At ordinary temperature and pressure, solid `NH_(4)Cl` dissolves in water to form `NH_(4)^(+)(aq) and Cl^(-)(aq) `ions. The process is endothermic. Indicate the signs `(+ or -)` of `DeltaS_(sys),DeltaS_("surr"),DeltaH and DeltaG`.

Explanation

(1) As the process is endothermic, `DeltaG gt0`.
(2) At ordinary temperature and pressure, the dissolution of solid `NH_(4)Cl` occurs spontaneously, so `DeltaG lt0`.
(3) `NH_(4)^(+) and Cl^(-)` ions in the crystal lattice of `NH_(4)Cl` are held at fixed position and consequently they are not able to move. but in an aqueous solution of `NH_(4)Cl ,NH_(4)^(+) and Cl^(-)` ions are distributed throughout the solution. naturally, the randomness of the ions in aqueous solution of `NH_(4)Cl` is greater than that in solid `NH_(4)Cl`. hence, in the dissolution process of `NH_(4)Cl,DeltaS_(sys) gt0`.
(4) As the process is endothermic, the system absorb heat from the surroundings, consequently, the surroundings lose heat. as a result, the entropy of the surroundings decreases `(DeltaS_(sys) lt0)`. however, the increase in entropy of the system is greater than the decrease in entropy of the surroundings. so, the net entropy change of the system and its surroundings is always positive, and the process occurs spontaneously.