13. Which one of these salts will form a neutral solution on dissolving in water

Question

13. Which one of these salts will form a neutral solution on dissolving in water? sirong actd 14. Which one of these salts will form a basic solution on dissolving in water? Neutral acidT 5. Phosphoric acid has three pKa values, pKa. I= 2.12, pKa, 2-68; and pKa, 13 = 12.5. which ne of these pKa values would be most useful to solve for the pH of a solution of 0.30 M H2PO4? ) pKa. B) pKa,2 C) pKa, 3 D) none of these would be useful ) impossible to answer without further information. 6. 1.25 moles of NOCI were placed in a 2.50 L reaction chamber at 427°C. After equilibrium was reached, 1.10 moles of NOCI remained. Calculate the equilibrium constant, Ke, for the reaction 2NOCI(g) 2NO(g) + Cl2(g). A) 3.0 × 10-4 B) 1.8 × 103 C) 1.4 x 10-3 D) 5.6 x 104 E) 4.1x 10-3

Explanation / Answer

13) A) KCl

Reason : KCl is a salt of strong base KOH and strong acid HCl

14) D) NH4NO3

Reason: NH4NO3 is a salt of weak base NH3 and strong acid HNO3

15) B) pKa,2

16)

we know that

concentration = moles / volume (L)

so

initial conc of NOCl = 1.25 / 2.5 = 0.5 M

equilibrium conc of NOCl = 1.1 / 2.5 = 0.44 M

now

consider the reaction

2 NOCl <---> 2 NO + Cl2

using ICE table

initial conc of NOCl, NO,Cl2 are 0.5 , 0 , 0

change in conc of NOCl, NO,Cl2 are -2y , +2y , y

equilibrium conc of NOCl,NO,Cl2 are 0.5-2y , 2y , y

now

[NOCl]eq = 0.5 - 2y = 0.44

y = 0.03

so

[NOCl]eq = 0.44 M

[NO]eq = 2y = 2 x 0.03 = 0.06 M

[Cl2]eq = y = 0.03 M

now

Keq = [NO]^2 [Cl2] / [NOCl]^2

Keq = (0.06)^2 (0.03) / (0.44)^2

Keq = 5.58 x 10-4

so

the answer is option D ) 5.6 x 10-4

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