However, over the long run, the Haber process has benefited humans as with increasing populations, traditional farming techniques were insufficient (e.g. crop rotation) as greater quantities of food were required, leading to the depletion of natural deposits of nitrogenous fertilisers, but the Haber process was able to overcome these shortages. The industrial synthesis of ammonia has facilitated the manufacture of fertilisers for food production, which has helped to sustain the world’s population. Part 3: Manufactured Products are Analysed Ion Testing Qualitative analysis of unknown chemicals such as precipitation tests and flame tests can identify many soluble ions. Ion Colour in Solution Confirmatory Test Spot Test Cation Barium Ba2+ Colourless H2SO4 solution forms white ppt. BaSO4 Sodium sulfate solution forms white BaSO4 ppt. Calcium Ca2+ Colourless Forms white ppt. with NaF Lead Pb2+ Colourless Forms bright yellow ppt. with KI Sodium hydroxide solution forms Pb(OH)2 ppt, which dissolves with excess NaOH Copper(II) Cu2+ Blue Sodium hydroxide solution blue ppt. of Cu(OH)2 Iron(II) Fe2+ Pale Green If left for a day, it changes to an orange brown solution. Decolourises KMnO4. K3Fe(CN)6 forms blue ppt. Sodium hydroxide solution green ppt., which does not dissolve with excess NaOH Iron(III) Fe3+ Orange-Brown Solution of K4[Fe(CN)6] forms blue ppt. of KFe[Fe(CN)]6 Sodium hydroxide solution forms reddish-brown Fe(OH)3 ppt., which does not dissolve with excess NaOH Anion Chloride Cl- Silver nitrate solution forms white AgCl ppt., which slowly darkens when exposed to light Sulfate SO42- Forms white precipitate with Ba2+ ions Carbonate CO32- Forms bubbles of CO2 when acid is added Evolve carbon dioxide gas when reacted with an acid
Part 5: Water Monitoring and Management Determining Water Quality Definition Impacts Possible Sources Cations, metal cations Positively charged ions Unhealthy balance of cations can impair cell functioning. Most heavy metals are toxic to living things, with organisms higher in food chain being more vulnerable. -Industrial discharge -Mine drainage -Road runoff -Atmospheric pollution Anions Negatively charged ions Nitrates and phosphates can cause eutrophication. If DO is low, sulfates can form H2S. If acidic, H2SO4 can form. -NO3- and PO43- come from ag. and urban runoff -SO42- and CO32- comes from surrounding geology Total Dissolved Solids The total mass of dissolved solids per unit volume of water High levels of dissolved salts can: -Impair cell function in aquatic organisms -Impact on crops -Be unsatisfactory for stock -Cause corrosion of irrigation equipment -Wastewater plant effluent -Urban runoff -Agricultural runoff (esp. in heavy fertilised areas) Hardness Measure of ability of water sample to lather soap (levels of Mg2+ and Ca2+) Difficult to use as it can: -Prevent effective washing -Cause blockages of pipes as Ca2+ precipitates in presence of CO32- -Geology (esp. in limestone areas) -Industrial influences (e.g. cement dust) Turbidity Measures of the suspended solids in Ability of the sample of scatter light High amounts of suspended solids can: -Smother gills (suffocation) -Block entry of light into water and limit photosynthesis -Impair recreational waters -Damage irrigation equipment (e.g. blockage) -Urban runoff (esp. in construction areas) -Roads -Agricultural areas (esp. cleared or turned ground) Acidity Measure of the pH (acidity/alkalinity) of sample Excessive changes to pH can: -Damage cell function -Damage egg hatching and spawning -Increase levels of toxic metals and ammonia being released into environment -Agricultural runoff (esp. manures and composts) -Acidic mine drainage -Acid rain Dissolved Oxygen Measures of amount of oxygen dissolved in the water Low levels of DO can: -Result in suffocation of organisms -Change water pH (toxicity effects) High levels or varying DO levels can: -Aquatic plants and algae supply DO, but too much leads to swings