Question

State whether each of the following aqueous solutions would be acidic, basic, or neutral and explain your answer. Include the appropriate net-ionic equations to show why a given solution is acidic or basic. (Use your text to look up Ka or Kb values if needed. HCO₂H = formic acid; (CH₃)₂ = dimethyl amine.)

A. KCl

B. HCO₂H

C. 50:50 mixture of HCO₂H + NaHCO₂

D. ((CH₃)₂NH₂)Cl

E. 50:50 mixture of (CH₃)₂NH + ((CH₃)₂NH₂)Cl

F. 50:50 mixture of 0.1 M NaNO₃ + 0.1 M HNO₃

Answer 1

A. K+ + OH- + H+ + Cl- ---> KCl(aq) + H2O (l)

KCl is a neutral salt as it is the salt of strong base KOH and strong HCl.

B. HCOOH (aq) ---> H+(aq) + HCOO- (aq)

Very less ionization, weak acid, equillibrium lies to the left.

C. HCOOH + NaHCO3 ---> HCOONa (aq) + CO2 (g)+ H2O(l)

CO2 gas evolved and the solution will be slightly basic.

D. (CH3)2NH + HCl ---> ((CH3)2NH2)Cl + H2O ----> (CH3)2NH2⁺ (aq)+ Cl^- (aq)

This a salt of a strong acid HCl and a week base dimethyl amine, so the aqueous solution will be slightly acidic.

E. 50:50 mixture of (CH3)2NH + ((CH3)2NH2)Cl

It will be slightly basic.

F. 50:50 mixture of 0.1 M NaNO3 + 0.1 M HNO3

This is a mixture of salts of strong acid and base and another strong acid which will make it acidic solution.