Mercury in the environment can exist in oxidation states 0, +1, and +2. One major question in environmental chemistry research is how to best measure the oxidation state of mercury in natural systems; this is made more complicated by the fact that mercury can be reduced or oxidized on surfaces differently than it would be if it were free in solution. XPS, X-ray photoelectron spectroscopy, is a technique related to PES (see Exercise 7.111), but instead of using ultraviolet light to eject valence electrons, X rays are used to eject core electrons. The energies of the core electrons are different for different oxidation states of the element. In one set of experiments, researchers examined mercury contamination of minerals in water. They measured the XPS signals that corresponded to electrons ejected from mercury's 4f orbitals at 105 eV, from an X-ray source that provided 1253.6 eV of energy 11 ev = 1.602 * 10-19J2. The oxygen on the mineral surface gave emitted electron energies at 531 eV, corresponding to the 1s orbital of oxygen. Overall the researchers concluded that oxidation states were +2 for Hg and -2 for O. (b) Compare the energies of the 4f electrons in mercury and the 1s electrons in oxygen from these data to the first ionization energies of mercury and oxygen from the data in this chapter.

Video transcript

hey everyone in this example we need to calculate the experimental ionization energy and units of joules per mole for 10. And strontium. If their experimental charges are 7.35 electron volts and 5.69 electron volts. So beginning with our calculation of ionization energy for 10, We would recall that that we would begin this by taking its charge given in the prompt as 7.35 electro volts. We're going to recall the charge of an electron which is 1.602 times 10 to the negative 19th power jules per electra vault. Which will allow us to cancel our units of electron volts. But because we want our final units to be killed jules Permal we would multiply by the conversion factor where we would recall that for one jewel we have our prefix kilo which means 10 to the negative third power kilo jewels. So now we're able to cancel our units of jewels. And now we want to apply by our last or multiplied by our last conversion factor. Where we would recall avocados number which tells us that we would have 6.022 times 10 to the 23rd power atoms per more. So what we're left with is units of kilograms times Adams Permal. Which we can interpret as kilo, joules per mole because our final answer here is going to equal a value of kayla jules Permal of An Atom of 10. So moving on to the ionization energy calculation for strontium, we're going to follow the same process where we're going to take the charge or the experimental charge given in the prompt for strontium as 5.69 electro volts. We're going to recall that our charge of an electron is 1.6 so two times to the negative 19th power jewels per electoral vote. So now we're able to cancel out our units of electron volts. And next we're going to again convert from jules, tequila jewels by recalling our prefix kilo tells us for one kg jule we have 10 to the negative third power kilo jewels. Next we're going to multiply by because we would be able to cancel our jewels. So we want to get two kg per mole by recalling avocados number which tells us we have six point oh 22 times 10 to the 23rd power atoms Permal. And so now what we're going to get here is a value equal to 549 kg jewels Permal as our ionization energy for strontium for an atom of strontium. And so for our final answers, we have these two values that were boxing in here to complete this example. So I hope that everything I explained was clear. If you have any questions, please leave them down below. Otherwise I'll see everyone in the next practice video