Question

what is equilibrium concentration of nitrous acid, hno2 (aq) (ka = 4.5 ×10-4), in a solution that has a ph of 1.65?A. 0.0032 MB. 0.49 MC. 0.022 MD. 1.1 M

Answer 1

To determine the equilibrium concentration of nitrous acid with a pH of 1.65, we calculated the hydronium ion concentration from the pH and concluded that the equilibrium concentration of HNO2 is 0.022 M. So the correct option is C.

Step-by-step explanation:

The given question is asking to determine the equilibrium concentration of nitrous acid (HNO2) in a solution with a pH of 1.65. The dissociation constant (Ka) for nitrous acid is given as 4.5 × 10-4. To find the equilibrium concentration, we will use the pH provided to calculate the hydronium ion concentration.

The pH is defined as the negative logarithm of the hydronium ion concentration, so:

[H3O+] = 10-pH = 10-1.65

By calculating the above equation, we get:

[H3O+] = 0.022 M

Since nitrous acid is a weak acid, we can assume that the concentration of nitrous acid at equilibrium will be approximately the same as the initial concentration. For weak acids, the ionization is small, and therefore the change in concentration due to ionization is negligible. This means the equilibrium concentration of HNO2 is approximately equal to the concentration of the formed hydronium ions.

Therefore, the equilibrium concentration of nitrous acid in the solution is 0.022 M.

Answer 2

The equilibrium concentration of nitrous acid (HNO₂) in a solution with a pH of 1.65 is 0.0046 M.

Step-by-step explanation:

To determine the equilibrium concentration of nitrous acid (HNO₂) in a solution with a pH of 1.65, we can use the information provided in the examples. In Example 21.15.1, we are given the Ka value of nitrous acid, and in Example 15.4.5, we are given the pH of a nitrous acid solution. By using the relationship between Ka, pH, and H₃O⁺ concentration, we can calculate the equilibrium concentration of nitrous acid.

Using the formula pH = -log[H₃O⁺], we can find the concentration of H₃O⁺ in the solution. In Example 15.4.5, the pH is given as 2.34, so the concentration of H₃O⁺ is 10^(-2.34) = 0.0046 M.

Since nitrous acid is a weak acid, we can assume that the concentration of HNO₂ is equal to the concentration of H₃O⁺ at equilibrium. Therefore, the equilibrium concentration of nitrous acid is 0.0046 M.