Diffusion is the process of substances mixing when they come into contact. This property is observed more rapidly in gases, while liquids show it to a lesser extent. Solids do not demonstrate diffusion with each other, but they can slowly diffuse in liquids. The solute and solvent molecules collide, causing constant random motion for the solute molecules.
II. OBJECTIVES:
- Elucidate the process of diffusion.
The purpose of this experiment is to compare diffusion and osmosis, demonstrate osmosis in cells, describe hypotonic, isotonic, and hypertonic solutions, and explain the impact of different salt concentrations on cells.
To begin the experiment:
A. Diffusion of Solid in Water
A small amount of potassium permanganate was placed in a 250ml beaker filled with water. The beaker was then left undisturbed for 10 minutes while observations were made every 2 minutes.
B. Diffusion through Membrane
A cellophane bag was filled with a starch solution and securely tied to prevent air from being trapped inside.
The cellophane bag with starch solution was placed in a beaker filled with Lugol’s iodine solution. The situation was observed and timed until the cellophane bag changed color from white to a blue-black solution.
C. Osmosis in Cells Around 1/4 of the wider end of the egg was removed, and the entire egg was placed in an upright position in a beaker of water with the membrane exposed by using a pebble for support. The egg in water was observed for an hour to observe any changes.
D.
The effect of different salt concentrations on plant cells was studied using a Rheo discolor mounted on a glass slide. Initially, the distribution of pigments in the Rheo discolor was observed under LPO using water as a solvent. Without moving the slide, a 10% salt solution was added twice to the edge of the cover. The appearance of three neighboring cells was then recorded under CPO one minute after the addition of the 10% salt solution. A new Rheo discolor slide was prepared and examined under LPO, but this time a 50% salt solution was used. The appearance of the same three neighboring cells was recorded once again.
The procedure was repeated, this time using a Hydrilla leaf as the slide and examining it under HPO.
IV. RESULTS AND OBSERVATIONS
5. a At the end of 10 minutes, the beaker experienced the following changes:
1-2 Minutes – Some of the solid KMnO4 dissolved, while most of it remained settled at the bottom of the beaker.
2-4 Minutes – A light pink cover appeared at the upper portion of the solvent, while undissolved KMnO4 was found at the bottom of the beaker.
4-6 Minutes – The pink cover of the solvent intensified, and undissolved KMnO4 was still present in the beaker.
-8 Minutes – Some of the undissolved KMnO4 at the bottom of the beaker rose, turning the solution light pink.
8-10 Minutes – More solid KMnO4 rose from the bottom of the beaker, causing the solution to turn dark pink. Undissolved KMnO4 still remained in the beaker.
5. b Three ways to speed up the rate of diffusion of potassium permanganate crystals:
1. Stir
2. Agitate
3. Heat the solution
B. Diffusion through Membrane
5c. The initial colors of the two solutions were as follows:
Iodine is black red;
Starch solution is white.
Describe the observed changes in color for both chemical solutions. The Iodine solution remains black-red while the starch solution turns blue-black.
How long does it take for the color to change? It takes 4 minutes.
Which substance was able to diffuse through the cellophane based on the results? Explain why. The Iodine was able to diffuse through because it had a higher concentration compared to the starch solution.
What would happen if both chemical solutions were able to diffuse through the cellophane? The solution would change from white to blue-black due to the Iodine-starch reaction.
After about an hour, remove the egg from the beaker. What happens to the exposed membrane? The exposed membrane of the egg becomes smooth and prominent compared to its original form as water enters through it.
Explain how osmosis occurs in the egg. The selectively permeable membrane allows water entry but prevents other solutes from passing through. As a result of water having a higher concentration, there is a net movement of water into the cell causing it to swell.
Explain why there is a change in distribution of violet pigment in Rheo discolor cells before and after adding 50% salt solution. Initially, violet pigments are evenly distributed within cells, but when a 50% salt solution is added, they become concentrated nears cell walls. This demonstrates diffusion’s role in transporting solutes within cells.
