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Chemistry—Semester 2

Chemistry—Semester 2

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Chemistry—Semester 2

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  1. Chemistry—Semester 2 The Plight of Onondaga Lake Dun, Dunnn, Dunnnnnnn……… Everyone take a seat and get ready for the NEW SEMESTER!

  2. Blog Assignments • Each Sunday, Holt will post 2 questions about the topics being covered in class. • You will have until Wednesday at 12:00 midnight to respond to them. • Some of the questions will be based on a calculation, some will be based on some conceptual understanding and some will be based on your opinion. • But you must base your opinion on some fact and list it. • Generally, I question will be a calculation-type question and the other will be one of opinion, based on research. Example of this might be… • Holt Post: Do you think that acid rain is a problem in the U.S.? • Student Post: No, I think that acid rain is a myth brought out by the media to scare us.

  3. Blog Assignments • If this was your post, you would receive very little credit (if any). • I am not interested in your opinion, unless you back it up with something. • Now, some questions I post for you might be of a topic of which you have no opinion. • The reason you have no opinion, is because you know little to nothing about that topic.

  4. Blog Assignments So, what I want you to do is do a little research on the topic, get both sides of an argument and give me your opinion after you have reviewed the topic. This is why I am giving you Sunday, Monday, Tuesday and most of Wednesday to respond. Then you will have until Saturday at midnight to read a few of your classmate’s responses and comment back to them. You may agree or disagree but again you need to support your position with fact or your opinion based on documented fact. You will not need to respond to the calculation-type questions.

  5. Blog Assignments • Grading—this weekly assignment will constitute your journal part of your portfolio and ½ of your HW grade for a total of 15% of your total grade. • Below is the rubric for this grading… • Respond to Post on Time 10 pts • Answer to calculation problem is correct 10pts • Opinion response is documented with • class notes or website 10pts • Response to classmate is coherent • and documented 10 pts • Response is free of grammatical errors 10 pts • There is no partial credit for any of the categories listed above. So, 1 misspelled word earns you a 40/50 at best.

  6. Blog Assignments • You may continue to do the normal journals for 2% EXTRA CREDIT added to your score at the end of the semester. • However, you may not miss a day and they must be written perfectly. There is no partial credit for extra credit.

  7. Labs • We will run our labs like a professional lab. • I will be the “lab supervisor” and you all will be the employees. • Think of your grades as your paycheck. Each member of the group starts with 10 points for the lab write up (book) and 10 points for laboratory technician behavior. • Each infraction below results in losing 1 point for lab technician behavior. The lab book will be graded as follows…pre-lab questions (2), introduction (2), materials and methods (2), data recording/graphs/tables (2) conclusion including post lab questions (2). • If you do not bring your lab book to class or you do not have the introduction written or you are not using the lab book throughout the lab, you will lose the points associated with the mistake—2 points if there is no intro, 2 points if you are not writing down the procedures as we go and 2 points if you are not writing data as we go.

  8. Labs • Each group (department) will be led by a team leader who will be in charge of the rest of the group. • Your job will be to keep your team in line, assign tasks and come to the supervisor (me) when needed. • If team members are not working or straying to other groups or being loud—you and your team will all lose points. • Your team may not come and talk to me and they may not ask me questions. • It is your job to make sure that your entire team understands the lab and what we are trying to accomplish in the lab. • I will come around and ask your team and you questions about the lab. • If a team member that I choose cannot answer the question, your team will be penalized. • It is also the team leader’s responsibility to explain the lab to the entire class when picked to do so. • The tasks being assigned by the team leader will be gathering equipment, gathering chemicals, labeler, experimenting, collecting data, interpreting lab and explaining steps to group and cleaning up. 

