\begin{matrix} Q_{Ab} = - Q_{Auf} \\ c_{w} \cdot m_{2} \cdot Δ T_{2} = - (c_{w} cdt m_{1} + C_{K}) \cdot Δ T_{1} \\ \Rightarrow - c \cdot m_{2} \frac{Δ T_{2}}{Δ T_{1}} = c_{w} \cdot m_{1} + C_{K} \\ \Rightarrow C_{K} = c_{w} \cdot m_{2} \frac{Δ T_{2}}{Δ T_{1}} - c_{w} \cdot m_{1} \\ = - 4,19 \frac{J}{g \cdot K} \cdot 50 g \cdot (\frac{- 14,0 K}{12,5 K}) - 4,19 \frac{J}{g \cdot K} \\ = 25,1 \frac{J}{K} \end{matrix}