Hypertonic; 50% salt solution
Hypotonic; 10% salt solution
V. DISCUSSION
When liquids, like water, come into contact with solids such as potassium permanganate, there is a process called intermixing of substances which occurs through diffusion. This diffusion of solids in liquids is slow. The movement of molecules across membranes involves fluid diffusion from areas with high concentration to areas with low concentration due to the presence of a concentration gradient. The rate of diffusion increases when there is a greater gradient.
If there are no external forces, diffusion will continue until the gradient reaches zero. This natural process occurs effortlessly and decreases free energy. Animal cells possess semi-permeable membranes. If the cytoplasm of an egg is more concentrated than pure water, osmosis will cause water to enter the cells, resulting in expansion and swelling. Conversely, when salt is introduced to plant cells, their concentrations change depending on the concentration of the added salt.
Osmosis is the process by which a cell tries to equalize its concentration with that of a salt solution. If the solution is hypertonic, the cell will shrink and potentially perish, while if it is hypotonic, it may swell or burst. In summary, diffusion involves particles moving from areas of high concentration to areas of low concentration along a concentration gradient. The rate at which diffusion takes place depends on the magnitude of the concentration difference, also referred to as the concentration gradient.
Both diffusion and osmosis involve the movement of materials from a concentrated area to one with a lower concentration. Diffusion refers to the spread of gas or dissolved substance particles, which happens due to their random movement. The rate of diffusion rises with increased temperatures. Conversely, osmosis takes place when two solutions are divided by a semipermeable membrane that permits certain particles to pass through while preventing others. Semipermeable membranes include cell membranes.
Water can freely pass through membranes, but substances like sugar molecules cannot. A hypotonic solution has a lower concentration of particles outside the cell compared to the inside. In these solutions, cells either expand or may burst. An isotonic solution has the same solute concentration as the cell. In these solutions, there is no net movement of water. A hypertonic solution has a higher concentration of solutes outside the cell compared to the inside. In these solutions, water moves out of the cell, causing it to shrink. Vil.
ANSWERS TO QUESTIONS 1.
Is it possible for a liquid substance to diffuse in another liquid substance? The diffusion of a liquid substance in another liquid substance depends on their nature and polarity. For example, blood can be diffused by water, but oil cannot.
Can a gas diffuse in another gas? Absolutely, due to the rapid movement of gas molecules, they will uniformly diffuse and spread. They can also mix with other gases as well as certain liquids and solids. When contained within a container, the moving molecules of a gas exert pressure on the inner walls of the container.
Is it possible for a gas to diffuse in a liquid? Diffusion occurs quickly for gases and somewhat for liquids. However, solids do not exhibit this process of diffusion among each other.
What is the importance of diffusion in solute transport within cells? Diffusion allows small particles to enter cells without requiring cellular energy consumption. This is how soluble solutions move across the cell membrane.The Sun is the primary source of energy for almost all living organisms.
Photosynthesis is a physico-chemical process that occurs in plants, algae, and certain bacteria. It transfers sunlight energy to the biosphere by using light energy to create organic compounds. This process relies on complex protein molecules found within or near a well-structured membrane. Through a series of energy transduction reactions, the photosynthetic machinery converts light energy into a long-lasting form that can persist for millions of years.
Photosynthesis is the process in which organisms that rely on chlorophyll (or bacteriochlorophyll) convert light energy into chemical free energy. These organisms include photosynthetic bacteria in the Bacteria domain, as well as algae and higher plants in the Eucarya domain.
The general equation for photosynthesis is 6 + 7 H20 -> C6H1206 + 6 02 + H20. However, synthesizing carbohydrates through photosynthesis requires a coordinated set of physical and chemical reactions.
To analyze the rate of photosynthesis under different light intensities, one can correlate it with the number of bubbles produced.
Three healthy sprigs of Hydrilla, about 1 inch long, were cut and placed in each of three 25ml test tubes filled with tap water. These test tubes were then inverted and placed in three separate beakers filled with water. The water in the beakers was blown with breath through a straw to increase the concentration of dissolved carbon dioxide. Beaker 1 was placed in direct sunlight, beaker 2 was placed under the shade of a tree, and beaker 3 was placed inside the laboratory room.
