Colloids and Solutions in the Environment Prepare for Recitation November 10th ALEKS Objective 11 due November 5th ANGEL Quiz 11 November 6th Note the special due dates Lecture 31 November 2nd Lecture 32 November 4th Lecture 33 November 7th Review for Exam Read Ch 13 5 13 6 Additional Preparation BLB 13 9 58 61 69 75 Packet 13 13 18 Exam 3 Monday November 7th Late Drop Deadline Friday November 11th CH110 FA10 SAS 1 Colloids and Solutions in the Environment KEY QUESTIONS THE BIG PICTURE What effects does solute concentration have on the physical properties of liquids What differences are there when the solutes do not form homogeneous mixtures Remember macroscopic properties come from microscopic origins What is the origin of colligative properties How do the colligative properties of solutions impact the environment How do colloids impact the environment By the end of Today s Lecture you should know Colloids Tyndall Effect Hydrophobic vs Hydrophilic Reverse Osmosis CH110 FA10 SAS 2 Colligative Properties Review Colligative properties are affected by the of solute not by Addition of a non volatile solute to a solvent lowers the vapor pressure Addition of a non volatile solute to a solvent depresses the freezing point and elevates the boiling point Addition of a non volatile solute to a solvent increases the osmotic pressure CH110 FA10 SAS 3 Osmosis pure solvent ordilute solution concentrated solution semipermeable membrane Osmosis the net movement of toward the solution with solute concentration movement continues until osmotic pressure builds up to stop it Osmotic Pressure CH110 FA11 SAS 4 What are Colloids Colloids Gravity does not cause particles to settle between solution and heterogeneous mixture particles are very large molecules or aggregates defined by the size of the particles phases are mutually insoluble small Particle size homogeneous colloids solution of 10 2000 nm molecules Not influenced by gravity CH110 FA10 SAS large heterogeneous mixture Influenced by gravity 5 Tyndall Effect Tyndall Effect Visible light passes through solutions without scattering particles very small Atoms are 10 10 m in size and do scatter x rays as a result Visible light is scattered by colloids 400700 nm similar to particle size Fog Left a colloid CH110 FA10 SAS 6 Why is the Sky Blue colloids scatter more blue than red Rising or Setting Sun Mid day Sun sun CH110 FA10 SAS 7 Solutions and Dilutions in the Environment Water on Earth Total volume 1 4 x 109 km3 1 4 x 1018 m3 1 4 x 1021 L 97 of water on earth is in oceans 2 1 of fresh water is frozen 1 is potable fresh water CH110 FA10 SAS 8 Ground Water Contamination in Central Pennsylvania Acid Mine Drainage Water draining from exposed limestone in surface mines or construction projects Construction of I 99 in State College was delayed by unforeseen environmental impacts from the project Sulfide salts of toxic heavy metals get into our drinking water CH110 FA10 SAS 9 Practice Problem Arsenic levels as high as 12 4 g L H2O have been observed in acid mine drainage from mines in Pennsylvania The EPA limit on arsenic in drinking water is 10 parts per billion What final volume would 1 L of this contaminated water have to be diluted to in order to be considered safe to consume For simplicity assume a density of 1 g mL CH110 FA10 SAS 10 Marcellus Shale What are the potential surface water impacts from natural gas development As of March 2011 1 605 billion gallons of water have been used for fracturing Bradford Clearfield Sesquehanna and Washington counties have already reported significant release incidents As a society we must develop energy resources CH110 FA10 SAS 11 Marcellus Shale Fracturing Chemical Mixtures Potential Hazards from Flowback chloride 5 150 g L sodium 2 75 g L barium 2 5 g L strontium 1 7 g L bromide 2 g L radium 226 100 16 000 pCi L Flowback is also very acidic CH110 FA10 SAS 12 Marcellus Shale Solutions innovations and outlook Better solutions for water sourcing Better solutions for water storage recycling and decontamination EPA has mandated tougher off site treatment standards Penn State Leadership www marcellus psu edu CH110 FA10 SAS 13 Water Crisis 16 of the world lacks access to potable water As the world s population grows this problem is expected to increase Recent changes in climate are putting additional stress on fresh water supplies CH110 FA10 SAS 14 Climate Change and Drought Lake Lanier Georgia 2008 CH110 FA10 SAS 15 Converting Salt Water to Potable Water Distillation Vaporization condensation of water Under reduced pressure Reverse Osmosis Up to 8 MPa Applied pressure must be greater than CH110 FA10 SAS 16 Practice Problem A reverse osmosis plant is set up near a body of salt water containing 1 2 M total solute If the plant is regulated at 25oC what is the minimum pressure that must be applied to force flow in the system into the pure water side of the semi permeable membrane CH110 FA10 SAS 17 What You Should Know Colligative Properties What are colligative properties and what do they depend on Do colligative properties matter in the environment Colloids What is the difference between a colloid and a homogeneous solution What are some common natural and anthropogenic colloids What is the tyndall effect Solutions in the Environment Do we have enough fresh water What is reverse osmosis CH110 FA10 SAS 18
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