>O and re-crystallized as washing soda<\/p>\n

                        \n
                      1. Na2<\/sub>CO3(s)<\/sub> + 10HsO (l)<\/sub>\n\t\t\t\t\t<\/li>\n<\/ol>\n

                        \u00a0The economic importance of the process.<\/p>\n

                          \n
                        1. The CO2<\/sub> required in the process is obtained by heating CaCO3<\/sub> in a lime kiln.\n<\/li>\n<\/ol>\n

                          \"\"\/ \u00a0\u00a0\u00a0\u00a0CaCO3<\/sub>(s) \u00a0\u00a0\u00a0\u00a0CaO(s) + CO2(g)<\/sub><\/p>\n

                            \n
                          1. \"\"\/CaO(s) + 2 NH4<\/sub>Cl(aq) <\/sub>\u00a0\u00a0\u00a0\u00a0CaCl2(aq)<\/sub> + H2<\/sub>O (l)<\/sub>\n\t\t\t\t\t<\/li>\n<\/ol>\n

                            \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0The NH3 is recycled. The raw materials are NaCl, CaCO3<\/sub>. The only waste product is CaCl2<\/sub>.<\/p>\n

                            \u00a0GENERAL\u00a0EVALUATION
                            \n<\/strong><\/p>\n

                              \n
                            1. Write an equation to show the reaction of sodium with air.\n<\/li>\n
                            2. Explain briefly the economics of the Solvay process.\n<\/li>\n
                            3. Explain the reaction of sodium with cold water.\n<\/li>\n
                            4. \n
                              Explain what happens to the following when they are exposed to the atmosphere;\n<\/div>\n

                              (a) washing soda (b) caustic soda pellets\n<\/li>\n<\/ol>\n

                              \u00a0WEEKEND ASSIGNMENT
                              \n<\/strong><\/p>\n

                                \n
                              1. Which of these is not an alkali? (a) Sodium hydroxide (b) Potassium hydroxide (c) Aqueous ammonia (d) none of the above\n<\/li>\n
                              2. \n
                                Which compound is added to fused NaCl to lower its melting point? (a)CaCO3<\/sub> (b) CaCl2<\/sub>\n\t\t\t\t\t\t<\/div>\n

                                (c) Ca(OH)2 <\/sub> (d) Ca(NO3<\/sub>)2<\/sub>\n\t\t\t\t\t\t<\/li>\n

                              3. NaHCO3<\/sub> is also called? (a) Chalk (b) Baking powder (c) Lime (d) Slaked lime\n<\/li>\n
                              4. What is the colour of sodium flame (a) white (b) red (c) black (d) green\n<\/li>\n
                              5. Sodium reacts explosively with cold water to liberate (a) Hydrogen (b) CO2<\/sub> (c) O2<\/sub> (d) Na2<\/sub>O.\n<\/li>\n<\/ol>\n

                                \u00a0THEORY
                                \n<\/strong><\/p>\n

                                  \n
                                1. (a)\u00a0Explain the Solvay process\n<\/li>\n<\/ol>\n

                                  \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0(b)\u00a0What is the function of NH3<\/sub> in the process<\/p>\n

                                    \n
                                  1. Why is it necessary to concentrate the ore before extraction of any metal?\n<\/li>\n<\/ol>\n

                                    \u00a0READING ASSIGNMENT <\/strong>New School Chemistry by O.Y Ababio pages 419-442.<\/p>\n

                                    \t\t\t\t\u00a0<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

                                    \u00a0WEEK FIVE TOPIC: PRELIMINARY PREPARATION Metals are found mixed with earthy materials as ores. Ores…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,307],"tags":[],"class_list":["post-3942","post","type-post","status-publish","format-standard","hentry","category-posts","category-second-term-ss3-chemistry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/posts\/3942","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/comments?post=3942"}],"version-history":[{"count":1,"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/posts\/3942\/revisions"}],"predecessor-version":[{"id":3943,"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/posts\/3942\/revisions\/3943"}],"wp:attachment":[{"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/media?parent=3942"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/categories?post=3942"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ecolebooks.com\/nigeria\/wp-json\/wp\/v2\/tags?post=3942"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}