【Daily Question】Theoretical Foundation 2019.5.30
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Multiple-choice question: Mixing equal volumes of 0.08 mol•dm-3 KI and 0.1 mol•dm-3 AgNO3 solutions yields a sol system; adding respectively: (1) MgSO4； (2)CaCl2 ； (3) Na2SO4: the order of its coagulation ability is: ( ) A. (1)＞(2)＞(3) B. (2)＞(1)＞(3) C. (3)＞(1)＞(2) D. (3)＞(2)＞(1) Answer: C. When there is an excess of AgNO3 solution, the AgI colloid nuclei preferentially adsorb silver ions, causing the colloid particles to carry a positive charge; the higher the valence of the anions, the stronger the coagulation ability. The valence of the cation in MgSO4 is higher than that in Na2SO4, so MgSO4 has the strongest coagulation ability. Tip: The answer can be seen in the reply
C.(3)＞(1)＞(2)
C.(3)＞(1)＞(2)
B.(2)＞(1)＞(3)
B.(2)＞(1)＞(3)