Based on the lab conditions below, determine the answer to all questions highlig

Question

Based on the lab conditions below, determine the answer to all questions highlighted in yellow.

To investigate the solvent properties of water, as well as see the effect temperature has on molecular motion and chemical reactions, try making tea (or coffee) at two different temperatures hot and cool. For the hot water trial, heat exactly one cup of water until it reaches the boiling point (when you see vigorous bubbling, not just little bubbles in the bottom of the container). You can do this in the microwave using a microwave-safe mug or glass, or heat the water in a pan on the stovetop: in either case, once the water is boiling, CAREFULLY (!!!!) pour it into a heat-safe glass. For the cool water trial, just pour exactly one cup of tap water into a clear glass. Place the glasses side-by-side (not touching) so you can get them both into one picture. Then, into each glass, at the same time, add one tea bag (or one teaspoon of ground coffee). If you are using tea, be sure the bags submerge, but do this as gently as possible. DO NOT STIR! Take a picture at the start of the process, right when you see the first hint of tea or coffee color in either of the glasses. We'll call this (time) t = 0. Be sure to take SIDE-VIEW pictures of everything in this lab, since that will show your experiments much more effectively than top-down pictures can! Set a timer for about 20 minutes and then take one more SIDE-VIEW picture. We'll call this t = 20 min. {Which trial has the darker color? Why would temperature alone make such a difference?}

Explanation / Answer

Hot water trial will have a darker colour.

Reason:

With increase in temperature the kinetic energy of molecules increases. This also increases rate of diffusion of particles. In this case diffusing particles are of tea. Due to faster diffusion of tea into hot water the colour changes frequently and becomes dark.

Where as in cold water, kinetic energy is low, diffusion takes place slowly. So appears lighter.

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