Question

A student adds 0.1-molar HCL to 0.1-molar KOH until the resulting solution is neutral. When this solution is evaporated to dryness. The substance that remains can be correctly described as which of the following?
I) a white, crystalline solid
II) A covalent solid
III) A water-soluble salt
A) I only
B) II only
C) III only
D) I and III only
E) I, II and III only

Answer 1

Hint: The chemical reaction of acid and base to form a salt and water is known as the neutralization reaction. The strong acid reacts with the strong base and neutralizes each other such that the $\text{ pH }$ solution is equal to 7. This neutralization reaction results in the neutral salt.

Complete step by step answer:
A chemical reaction in which the acid and base quantitatively react with each other to form salt and water is known as the neutralization reaction. In the neutralization reaction, the proton $\text{ }{{\text{H}}^{\text{+}}}\text{ }$ (from acid) reacts with the hydroxide ion $\text{ O}{{\text{H}}^{-}}\text{ }$ to form a water molecule. An acid-base neutralization reaction is as shown below,
$\text{ Acid + Base }\to \text{ Salt + water }$
The $\text{ pH }$ and the strength of salt depends on the strength of the acid and base undergoing the neutralization reaction.
We have given that the $\text{ 0}\text{.1 M HCl }$ reacts with the$\text{ 0}\text{.1 M KOH }$. The hydrochloric acid is a strong acid. Similarly, the potassium hydroxide is a strong base.
In a neutralization reaction of a strong base with the strong acid results in the neutral solution having$\text{ pH = 7 }$.
The neutralization reaction between the $\text{ 0}\text{.1 mole }$ of hydrochloric acid and the $\text{ 0}\text{.1 mole }$potassium hydroxide given as follows,
$\text{ HCl + KOH }\to \text{ KCl + }{{\text{H}}_{\text{2}}}\text{O }$
The product that is potassium chloride $\text{ KCl }$is a white, crystalline solid. It is an ionic salt of potassium ion $\text{ }{{\text{K}}^{\text{+}}}\text{ }$ and chloride ion$\text{ C}{{\text{l}}^{-}}\text{ }$. Since it is an ionic salt, in aqueous solution it dissociates into its corresponding potassium and chloride ions. The reaction is as follows,
$\text{ KCl }\to \text{ }{{\text{K}}^{\text{+}}}\text{ + C}{{\text{l}}^{-}}\text{ }$
Potassium chloride is an odourless and white or colourless vitreous crystalline salt. It readily dissolves in water and tastes like table salt. Potassium chloride is ionic salt. It is not a covalent compound.
Thus, here the obtained salt is white, crystalline, and water-soluble.

Hence, (D) is the correct option.

Note: The nature of salt and $\text{ pH }$ the solution depend on the strength of acid and base. This is given as follows,

Strength of Acid	Strength of Base	Resultant $\text{ pH }$
Strong	Strong	$\text{ 7 }$
Strong	weak	$\text{ }<\text{7 }$
weak	Strong	$\text{ }>\text{7 }$
weak	weak	If,\[\begin{align} & \text{ }{{\text{K}}_{\text{a}}}>{{\text{K}}_{\text{b}}}\text{ }\Rightarrow \text{ pH }<\text{7} \\ & \text{ }{{\text{K}}_{\text{a}}}\text{=}{{\text{K}}_{\text{b}}}\text{ }\Rightarrow \text{ pH =7} \\ & \text{ }{{\text{K}}_{\text{a}}}<{{\text{K}}_{\text{b}}}\text{ }\Rightarrow \text{ pH }>\text{7} \\ \end{align}\].