which of the following could be an approximate value of the pH at the equivalenc
ID: 502558 • Letter: W
Question
which of the following could be an approximate value of the pH at the equivalence point of a situation of a strong acid with a weak base? A) 1 B) 12 C) 9 D) 7 E) 4-6 Which results in a buffered solution? A) A training a strong acid and its conjugate base B) A solution containing a strong base and its conjugate acid C) A a catalyst D) A solution containing two organic liquids E) A solution containing weak acid and its conjugate base write the ion product expression for calcium phosphate, Ca_2(PO_4)_2. A) [Ca^2+]_3 [PO_4^3-]_2 B) 3[Ca^2+] times 2[PO_4^3-] C) [3 times Ca^2+]^3 [2 times PO_4^3-]^2 D) 3[Ca^2+]^3 + 2[PO_4^3-]^2 E) [Ca^2+]^3 [PO_4^3-]^2 Which is the best acid to prepare a buffer with the lowest pH? A) C_5H_5O_5COOH, K_a = 4.0 times 10^-6 B) HPC_6H_4OCOOH, K_a = 1.0 times 10^-3 C) HbrO, K_a = 2.43 times 10^-9 D) C_6H_4(COOH)_2, K_a = 2.9 times 10^-4 E) CH_3COOH, K_a = 1.8 times 10^-5 Calculate the solubility of silver carbonate, Ag_2CO_3, in pure water [K_sp(Ag_2CO_3) = 8.1 times 10^-12] A) 6.0 times 10^-6 mol L^-1 B) 2.0 times 10^-4 mol L^-1 C) 4.3 times 10^-6 mol L^-1 D) 1.3 times 10^-4 mol L^-1 E) 1.6 times 10^-4 mol L^-1 What is deltaG degree for the following reaction? 2Na(I) + FeCl_2(s) 2NaCl(s) + Fe(s) E degree_cell = 2.35 v A) -454 kJ B) 454 kJ C) -907 kJ D) -907 kJ E) 227 kJ What is the E degree_cell for the following reaction? Cu^2+(aq) + Co(s) rightarrow Cu(s) + co^2+(aq) A) 0.62 v B) 0.06 v C) -0.62 v D) 0.43 v E) none of aboveExplanation / Answer
10) At the equivalence point of titrationof strong acid with weak base , a salt is formed , whose pH is acidic.
Thus the pH at equivalence would be around 4-6 . Option E
11) Option E
a solution containing a weak acid and its conjugate base forms a buffer.
12) option E
Ca3(PO4)2 ----->3 Ca+2 + 2PO4-2
Thus Ksp = [Ca+2]3[Po4-2]]2
13) The buffer behaves best when pH = pKa .Thus to have lowest pH buffer , we choose the acid with lowest pKa , that is optionB.
14) Ag2CO3 <-----> 2Ag+ + CO3-2
s 2s s
Thus Ksp = [Ag+]2[CO3]
= (2s)2 s
8.1x10-12 = 4s3
or s = 1.26x10-4 M
Thus option D is correct.
15) we know delta g = -nFE
= -2 x 96500 C x 2.35V
= -453550 J
= -453.55 kJ
Thus option A
16) option A
SRP of Cu = =0.34 V and SRP of Co = -0.28 V
Thus for the given cell E cell = 0.34V -(0.28)
= 0.62V
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