Question

pH of salts

Determine if the following salts will raise, lower, or not change the pH of pure water when dissolved in the water.

a) NaCN

b) FeCl₃

c) HCOOH

d) K₂SO₄

e) K₃PO₄

f) SrCl₂

g) (CH₃)₂NH

h) Al(NO₃)₃

i) Li₂CO₃

j) KBr

k) Ca(NO₃)₂

l) NH₄Cl

m) KBrO₂

n) Zn(OH)₂

o) Ba(OCl)₂

p) CH₃NH₃Br

q) NaMnO₄

r) Li₂SO₃

s) BaI₂

t) SnBr₄

Answer 1

a) NaCN: raise

because it is the salt of weak acid and strong base.

b) FeCl3: lower

FeCl3 is an acidic salt which is formed by the reaction between a strong acid, HCl and a weak base, Fe(OH)3.

c) HCOOH: Lower

as it is weak acid.

HCOOH + H2O ...........> HCOO- + H3O+

d) K2SO4: do not change

As H2SO4 is a strong acid and KOH is a strong base,so K2SO4 is a neutral salt.

e) K3PO4: raise

becaue it is the salt of of weak acid and strong base.

f) SrCl2: do not change

as it is the salt of strong base and strong acid.

g) (CH3)2NH: raise

as it is weak base.

h) Al(NO3)3: lower

becaue it is the salt of weak base and strong acid.

i) Li2CO3: Raise

as it is the salt of stong base and weak acid.

j) KBr: do not change

k) Ca(NO3)2: lower

it is a salt of a Weak Base Ca(OH)2 and a Strong Acid HNO3, the salt is acidic in nature.

l) NH4Cl: lower

as it is the salt of weak base and strong acid.

m) KBrO2: raise

n) Zn(OH)2: raise

o) Ba(OCl)2: raise

p) CH3NH3Br: lower

q) NaMnO4: do not change

r) Li2SO3: raise

s) BaI2: do not change

t) SnBr4: lower