SASS Chem Air Notes

_______________________________________________________________________________________________________________________________________________________________________________________ Page 1 ST ANDREW’S SECONDARY SCHOOL NAME CLASS DATE SCIENCE(CHEMISTRY) Topical Notes (Additional) Air and Atmosphere /uni0032/uni0020/uni004F/uni0052/uni0047/uni0041/uni004E/uni0049/uni0053/uni0041/uni0054/uni0049/uni004F/uni004E/uni0020/uni004F/uni0046/uni0020/uni0054/uni0048/uni0045/uni0020/uni004F/uni0052/uni0047/uni0041/uni004E/uni0049/uni0053/uni004D /uni0059/uni004F/uni0055/uni0052/uni0020/uni004E/uni004F/uni0054/uni0045/uni0053 /uni0031/uni0031/uni0020/uni0041/uni0049/uni0052/uni0020/uni0026/uni0020/uni0057/uni0041/uni0054/uni0045/uni0052 /uni0073/uni0061/uni0076/uni0065/uni006D/uni0079/uni0065/uni0078/uni0061/uni006D/uni0073/uni002E/uni0063/uni006F/uni002E/uni0075/uni006B /uni0050/uni0061/uni0067/uni0065/uni0020/uni0020/uni0033© /uni0063/uni006F/uni0070/uni0079/uni0072/uni0069/uni0067/uni0068/uni0074/uni0020/uni0053/uni0061/uni0076/uni0065/uni0020/uni004D/uni0079/uni0020/uni0045/uni0078/uni0061/uni006D/uni0073 /uni0043/uni0049/uni0045/uni0020/uni0049/uni0047/uni0043/uni0053/uni0045/uni0020/uni0043/uni0068/uni0065/uni006D/uni0069/uni0073/uni0074/uni0072/uni0079/uni0020/uni0052/uni0065/uni0076/uni0069/uni0073/uni0069/uni006F/uni006E/uni0020/uni004E/uni006F/uni0074/uni0065/uni0073 /uni0043/uni0049/uni0045/uni0020/uni0049/uni0047/uni0043/uni0053/uni0045/uni0020/uni0043/uni0068/uni0065/uni006D/uni0069/uni0073/uni0074/uni0072/uni0079/uni0020/uni0052/uni0065/uni0073/uni006F/uni0075/uni0072/uni0063/uni0065/uni0073 /uni0052/uni0045/uni0056/uni0049/uni0053/uni0049/uni004F/uni004E/uni0020/uni004E/uni004F/uni0054/uni0045/uni0053/uni0020/uni0020/uni0020/uni0020/uni0020/uni0020/uni0054/uni004F/uni0050/uni0049/uni0043/uni0020/uni0051/uni0055/uni0045/uni0053/uni0054/uni0049/uni004F/uni004E/uni0053/uni0020/uni0020/uni0020/uni0020/uni0020/uni0020/uni0050/uni0041/uni0053/uni0054/uni0020/uni0050/uni0041/uni0050/uni0045/uni0052/uni0053 /uni0031/uni0031/uni002E/uni0031/uni002E/uni0032/uni0020/uni0041/uni0049/uni0052 /uni0045/uni0058/uni0054/uni0045/uni004E/uni0044/uni0045/uni0044/uni0020/uni004F/uni004E/uni004C/uni0059/uni0020 /uni0041/uni006E/uni0020/uni0049/uni006E/uni0061/uni0064/uni0065/uni0071/uni0075/uni0061/uni0074/uni0065/uni0020/uni0053/uni0075/uni0070/uni0070/uni006C/uni0079/uni0020/uni006F/uni0066/uni0020/uni0057/uni0061/uni0074/uni0065/uni0072 • Clean and safe water supply is very important to mankind • Many problems arise in the event of an inadequate water supply, including: • Food shortages and famine due to a lack of crops which cannot grow without a clean water supply • Poor sanitation leads to spread of bacteria and disease as drinking water becomes infected /uni0054/uni0068/uni0065/uni0020/uni0043/uni006F/uni006D/uni0070/uni006F/uni0073/uni0069/uni0074/uni0069/uni006F/uni006E/uni0020/uni006F/uni0066/uni0020/uni0041/uni0069/uni0072 /uni0050/uni0069/uni0065/uni0020/uni0063/uni0068/uni0061/uni0072/uni0074/uni0020/uni0073/uni0068/uni006F/uni0077/uni0069/uni006E/uni0067/uni0020/uni0074/uni0068/uni0065/uni0020/uni0061/uni0070/uni0070/uni0072/uni006F/uni0078/uni0069/uni006D/uni0061/uni0074/uni0065/uni0020/uni0070/uni0065/uni0072/uni0063/uni0065/uni006E/uni0074/uni0061/uni0067/uni0065/uni0073/uni0020/uni0062/uni0079/uni0020/uni0076/uni006F/uni006C/uni0075/uni006D/uni0065/uni0020/uni006F/uni0066/uni0020/uni0074/uni0068/uni0065/uni0020/uni006D/uni0061/uni0069/uni006E/uni0020/uni0067/uni0061/uni0073/uni0065/uni0073/uni0020/uni0020 /uni0069/uni006E/uni0020/uni0075/uni006E/uni0070/uni006F/uni006C/uni006C/uni0075/uni0074/uni0065/uni0064/uni002C/uni0020/uni0064/uni0072/uni0079/uni0020/uni0061/uni0069/uni0072 /uni0055/uni0073/uni0065/uni0073/uni0020/uni006F/uni0066/uni0020/uni0061/uni0069/uni0072 • The gases available in the air have many important applications • Oxygen is used in steel making, welding and in