Prep. Photocopy pH activity from “Marine Life,” by Dudley. Prep. cups with seawater and filtered water. Stirring rods or skewers

Do Now (8 min.) Read background information. Read the “Question” Come up with a hypothesis.

What solution can buffer pH better – filtered or sea water What solution can buffer pH better – filtered or sea water? – An Experimental Approach Mr. M. Gonzalez

Objectives I can properly use lab equipment. I can change the pH of a solution using an acid. I can explain the difference in buffering capacity between filtered and sea water.

Buffering Capacity The Buffering Capacity of a solution is the ability that solution has to resist changes in it’s pH. In other words, if you add a base or acid to the solution the pH will change more slowly if the solution has a high buffering capacity.

Buffering Capacity The Buffering Capacity is determined by certain salts or molecules in the water such as Calcium Carbonate, Bicarbonate and others.

Review Writing a Hypothesis How is a hypothesis written? A hypothesis is written as an if…then…because statement. Can you give an example of a hypothesis? If an acid is added to filtered and seawater then the pH will fall faster in the filtered water because is pure and will not be able to buffer.

Activity Read Procedures and wait for instructions to begin lab. REMEMBER, You will only be adding 2 drops of acid at a time to each solution. TO SAVE TIME, one group will work with the filtered water and another with the seawater.

What’s today’s lab about? Write your answers on the next page of the worksheets. WASH YOUR HANDS BEFORE LEAVING. BE SAFE. BRING THE WORKSHEET BACK TOMORROW FOR CLASS.

Clean up. Measuring pH Rinse the probe after each sample solution. Read other assigned samples. After your final rinse place 2 drops of pH storage solution into the little cup located inside the probe cap.

Clean up Clean-up Recap the probe FIRMLY by lining up the lettering on the cap and the face of the meter. Wait for clean-up instructions. Clean up your area, dump your rinse water out, dispose of gloves, and return materials. Begin work on your bar graph and analysis questions.

Log activity Explain how to properly use a dropper bottle? Explain the difference in buffering capacity between filtered and sea water.