  9. Labs • The equipment gatherer must get the needed beakers, thermometers, hot plates, etc as needed and put them back in their places after they are cleaned. • If equipment is left at your station or put away dirty the leader and equipment person will lose points. • The chemical gatherer must get the necessary chemicals used in the lab. • They must not take the chemicals from the prep table back to your table. • If any chemicals leave the lab table, your team will lose points. (The leader and the chemical person.) • The labeler’s job is to make certain that all chemicals are labeled at your station. • If the supervisor comes to your lab station and there are any beakers, test tubes, etc ,that have chemicals (including water) and they are not labeled, you will lose points. (The leader and the labeler.) • The experimenter is the person that carries out the experiment. • I would suggest that everyone be involved in this even though one person is truly responsible for this. • However, if the experiment is not going as planned or there are mistakes, broken glassware, spills, etc, the leader and experimenter lose points.

  10. Labs • Along with the experimenter there will be a main data collector. • Each person should be collecting data in their own books, but if I come around, I will mainly look for the main data collection book or paper and check it. • The chosen data collector must produce this from their book or paper in their handwriting or the leader and data collector loses points. • There is also a person that is in charge of explaining the steps of the lab and interpreting the data throughout the experiment. • This person should know what is going on before it happens and be able to explain what the results mean. • They are responsible for making sure that each member totally understands what is expected and what is meant in each step. • If I come by and ask anyone in the group what is going on or what just happened or what was supposed to happen and they are unable to do it, that person the leader and the explainer all lose points.

  11. Labs • The clean up person is in charge of clean up. • The chemical person is to dispose of the chemicals and the equipment person takes care of the equipment, but the clean up person makes sure that the table and sink are in perfect condition before the group goes back in to the room. • Failure to do so costs each person in the group points. • You will notice that there are 7 jobs not including the leader of the group. • The leader may pick one of the 7 jobs to do along with their leadership duties, however, no more. • The leader is really in charge of all the jobs being carried out. • But they are there to make sure that everything is being done by all, not doing it all themselves. • I will be watching closely to make sure that the leader isn’t hogging the jobs and that the workers are working hard so that the leader needs to pick up the slack to save them. • Everyone must work as a team doing their own jobs. A group cannot do all the jobs together—someone must be in charge of each task. • Also there must be a sheet taped to your stations with the names of the group and jobs for each. If there is not a sheet taped to each station, then the entire team loses points.

  12. Labs • At the end of the lab, each member of the group is to comment on how the behavior and work ethic of each member enhanced the productivity of the lab. • Were your group members • helpful or not, • did they take care of their responsibilities, • were they actively involved in the experiment and • either answering questions or asking questions for clarification. • You are looking to come up with at least 2 positive things each group member did and 1 thing they need to improve upon next time. • These are strictly confidential and will only be seen by me. • You will receive a copy of these comments when you turn in your completed lab write up.

  13. Environmental Chemistry • One of the hottest topics in today’s world is environmental chemistry. • Topics considering pollution, recycling, ozone layer depletion, alternative fuels and global warming are all around us—newspapers, magazines, CNN, and regular cable TV discuss the possibilities of these environmental factors.

  14. Environmental Chemistry • What does the Bible state about our stewardship toward the environment? Are we following God’s plan? • I am not going to tell you what to think about today’s environmental issues—enough people do that. • But I am going to ask you to think. • I want you to have your own opinions about this before the end of the school year.

  15. Environmental Chemistry • I have spoken to many educated people about Global Warming and the Environment and their responses range from… • “I don’t care cuz I can’t change it” to… • “There is no problem, it’s all a scam” to… • “There is a problem, but I don’t know how to fix it” to… • “There is a huge problem and if we don’t fix it, the Earth is toast.” • But most of them have no background evidence to support their thoughts or… • They only look at one side of the argument.

  16. Environmental Chemistry • However, they act as though they know so much about the topic because they spout off the most. • This is annoying to me and… • You are going to be different. • I don’t care what your position is as long as you can back up your thoughts and you have looked at arguments for and against your initial beliefs. • It is probably best to have no pre-conceived ideas at this point although that is going to be difficult.

  17. Environmental Chemistry • We are going to use documented environmental issues to learn chemistry for the rest of the year and shape our belief system of the environment of which we live..

  18. Are There Problems at Onondaga Lake? We are going to take a deeper look at solution chemistry through a case study of Onondaga Lake in Syracuse, NY. Get Sheets over by the window—it’s a Graph and the Solvay Process! Whoo-Hoo HW: Look up and define the characteristics of an unsaturated, saturated and super-saturated solution.

