Hello Everyone!
13 March 2026
This Term in science we have been doing experiments about heat and recording our observations in a Google Doc.
Conduction:
Conduction is the transfer of heat through solid materials when particles pass energy to neighbouring particles. We set up a retort stand and applied petroleum jelly to thumbtacks, then placed them at equal distances along a metal rod. After that we set it up above a Bunsen burner. Finally, we lit the Bunsen burner and timed when the thumbtacks would fall and recorded it on a document.
Conduction plays a vital role in everyday life and industry by transferring thermal energy directly through materials ( typically solids ).
Convection: Favourite Experiment
Aim- The aim of this experiment was to see what the potassium would do to the water when heated
Hypothesis- I predicted that The potassium permanganate crystals would create a convection current when used in hot water.
Equipment:
- Bunsen burner
- Tripod
- Beaker
- Matchsticks (Fire)
- Heatproof Mat
- Gauze Mat
- Straw
- Gas
- Safety goggles
Method-
- Fill a glass beaker with cold water and place it on a tripod over a Bunsen burner or a heat source. Let the water sit until it is completely still.
- Use a pair of tweezers to carefully drop potassium permanganate into a straw to the very bottom of the beaker. Avoid stirring the water.
- Light the Bunsen Burner on a low, blue flame and position it directly underneath the tripod.
- Watch as the heated water at the bottom becomes less dense and rises, carrying a purple streak of dissolved potassium towards the surface.
- Observe the purple dye spreading across the top and then sinking down the cooler sides of the beaker, completing the convection current loop.
Results- Heating a potassium permanganate crystal at the bottom of a beaker causes the purple dye to rise in a narrow column, spread across the surface, and then sink down the cooler sides, visually demonstrating a circular convection current.
Table-
|
Step
|
Action |
Result |
| 1 |
Fill a beaker with water and place it on a tripod. |
The water becomes still and ready for the experiment. |
| 2 |
Drop a potassium permanganate crystal to the bottom. |
The crystal sits at the bottom, slightly tinting the nearby water. |
| 3 |
Apply gentle heat directly under the crystal. |
The water at the bottom warms up and becomes less dense. |
| 4 |
Observe the purple streak rising to the surface. |
A visible convection current carries the dye upward. |
| 5 |
Watch the dye spread and sink at the cooler sides. |
The water cools, becomes denser, and completes the loop. |
Convection is the transfer of heat in liquids or gases when warmer, less dense fluid rises and cooler denser fluid sinks, creating a convection current.
Convection plays a crucial role in heat transfer by moving warm, less-dense fluids upward while allowing cooler, denser fluids to sink, a continuous circulation pattern known as convection current.
Contraction:
Contraction is when materials becomes smaller in size, volume, or length when it cools down. In this experiment we set up a Bunsen burner under a tripod and gauze mat We poured approximately 50-60 ml of water into a metal can and heated it using the Bunsen burner. After heating the can, it was cooled quickly. As the temperature dropped, the air and steam inside the can contracted, causing the can to collapse inward.
This experiment showed how contraction happens when materials cool down and the particles move closer together.
Diffusion:
Diffusion is the movement of particles from an area of high concentration to an area of low concentration until they spread out evenly.
To begin the experiment, I filled a petri dish halfway with water and placed it on the workbench so the water could settle. The teacher then used tweezers to place a crystal of potassium permanganate into a straw. Using a Chromebook timer, I recorded how long it took for the water to turn from clear to purple. I repeated the experiment using hot water instead of cold water to compare the results.
This experiment showed how particles spread out in water through diffusion.
Diffusion is a fundamental physical process that plays a vital role in science by driving the exchange of materials in biological systems, facilitating chemical reactions, enabling industrial processes.
Expansion:
Expansion is the increase in a material’s volume, length, or area when heated caused by particles vibrating faster and moving further apart. I started to inspect the ball and hoop to ensure the ball just fits through the hoop. Then turned on the Bunsen burner using knowledge learnt earlier, I turned the flame into a blue flame by opening the air hole. I held the ball over the flame with tongs for one minute. After heating the ball over the Bunsen burner for one minute, we tried to pass it through the hoop again. The ball no longer fit through the hoop because the metal had expanded when heated.
Expansion plays a vital role in science by acting as a fundamental principle governing the behaviour of matter, energy, and the universe itself.
To recap- Conduction is about heat moving through touch, convection is about heat moving through flowing liquids or gases, and diffusion is about particles spreading out. Contraction and expansion also show how materials change when temperature changes.
Reflection: Doing these experiments made me realise how heat moves and changes materials, which I can see happening all around me.
Thank you for reading my blog post!
