Green Chemistry

Lessons

Pesticide Label and MSDS Interpretation Lesson

After the lecture on the classes of pesticides each day of the unit, pass out pesticide labels and MSDS sheets for the chemicals that are examples for the day's lesson. Have students work in groups and fill out the following worksheet for each of the chemicals explored. If you want to use this format, you can cut and paste the cells below into Word and expand the table to make enough space for them to write in the pertinent information on the chemicals you are working with. There are many places to find the MSDS and Labels for these chemicals online, but I found one company that must sell just about every agrochemical you can think of. It makes it a one stop shop for these and they are in PDF format so you can save them or print them out for your classes.[20]

Understanding how the pesticides will move in the environment is another piece that is critical for students to make informed decisions on which pesticides to apply to the land so as to not contaminate our most valuable resource, our water supplies. Have students also keep a running Excel file on all the chemicals you discuss throughout this unit on a spreadsheet like the one below. Students will have an excellent resource by the time they are done with the unit and it should put your students on the right track to determining these values for the chemicals you will be exploring with them.[21]

Eggshell Thinning Lab

This lab will work well to use as an ongoing piece during the days in which you are talking about each class of pesticides. This lab was adapted from an access excellence lesson published online.[10] This lab also is a great way to have students work on their lab skills and it helps them to conceptualize the effects of pesticides on biological systems. There are a number of steps to this lab and advance preparation is needed to be sure all the materials are readily available. The first day do steps 1 and 2, the second day do steps 3 and 4, the third day do steps 5 and 6, and the final day do steps 7 and 8.

This activity will be done individually (ideal) or in pairs so each group will need:

Eggshells brought from home (3)

(Eggshells from nestbox monitoring would be an interesting variable…)

Mortar and pestle

Hot Plate

Pipette

Phenolphthalein

Step 1: Preparing the eggshells

• Boil three eggshells and remove the membrane from the shells
• Grind the shells in a mortar and pestle into a fine powder
• Place in a drying oven overnight
• Weigh out 1.0 gram of shell material

Step 2: reparing a standard acid

• Label the four 125 ml Erlenmeyer flasks
• On a zeroed balance, weigh four 0.61 g samples of KHP, potassium acid phthalate
• Design a data table to record the exact amount of KHP that was placed in each

  Place samples in each of the flasks and dissolve the KHP in 25 ml of distilled H ₂O

  Add three drops of phenolphthalein

Step 3: Preparing the working base

(go over how to make a 0.1 M NaOH solution on the board and make up the solution as a demo and have students make subsequent solutions if needed due to number of students)

• Prepare 1 liter of a 0.1 M NaOH solution in a 1000 ml volumetric flask
• Cap this tightly. Keep the cap on all of the time!

Step 4: Titrating the base

• Prepare a burette for titration
• Fill burette up to the top mark with NaOH solution (don't forget the cap!)
• Titrate one KHP sample swiftly with the base solution to determine the end point
•     Read and record the volume of NaOH that was required to neutralize the acid
• Titrate the other samples slowly with the base solution to determine the end points
• Calculate the exact concentration of your NaOH solution using each sample

Weight of KHP (g) X 1 mmol KHP/0.2042 g KHP = mmol of KHP

mmol KHP = mmol NaOH

mmol NaOH / ml NaOH = Molarity (M) of NaOH

Step 5: Making an acid to react with eggshell

(go over how to make a 0.2 M HCl solution on the board and make up the solution as a demo and have students make subsequent solutions if need due to number of students measure out carefully! Remember acid into water!)

Prepare 500 ml of a 0.2 M HCl solution

Step 6: Determining the concentration of the acid

• Pipette four 25 ml samples of the 0.2 M HCl solution into the 125 ml Erlenmeyers
• Add three drops of phenolphthalein
• Fill burette up to the top mark with NaOH solution and titrate acid samples
• Titrate the four samples for accuracy. Record the volume of each trial.
• Calculate the concentration of the HCl reaction acid

