Which one of the following salts is obtained by the reation of a weak acid with a strong base.
MgCl2
NH4F
LiClO4
NaCl
K2SO3
To determine which of the following salts is obtained by the reaction of a weak acid with a strong base, you need to understand the concept of salt formation and the strength of acids and bases.
In a neutralization reaction between an acid and a base, the acid donates a proton (H+) to the base, forming water (H2O) as a product. The remaining part of the acid is called the conjugate base, and the remaining part of the base is called the conjugate acid. When a weak acid reacts with a strong base, the resulting salt will contain the conjugate base of the weak acid and a cation from the strong base.
Let's analyze each option:
1. MgCl2:
This salt is formed by the reaction of a strong acid (HCl) with a strong base (Mg(OH)2), not a weak acid with a strong base. Therefore, it is not the correct answer.
2. NH4F:
Ammonium fluoride (NH4F) is formed by the reaction between a weak acid (NH4OH) and a weak base (HF) rather than a weak acid with a strong base. So, it is not the correct answer.
3. LiClO4:
Lithium perchlorate (LiClO4) is formed by the reaction between a strong acid (HClO4) with a strong base (LiOH), not a weak acid with a strong base. Hence, it is not the correct answer.
4. NaCl:
Sodium chloride (NaCl) is formed by the reaction between a strong acid (HCl) and a strong base (NaOH) rather than a weak acid with a strong base. Therefore, it is not the correct answer.
5. K2SO3:
Potassium sulfite (K2SO3) is the salt obtained by the reaction of a weak acid (H2SO3) with a strong base (KOH). Sulfurous acid (H2SO3) is a weak acid, and potassium hydroxide (KOH) is a strong base. Therefore, K2SO3 is the correct answer.
So, the correct answer is K2SO3, which is obtained by the reaction of a weak acid with a strong base.
You must go through each one as in the first.
MgCl2 must come from Mg(OH)2 and HCl
NH4F must come from NH3 and HF
How do you know the acid and base are strong or weak. Look in the table of ionization constants. Listed are the weak ones. Not listed means they are strong.