To calculate the pH of a buffer solution containing 2.0 M nitrous acid (HNO₂) and 1.48 M lithium nitrite (LiNO₂), we can utilize the Henderson-Hasselbalch equation, which is particularly useful for buffer solutions. The equation is expressed as:

pH = pKa + log₁₀([A^-]/[HA])

In this case, HNO₂ is the weak acid (HA), and LiNO₂ provides the conjugate base (A^-), which is nitrite ion (NO₂^-). Given that the acid dissociation constant (K_a) for nitrous acid is 4.6 × 10^-4, we first need to calculate the pK_a:

pK_a = -log₁₀(K_a) = -log₁₀(4.6 × 10^-4)

Calculating this gives us:

pK_a ≈ 3.34

Next, we substitute the values into the Henderson-Hasselbalch equation:

pH = 3.34 + log₁₀(1.48/2.0)

Calculating the log term:

log₁₀(1.48/2.0) ≈ log₁₀(0.74) ≈ -0.128

Now, we can find the pH:

pH ≈ 3.34 - 0.128 ≈ 3.21

Thus, the pH of the buffer solution is approximately 3.21. This calculation demonstrates how the combination of a weak acid and its conjugate base can effectively resist changes in pH, a key characteristic of buffer solutions.