Potassium and hydrogen react to form the ionic compound
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Question

Potassium and hydrogen react to form the ionic compound 
potassium hydride. (b) Use data in Figures 7.10 and 7.12 to determine 
the energy change in kJ/mol for the following two reactions: 
K1g2 + H1g2 ¡ K+1g2 + H-1g2 
K1g2 + H1g2 ¡ K-1g2 + H+1g2

Accepted Answer

hey everyone in this example, we need to calculate the change in energy for the given reactions based on the ionization energy and electron affinity of the involved elements. So looking at part A were given lithium solid reacting with chlorine gas to form our lithium an ion and our chlorine catty on. So for part A we're going to find our change in energy by taking our electron affinity for our lithium adam and then adding that to the ionization energy. The first ionization energy for chlorine. So what we would have for part A is that delta E. Is equal to in our textbooks, we would see that lithium has an electron affinity equal to a value of negative kg jewels. And we would add this to our ionization energy of chlorine from our textbooks which equals a value of 1251 kg joules. So what we're going to get is that our value for delta E. Is equal to 1191 kg jewels as our final answer for part A. And the change in energy. So moving on to part B, we recognize that it says that we are dealing with lithium reacting with chlorine gas to produce the lithium catalon and the chloride an ion. So because this time we have formed our lithium Cagayan, we're going to now find our change in energy by taking our ionization energy of our caddy on lithium and then adding that to our electron affinity of our an ion, which in this case is now chlorine. So what we're going to have is that the change in energy is equal to the ionization energy of lithium From our textbooks, which is equal to a value of 520 kg jewels. And now we're going to add this to the electron affinity of chlorine from our textbooks, which we would see equals a value of negative 3 49 kilo jewels. And adding these two up, we're going to get a value of 171 kg jewels as our final answer for the change in energy of equation B. So everything boxed in blue represents our final answers for parts A and B. If you have any questions, please leave them down below and I will see everyone in the next practice video.

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