Consider porous catalyst particles in the shape of thin disks, such that the surface area of the edge of the disk is small in comparison with that of the two circular faces. The catalyst reacts with a gas A with first order kinetics with a rate constant �! per unit surface area. The disk surface is exposed to a concentration of �"# which is held constant and the available surface area per unit volume is �. The rate of reaction �" per unit volume is given as �" = −�!��". (a) Show that the steady state concentration profile of A inside the disk is

If you chip a tooth, most likely you will go to the dentist to have the missing material filled in. currently the material used to fill in teeth is a polymer that is flexible when put in, yet is hardened to the strength of a tooth after irradiation with blue light at a wavelength of 461 nm. what is the energy in joules for a photon of light at this wavelength?

Of the following elements, which is the least reactive? a. c b. h c. li d. he

Can anyone explain 1. review your spectrometry data and use the known elements to identify the star's composition. which unknown elements make up this star? justify your element selections. 2. in parts i and ii of the lab, what happened to the electrons of each element to produce the different colors of light? explain your answers using important terms from the lesson and information provided in the laboratory. 3. stars composed of heavier (more massive) elements are often slightly older than stars made predominantly from hydrogen and helium. based on your data, is the newly discovered star a younger star? explain your answer.