Gasoline is a common fuel. most gas stations sell multiple grades of gasoline. these grades are distinguished by their octane content. octane (c8h18) is one of the components of gasoline, which may also contain many other types of hydrocarbons (such as decane, dodecane, and nonane). the fraction of gasoline that is made up of octane affects how the gasoline burns in a car’s engine. higher octane ratings are typically more expensive and can improve performance in certain types of engines. is gasoline a compound or a mixture? compound mixture explain your reasoning.

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.