My definition of diffusion (as learnt in Biology!) is the movement of particles from a region of higher concentration that of a lower concentration until equilibrium is reached.
Diffusion can be explained by an assumption of the Kinetic Particle Theory, which is that particles are always in constant and random motion.
In today's laboratory lesson, we were given a demonstration on diffusion of two highly corrosive substances, hydrochloric acid and ammonia gas. We were not allowed to handle these substances by ourselves. It felt really scary when a cloud of fumes appeared immediately after the lid of the container was lifted.
So these two acids were each soaked with cotton wool and then placed at opposite ends of a tube. After a while, a white cloud was observed near the cotton wool with hydrochloric acid. The particles of the ammonia gas had diffused with the hydrochloric acid, forming the white cloud. The reason the cloud was formed nearer to the hydrochloric acid is that the molecular mass of hydrogen chloride is heavier than that of ammonia gas. Heavier particles move and travel slower than lighter particles.
After that, we did our own experiment which was very simple actually. Firstly, we poured 50cm3 of sand and 50cm3of beans into two separate measuring cylinders. Next, we just mixed them together. The resulting volume of the mixture is not 100cm3 but around 80cm3 (we all had varying values around there). Based on my prior knowledge, my prediction to the volume of the mixture was correct.
This experiment proves that there are actually spaces in between the beans (and really tiny ones between the sand particles). The amount of space between the particles is about 20cm3.
The next experiment we did was to mix the same amount of ethanol with the same amount of water (I didn't take any pictures for this though). Ethanol and water are two miscible liquids - they can mix with each other. We put the two liquids in a tube and Cindy (my lab partner) sealed the tube with her thumb. When she shook the tube to mix them, there was a vacuum created inside the tube, causing her thumb to look all weird like it was being sucked into the tube. The resulting volume was lower than what we expected it to be. The mixture also felt quite warm.
I felt quite surprised that the volume of the mixture was lower than I expected but I was glad I learnt that the volume actually decreases when you mix them together, as they take up the space between particles.
Till next time! :)
In today's laboratory lesson, we were given a demonstration on diffusion of two highly corrosive substances, hydrochloric acid and ammonia gas. We were not allowed to handle these substances by ourselves. It felt really scary when a cloud of fumes appeared immediately after the lid of the container was lifted.
So these two acids were each soaked with cotton wool and then placed at opposite ends of a tube. After a while, a white cloud was observed near the cotton wool with hydrochloric acid. The particles of the ammonia gas had diffused with the hydrochloric acid, forming the white cloud. The reason the cloud was formed nearer to the hydrochloric acid is that the molecular mass of hydrogen chloride is heavier than that of ammonia gas. Heavier particles move and travel slower than lighter particles.
After that, we did our own experiment which was very simple actually. Firstly, we poured 50cm3 of sand and 50cm3of beans into two separate measuring cylinders. Next, we just mixed them together. The resulting volume of the mixture is not 100cm3 but around 80cm3 (we all had varying values around there). Based on my prior knowledge, my prediction to the volume of the mixture was correct.
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| Our experiment! |
This experiment proves that there are actually spaces in between the beans (and really tiny ones between the sand particles). The amount of space between the particles is about 20cm3.
The next experiment we did was to mix the same amount of ethanol with the same amount of water (I didn't take any pictures for this though). Ethanol and water are two miscible liquids - they can mix with each other. We put the two liquids in a tube and Cindy (my lab partner) sealed the tube with her thumb. When she shook the tube to mix them, there was a vacuum created inside the tube, causing her thumb to look all weird like it was being sucked into the tube. The resulting volume was lower than what we expected it to be. The mixture also felt quite warm.
I felt quite surprised that the volume of the mixture was lower than I expected but I was glad I learnt that the volume actually decreases when you mix them together, as they take up the space between particles.
Till next time! :)
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