Use the data to calculate the heats of hydration of lithium chlor...

Question

Use the data to calculate the heats of hydration of lithium chloride 
and sodium chloride. Which of the two cations, lithium or 
sodium, has stronger ion–dipole interactions with water? Why?
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Accepted Answer

hey everyone in this example we need to determine between which of the two cat ions. Either rubidium nitrate or potassium nitrate will be more strongly hydrated in solution and we need to explain why. So for rubidium nitrate we want to recognize that it's entropy of the solution is going to equal the entropy of our salute added to its entropy of hydration. We should recall that the entropy of our salute is going to equal negative one times the entropy of our lattice. So according to the prompt, our rubidium nitrate has a solution. Entropy Equal to a value of 36.48 kg jewels Permal. And because we recall that our entropy of our salute is equal to the negative or negative one times the entropy of our lattice. We can say that our entropy of our salute for rubidium nitrate is equal to negative one times the prompt tells us that our Lattice entropy for rubidium nitrate is equal to negative 620 or negative 662 rather point oh kayla jewels per mole. So this gives us a value equal to positive 662 point oh kayla jewels per mole. So what we want to find is our entropy of hydration for rubidium nitrate first. And we would say that by reorganizing this formula here above. We can take our entropy of our solution which from the prompt and from above we stated is 36. kg jewels Permal. And because this is a change that is lost. We would say that this would be negative and we're going to subtract subtract this from our entropy of our salute which above we stated is equal to 662.0 Kayla jewels per mole. So this difference will give us our entropy of our hydration equal to a value of negative 698.5 kg joules per mole for rubidium nitrate. So below will follow the similar steps to determine the entropy of hydration for caesium nitrate. Where according to the prompt the entropy of our solution of caesium nitrate is equal to a value of 40 kayla jewels per mole. Since this is a change that we will observe in our solution we are also going to make this value negative here. So this should also be negative above as we stated earlier. And for the entropy of our salute in cesium nitrate we're going to take negative one times according to the prompt. It has a lattice entropy of -648. Kayla jewels per mole. So this would give us a positive value of 648.0 Kayla jewels per mole. And so calculating for the entropy of hydration For cesium nitrate we would take the difference between the entropy of our solution and the entropy of our salute. So we would have negative 40 killing joules per mole for our solution subtracted from the entropy of our salute which above the stated is positive 648 kg joules per mole. And so this difference gives us a value equal to -688 kayla jewels per mole for our caesium nitrate. So based on these two anthologies of hydration we can determine that therefore the Antebi of hydration for rubidium nitrate is greater than the entropy of hydration for sassy um nitrate. And so thus and we're going to scroll down for more room. We're going to say rubidium nitrate is more strongly hydrated in solution. Sorry this is solution due to it's smaller atomic radius creating a higher sorry that says higher charge density of rubidium plus one as a caddy on in comparison to C. C. Um So we would recall our trend of atomic radius on the periodic table which is increasing as we go towards the bottom left of our periodic table. And we would see based on the trend that cesium is a larger atom compared to rubidium. And so that's why for our final answer we stated that rubidium nitrate, sorry, rubidium nitrate here is going to be more strongly hydrated. It's going to have a higher charge density due to that because it has a smaller atomic radius compared to C. C. Um And so everything highlighted in yellow represents our explanation for why rubidium nitrate is more strongly hydrated in solution and we also will highlight our and copious of hydration for first caesium nitrate here and then second are entropy of hydration for rubidium nitrate. So everything highlighted in yellow represents our final answers. I hope that everything I explained was clear. If you have any questions, please leave them down below and I will see everyone in the next practice video.

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