Presentation on theme: "Section 3. Chemical energy is the energy stored in chemical compounds In the 1780s, Luigi Galvani was studying the anatomy of a frog. He was using."— Presentation transcript:
Chemical energy is the energy stored in chemical compounds In the 1780s, Luigi Galvani was studying the anatomy of a frog. He was using an iron hook to hold the leg muscle in place. He accidentally touched the hook to an iron railing and the frogs leg twitched. Alessandro Volta claimed that Galvani caused a chemical reaction, which made the leg twitch. A chemical reaction is a process in which substances change into new substances with different properties. Volta built the first electrical battery by layering zinc, paper soaked in salt water, and silver.
An electrochemical cell is a device that transforms chemical energy into electrical energy. An electrochemical cell consists of two metals called electrodes. Electrodes are metals immersed in a substance called an electrolyte. An electrolyte is a substance that conducts electric current. Volta used silver and zinc as electrodes and salt water as an electrolyte.
A terminal is used to connect the cell to a circuit. Chemical reactions occur between the electrolyte and the electrodes in an electrochemical cell. These reactions cause one electrode to become negatively charged and one electrode to become positively charged. Because of the opposite charges, voltage occurs.
A battery is a combination of 2 or more electrochemical cells in a series. The positive terminal of one cell is connected to the negative terminal of another cell.
There are 2 kinds of electrochemical cells: wet and dry cells. Wet cells are electrochemical cells in which the electrolytes are liquids. You will find these types of batteries in cars, boats, etc.
A dry cell is an electrochemical cell in which the electrolyte is a paste. Batteries that you find in flashlights are dry cells.