A volume of 20 ml of 0.8 M-HCN solution is mixed with 80 ml of 0.4 M - NaCN solution. Calculate

step 1 In this question, pH is equal to P of H is equal to P of KA plus low of global CN negative 0, gu

A volume of 20 ml of 0.8 M-HCN solution is mixed with 80 ml...

A volume of $20 \mathrm{ml}$ of $0.8 \mathrm{M}-\mathrm{HCN}$ solution is mixed with $80 \mathrm{ml}$ of $0.4 \mathrm{M}$ - NaCN solution. Calculate the pH of the resulting solution. $K_{\mathrm{a}}$ of $\mathrm{HCN}=2.5 \times 10^{-10} .$ $(\log 2=0.3)$ (a) $9.9$ (b) $9.3$ (c) $4.1$ (d) $4.7$

A volume of $20 \mathrm{ml}$ of $0.8 \mathrm{M}-\mathrm{HCN}$ solution is mixed with $80 \mathrm{ml}$ of $0.4 \mathrm{M}$
- NaCN solution. Calculate the pH of the resulting solution. $K_{\mathrm{a}}$ of $\mathrm{HCN}=2.5 \times 10^{-10} .$ $(\log 2=0.3)$
(a) $9.9$
(b) $9.3$
(c) $4.1$
(d) $4.7$

Key Concepts

Acid-Base Equilibrium

Acid-base equilibrium refers to the balance established in a solution containing a weak acid and its conjugate base. The equilibrium is characterized by the dissociation of the weak acid into its ions, with the acid dissociation constant (Ka) quantifying the extent of this dissociation.

Buffer Solution

A buffer solution is composed of a weak acid and its conjugate base (or a weak base and its conjugate acid) that resists changes in pH when small amounts of acid or base are added. This balance enables the solution to maintain a relatively stable pH, which is key in many chemical and biological systems.

Henderson-Hasselbalch Equation

The Henderson-Hasselbalch equation is a formula used to calculate the pH of buffer solutions. It relates the pH to the pKa of the acid and the ratio of the concentrations of the conjugate base to the weak acid: pH = pKa + log([base]/[acid]). This equation simplifies the analysis of acid-base equilibria in buffer systems.

Acid Dissociation Constant (Ka) and pKa

The acid dissociation constant, Ka, measures the strength of a weak acid in solution by indicating how much it dissociates into its ions. The pKa, which is the negative logarithm of Ka, provides a more convenient scale for comparing acid strengths. These constants are essential for determining the pH of solutions, especially in buffer systems.

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