A potassium vapor sign consists of K atoms which give off violet light ( = 425.4 nm). a. Calculate the frequency for this wavelength. b. Calculate the E when only one atom gives off light and when 0.333 moles of atoms give off light simultaneously. (c = 2.9979 x 108 m/s, h = 6.626 x 10-34 J*s)

1. suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3.

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion

Calculate - analysis of compound composed of iron and oxygen yields 174.86 of fe and 75.14g of o. what is the empirical formula for this compound?