Please answer all A sait that could be used with HNO_3 to make a buffer is NH_4C

Question

Please answer all A sait that could be used with HNO_3 to make a buffer is NH_4Cl NaC_2H_2O_2 neither A, B, or C Which of the following mixtures is suitable for making a buffer solutions with an optimum pH of 4.6-4.8? NaNO_2/HNO_2 k_a = 4.5 times 10^-4 HA/NaA k_a = 5.6 times 10^20 NaOCl/HOCl k_a = 3.2 times 10^-8 CH_3CO_2Na/CH_3CO_2H k_a = 1.8 times 10^-4 Choose the most effective buffer of the following solutions a solution that is 0.10M NaCl and 0.10M HCl a solution that is 1.0 M HNO_2 and 1.0 M NaNO_2 a solution that is a0.10 M NaOH and 0.10M HNO_3 a solution that isa0.1 M HNO_2 and 0.1M NaNO_2 A 1.0L buffer solution is 0.10 M in HF and 0.05M in NaF. Which action would destroy the buffer? Adding 0.05 mol of HCI Adding 0.05 mol of NaF Adding 0.05 mol NaOH Adding 0.05 mol HF When titrating a strong monoprotic acid with KOH at 25 degree C, the pH will be less than 7 at the equivalence point. pH will be greater than 7 at the equivalence point pH will be equal to 7 at the equivalence point titration will require more moles of base than acid to reach the equivalence point Which of the following would decrease the solubility of Pbl_2? Pbl_2(s) irreversible Pb^2+(aq) + 2I^-(aq) add Pb(NO_3)_2 add KI both A and B neither A, B or C

Explanation / Answer

Q19

For a buffer, we need conjugate acid/bases so:

Note that by definition, the HNO3 will NOT form buffer, since it is strong acid

so, a b and c are not possible answers

choose D

Q20

if pH range is 4.6 to 4.8

we need

the inverse function of p

Ka = 10^-pKa = 10^-4.7

Ka = 1.8*10^-5 approx

the best option is the value of Ka neares to the range

that will be the

answer in D,

Q21

most effective buffer --> will hav ethe larges concentrations

a, c and d are all of 0.1 M which is pretty low

choose B which is larger amount, i.e. 1 M

Q22

0.05 mol of acid, since

NaF + H+ = HF which will have only HF acid an no F- ions left

Q23

for a monoprotic acid... expect a hydrolysis similar to:

A- + H2O <-> HA + OH-

so expect a pH > 7

Q24

For decrease in solubility, we must increase either Pb+2 ions of I- ions

so choose KI or Pb(NO3)2

choose C

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