  19. Onondaga Lake • In 1847, the mayor of a middle-sized city in a developing country shared his vision for the lake adjoining his municipality. Read what he had to say about his nice, little town… • Our beautiful lake will present continuous villas ornamented with shady groves and hanging gardens and connected by a wide and splendid avenue that shall encircle its entire waters and furnish a delightful drive for the happy and prosperous citizens of the town who will, towards the end of each summer’s day, rush to it for pleasure, relaxation or improvement of health. --Harvey Baldwin

  20. Onondaga Lake • This indeed was the scene in Syracuse, NY on the banks of Lake Onondaga. The area prospered as a number of 5 Star hotel resorts dotted the shoreline, the citizens of the area rushed to it for play, and a thriving fishing industry sprang up. • But in 1920, the fishing industry and resorts were gone. The fish taken out of this lake are no longer allowed to be eaten. You are not allowed to swim in the cloudy waters. The city of Syracuse does not draw its water from this lake for human usage. • Lake Onondaga is now called one of the world’s most polluted lakes and the most polluted lake in the country.

  21. Onondaga Lake At first glance this may seem like a problem only to the residents near the lake in Syracuse, but it is not. This is an account of a typical risk/benefit dilemma that many other societies faced in the past are now facing or will face in the future. Initially technology brought new opportunities and new prosperity to the shores of Lake Onondaga, but environmental deterioration began to negate those advantages—it is an account of industrialization on a developing society. What went wrong?

  22. Onondaga Lake • This story of salt, soda and Syracuse is on of industrial development, environmental impact and technology’s response. • It begins with a look at the rich natural resource of the brine springs that made Syracuse an ideal location for chemical manufacturing. • There was an increasing need for sodium carbonate (soda ash) that was plentiful in this area. • With this great natural resource a chemical procedure called the Solvay Process was used to extract this compound.

  23. Onondaga Lake This process was revolutionary for its time and was considered to be environmentally responsible. However, over the years of using this process, a great amount of unused by-products began to wash into the lake and contribute to its contamination. Along with the Solvay process, the chlor-alkali process, developed to produce chlorine and sodium hydroxide, released large quantities of toxic mercury to the already troubled waters. These two processes along with an old way of wastewater treatment system, caused the lake to end up in the poor shape that it is today.

  24. Onondaga Lake • Onondaga Lake is about 4.5 miles long and 1 mile wide. Muskegon Lake is 5.5 miles long and 2.2 miles wide. • It has an average depth of about 35 feet. It drains into the Seneca River which empties into Lake Ontario. • The relatively small size misrepresents its importance. • It provides a textbook case of the impact of industrial processes on the environment and society. • The Native Americans were the first to discover the springs of brine (concentrated solutions of sodium chloride) that are common in this area.

  25. Onondaga Lake By around 1800, almost all of the salt used in the U.S. came from this area. Two methods were used to produce salt along the shores of the lake. The brine was boiled down in large iron kettles heated by wood fires. As the water evaporated, the solution became more concentrated.

  26. Onondaga Lake At the saturation point, the crystals began to form on the surface of the liquid and on the sides of the containers. The salt was removed with large wooden scoops and placed in baskets to dry. However, as the forests were cleared for farmland and burned for fuel, the cost of this method became too expensive.

  27. Onondaga Lake • Then they moved to a solar process where the sun evaporated the brine to reveal the salt crystals. • However, salt mines were discovered in the west and in other more sunny areas of which took over the salt yards and by 1926, the last of the Onondaga salt yards closed. • However, before the salt mines had closed a process was discovered whereby sodium carbonate was made from sodium chloride. • Sodium carbonate is used in the manufacturing of soap, paper, water softeners and glass.

  28. Onondaga Lake Even today sodium carbonate ranks 11th among industrial chemicals produced. As a water softener, the carbonate ion (CO32-) reacts with calcium and magnesium ions in a double replacement reaction whereby insoluble CaCO3 and MgCO3 are formed and settle to the bottom of the tank. In the very early days sodium carbonate was produced by extracting the ashes of seaweeds.

