10. Which of the following description ..-阿摩線上測驗
10. Which of the following description is correct? (4%)
(A) The solubility product constant (Ksp) of aluminum hydroxide (Al(OH)3) is 3 ×10-34; the Ksp of cadmium sulfide (CdS)
is 1× 10-27. Based on this information, we know that Al(OH)3 is less soluble than CdS in pure water.
(B) A glass of aqueous solution (100 mL) contains [Ca2+] = 2.13✖10-4 M, [F-] = 4.26✖ 10 -4 M, and 0. 781 g of insoluble
Caf2 solid. Based on this information, we can estimate the Ksp of Caf2 to be ~3.9 x 10-11
(C) Even through the same chemical can sometimes exist in more than one crystalline form, e.g., CaCO3 can be both
calcite and aragonite, they are always equally soluble.
(D) The pKa1and pKa2 of methionine are 2.28 and 9.21. Based on this information, we know that methionine has the
best buffering power (capacity) at pH 5.75 (the mid-point between the two pKa values).
(E) The hydrogen cation concentration ([H+]) of a pH 6.5 solution is 5.0 ✖10-7 M.