Asked by ciaociao

Which of the following substances will give an aqueous solution of pH closes to 7 and why?

KNO3
NaHCO3
NH4I
NH3
NaF

Looking through my notes for an hour--can't find this one. Thanks in advance!
Answered by ciaociao
*closest to 7
Answered by DrBob222
Take these one at a time.
KNO3 is a salt. The pH of salts is determined by the hydrolysis of the salt. KNO3 is made up of KOH and HNO3, both strong electrolytes; therefore, neither is hydrolyzed and the pH is 7.0
NaHCO3 is the salt of NaOH (a strong base) and H2CO3(a weak acid); therefore, it will be basic in solution(greater than 7).
NH4I is the salt of NH3(a weak base)
and HI(a strong acid); therefore, it will be acidic in solution(less than 7).
NH3 is a weak base and reacts with H2O as NH3 + HOH ==> NH4^+ + OH^-; therefore it will be basic (greater than 7).
NaF is the salt of NaOH (a strong base) and HF(a weak acid); therefore, it will be basic in solution(greater than 7)
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