Question

22. Which of the following pairs of compounds and ions could be used to form a buffer solution? (a) 0.10 M HCl and 0.10 M Naci (b) 0.10 M NH4Cl and 0.10 M NH3 (c) 0.10 M HNO2 and 1.0 x 10'M NaNO, 23. An activity coefficient (a) measures the deviation of behavior of ions from ideality. (b) is obtained by multiplying the concentration of a solution times the ionic strength. (c) replaces the concentration term in chemical calculations. It corrects for the ionic strength of the solution. 24 The Debye-Hückel equation is log v = (-0.51241/(1+(ava/305). Which of the following statements is true? (a) As the ionic strength increases, the activity coefficient increases. (b) As the charge of the ion increases, the departure of its activity coefficient from unity decreases. (c) The smaller the hydrated radius of the ion, the more important activity effects become. 25. At very low concentrations the activity coefficients approach 1. Ignoring activity coefficients, calculate the solubility of Co(OH), in a saturated solution of Co(OH), K for cobalt(II) hydroxide = 3x 10*5. (a) 3 x 10 molar (b) 3 x 10 molar (c) 3 x 10 molar

Answer 1

Question 22)

Since buffer solutions are those solutions which contain mixture of weak acid and its conjugate base or weak base and its conjugate acid. Sometime this buffer can also be prepared by mixture of weak acid and their salt or weak base and their salt.

For option a HCl is strong acid and NaCl is a salt and according to definition buffer solution should contain weak acid or base. So 0.1 M HCl and 0.1 M NaCl is not buffer system.

Option b is buffer system since its contain weak base and its salt. Therefore 0.1 M NH4Cl and 0.1 M NH3 is buffer system.

Option c is buffer system since its contain weak acid and its conjugate base. Therefore 0.1 M HNO2 and 0.1 M NaNO2 is buffer system.

Therefore option b and c are buffer system. Therefore it is correct.

Since option A is not buffer system. Therefore it is incorrect.

In multiple question we solve only one question at a time. Thanks.