Which of the following seems the most reasonable pH of 0.02 M NH_3 solution? 6.1

Question

Which of the following seems the most reasonable pH of 0.02 M NH_3 solution? 6.10 pH 7.00pH 10.25pH 12.31 pH Calculate pH of a solution with [OH^-] = 7.32 Times 10^5 M. 12.86 1.13 7.00 12.10 What is the acid for the conjugate base HCOO^-? HCHOOH COO^2- HCOH^- HCOOH How would dissociation of HCO^-_3 (weak base) look like in water? HCO_3^- (aq) + H_2O(l) doubleheadarrow CO_3^2-(aq) + OH^-(aq) HCO_3^- (aq) + OH(aq) doubleheadarrow CO_3^2-(aq) + H_2O(l) HCO_3^- (aq) + H_2O(l) doubleheadarrow H_2CO_3(aq) + OH^-(aq) HCO_3^- (aq) + H_2O(l) doubleheadarrow CO_3^2-(aq) + H_3O^+(aq) What is the pH of 8.15 Times 10^4 M HNO_3 2.34 3.10 8.15 7.00 Which of the following sets is correct? Which of the following is not a strong acid? HNO_3 H_2SO_4 HI HClO_3

Explanation / Answer

Solution :-

Q16) NH3 is the weak base with kb = 1.8*10^-5

So the most reasonable pH for the   0.02 M NH3 is 10.25 because 10.25 is the basic pH which is suitable for the weak base

So the answer is option C

Q17) [OH-] = 7.32*10^-2

Lets calculate the H3O+ from the given OH-

[H3O+] = Kw/ [OH-]

             = 1*10^-14 / 7.32*10^-2

             = 1.37*10^-13

Now lets calculate the pH

pH= -log [H3O+]

     = -log [ 1.37*10^-13]

   = 12.86

So the correct answer is option A

Q 18)

Conjugate acid and base differ by the one proton so the conjugate acid for the HCOO- is HCOOH

So the correct answer is option D

Q19)

HCO3^- is weak base so when it reacts with water then it forms conjugate acid and OH-

So the correct equation is as follows

HCO3- + H2O ----- > H2CO3 + OH-

So the correct answer is option C.

Q20) HNO3 is the strong acid so we directly use the given concentration to calculate the pH

pH= -log [H3O+]

pH= -log [8.15*10^-4]

pH= 3.10

so the correct answer is option B

Q21)

pH= -log [H+]

pH= -log [6.46*10^-3]

pH= 2.19

pOH= 14 – pH

       = 14 – 2.19

       = 11.81

So the set A is not correct

Set B

pH= -log [3.16*10^-5] = 4.50

so the set B is not correct

Set C

pH= -log [5.62*10^-10] = 9.25

pOH = 14 – 9.25 = 4.75

so the set C is correct

Set D

Set D is not correct because [H+] [OH-] = 1*10^-14

So the answer is only set C is correct.

Q22) HClO3 is not the strong acid among the given acid list.

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