Question

What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M methylamine, CH3NH2, with 25.00 mL of 0.10 M methylammonium chloride, CH3NH3C1? Assume that the volume of the solutions are additive and that Kb = 3.70 times 10-4 for methylamine. 10.27 10.57 10.87 11.78 Which statement about buffers is true? Buffers have a pH = 7. Buffers consist of a strong acid and its conjugate base. A buffer does not change pH on addition of a strong acid or strong base. Buffers resist change in pH upon addition of small amounts of strong acid or strong base. What is the pH of a buffered system made by dissolving 17.42 g of KH2PO4 and 20.41 g of K2HPO4 in water to give a volume of 200.0 mL? The Ka2 for dihydrogen phosphate is 6.2 times 10-8 and the equilibrium reaction of interest is 7.03 7.17 7.38 7.58 TRIS ((HOCH2)3CNH2) is one of the most common buffers used in biochemistry. A solution is prepared by adding enough TRIS and 12 M HCl(aq) to give 1.00 L of solution with [TRIS] = 0.30 M and [TRISH+] = 0.60 M. What is the pH of this buffered system if the pKb is 5.92? 5.92 6.22 7.78 8.08 A buffer solution is prepared by dissolving 27.22 g of KH2PO4 and 3.37 g of KOH in enough water to make 0.100 L of solution. What is the pH of the H2PO4-/HPO42-buffer if the Ka2 = 6.2 times 10-8? 6.84

Answer 1

N2= Akta Lem then of CH3NH2 in mixtures? V2 final Volume of ta mix 5+25)m-50ml. (m) =0.05m 5b 2 Similayfr meleyl am methyl ammomium D-b5 so, pH= 부8, 14- POH = 14-3:43s to.57 6. Tue s tute mnt aluent bauffea is:- 6) Buffers Tesist ehange in pH upon addition of smalu amounts of stong base吖stm9 acid F. Mole Culst height of KHp0 134Imne cnd maeaua 4 is- 오oomL. Solution erntais l742 g kHPO4 and r2b411 K2HPO4 20 41 174 n T:42 male ma e 136 -0 128O7 0.64 " " " 6.585

0 b64 pH=7.21-0.04 = 717 o t рон = 59114630) CTRi5T 6.60 o 30) Рон = 6, 22