Question

KNO3(s) --> K+(aq) + NO3-(aq)

Answer 1

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!