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Here's the problem 40.
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Potassium nitrate has a lattice energy equal to negative 163 .8 kilo -calvin per mole, and a heat of hydration equal to negative 155 .5 kilocalvin per mole.
00:33
So the question is asking how much potassium nitrate has to dissolve in water, to absorb 1 times 10 to 2 kilojew of heat.
00:51
So we know that the enthalpy of solution, delta h of solution, is equal to the sum of entropy of solute plus the enthalpy of hydration, delta h of hydrogen.
01:15
And for ionic compounds, the entropy of solute is equal to the negative of lattice energy, or the lattice enthalpy.
01:25
So we have delta h of solute equal to negative delta h of lattice.
01:41
So we can calculate the amount of delta h of solute equal to negative negative 163 .8 kilo calve per mole.
01:58
And this will give you a positive number of 163 .8 kilocalvin per mole.
02:07
So this is the enthalpy of solute.
02:10
Then calculate the entropy of the solution will be equal to 163 .8 kilo -calorie per mole plus negative 155 .5 kilocalory per mole.
02:37
Because delta -h solution is equal to delta h of salute which is calculated right here and delta h of hydration is equal to this number so this is this part and this is this number so we get a number of positive 8 .3 kilocalorie per mole all right so then the relationship between kilo calorie and kilojoules is that 1 kilocalory equal to 4 .184 kilojoules...