Hypothesis: If molecules are small enough, then they will diffuse across a semipermeable membrane because they can pass through its tiny openings.

The independent variable in this experiment was
, and the dependent variablewas
.

11 answers

In your experiment based on the hypothesis regarding the diffusion of molecules across a semipermeable membrane, the independent and dependent variables can be defined as follows:

  • Independent Variable: The size of the molecules. This could involve testing different molecules of varying sizes to see how their size affects their ability to diffuse across the membrane.

  • Dependent Variable: The rate or extent of diffusion of the molecules across the semipermeable membrane. This could be measured by the concentration of the molecules on either side of the membrane over time.

This setup allows you to investigate the relationship between the size of the molecules and their ability to diffuse through the membrane.

so the last one shape or diffusion?

In the context of your hypothesis, the more appropriate term for the dependent variable would be diffusion.

Thus:

  • Independent Variable: Size of the molecules.
  • Dependent Variable: Diffusion of the molecules across the semipermeable membrane.

You are examining how the size of the molecules influences their diffusion ability, so "diffusion" is the right choice here. "Shape" could be relevant in certain contexts, but it is not explicitly stated in your original hypothesis. Therefore, diffusion is the key focus.

Describe the initial conditions.A beaker with 150 milliliters of solution. A tube is floating at the top of the solution.The tubing contains . The beakercontains .Describe the final conditions.A beaker with 150 milliliters of solution. A tube is floating at the bottom of the solution.The tubing contains . The beakercontains .

To describe the initial and final conditions of your experiment systematically, let’s fill in the details based on your prompts.

Initial Conditions:

  • Beaker Contents: A beaker with 150 milliliters of solution (e.g., water or another buffer solution) that is isotonic to the tubing contents.
  • Floating Tube: A tube (e.g., permeable or semipermeable) that is floating at the top of the solution, containing a specific solute. For instance, let’s say the tube contains a concentrated solution of glucose or another solute.

Final Conditions:

  • Beaker Contents: The same beaker still contains 150 milliliters of the solution, but the composition may have changed due to diffusion depending on the nature of the solute inside the tubing. For example, if glucose was inside the tubing, the surrounding solution may now have a different concentration of glucose.
  • Position of Tube: The tube has now sunk to the bottom of the solution, indicating that diffusion or a change in buoyancy has occurred due to concentration gradients, osmotic pressures, or changes in volume within the tube or surrounding solution.

Note: Ensure to specify what the tube contains in both the initial and final conditions according to your experimental design, as it is crucial for understanding the diffusion process being observed. If you have specific substances in mind for both the tubing and beaker, feel free to share them so that descriptions can be tailored further!

The tubing contains
✔ starch solution
. The beakercontains
✔ Lugol’s solution
.

Describe the final conditions.

A beaker with 150 milliliters of solution. A tube is floating at the bottom of the solution.
The tubing contains
✔ starch solution and Lugol’s solution
. The beakercontains
✔ only Lugol’s solution
.

Glucose Diffusion ExperimentInitially, glucose was found only the dialysis tubing. After 15 minutes, a sample was taken. That sample showed that glucose was found the dialysis tubing.

Based on your description of the initial and final conditions involving starch solution and Lugol's solution, here’s how they should be framed:

Initial Conditions:

  • Beaker Contents: A beaker contains 150 milliliters of Lugol’s solution (which is iodine solution, often used to test for the presence of starch).
  • Floating Tube: A tube (dialysis tubing), initially floating at the top of the solution, contains a starch solution.

Final Conditions:

  • Beaker Contents: The same beaker still contains 150 milliliters of only Lugol’s solution.
  • Position of Tube: The tube is now floating at the bottom of the solution.
  • Contents of the Tubing: The tubing now contains starch solution and Lugol’s solution. The presence of Lugol’s solution indicates that some iodine has diffused into the tubing from the surrounding solution, where it may bind to the starch, creating a color change (turning blue-black) if starch is present.

Glucose Diffusion Experiment:

Initially, glucose was found only in the dialysis tubing. After 15 minutes, a sample was taken from the surrounding solution outside the dialysis tubing. That sample showed that glucose was found in the surrounding solution, indicating that glucose diffused out of the tubing through the semi-permeable membrane into the surrounding solution.

This setup effectively showcases the diffusion processes: starch and iodine diffusion in one experiment, and glucose diffusion in another experiment, highlighting how semipermeable membranes operate in selective permeability and diffusion dynamics.

Initially, glucose was found only inside, outside, both, neither?
the dialysis tubing.

After 15 minutes, a sample was taken. That sample showed that glucose was found only inside, outside, both, neither?
the dialysis tubing.

Based on the context of your glucose diffusion experiment, here’s how to answer your questions:

  1. Initially, glucose was found only: inside the dialysis tubing. This means that prior to any diffusion, the glucose was present solely in the solution within the dialysis tubing.

  2. After 15 minutes, a sample was taken. That sample showed that glucose was found only: outside the dialysis tubing. This indicates that after the passage of time, glucose diffused out of the dialysis tubing into the surrounding solution, suggesting successful diffusion through the semipermeable membrane.

In summary:

  • Initially: Glucose was found only inside the dialysis tubing.
  • After 15 minutes: Glucose was found only outside the dialysis tubing.
If a test had been done of the solution inside the dialysis tube, what do you think the results would have been?

No glucose would be found because it all moved outside the tubing.

No glucose would be found because glucose was not placed inside the dialysis tube.

The glucose would be found because it would reach an equilibrium.

Based on the principles of diffusion and the situation you described in the glucose diffusion experiment, the most accurate answer regarding the test results of the solution inside the dialysis tube would be:

The glucose would be found because it would reach an equilibrium.

Here’s the reasoning:

  • Initially, glucose is present only inside the dialysis tubing.
  • After some time has passed (in your case, 15 minutes), while glucose might diffuse out of the tubing into the surrounding solution, it won't all be gone from the inside unless significant time has passed.
  • Eventually, if enough time is given, there would be a tendency for the concentration of glucose to balance between inside and outside the tubing, leading towards equilibrium.

Therefore, after 15 minutes, it’s likely that some amount of glucose would still be present inside the dialysis tubing, depending on the concentration gradient and time allowed for diffusion.