[填空题]
Acids and bases can be classiflt*mh3r *r:jmmtjtcq e0-u ; ih73kp8ied as5j9c .lnmfu 7oqhac)bq;k;a2 strong or weak.
1.Explain why ammonia,$NH_3$ in an aqueous solution, acts as a weak base, using an equation.
2.An experiment was carried out to determine the energy change during the following reaction:
$2NH_3(aq) + H_2SO_4(aq) \rightarrow (NH_4)_2SO_4(aq)$
Initial temperature of each solution =$21.4^{\circ}C$
Final temperature of the mixture = $23.8^{\circ}C$
1.State with a reason whether the sign of the enthalpy change for this reaction is positive or negative.
2.Suggest with a reason whether the magnitude of the enthalpy change will be if aqueous ammonia is replaced with potassium hydroxide.