LNL #6

»Read through the entire experiment so you will know what is coming up next. »Write your hypothesis using the “If- Then” format. Each experiment will have its own hypothesis. »Follow the procedure, recording all data. (That means write it all down in an orderly way.)

»Before you can write the hypothesis, you need to understand the purpose of the experiment. What are you trying to ‘prove’ or find out by doing the experiment? Where do you go for ideas about the purpose of the experiment? ˃ What is the title of the experiment? ˃ What are the objectives/goals of the experiment? ˃ What is in the background information/introductory paragraph that will help you?

»Read the Background section very carefully. »Procedures can be re-written or copied and pasted into the blank lab report. »There are 4 experiments to complete. »Experiments #1 and 2 are to show diffusion occurring by watching color changes

»Experiment #3 you will monitor the rate of diffusion of acetic acid through the dialysis membrane by measuring the change of the pH of the solution in the beaker over time. The concentration of the acetic acid is decreased with each trial. The solution will become more acidic as diffusion occurs. A pH of 7 is neutral. A pH below 7 is acidic ; the lower the pH, the more acidic the solution.

»Experiment #4 You will use the same method as before for determining the rate of diffusion, using a pH meter to monitor the change of the pH of the solution in the beaker, only this time you will use acids with different size molecules. Smaller molecules will pass through the membrane more easily. The higher the molecular weight, the bigger the molecule. In this experiment you will attempt to determine the relationship of between molecular weight and the rate of diffusion.

»Experiment # 5 you will confirm both the impermeability of the dialysis membrane to albumin as well as the movement of water across the membrane. Osmosis is the transfer of water across a semi-permeable membrane. The dialysis tubing used in these experiments allows water molecules to pass through it, but not the egg albumin. So the albumin in solution is trapped on either side of the membrane. An imbalance in the concentration of albumin on the two sides of the membrane creates pressure that forces water to move across the membrane.

»In Experiments #1 and 2, answer the questions. »In Experiments #3 and 4, complete the tables. »In Experiment #5, answer the questions.

»There are no calculations in this lab. »Answer the questions in each section of the lab report based on the data (information) collected in the experiments. »The Background information may be helpful in answering the questions.

»Use the template to write your report. »Type your hypothesis immediately after the directions for it. »Type (or copy and paste) your procedure immediately following the directions for it. »Answer all of the questions in the calculations/interpretations section. »Write your conclusion telling if your hypothesis was correct or incorrect and support your statement with your results. This should be about a paragraph in length.