How much potassium nitrate has to dissolve in water to absorb 116 kj of heat?
Monday, February 8th, 2010 at
5:37 AM
Potassium nitrate has a lattice energy of -163.8 kcal/mol and a heat of hydration of -155.5 kcal/com.
I really need help!
Filed under: Water
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_____Summing dHs
____KNO3 (s) —-___–> KNO3 (bits) -___—-> solvated KNO3 (bits)
____________-163.8kcal/mole_________dH= -155.5 kcal/mole
dHsolv = -155.5 + 163.8 kcal/mole
g KNO3 = MW KNO3 g/mole * (116kJ / 4.186 kJ/kcal) / (-dHsolv kcal/mole) = ??
heat required to solvate KNO3 = 8.34 kcal/mole * 4.186 kJ/kcal = 34.9 kJ/mole
Looks like 300-400 g
Plug and SOLVE
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