If you prepare it as a buffer solution to control the pH, is possible to prevent the precipitation of Aluminum Hydroxide from a 0.00452 M Aluminum nitrate solution. Which of the following buffers solutions would not result in the precipitation of Aluminum Hydroxide from this solution
Ksp for Al(OH)3 3.0 x 10-34
Weak Acid Ka
CH3COOH (acetic acid) 1.8 X 10-5
C6H5COOH (benzoic acid) 6.5 x 10-5
C6H5OH (phenol) 1.3 X 10-10
HNO2 (nitrous acid) 4.5 X 10-4
a. 10.0 M CH3COOH with 1.0 M CH3COONa
b. 1.0 M HNO2 with 4.0 M NaNO2
c. 1.0 M HNO2 with 1.0 M NaNO2
d. 1.0 M C6H5COOH (benzoic acid) with 0.25 C6H5COONa
e. 1.0 M CH3CoOH with 1.0 M CH3COONa
f. 2.0 M C6HsOH with 1.32 M KC6HsO
g. 1.0 M C6HsOH with 1.0 M KC6HsC0

answer : the correct answer is 2) hno₃ and naoh .

arrhenius concept of acid and base :

acid :

according to arrhenius acid are those which release h⁺ or hydronium ion (h₃o⁺) in aqueous solution .

example : hcl +h₂o ↔ h₃o⁺ + cl⁻

hcl is giving h₃o⁺ ion in water , hence it is an arrhenius acid .

base :

according to arrhenius , bases are those which releases oh⁻ ions in aqueous solution .

example : koh (aq) ↔ k⁺ + oh⁻

since koh is producing oh⁻ ions hence , it is an arrhenius base .

checking the options :

1) ch₃oh and naoh :

ch₃oh is known as methanol , an organic compound , which is neutral compound . the dissociation of ch₃oh is negligible . it is very very weak acid (ka = 3.2 * 10 ⁻¹² ) .

naoh being ionic gives na⁺ and oh⁻ ions in aqueous solution as :

naoh ↔ na⁺ + oh⁻ . hence it is an arrhenius base

it can be concluded that ch₃oh and naoh is not arrhenius acid and base.

2) hno₃ and naoh :

hno₃ is an ionic compound which gives ions h⁺ and no₃⁻ ion in aqueous solution as:

hno₃ + h₂o ↔ h₃o⁺ + no₃⁻

since it is giving h⁺ ion . hno₃ is arrhenius acid .

naoh being ionic gives na⁺ and oh⁻ ions in aqueous solution as :

naoh ↔ na⁺ + oh⁻

. hence it is an arrhenius base .

it can be said that hno₃ and naoh are arrhenius acid and base.

3) ch₃oh and hcl

as discussed ch₃oh is neutral compound .

while hcl in aqueous solution dissociates to give h⁺ and cl⁻ ions as :

hcl + h₂o→ h₃o⁺ + cl⁻ . so hcl is arrhenius acid .

hence , ch₃oh and hcl are not arrhenius acid and base.

4) hno₃ and hcl :

hno₃ as discussed gives h⁺ in aqueous solution , while hcl also gives h⁺ in aqueous solution .

hence both hno₃ and hcl are arrhenius acid they are not acid and base .

so the arrhenius acid and base are 2) hno₃ and naoh.