Solubility factors Chemical Reactions Chapter 17 Temperature of substances Types of molecules Polar molecules are soluble in polar solvents Nonpolar molecules are soluble in nonpolar solvents Soap and grime Does not dissolve to any appreciable extent in the solvent Salt is insoluble in oil Salt is soluble in water Acidity of solvent especially for polar molecules Precipitate Solute that comes out of solution Often caused by change in temperature Insoluble Hard Water Contains Mg and or Ca ionic compounds Less soluble than Na ionic compounds Leave scale in pipes and on surfaces Soap Non polar and polar properties Polar part attracts water CH chain Non polar part attracts grime NaCO2 Detergent Washing in Hard Water Stronger grease penetration Lower cost of production Sulfate or sulfonate group attached to CH chain Ions of Ca2 or Mg2 ions bond to the polar end of the cleansing compound and reduce the quantity available for cleaning Detergent mixtures often contain Na2CO3 to bond with the Ca2 and Mg2 ions 1 Home water softeners Ion Exchange resin Ion exchange resin Charge with salt NaCl to have Na ions available to treat hard water Water ions attracted to resin and exchange the Na ions for its Ca2 or Mg2 ions Purifying the Water We Drink Water is then aerated to improve the taste and smell Lastly the water is disinfected with chlorine gas or ozone Osmosis Purifying the Water We Drink The first step to purifying water is removing particles and bacteria Purifying the Water We Drink Distillation Sea water can be converted to drinking water through desalination Distillation Reverse osmosis Reverse Osmosis Wastewater Treatment Screening removes large insoluble items Primary treatment allows smaller insolubles to settle to the bottom or rise to the top for removal Secondary treatment aerates the water and allows finer particles to settle for removal Tertiary treatment filters the water 2 Primary Wastewater Treatment Secondary Wastewater Treatment Chemical Equations C O2 CO2 C s O2 g CO2 g Reactants on left products on right Each are balanced because same number of atoms of reactants as products Some equations show the phase of the substances also solid liquid gas Balancing Chemical Equations Water balancing Molecules of reactants and products shown Cannot change the molecule Can change how many of them Cannot add or delete reactants or products Balanced equal number of same atoms on each side Rusting of Iron Fe O2 Fe2O3 not balanced start with oxygen Fe 3 O2 2 Fe2O3 next do iron 4 Fe 3 O2 2 Fe2O3 Balancing Tips Never change the molecular formula of reactants or products Count atoms in reactant and products Always add whole molecules not parts Start by balancing atoms in compounds Save element reactants or products for last to make up any imbalance Combustion of propane Volume Relationships C3H8 O2 CO2 H2O fix hydrogen first it s in two compounds C3H8 O2 CO2 4 H2O need more carbon product C3H8 O2 3 CO2 4 H2O Do oxygen last because it is single C3H8 5 O2 3 CO2 4 H2O Equal volumes of gases at the same temperature and pressure have the same number of molecules Gases react in small whole number quantities Avogadro s hypothesis chemicals react in consistent small whole number ratios 3 Avogadro s hypothesis Combustion of propane C3H8 5 O2 3 CO2 4 H2O What volume of oxygen is needed to burn 0 5 L of propane Ratio of Oxygen molecules to propane molecules is 5 1 2 5 L Oxygen 0 5 L x 5 L O2 1 L Propane 4
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