Step 7: Determining the calcium carbonate content of shells

• Weigh and record 0.15 grams of shell into a clean and dry 125 ml Erlenmeyer
• Add 5 ml of ethanol to the flask
• Pipette 25 ml of the acid solution into the flask to dissolve the eggshell
• Dissolve the eggshell by gently swirling the flask to mix and washing down the sides with distilled H ₂O until the volume is approximately 50 ml
• Gently boil the solution for 5-10 minutes until all of the shell is dissolved, washing the sides with distilled H ₂O to ensure the volume is approximately 50 ml
• Once cool, add 4 drops of phenolphthalein to each flask

Step 8: Calculating the percent calcium carbonate in shells

Devise a data and calculation table to arrive at the following items:

Wrap Up

Landscape Pesticide Use Scenarios

This activity will be very beneficial for your students and will start them really looking critically at the impact of the chemicals that are applied to the landscape. This activity will utilize the worksheets they compiled on the various chemicals explored through the unit and the Excel sheet they constructed with the persistence and sorption data and potential impact on water resources. The idea with this activity is to mimic the decision making process that should happen on the job as a landscape professional.

Scenario #1 Broadleaf Weeds in Turfgrass

Mr. Griffith's lawn is a great place for you and your FFA agronomy team to study weeds since it contains just about every broadleaf weed imaginable. He has hired the company you work for to apply a round of selective herbicide in order to kill off the weeds from his tall fescue lawn. Living along a country club, his backyard has a mild slope that leads to the water hazard on hole number four. His children love to go to the water to observe the large population of crayfish and fish that live among the native wetland vegetation on the edges of the water. You go to the herbicide storage closet at work and pull out the products you could possibly use on the turf area. Your options are Atrazine 90DF (Atrazine), Envoy Plus (Clethodium), Confront (Triclopyr), Lontrel (Clopyralid), Quicksilver (Carfentrazone-ethyl), and Round-up (Glyphosate). Which herbicide will you use for the job and why is this herbicide the best choice compared to the other options?

Scenario #2 Spider mite Infestation in Landscape Plantings

Mrs. Dobbs loves her Dwarf Alberta Spruce trees she has in her yard, especially when she puts lights on them around the holidays. She recently has noticed that they are starting to turn brown in patches and it looks like there are spider webs all over them. She tried spraying some methyl ethyl death she bought at the local hardware store but the trees are continuing to turn brown. She finally decided to call a professional and you and your crew were assigned to her job. Upon assessing the situation you determine that there is a very bad infestation of spider mites. You also notice that her soils are very sandy and since she lives in the coastal plain of Delaware the water table is rather close, under 20 feet, from the ground's surface. You go to the pesticide storage closet at work and pull out the products you could possibly use on the shrubs. Your options are Acephate Pro 75 (Acephate), Carzol (Formetanate hydrochloride), Supracide 2E (Methidathion), Talstar (Bifenthrin), Temik (Aldicarb), and Warrior (Lambda-cyhalothrin). Which pesticide will you use for the job and why is this pesticide the best choice compared to the other options?

Scenario #3 Aphid Infestation in Landscape Plantings

Mrs. Reardon's landscape is full of large perennial flower beds which she loves to add to each year to increase the diversity of plants in them. This season she was at the big box store and saw this great deal on some Montauk Daisy plants. They were a bit wilting but she bought all that they had since they were such a great deal, and she cannot pass up a bargain! Over the Memorial Day weekend she planted numerous daisy plants in each of her perennial beds to add a splash of white accenting the other flowers in her garden. In the last month and a half, most of the flowers in her gardens have started to show wilting signs and she has noticed a large population of small green insects all around the different flowers as she cuts them to put in vases in her house and that they all are rather sticky. She calls the company you are working for and you are assigned to the job. You go to assess the extent and cause of the problem. You determine that the plants that she bought for such a bargain must have been infested with aphids and that by letting it go for so long they have exponentially increased in numbers and your only choice is to treat them with chemicals. You are also introduced to her three cats and two Jack Russell terriers that are always playing and hiding in the landscape beds. You go to the pesticide storage closet at work and pull out the products you could possibly use on the shrubs. Your options are Astro (Permethrin), Acephate Pro 75 (Acephate), Malathion (Malathion), Sevin (Carbaryl), Talstar (Bifenthrin), and Temik (Aldicarb. Which pesticide will you use for the job and why is this pesticide the best choice compared to the other options?