Why don't the gases in the atmosphere form different layers of gases based on their densities/weights? For example, if there are trace amounts of neon in the atmosphere, why doesn't neon make up a small layer at the bottom of the atmosphere. Furthermore, if oxygen is the 3rd lightest gas in the atmosphere, why isn't all the oxygen at the top of the atmosphere, near space?

Water (2510 g ) is heated until it just begins to boil. if the water absorbs 5.09×105 j of heat in the process, what was the initial temperature of the water?

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.

The small bags of silica gel you often see in a new shoe box are placed there to control humidity. despite its name, silica gel is a solid. it is a chemically inert, highly porous, amorphous form of sio2. because water vapor readily adsorbs onto the surface of silica gel, it acts as a desiccant. despite not knowing mechanistic details of the adsorption of water onto silica gel, from the information provided you should be able to make an educated guess about the thermodynamic characteristics of the process. predict the signs for δg, δh, and δs for the adsorption of water.