OIL + WATER · EFFERVESCENT TABLET TEST
Build a lava lamp
INVESTIGATION QUESTIONHow does effervescent-tablet amount change the duration of visible bubbling?
Watch one short model at a time. Press Play for synchronized English narration; Next unlocks after the clip and narration finish.
Add equal water and oil to three open bottles. Denser water settles below the oil.
Build three matched bottles
Add the same colored water and oil to three identical open plastic bottles. Let the layers settle.
WATCH FORWater settles beneath oil; the three samples should begin with the same amounts.
Press Play to hear English narration for this step.
Press Play to start the clip and English narration together. Pause and Replay control both.
Why do the colored drops rise?
The tablet reacts in water and releases carbon dioxide. Bubbles attach to colored water and lift it through the oil. At the surface the gas escapes, and denser water droplets sink again.
How do you measure it?
Use matched open bottles, equal oil and water volumes, and the same tablet brand. Time each sample from contact with water until no new bubbles appear for 10 seconds. Repeat every tablet amount.
Why time the real trial?
The clip is an authored illustration. It does not contain measured reaction durations; fragment size can affect both total reactant and dissolving rate.
DEDICATED LAVA LAMP INVESTIGATION · GRADES 3–7
Run your own three-sample bench
Change tablet amount while keeping the bottle, water, oil, coloring and tablet brand matched. Predict, run each sample, then compare your own timed observations.
REAL-WORLD DATA
What to record
01 · START THE TIMER Start when the tablet touches the water layer, not when it leaves your hand.
02 · APPLY ONE ENDPOINT Stop after no new bubbles appear for 10 seconds; use that same rule for every trial.
03 · REPEAT EACH AMOUNT Use fresh matched liquids and repeat each portion. Compare averages rather than one run.
The bottle is a simplified “lava lamp”: carbon dioxide drives the motion. A traditional wax lava lamp uses heating and density changes, so the two systems are not the same mechanism.