What is the frequency and wavelength of a photon absorbed in the transition of an electron from the n=5 to the n=8 of dye #3 (1-1’-diethyl-2-2’-dicarbocyanine iodide).

to do this calculation, you will need to make a reasonable assumption for the value of l. as a first approximation, we will assume that the value of lcc in these molecules is the same as in benzene and pyridine, two similar delocalized systems: lcc = 0.140 nm (benzene) lcn = 0.134 nm (pyridine)

the aromatic rings capping the ends of the dye molecules complicate the unambiguous assignment of length. indeed, several reasonable choices are possible. one simple choice is assume the length of the molecule to be from one n atom to the other n atom. the effect of the rest of the aromatic rings is then considered to be absorbed into the parameter ‘p’ (equation 7). considering the information given above, estimate the value of ‘p’. ex: do you think the electron will penetrate far outside the nitrogen caps, or vice versa? (after comparing your predictions to the experiment, you will be able to derive a more accurate value for ‘p’.)

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.

Voltaic cells produce a positive overall charge. what does this indicate? a. the reaction is likely to be endothermic. b. the reaction is spontaneous. c. the reaction is not likely to occur. d. the reaction is not spontaneous.

At stp, which substance is the best conductor of electricity? a. nitrogen b. neon c. sulfur d. silver