breathing apparatus • Nitrogen is used in food packaging, the production of ammonia and in the production of silicon chips • Both of these gases are separated from air by fractional distillation /uni0031/uni0031/uni002E/uni0031/uni002E/uni0031/uni0020/uni0057/uni0041/uni0054/uni0045/uni0052/uni0020/uni0020/uni0063/uni006F/uni006E/uni0074/uni002E/uni002E/uni002E

_______________________________________________________________________________________________________________________________________________________________________________________ Page 2 /uni0031/uni0031/uni0020/uni0041/uni0049/uni0052/uni0020/uni0026/uni0020/uni0057/uni0041/uni0054/uni0045/uni0052 /uni0059/uni004F/uni0055/uni0052/uni0020/uni004E/uni004F/uni0054/uni0045/uni0053 /uni0073/uni0061/uni0076/uni0065/uni006D/uni0079/uni0065/uni0078/uni0061/uni006D/uni0073/uni002E/uni0063/uni006F/uni002E/uni0075/uni006B /uni0050/uni0061/uni0067/uni0065/uni0020/uni0020/uni0034© /uni0063/uni006F/uni0070/uni0079/uni0072/uni0069/uni0067/uni0068/uni0074/uni0020/uni0053/uni0061/uni0076/uni0065/uni0020/uni004D/uni0079/uni0020/uni0045/uni0078/uni0061/uni006D/uni0073 /uni0043/uni0049/uni0045/uni0020/uni0049/uni0047/uni0043/uni0053/uni0045/uni0020/uni0043/uni0068/uni0065/uni006D/uni0069/uni0073/uni0074/uni0072/uni0079/uni0020/uni0052/uni0065/uni0076/uni0069/uni0073/uni0069/uni006F/uni006E/uni0020/uni004E/uni006F/uni0074/uni0065/uni0073 /uni0043/uni0049/uni0045/uni0020/uni0049/uni0047/uni0043/uni0053/uni0045/uni0020/uni0043/uni0068/uni0065/uni006D/uni0069/uni0073/uni0074/uni0072/uni0079/uni0020/uni0052/uni0065/uni0073/uni006F/uni0075/uni0072/uni0063/uni0065/uni0073 /uni0052/uni0045/uni0056/uni0049/uni0053/uni0049/uni004F/uni004E/uni0020/uni004E/uni004F/uni0054/uni0045/uni0053/uni0020/uni0020/uni0020/uni0020/uni0020/uni0020/uni0054/uni004F/uni0050/uni0049/uni0043/uni0020/uni0051/uni0055/uni0045/uni0053/uni0054/uni0049/uni004F/uni004E/uni0053/uni0020/uni0020/uni0020/uni0020/uni0020/uni0020/uni0050/uni0041/uni0053/uni0054/uni0020/uni0050/uni0041/uni0050/uni0045/uni0052/uni0053 /uni0045/uni0058/uni0054/uni0045/uni004E/uni0044/uni0045/uni0044/uni0020/uni004F/uni004E/uni004C/uni0059/uni0020 /uni0046/uni0072/uni0061/uni0063/uni0074/uni0069/uni006F/uni006E/uni0061/uni006C/uni0020/uni0044/uni0069/uni0073/uni0074/uni0069/uni006C/uni006C/uni0061/uni0074/uni0069/uni006F/uni006E/uni0020/uni006F/uni0066/uni0020/uni0041/uni0069/uni0072 • The air is first filtered to remove dust, and then cooled in stages until it reaches –200°C • At this temperature the air is in the liquid state • Water vapour and carbon dioxide freeze at higher temperatures and are removed using absorbent filters • The Noble gases are still in the gaseous state at -200ºC, leaving a mixture of liquid nitrogen and oxygen • The liquefied mixture is passed into the bottom of a fractionating column • Note that the column is warmer at the bottom than it is at the top • Oxygen liquefies at -183°C and nitrogen liquefies at -196°C • Nitrogen has a lower boiling point than oxygen so it vaporises first and is collected as it rises in the gaseous state to the top of the column • The liquid O2 is then removed from the bottom of the column /uni0044/uni0069/uni0061/uni0067/uni0072/uni0061/uni006D/uni0020/uni0073/uni0068/uni006F/uni0077/uni0069/uni006E/uni0067/uni0020/uni0074/uni0068/uni0065/uni0020/uni0066/uni0072/uni0061/uni0063/uni0074/uni0069/uni006F/uni006E/uni0061/uni006C/uni0020/uni0064/uni0069/uni0073/uni0074/uni0069/uni006C/uni006C/uni0061/uni0074/uni0069/uni006F/uni006E/uni0020/uni006F/uni0066/uni0020/uni006C/uni0069/uni0071/uni0075/uni0069/uni0064/uni0020/uni0061/uni0069/uni0072/uni0020/uni0020 /uni0074/uni006F/uni0020/uni0070/uni0072/uni006F/uni0064/uni0075/uni0063/uni0065/uni0020/uni004E/uni0032/uni0020/uni0067/uni0061/uni0073/uni0020/uni0061/uni006E/uni0064/uni0020/uni006C/uni0069/uni0071/uni0075/uni0069/uni0064/uni0020/uni004F/uni0032 /uni0031/uni0031/uni002E/uni0031/uni002E/uni0032/uni0020/uni0041/uni0049/uni0052