Heat of Reaction of Alkali metal with water. 2

[bbqnw12]

Please, can someone help me out with the actual values of the Heat of Reaction of Potassium + Water, and Calcium Hydride + Water?

Thanks in advance.

 

[kenvlach]

This is similar to the prior case for NaH.
Data are from Perry’s, 7th ed., Table 2-220.

For potassium + water, the stoichiometric reaction (no excess water) is

K(s) + H₂O(l) --> KOH(s) + ½ H₂(g)

&[ignore]Delta[/ignore];H_{Rxn, 25 C} = -102.02 + 0 – 0 – (-68.32) = -33.7 kcal/mol

For potassium + water, with excess water (value is for final solution KOH in 400 H₂O), the reaction is

K(s) + H₂O(l) --> KOH(aq, 400H₂O) + ½ H₂(g)

&[ignore]Delta[/ignore];H_{Rxn, 25 C} = -114.96 + 0 – 0 – (-68.32) = -46.64 kcal/mol

For CaH₂, the stoichiometric reaction (no excess water) is

CaH₂(s) + 2 H₂O(l) --> Ca(OH)₂(s) + 2 H₂(g)

&[ignore]Delta[/ignore];H_{Rxn, 25 C} = - 235.58 + 0 – (-46) – 2(-68.32) = -52.94 kcal/mol

For CaH₂, the reaction with excess water is

CaH₂(s) + 2 H₂O(l) --> Ca(OH)₂(aq, 800H₂O) + 2 H₂(g)

&[ignore]Delta[/ignore];H_{Rxn, 25 C} = - 239.2 + 0 – (-46) – 2(-68.32) = -56.56 kcal/mol

These reactions may be vigorous, and possibly explosive without excess water. Lots of heat (even more if the H₂ ignites!). What is your application?

 

[bbqnw12]

kenvlach, the application is confidential, but I can tell you that I wish to generate an enormous amount of heat, albeit via as cheap a reaction as possible. Thank you for your reply, as it further helps me in my investigation. Any ideas you may have along these lines would be equally helpful. You have my vote...