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When a 2.00 g sample of KCl is dissolved in water in a calorimeter that has a total heat capacity of 1.28 kJ ⋅ K − 1 , the temperature decreases by 0.360 K . Calculate the molar heat of solution of KCl .

Respuesta :

Answer : The molar heat of solution of KCl is, 17.19 kJ/mol

Explanation :

First we have to calculate the heat of solution.

[tex]q=c\times (\Delta T)[/tex]

where,

q = heat produced = ?

c = specific heat capacity of water = [tex]1.28kJ/K[/tex]

[tex]\Delta T[/tex] = change in temperature = 0.360 K

Now put all the given values in the above formula, we get:

[tex]q=1.28kJ/K\times 0.360K[/tex]

[tex]q=0.4608kJ=460.8J[/tex]

Now we have to calculate the molar heat solution of KCl.

[tex]\Delta H=\frac{q}{n}[/tex]

where,

[tex]\Delta H[/tex] = enthalpy change = ?

q = heat released = 460.8 J

m = mass of [tex]KCl[/tex] = 2.00 g

Molar mass of [tex]KCl[/tex] = 74.55 g/mol

[tex]\text{Moles of }KCl=\frac{\text{Mass of }KCl}{\text{Molar mass of }KCl}=\frac{2.00g}{74.55g/mole}=0.0268mole[/tex]

Now put all the given values in the above formula, we get:

[tex]\Delta H=\frac{460.8J}{0.0268mole}[/tex]

[tex]\Delta H=17194.029J/mol=17.19kJ/mol[/tex]

Therefore, the molar heat of solution of KCl is, 17.19 kJ/mol

mickymike92

Based on the data provided, the molar heat of solution of KCl is 17.19 kJ/mol

What is the molar heat of solution of a substance?

The molar heat of solution of a substance is the amount of heat evolved or absorbed when 1 mole of that substance dissolves.

To calculate the molar heat of solution of KCl, we calculate the heat of solution:

  • q = c×ΔT

where,

q = quantity of heat produced

c = heat capacity of calorimeter = 1.28kJ/K

ΔT = change in temperature = 0.360 K

Substituting the values:

q = 1.28kJ/K × 0.360K

q = 0.4608kJ

q = 460.8J

The molar heat of solution is then calculated using the formula below:

  • ΔH = q/n

where,

  • ΔH = enthalpy of solution
  • q = heat released = 460.8 J
  • n = number of moles of KCl
  • n = mass/molar mass

mass of KCl = 2.00 g

Molar mass of KClKCl = 74.55 g/mol

moles of KCl 2.00/74.55

moles of KCl = 0.0268 moles

Therefore;

ΔH = 460.8 J / 0.0268 moles

ΔH = 17194.029J/mol

ΔH = 17.19kJ/mol

Therefore, the molar heat of solution of KCl is 17.19 kJ/mol

Learn more about enthalpy of solution at: https://brainly.com/question/9423112

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