This course explains how chemical processes help drive the Earth system. Earth and space scientists require a strong background in the fundamentals of matter and chemistry in order to interpret processes that shape the Earth system. A raindrop falls through the air, interacting with the CO2 and becoming slightly acidic. Water that would have simply flowed through rock, if neutral, now reacts with the minerals in the rock and turns them into clay that will easily erode away. Ocean water reacts with volcanic rocks on the ocean bottom so that their physical properties change completely. When these rocks are dragged down into the Earth along plate boundaries, minerals that were once strong enough to withstand great forces now act as lubricants along this great plate boundary fault system. Heat generated deep within the Earth flows outward by conduction and convection, working to equalize the temperature difference between Earth’s interior and outer space. This expression of thermodynamics turns an otherwise dead planet into a hotbed of geologic activity plagued by volcanoes and earthquakes. In each case, an Earth or space scientist is studying the chemistry of the situation, perhaps using a computer model to fast forward millions of years of chemical reactions to explain what we see on Earth today. Alongside this scientist is a team of engineers, looking hoping to use this understanding to design and test solutions to many of society’s problems from natural hazards to global warming or to minimize our impact on the natural world.