Osmosis - GCSE Science Required Practical

Summary

This video demonstrates an osmosis experiment using potato tissue and varying concentrations of sucrose solutions. The potato cylinders are prepared identically and submerged in distilled water, 0.25 molar, and 0.5 molar sucrose solutions for 24 hours. The experiment measures changes in mass and length, indicating osmosis effects. The results show increased mass and length in distilled water, minor changes in the 0.25 molar solution, and decreased mass and length in the 0.5 molar solution, illustrating the impact of solute concentration on osmosis.

Takeaways

• 🥔 The experiment involves observing osmosis in potato tissue by submerging it in solutions of varying concentrations.
• 🔪 A cork board is used to ensure that potato samples are cut to the same diameter for consistency.
• 📏 Three cylinders from the same potato are prepared to eliminate variability between samples.
• ✂️ The potato samples are trimmed to approximately three centimeters in length to standardize the experiment.
• 📊 The initial length and mass of each potato cylinder are measured to establish a baseline for comparison.
• 💧 Distilled water, 0.25 molar sucrose solution, and 0.5 molar sucrose solution are used to create different osmotic conditions.
• 🌡 The experiment is allowed to run for 24 hours to observe significant changes in the potato tissue.
• 📉 After 24 hours, the potato cylinders are removed, excess liquid is blotted off, and their length and mass are remeasured.
• 📈 The change in length and mass is recorded to determine the effect of the different solutions on the potato tissue.
• 📊 A percentage change calculation is suggested to compare results more effectively despite initial variations in potato mass.
• 📋 The results are expected to show an increase in mass in pure water, little to no change at a certain sucrose concentration, and a decrease in mass in more concentrated sucrose solutions, illustrating osmosis.

Q & A

What is the purpose of the experiment described in the transcript?

The purpose of the experiment is to observe the effect of different concentrations of solutions on plant tissue, specifically a potato, to study the process of osmosis.

Why is a cork board used in the experiment?

A cork board is used to take samples of potato that are all the same diameter, which is important for consistent and comparable results.

What is the significance of cutting the potato samples to the same length?

Cutting the potato samples to the same length ensures that the results can be accurately compared, as variations in length could otherwise affect the outcome of the osmosis experiment.

Why are the ends of the potato cylinders cut off?

The ends of the potato cylinders are cut off because the potato skin is impermeable and would not allow water to move into the tissue, which is a key aspect of the osmosis experiment.

What are the three different concentrations of solutions used in the experiment?

The three different concentrations of solutions used are distilled water, 0.25 molar sucrose solution, and 0.5 molar sucrose solution.

Why is it important to measure the length and mass of the potato cylinders before and after the experiment?

Measuring the length and mass of the potato cylinders before and after the experiment allows for the observation of changes in size and weight due to osmosis, which is crucial for understanding the effect of the solutions.

What is the role of the boiling tube in the experiment?

The boiling tube is used to contain the potato cylinders and the solutions, providing a controlled environment for the osmosis process to occur.

Why is a bunsen burner mentioned in the transcript, and is it necessary for the experiment?

The bunsen burner is mentioned as a way to prevent evaporation of the liquid in the boiling tube if the experiment is conducted in hot weather or over a long period. However, it is not necessary if the experiment is done for a short time or in cooler conditions.

How long were the potato samples left in the solutions?

The potato samples were left in the solutions for 24 hours to allow for significant results to be observed.

What is the significance of the observed changes in mass and length of the potato cylinders?

The changes in mass and length of the potato cylinders indicate the direction and magnitude of water movement into or out of the plant cells due to osmosis, which is influenced by the concentration of the surrounding solution.

What is the percentage change calculation mentioned in the transcript, and why is it used?

The percentage change calculation is used to standardize the results and make them easier to compare, despite the initial differences in mass of the potato cylinders. It is calculated by dividing the change in mass by the initial mass and multiplying by 100.

How does the concentration of the sugar solution affect the mass of the potato cylinders?

As the concentration of the sugar solution increases, the mass gain of the potato cylinders decreases until a point is reached where there is no change in mass, and then mass loss occurs as the solution becomes more concentrated.