This activity explores relationships between a fluid\'s density and convection c

Question

This activity explores relationships between a fluid's density and convection currents. Does hot water rise and cool water fall? a. Make several ice cubes that have been dyed with food coloring. b. Place an ice cube gently in a beaker of warm water. c. Observe the ice-water mixture for several minutes. d. Empty the beaker, and refill it with warm water. Add as much salt as will dissolve in the water. e. Repeat steps b and c. f. What differences did you observe between the fresh water and the salt water?

Explanation / Answer

Any object or substance that is less dense than a fluid will float in that fluid. Naturally hot wter which is less dense will float in the cold water. When the fluids are cooled, they contract and therefore become much denser. So any object which is denser will try to sink i.e., the cold water will thus sink or fall.

so if we have dry ice and they are being put in warm water. Ice cubes will melt in warm water and the rate at which it mels is influenced by the salinity of the water. (density and density driven currents in ocean)

the ice cubes in the beaker containing the fresh water will melt faster because the freshly melt water from the cube is colder than the room temperature or the water in beaker and it will sink. This will be replaced by warmer water at the ice cube and thus creating positive feedback for more ice to be melted. In the case of salt water the cold and fresh melt water in the salt water cup is less dense so it will not sink as a result it replaces the warm water. As a result, we can see the circulation as the food dye color can be seen. Hence this water in the dye color will not induce a circulation like in the case of pure water.

So in the case of fresh water, the whole water column changes the color while in the case of salt water, the ice melts very slow and the color can only be seen on the surface.

Hope this answer helps. Please rate.

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