When dilute aqueous solutions of two salts are mixed, the process is associated with
A
Decrease in temperature
B
Increase in temperature
C
No change in temperature
D
Change in temperature which is a function of composition
Correct Answer: Increase in temperature
According to the first law of thermodynamics$$\delta Q = dU + \delta W$$
So, as there is no heat exchange and assuming no work is done $$w$$ can write
$$\eqalign{ & d{U_{1\,\left( {salt} \right)}} + d{U_{2\,\left( {salt} \right)}} = 0 \cr & \Rightarrow m{C_A}\left( {{T_f} - {T_A}} \right) = m{c_B}\left( {{T_f} - {T_B}} \right) \cr & {\text{So,}}\,{T_f} = \frac{{{m_A}CATA + {m_B}cBTB}}{{{m_A}{c_A} + {m_B}{c_B}}} \cr} $$
So, the final temperature is dependent on concentration or composition.