  29. Onondaga Lake This was a tedious process and the demand for this product was much greater than what could be produced. Enter…technology. In 1865 Albert and Ernest Solvay came up with a way to manufacture sodium carbonate from sodium chloride. The Solvay Process starts with two of the cheapest and most abundant chemicals in the Earth’s crust: NaCl and CaCO3. The overall reaction is 2NaCl + CaCO3 Na2CO3 + CaCl2

  30. Onondaga Lake • The starting materials for the Solvay Process were available in abundance near Syracuse. • For this reason it is not hard to understand why in 1884, the Solvay Process Company began making sodium carbonate along the Onondaga. • In fact, from 1960 to 1985, 2000-2800 tons of Na2CO3 were produced daily by Allied Chemical Company, the successor to the Solvay Process Company. • This booming industry gave the residents jobs, great public schools with extensive athletic, music, art and other extracurricular activities—even dental care was free for students.

  31. Onondaga Lake However, with time, it became obvious that the Solvay Process was also contributing some less desirable by-products to the town and to Lake Onondaga. One key point is that the reaction above does not occur directly. If you mix NaCl, CaCO3 and water, the NaCl would dissolve and the CaCO3 would not. No reaction would take place and no sodium carbonate would be formed. A series of reactions with a variety of by-products would need to be made to get to the end product.

  32. Onondaga Lake Some of those by-products are NH3, NH4Cl, CaO, Ca(OH)2, CO2 and NaHCO3. A particularly crucial step involves four of these compounds. It is the reaction that occurs when CO2 and NH3 are bubbled through a salt solution at 0°C. NH3(g) + CO2(g) + NaCl(aq) + H2O(l) NaHCO3(s) + NH4Cl(aq) In this equation we see that sodium bicarbonate is produced as a solid and ammonium chloride is produced dissolved in solution.

  33. Onondaga Lake • Both of these chemicals form in the water solution, but under these cool conditions the solubility of the NaHCO3 is less than that of the NH4Cl. • The solubility curve of these two compounds show this phenomenon. • The line for each shows the amount of compound that will dissolve per 100mL of water solution.

  34. Onondaga Lake You can see that at all temperatures the ammonium chloride will dissolve more solid than sodium bicarbonate. So at 0°C the solubility of NH4Cl is about 30g / 100mL whereas the solubility of sodium bicarbonate is only 7.0g / 100mL. This means that the sodium bicarbonate crystallizes, separating as a solid, while the ammonium chloride remains behind in solution.

  35. Onondaga Lake • To illustrate this process of fractional crystallization, suppose we start with 100mL of a solution containing 12.0g of NaHCO3 and 24.0g of NH4Cl at 50°C. • The solution is cooled to 0°C. • Only about 7.0g of NaHCO3 will stay in solution whereas all the NH4Cl will be in solution. So, the only compound precipitating out will be the NaHCO3.

  36. Onondaga Lake So, the amount of NaHCO3 that crystallizes out will be 5.0g. The percentage that remains in solution is 7.0/12.0 or 58% and the amount that precipitates out is 5.0/12.0 or 42%. The solid sodium bicarbonate is filtered out and then this solid is converted to the desired Na2CO3 by heating it to about 300°C… NaHCO3 + heat  Na2CO3 + CO2 + H2O

  37. Time to Put this Solvay process together… • Sit down and get out your notes and your solubility curves and your Solvay Process summary sheets… • We need to start right away so that we can get through everything to be ready for our Lab on Friday… • Write your name on a small piece of paper and give it to me

  38. Your Turn Suppose that 100mL of a solution containing 40.0g NH4Cl and 10.0g NaHCO3 at 40°C is cooled to 0°C. Calculate the masses of each compound that would crystallize and the masses of the two compounds remaining in the solution. Would this be a good method for obtaining pure NaHCO3?

