Chapter 17, Problem 7TE

To determine

Which one out of hot water or cold-water solution turns red first when red-coloured Kool-Aid crystals are added to water

Answer to Problem 7TE

Hot water turns red first because in hot water kinetic energy of molecules is high.

Explanation of Solution

When the red-coloured Kool-Aid crystals are added to water they sink to the bottom because they are high in density. With time the molecules of crystal get dissolved in water by occupying the empty spaces in between the water molecules.

If the water is hot the kinetic energy of molecules will be higher whereas in cold water the kinetic energy of molecules will be less. As a result, the crystals will dissolve faster in hot water.

Conclusion:

Therefore, hot water turns red first because in hot water kinetic energy of molecules is high.