Question

(ASAP) Indicate whether each of the following compounds will gave an acidic, basic or neutral solution when dissolved in water. Clear All ammonium bromide calcium fluoride potassium perchlorate potassium bromide The pH will be less than 7. The pH will be approximately equal to 7. The pH will be greater than 7.

ammonium bromide

calcium fluoride

potassium perchlorate

potassium bromide

Answer 1

a) Ammonium Bromide

NH4Br . This is a salt of Weak base NH4OH and strong acid HBr. So the aqueous solution of these salt is acidic in nature.Because cationic hydrolysis takes place.

NH4Br --------------- NH4+ + Br-

H2O ------------------- H+ + OH-

--------------------------------------------

NH4Br + H2O ------------- NH4OH +   HBr

                                     weak base    strong acid

NH4+ + H2O -------------------- NH4OH + H+

PH is lessthan 7.( PH<7)

2) CaF2

    It is a salt of weak base Ca(OH)2 and weak acid HF. So the nature of the solution depends on Kb and Ka values.

Kb of Ca(OH)2 = 3.7x10^-3

Ka of HF = 6.6x10^-4

Kb>Ka. So the nature of the solution is basic

PH is greater than 7. ( PH>7)

3) potassium perchlorate

KClO4. It is a salt of strong base KOH and strong acid HClO4. So the natrure of aqueous solution is neutral.Because No hyrolysis takes place.

PH=7

4) Potassium bromide

KBr. It is a salt of strong base KOH and strong acid HBr. So the natrure of aqueous solution is neutral.Because No hyrolysis takes place.

PH=7