Question

Consider the following salts. Which one(s) when dissolved in water will produce a basic solution?

1)NaNO3 2)K2S 3) Na2CO3

a) 2and3

b) 1and2

c) only 3

d) only 1

e) only 2

Answer 1

1) When Sodium nitrite (NaNO_​​​2) is dissolved in water, the resulting solution is basic.

But when Sodium nitrate (NaNO_​​​3​​) is dissolved in water , the resulting solution is Neutral. NO_{​​​​​3} will not react with water so that solution become neutral.

NaNO_​​​3  = Na⁺ + NO_{​​​​​3}^​- { NO_{​​​​​3}​ is conjugate base of strong acid HNO_{​​​​3}}.

2) when K_{​​​​​​2}​​​​​​​​​​S is dissolved in water, the reaction is,

K₂S(s) --> 2 K⁺(aq) + S_{​​​​​​2}^{​​​​​-}(aq)

In reality, the S_{​​​​​​2}^{​​​​​-} that forms is going to react with water.

K2S(s) + H2O(l) --> 2 K+(aq) + HS-(aq) + OH-(aq)

Because the presence of OH^{​​​​​-}​​​​, the solutions become basic.

3) Na_{​​​​​2}​CO_​​3 is formed by reaction between strong base (NaOH) and week acid (H_{​​​​​​2}​​CO_​​​3)

on ionisation of Na2CO3 on aquas solution....Na ion combine with water to form base

thus it is basic.

so the answer is a) 2 and 3

I hope you will understand well....... thank you ?