OIL SPILLS
Name(s):
Vance Ballard and Eddie Bonnell
Title of Lesson:
pH
Date of Lesson:
Length of Lesson:
Approximately 50 minutes
Description of the Class:
Name:
Grade
Level:
Source of the Lesson:
Water Quality with Computers
TEKS Addressed:
(1) Scientific processes. The student conducts field and laboratory investigations using safe, environmentally appropriate, and ethical practices. The student is expected to:
(A) Demonstrate safe practices during field and laboratory investigations; and
(B) Make wise choices in the use and conservation of resources and the disposal or recycling of materials.
(C) Collect data by observing and measuring;
(D) Organize, analyze, evaluate, make inferences, and predict trends from direct and indirect evidence;
(E) Communicate valid conclusions; and
(F) Construct graphs, tables, maps, and charts using tools including computers to organize, examine, and evaluate data.
(2) Science concepts. The student knows that substances have chemical and physical properties. The student is expected to:
(A) Demonstrate that substances may react chemically to form new substances
The purpose of this lesson is to explain the relationship between H+ concentration and pH. We will also discuss the effects of H+ concentrations on aquatic habitats.
The student will be able to:
1. Graph and interpret data collected from pH sensors.
2. Describe relationship between H+ concentration and pH.
3. Explain some effects of pH that's too high/low on aquatic habitat.
4.
Each lab group will receive:
Computer, pH sensor, bottle of distilled water, 250 ml beaker, paper towels, various water samples to test, lab manual with graph, and goggles if available.
IV.
Safety Considerations
The main concern will be spills. Students will be asked to notify an instructor of any spills, so we can insure they are completely cleaned up. The safe handling of technological devices will be stressed as we will have them near water.
V.
Supplementary Materials, Handouts
The students will be provided a lab manual and graph sheets to conduct their experiment.
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Engage: Students will be asked to sit in lab groups as assigned by Mr. Campbell. Students will be given index cards and asked to fold them lengthwise. Place the name they want to be called on the name plate and display it where we can see it. Introduce ourselves as U.T. students and tell them we are here to teach them a lesson about acids and bases. Ask them to talk about what an acid is. Are all acids bad? What are bases? Are all bases bad? How do we know if a substance is acidic or basic? What is does a pH scale tell us? How accurate are they? Ok. Let's see if we can take some pH readings and come up with some idea what they tell us. |
Comply and put reasonable names on the nameplates where we can read them. Give various examples of acids. No, give some examples of foods. Opposite of acid No, give examples pH scale the concentration of H+ in solution the scale is mathematical, but equipment varies |
Are students engaged and providing reasonable answers? Do they show interest? Are we doing most of the talking?
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Explore: 1. Note the sample labels on your graph sheets so you can accurately track your data. 2. Position the computers and paperwork safely away from the area you will work with the water samples. 3. Go to Logger Pro. 4. Open the Water Quality with Computers folder. 5. Open the Ò02 pHÓ folder. ONCE YOU'VE GOT YOUR 02 pH FOLDER OPEN, RAISE
YOUR HAND. You are ready to begin collecting your data. 6. Remove the pH sensor from the storage bottle, and rinse the tip with your distilled water bottle. 7. Place it in your 1st sample. Make sure you leave the tip submerged 3 to 4 cm. 8. If the pH value appears stable, simply record it on your data sheet. If not, click COLLECT button on your graph screen to collect a 10 second sample. IMPORTANTÉ.you must leave the tip submerged the entire time. 9. Return the probe to the distilled water sample. Repeat steps 6 Ð 9 for each sample you have in your collection. |
Label the various samples on the graph sheets, hopefully in the order they will test them. Isolate the computers and paperwork away from the area they will work with the water. Open the Logger Pro program. Open the Water Quality with Computers folder. Open the Ò02 pHÓ folder ONCE YOU'VE GOT YOUR 02 pH FOLDER OPEN, RAISE
YOUR HAND. Remove and rinse the probe for testing. Collect accurate pH sample from 1st solution. It may be easier to just calibrate mean pH on all samples. Questions as we go. Why is it important to rinse the probe each time we take a sample? What could happen if we cross contaminate the samples? Does the distilled water cross contaminate the samples? |
Assist with readings as necessary, and answer any questions with questions that provoke deeper thought if possible.
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Explain: Ask the students to compile their data and print graphs. Ask specific members to discuss the group's findings. Ask the groups to discuss what concentrations are? What is the effect of dilution? |
Print graphs and discuss what they think the relationship is. Determined that the lower pH values have higher concentrations of H+ Determine the concentration is a relationship between the amount of H+ to the total amount of solution The amount of solution increases, but the H+ stays the same. |
Do they understand the solute will not increase unless we add more, or vice versa? We can manipulate the solution or solute and it affects the pH.
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Extend/Elaborate: Who can tell me how to calculate the pH? (The formula) Who can tell me how to calculate the [H+] from pH? We could theoretically calculate the H+ concentration of any pH if we know the molar concentration of the source acid and its dissolution constant. Given the samples you've calculated, calculate the concentrations for pH of 3, 5, 7, 9. Why do you think scientists (more specifically biologists) are concerned with the pH of lakes and streams? What are some sources of pH imbalances? How can we modify or control these things? |
pH = -log [H+] 10^ X -[pH] It's ok if you don't understand the math formulas, but just remember the calculations work both ways depending on which piece of the formula you have. You can go either way. Take 10^ X Ð[pH] of these values These are the H+ concentrations for this concentration of particular acid. Biologists can use the information to help preserve habitats. If they are able to determine the causes of higher pH readings, they can take appropriate steps to prevent contamination of sensitive biological habitats. Pollution, chemical spills, and acid rain. Protect aquifers and prevent recharge zones from becoming polluted with chemicals and trash. Possibly introduce buffers into the system that will help maintain safe levels. |
Evaluate
This last part is probably too much because they don't have the math background to understand logs, but it will be something they can reflect upon later in their academic careers.