Respuesta :
Answer : The [tex]\Delta H_{soln}[/tex] for KF is -5.935 KJ/mole.
Solution : Given,
Mass of potassium fluoride = 117 g
Volume of water = 599 ml
Density of water = 1 g/ml
Molar mass of potassium fluoride = 58 g/mole
Temperature = [tex]4^oC[/tex]
Specific heat capacity of water = [tex]4.18J/g^oC[/tex]
First we have to calculate the mass of solution.
Mass of water = Density × Volume = 1 × 599 = 599 g
Mass of solution = Mass of water + Mass of KF = 599 + 117 = 716 g
Now we have to calculate the heat absorbed by the solution.
Here, we assume that the specific heat capacity of the solution is the same as that of water.
Heat absorbed by the solution = [tex]m\times c\times \Delta T[/tex]
Heat absorbed by the solution = [tex](716g)\times (4.18J/g^oC)\times (4^oC)=11971.52J[/tex]
Since the solution absorbed heat, the dissolution of KF must be exothermic and must have released [tex]-11971.52J[/tex]
Now we have to calculate the moles of KF dissolved in solution.
Moles of KF = [tex]\frac{\text{ Mass of KF}}{\text{ Molar mass of KF}}=\frac{117g}{58g/mole}=2.017moles[/tex]
Now we have to calculate the [tex]\Delta H_{soln}[/tex] for KF.
[tex]\Delta H_{soln}=\frac{\text{ Heat absorbed by the solution}}{\text{Moles of KF}}=\frac{-11971.52J}{2.017moles}=-5935.309J/mole=-5.935KJ/mole[/tex] [tex](1KJ=1000J)[/tex]
Therefore, the [tex]\Delta H_{soln}[/tex] for KF is -5.935 KJ/mole.
-5.935kJ/mol is the ΔH for the solution for potassium fluoride.
How we calculate ΔH for the solution?
ΔH for the KF in the given solution will be calculated as:
ΔH = Heat absorbed by the solution / Moles of KF
Heat absorbed by the solution is calculated as:
Q = mcΔT, where
c = specific heat of water = 4.18J/g.°C
ΔT = change in temperature = 4 °C
m = mass of the solution = mass of water + mass of KF (given)
Mass of water = density × volume = 1.00 g/mL × 599 mL = 599g
m = 599 + 117 = 716g
Now, Q = 716 × 4.18 × 4 = 11971.52 J
If we add potassium fluoride then the dissolution of KF will release energy and its value will be -11971.52 J.
Moles of KF will be calculated as:
n = W/M, where
W = given mass = 117g
M = molar mass = 58 g/mol
n = 117 / 58 = 2.017 moles
ΔH for the solution = -11971.52 / 2.017 = -5935.309 J = -5.935kJ/mol
Hence, ΔH for the solution is -5.935kJ/mol.
To know more ΔH, visit the below link:
https://brainly.com/question/26491956
