Menghitung pH Larutan Garam : KIMIA SMA KELAS 11

Summary

This video explains how to calculate the pH of salt solutions, focusing on salts formed from strong acids and weak bases, weak acids and strong bases, and weak acids and weak bases. The video walks through various formulas and methods to determine pH, depending on the type of salt and its ionization. It provides clear examples, demonstrating the step-by-step calculation process for each type of salt. Viewers will learn about the relationships between salt concentration, ionization constants, and the pH of solutions, making complex concepts more accessible with practical applications and examples.

Takeaways

• 😀 The pH of a salt solution can be calculated based on the type of acid and base that formed the salt.
• 😀 Salts formed from a strong acid and a weak base result in an acidic solution with a pH less than 7.
• 😀 For salts formed from a strong acid and a weak base, the pH can be calculated using the formula for H+ concentration: H+ = √(KW / KB × molarity of the salt).
• 😀 Salts formed from a weak acid and a strong base result in a basic solution, and their pH can be determined by calculating OH- concentration using a similar formula.
• 😀 Salts formed from a weak acid and a weak base can be either acidic, basic, or neutral depending on the strength of the acid and base, and their pH is calculated using a derived formula for H+ concentration.
• 😀 For salts formed from a strong acid and a strong base (like NaCl or KNO3), the pH is neutral (pH = 7).
• 😀 To calculate pH for salts from a weak acid and weak base, the concentration of H+ ions is found using the formula H+ = √(KW × KA / KB).
• 😀 The example of NaF shows that for salts from a weak acid and strong base, the pH is calculated by determining the OH- concentration, and then using pH = 14 - pOH.
• 😀 In the case of NH4Cl, a salt of a weak acid and weak base, the pH can be calculated using a similar method, considering both the acid and base dissociation constants.
• 😀 For titration reactions between a strong base and a weak acid (like KOH and CH3COOH), the resulting pH depends on the molarities of the components and the final concentrations of salt in the solution.

Q & A

What is the process to calculate the pH of a salt solution formed from a strong acid and a weak base?

For salts formed from a strong acid and a weak base, the cation from the salt undergoes hydrolysis in water. To calculate the pH, you use the formula: [H+] = √(KW / KB × Molarity of the cation). After calculating the concentration of H+, pH can be determined using pH = -log[H+].

How do you calculate the pH of a salt solution formed from a weak acid and a strong base?

For salts formed from a weak acid and a strong base, the anion from the salt undergoes hydrolysis in water. The pH is calculated using the formula: [OH-] = √(KW / KA × Molarity of the anion). After finding the concentration of OH-, pH is determined using pH = 14 - (-log[OH-]).

What happens when a salt is formed from a weak acid and a weak base in terms of pH calculation?

When a salt is formed from a weak acid and a weak base, both the cation and anion undergo hydrolysis, and the pH depends on the relative strengths of the acid and base. If the acid is stronger than the base, the solution will be acidic; if the base is stronger, the solution will be basic. The pH can be calculated using the formula [H+] = √(KW × KA / KB), then applying the formula pH = -log[H+].

How do you calculate the pH of a neutral salt solution, such as NaCl?

For a neutral salt formed from a strong acid and a strong base (like NaCl), the pH is always 7, since neither the cation nor the anion undergo hydrolysis in water.

What is the formula for calculating the pH of an NH4Cl solution, which is a salt of a weak base and a strong acid?

To calculate the pH of an NH4Cl solution, use the formula: [H+] = √(KW / KB × Molarity of NH4+). Then, calculate the pH using pH = -log[H+].

How do you calculate the pH of a solution of NaOAc (Sodium Acetate), which is a salt of a weak acid and a strong base?

To calculate the pH of Sodium Acetate (NaOAc), you first calculate the concentration of OH- ions using the formula: [OH-] = √(KW / KA × Molarity of Acetate anion). Then, calculate pH as pH = 14 - (-log[OH-]).

What is the procedure for calculating the pH of a salt formed from a strong acid and a weak base, such as NH4Cl?

For salts like NH4Cl, the cation (NH4+) undergoes hydrolysis, releasing H+ ions. The pH is calculated using the formula: [H+] = √(KW / KB × Molarity of NH4+), then pH is determined by using pH = -log[H+].

How is the pH of a solution of KNO3 determined?

KNO3 is a salt formed from a strong acid (HNO3) and a strong base (KOH), so it does not undergo hydrolysis in water. The pH of the solution will be neutral, or pH = 7.

What happens when 50 ml of 0.5 M KOH is mixed with 50 ml of 0.5 M CH3COOH in terms of pH calculation?

When KOH is mixed with CH3COOH, they react in a 1:1 molar ratio to form water and a salt, CH3COOK. Since both reactants are neutralized, the resulting solution will contain only the salt. The pH is calculated based on the salt's properties, with CH3COOK being a salt of a weak acid and a strong base. The resulting pH will be greater than 7, indicating a basic solution.

How do you calculate the mass of NH4SO4 required to obtain a specific pH in a solution?

To calculate the mass of NH4SO4 needed for a solution with a desired pH, first calculate the required concentration of NH4+ ions using the formula: [H+] = √(KW / KB × Molarity of NH4+). Once the required concentration is determined, calculate the molarity of NH4SO4 based on the ionization coefficients. Finally, use the formula Molarity = Mass / (Molar Mass × Volume) to determine the mass of NH4SO4 required.