Silicon has a band gap of 1.1 eV at room temperature.
(a) What wavelength of light would a photon of this energy correspond to?
(b) Draw a vertical line at this wavelength in the figure shown, which shows the light output of the Sun as a function of wavelength. Does silicon absorb all, none, or a portion of the visible light that comes from the Sun?
(c) You can estimate the portion of the overall solar spectrum that silicon absorbs by considering the area under the curve. If you call the area under the entire curve “100%,” what approximate percentage of the area under the curve is absorbed by silicon?
CHM 031 Chemical Equilibria in Aqueous Systems Chapter 18 Notes Chapter 18 Electrochemistry: The Quest for Clean Energy 18.1 Running on Electrons: Redox Chemistry Revisited ❏ Electrochemistry - the branch of chemistry that examines the transformations between chemical and electrical energy ❏ Electrochemical cell - an apparatus that converts chemical energy into electrical work or electrical work into chemical energy ❏ Anode - an electrode at which an oxidation half-reaction (loss of electrons) takes place ❏ Cathode - an electrode at which a reduction half-reaction (gain of electrons) takes place 18.2 Voltaic and Electrolytic Cells ❏ Voltaic cell - an electrochemical cell in which chemical energy is transformed into electrical work by a spontaneous cell reaction ❏ Electrolysis - a process in which electrical energy is used to drive a nonspontaneous chemical reaction ❏ Electrolytic cell - a device in which an external source of electrical energy does work on a chemical system, turning reactant(s) into higher-energy product(s) ❏ Cell diagram - symbols that show how the components of an electrochemical cell are connected 18.3 Standard Potentials ❏ Standard reduction potential (E ) - the potential of a reduction half-reaction in which o all reactants and products are in their standard states at 25 C ❏ Standard cell potential (E
