|St Albans' Science Club||
The questions posed were 'Are all liquids the same?' and 'What happens when you mix two liquids together?'.
We first tried with two different coloured waters. When poured together they mixed straight away. We then mixed oil and water together and observed that the oil floated on top of the water. When drops of food colouring were added they slowly sank in droplets through the oil and then mixed with the water at the bottom.
The next part of the experiment was to add an alka seltzer tablet that didn't react to the oil but did with the water. This effect creates a lava lamp in a jar.
The oil floats on top of the water because it is less dense or lighter than water. The food coloring has the same density as the water so it sink through the oil and mixes with the water.
When you add the tablet it sinks to the bottom then starts to dissolve. As it dissolves it makes gas, carbon dioxide. Gas or air, is lighter than water so it floats to the top. The air bubbles bring some colored water with them to the top. When the air comes out of the colored water blob, the water gets heavy again and sinks. It does this over and over again until the tablet is completely dissolved.