Question

Predict if the solutions of the following salts are neutral, acidic or basic: NaCl, KBr, NaCN, $NH_{4}NO_{3}$, $NaNO_{2}$ and KF.

Answer 1

"A strong acid is an acid that is completely dissociated from water. In other words, all acid molecules break into ions and solve water molecules. The hydronium ion concentration in a strong acid solution is therefore equal to the acid concentration.

$(i)\quad NaCl\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} NaOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} HCl \\ Strong\quad Acid \end{matrix}$

It is a neutral solution.

$(ii)\quad KBr\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} KOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} HBr \\ Strong\quad Acid \end{matrix}$

It is a neutral solution.

$(iii)\quad NaCN\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} NaOH \\ Weak\quad Acid \end{matrix}\quad +\quad \begin{matrix} HCN \\ Strong\quad Acid \end{matrix}$

It is a basic solution.

$(iv)\quad { NH }_{ 4 }{ NO }_{ 3 }\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} { NH }_{ 4 }OH \\ Weak\quad Base \end{matrix}\quad +\quad \begin{matrix} { HNO }_{ 3 } \\ Strong\quad Acid \end{matrix}$

It is an acidic solution.

$(v)\quad Na{ NO }_{ 2 }\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} NaOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} { HNO }_{ 3 } \\ Weak\quad Acid \end{matrix}]$

It is a basic solution.

$(vi)\quad KF\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} KOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} HF \\ Weak\quad Acid \end{matrix}$

It is a basic solution."

Answer 2

"A strong acid is an acid that is completely dissociated from water. In other words, all acid molecules break into ions and solve water molecules. The hydronium ion concentration in a strong acid solution is therefore equal to the acid concentration.

\begin{lgathered}(i)\quad NaCl\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} NaOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} HCl \\ Strong\quad Acid \end{matrix}\end{lgathered}

(i)NaCl+H

2

O→

NaOH

StrongBase

+

HCl

StrongAcid

It is a neutral solution.

\begin{lgathered}(ii)\quad KBr\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} KOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} HBr \\ Strong\quad Acid \end{matrix}\end{lgathered}

(ii)KBr+H

2

O→

KOH

StrongBase

+

HBr

StrongAcid

It is a neutral solution.

\begin{lgathered}(iii)\quad NaCN\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} NaOH \\ Weak\quad Acid \end{matrix}\quad +\quad \begin{matrix} HCN \\ Strong\quad Acid \end{matrix}\end{lgathered}

(iii)NaCN+H

2

O→

NaOH

WeakAcid

+

HCN

StrongAcid

It is a basic solution.

\begin{lgathered}(iv)\quad { NH }_{ 4 }{ NO }_{ 3 }\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} { NH }_{ 4 }OH \\ Weak\quad Base \end{matrix}\quad +\quad \begin{matrix} { HNO }_{ 3 } \\ Strong\quad Acid \end{matrix}\end{lgathered}

(iv)NH

4

NO

3

+H

2

O→

NH

4

OH

WeakBase

+

HNO

3

StrongAcid

It is an acidic solution.

\begin{lgathered}(v)\quad Na{ NO }_{ 2 }\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} NaOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} { HNO }_{ 3 } \\ Weak\quad Acid \end{matrix}]\end{lgathered}

(v)NaNO

2

+H

2

O→

NaOH

StrongBase

+

HNO

3

WeakAcid

]

It is a basic solution.

\begin{lgathered}(vi)\quad KF\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad \begin{matrix} KOH \\ Strong\quad Base \end{matrix}\quad +\quad \begin{matrix} HF \\ Weak\quad Acid \end{matrix}\end{lgathered}

(vi)KF+H

2

O→

KOH

StrongBase

+

HF

WeakAcid

It is a basic solution."