  39. The Solvay Process Summary • We want this reaction (we want sodium carbonate)… • NaCl + CaCO3 Na2CO3 + CaCl2 • But the Solvay process had to get around the insolubility of calcium carbonate. • step (1) calcium carbonate (limestone) is heated… • CaCO3 + heat  CaO + CO2 • step (2) ammonia, CO2 from step 1, salt and water react… • NH3 + CO2 + NaCl + H2O  NaHCO3 + NH4Cl • Step (3) sodium bicarbonate is heated… • 2 NaHCO3 + heat  Na2CO3 + H2O + CO2 • step (4) the ammonium chloride and calcium oxide react… • 2 NH4Cl + CaO  2 NH3 + H2O + CaCl2 Not re-used

  40. Your Turn • If in this step, 34.5g of NaCl was used in excess NH3, CO2 and H2O, how much solid NaHCO3 and solid NH4Cl would be produced? • How much Na2CO3 would be produced from the previous amount in step 3?

  41. Today in Chem Sit at your desk and quickly contemplate the life of a ground hog. This should only take about 5-10sec. Next, get out your solubility curve, Solvay Summary sheet and your notes. Take out a sheet of paper—not part of your notes and get ready for a quiz… I want to show you a video of a cool Friday Fire experiment I would like to try tomorrow because lab went so well on Friday… If you bring in supplies—you can play with the fire. If not, you can just watch.

  42. Surprise Quiz (no talking—you have 8 minutes to turn this in…) Let’s say that you were working for the Solvay company and Big Man Solvay wanted to test your understanding of his system. He looks you square in the face and says, “OK Mr./Ms. Smarty Pants. If I used 30.0g of pure sodium chloride, how much sodium bicarbonate could I make? At what temperature would I need to carry this out to get pure SB and how much pure SB would I make? How much sodium carbonate could I make in step 4 from this amount of sodium chloride?”

  43. Review Questions from Some HW • ___ ___________ solution is one in which more solute could still be added. • ___ ___________ solution is one in which no more solute could be added at this temperature and dissolve. • ___ ___________ solution is on in which more solute was forced into the solution by adding heat and then slowly cooling it down so that the solute stays in the solution. • If the solution is cooled rapidly, or it is disturbed, the solute will come out.

  44. Back to Notes on Onondaga Lake • From what we have stated thus far, it would seem that the Solvay Process would be an ideal example of enlightened chemical manufacturing. • Two cheap and plentiful naturally occurring substances—salt and limestone—are converted into two useful products—sodium carbonate and calcium chloride. • However, CaCl2 is not in as demand as Na2CO3.

  45. Onondaga Lake CaCl2 is used in concrete mixtures, to melt snow and ice and in certain solar heating units to name a few. But over the years the sales of calcium chloride from the Onondaga plant did not keep pace with the sales of sodium carbonate. The excess calcium chloride was allowed by state and federal regulations to be dumped in solution into a tributary of the Onondaga Lake.

  46. Onondaga Lake • Also large amounts of unmarketable salts were dumped into solitary marshes along the coastline of Onondaga Lake—up to 500 tons every day. • It was mostly CaCl2 but also some un-reacted NaCl and CaSO4. • However, calcium, sodium and chloride ions leached from the marshes by rainwater into the lake.

  47. Onondaga Lake In 1943 a barrier holding back a waste bed measuring 70 feet high and covering 400 acres of area broke and released a flood that buried over 20 houses. Most of the substances in the waste beds are ionic compounds. Their water solubility is very important to the composition of Onondaga Lake. Some salts including NaCl and CaCl2 are water soluble—others such as CaCO3 are not.

  48. Onondaga Lake • The following solubility rules will help us understand which ionic solids are generally soluble in water and which ones are insoluble in water.  • Salts containing Group 1 metals and the ammonium ion are soluble in water. • Salts containing nitrates and acetates are soluble in water.

  49. Onondaga Lake Salts containing halogens (except F) are soluble in water unless they are combined with Ag, Hg or Pb. Salts containing sulfates are soluble in water unless they are combined with Ag, Hg, Pb, Sr, or Ba. Salts containing sulfides, oxides, phosphates, carbonates and hydroxides are insoluble unless with Group 1 metals and NH4+.

  50. Your Turn • Using the solubility rules, determine if the following salts are soluble… • Magnesium hydroxide • Barium sulfate • Lithium carbonate • Strontium nitrate