Answer:
KNO₃(s) + 35,1 kJ → K⁺(aq) + NO₃⁻(aq)
Explanation:
In the reaction:
KNO₃(s) → K⁺(aq) + NO₃⁻(aq)
The heat absorbed for the reaction (Because the temperature decreases) is:
Q = C×m×ΔT
Where C is specific heat (4,18J/g°C); m is mass (100g); ΔT is (30,0°C-21,6°C = 8,4°C)
Replacing:
Q = 4,18J/g°C×100g×8,4°C
Q = 3511 J
Now, moles of KNO₃ are:
10,1g×(1mol / 101g) = 0,1 moles.
Heat of solution in kJ/mol is:
3,511 J / 0,1 mol = 35,1 kJ
As the heat was absorbed for the reaction, right answer is:
KNO₃(s) + 35,1 kJ → K⁺(aq) + NO₃⁻(aq)
That means the reaction needs the heat to occurs.
I hope it helps!