Hidrolisis Garam By Tetty Afianti

Summary

This chemistry lesson covers the topic of salt hydrolysis, explaining the breakdown of salts in water to form acids and bases. It covers four types of reactions: strong acid + strong base (neutral salt), strong acid + weak base (acidic salt), weak acid + strong base (basic salt), and weak acid + weak base (neutral salt). The video also provides formulas to calculate pH and hydrolysis constants (KH) and walks through two example problems involving NH₄Cl and CH₃COONa. The lesson emphasizes understanding how the strength of acids and bases influences the hydrolysis process.

Takeaways

• 😀 Hydrolysis is the process of salt decomposition in water, leading to the formation of an acid and a base.
• 😀 There are four types of salt hydrolysis, based on the strength of the acid and base involved: strong acid + strong base, strong acid + weak base, weak acid + strong base, and weak acid + weak base.
• 😀 Strong acid + strong base hydrolysis results in a neutral salt (e.g., NaCl).
• 😀 Strong acid + weak base hydrolysis leads to an acidic solution because the acid dominates (e.g., NH4Cl).
• 😀 Weak acid + strong base hydrolysis results in a basic solution (e.g., CH3COONa).
• 😀 Weak acid + weak base hydrolysis results in a neutral solution (e.g., NH4CH3COO).
• 😀 To determine the pH of a salt solution in partial hydrolysis, formulas involving pKa, pKb, and molarity of the salt are used.
• 😀 pH calculations for salt hydrolysis depend on whether the salt is acidic or basic, requiring different formulas for different cases.
• 😀 The formula for determining pH for weak acid + weak base hydrolysis involves both pKa and pKb values, and it affects the overall pH of the solution.
• 😀 For hydrolysis problems, constants like pKa, pKb, and the molarity of the salt are essential to finding the pH and hydrolysis constant (KH).

Q & A

What is the meaning of 'hydrolysis of salts'?

Hydrolysis of salts refers to the process of salts breaking down in water, resulting in the formation of acids and bases.

What are the two types of acids discussed in the script?

The two types of acids discussed are strong acids (such as HCl and H2SO4) and weak acids (such as CH3COOH).

What are the two types of bases mentioned?

The two types of bases mentioned are strong bases (such as NaOH and KOH) and weak bases (such as NH4OH).

What does the term 'partial hydrolysis' mean?

Partial hydrolysis refers to a situation where the salt formed from a strong acid and a weak base results in a solution that is acidic in nature.

What happens in a hydrolysis reaction between a strong acid and a strong base?

In a hydrolysis reaction between a strong acid and a strong base, the salt formed is neutral, and there is no significant change in the pH of the solution.

How is the pH calculated for partial hydrolysis of salts formed from weak bases and strong acids?

The pH for partial hydrolysis of such salts can be calculated using the formula: pH = (1/2) * (14 - PKb - log[molarity of salt]), where PKb is the negative logarithm of the base ionization constant (KB).

What formula is used to calculate the pH of salts formed from weak acids and strong bases?

The pH for salts formed from weak acids and strong bases is calculated using the formula: pH = (1/2) * (14 + PKa + log[molarity of salt]), where PKa is the negative logarithm of the acid dissociation constant (Ka).

What is 'total hydrolysis' in the context of salt reactions?

Total hydrolysis occurs when both the acid and the base involved are weak, resulting in a solution that is neither strongly acidic nor strongly basic, but undergoes complete dissociation.

How do you calculate the pH for a salt formed from weak acids and weak bases?

For salts formed from weak acids and weak bases, the pH is calculated using the formula: pH = (1/2) * (14 + PKa - PKb), where PKa and PKb are the negative logarithms of the acid and base ionization constants, respectively.

What is the relationship between the acid dissociation constant (Ka) and the base dissociation constant (Kb) in determining hydrolysis constants?

The hydrolysis constant (KH) can be calculated using the formula: KH = KW / Ka or KH = KW / Kb, where KW is the ionization constant of water (10^-14).