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

Answer: Option B

Solution(By Examveda Team)

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.