ACTIVITY 4: DIALYSIS

Summary

This instructional video demonstrates the process of dialysis activity number four. It begins with preparing the materials, including cutting cellophane and adding starch and sodium chloride solutions. The cellophane is then tied and submerged in a beaker of water. After an hour, the contents are transferred for qualitative tests, involving the use of concentrated nitric acid, silver nitrate, and betadine. The video captures the color changes and reactions, providing a visual guide for understanding dialysis.

Takeaways

• 🔬 The activity involves setting up a dialysis experiment, starting with preparing agents and materials.
• 🧪 Step one requires cutting cellophane to size and placing it on a dry evaporating dish or a small bowl.
• 💧 In step two, 10 ml of starch solution and 10 ml of sodium chloride solution are added to the cellophane.
• 📏 A 5 ml pipette is used to measure the solutions, requiring two aspirations for each to reach 10 ml.
• 📦 After adding the solutions, the cellophane is gathered at the ends and tied with a string or rubber band to seal it.
• 💦 Step three involves suspending the sealed cellophane in a beaker filled with water, ensuring it's fully submerged without touching the sides.
• ⏱ The setup is left to stand for one hour to allow for dialysis to occur.
• ✂️ After the hour, a hole is made in the cellophane to transfer its contents into a clean, dry beaker labeled 'A'.
• 🔑 Beaker 'A' contains the solution from inside the cellophane, and 'B' contains the water from the beaker used for dialysis.
• 🧪 Qualitative tests are performed on the solutions from beakers 'A' and 'B' using test tubes and reagents like nitric acid, silver nitrate, and betadine.
• 📝 Observations of color changes and reactions in the test tubes are key to understanding the dialysis process.

Q & A

What is the first step in setting up the dialysis activity described in the script?

The first step is to prepare and gather the agents and materials needed for the setup of the analysis.

What materials are used to set up the dialysis in the script?

Clean cellophane, a dry evaporating dish or a small bowl, a 5 ml pipette, starch solution, sodium chloride solution, string or rubber band, and a beaker are used.

How much starch solution and sodium chloride solution are added to the cellophane?

10 ml of starch solution and 10 ml of sodium chloride solution are added to the cellophane.

What is the significance of cutting the cellophane according to size and placing it atop the dry evaporating dish or small bowl?

This is done to prepare a clean environment for the dialysis process and to ensure that the cellophane can hold the solutions without leaking.

Why is it necessary to dispense the fluid beyond the zero mark when using a 5 ml pipette?

Dispensing the fluid beyond the zero mark ensures that the pipette is primed correctly, allowing for accurate measurement of 5 ml when it is brought back to the zero mark.

How is the cellophane sealed after adding the solutions?

The ends of the cellophane are gathered and tied with a string or rubber band to prevent leakage.

What is the purpose of suspending the cellophane in a beaker filled with water?

The cellophane is suspended in water to allow for the diffusion of substances through the cellophane while preventing the solutions from mixing directly.

Why is it important that the cellophane is completely submerged but not touching any part of the beaker or the looking glass?

This ensures that the dialysis process occurs evenly and that the cellophane is fully exposed to the water, but prevents contamination or interference with the experiment.

How long does the cellophane need to stand in the beaker of water?

The cellophane needs to stand for one hour to allow sufficient time for the dialysis process to occur.

What is the purpose of the qualitative tests on the solutions inside and outside the cellophane?

The qualitative tests are performed to analyze the composition of the solutions and to observe any changes that occurred during the dialysis process.

What reagents are used for the qualitative tests in the script?

Concentrated nitric acid and silver nitrate are used for testing the solution inside the cellophane (test tubes one and three), while betadine is used for the dialysate (test tubes two and four).