222. $8.4\ \text{g}$ of potassium hydroxide $(M = 56\ \text{g.mol}^{-1})$ is added to $150\ \text{g}$ of water. If the initial temperature of all substances is $25^\circ\text{C}$ and the specific heat capacities of water and potassium hydroxide solution are $4.2$ and $1\ \text{J}$ per gram per degree Celsius respectively, and the system reaches equilibrium at $40^\circ\text{C}$, what is the approximate enthalpy of dissolution of KOH in $\text{kJ.mol}^{-1}$? (Heat absorbed by the calorimeter is neglected.)
(1) $59/8$ (2) $56$ (3) $63/8$ (4) $75$
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\textbf{222.} $8.4\ \text{g}$ of potassium hydroxide $(M = 56\ \text{g.mol}^{-1})$ is added to $150\ \text{g}$ of water. If the initial temperature of all substances is $25^\circ\text{C}$ and the specific heat capacities of water and potassium hydroxide solution are $4.2$ and $1\ \text{J}$ per gram per degree Celsius respectively, and the system reaches equilibrium at $40^\circ\text{C}$, what is the approximate enthalpy of dissolution of KOH in $\text{kJ.mol}^{-1}$? (Heat absorbed by the calorimeter is neglected.)
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(1) $59/8$ \quad (2) $56$ \quad (3) $63/8$ \quad (4) $75$
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