If you could please answer these in detail, that way I will understand better! T
ID: 705491 • Letter: I
Question
If you could please answer these in detail, that way I will understand better! Thank you so much!
32. You want to make a 1.0 L solution at pH 4.8 that has a buffering capacity to withstand acid or base addition of 50 mol/L. Which of the following buffers will be best for this purpose? (pKa's of acids as follows acetic acid 4.8, citric acid 5.4, oxalic acid 4.2) a)0.1 M sodium acetate at pH 4.8 b) 02M sodium citrate at pH 438 c) 0.2 M sodium oxalate at pH 4.8 d) 0.2 M sodium acetate at pH 4.8 e)0.05 M sodium acetate at pH 4.8 33. What is the pH of a buffer that is 0.2 mol L in lactic acid (CH3CH OH)COOH) and 0.10 mol L1 in sodium lactate? pKa of lactic acid is 3.9. a)3.6 b)3.4 4.4 d) 4.2 e)3.9 34. The AgCI(s) solubility product Ksp-1.7 x 10.10 at 298 K. What is the solubility of AgCl(s) in mol L-1 1.3 x 10-5 mol L-1 b)1.3 x 10-6 mol L 1.7 x 10-10 mol L -1 d) 1.7x 10 mol L 1.3 x 104 mol L-1Explanation / Answer
33. According to the Henderson hasselbalch equation,
pH = pKa + log (salt/acid)
pH = 3.9 + log (0.1/0.2)
pH = 3.6
A option
34. Ksp is the solubility product with formla equal to product of concentration of products raised to power of their stoichiometric coofficients.
Ksp = (Ag+)(Cl-) = s^2 = 1.7* 10^-10 where s is solubility
So solubility = 1.3*10^-5 mol/L
A option
31. Weak acid is titrated with a strong base. pH of a weak acid will be slightly less than 7 and will increase on addition of base. Since it is a strong base the pH must rise abruptly let's say to reach pH 10. So earlier the pH was less than 7 and finally pH reaches 10. Phenolphthalein shows colour change within this range so it will be appropriate to use it. Colour change will be from colourless to pink. D option