Question

Which of the following mixtures does not result in a buffer?

A. 25 mL of 0.1M NaBrO with 40 mL of 0.2M HBrO

B. 25 mL of 0.1M NaOH with 40 mL of 0.2M HBrO

C. 100 mL of 0.1M HCl with 100 mL of 0.3M NH₃

D. 50 mL of 2M NH₄Cl with 75 mL of 3M NH₃

E. 25 mL of 0.1M NaOH with 40 mL of 0.2M NH₃ (correct answer)

weal Weak Stron sk meal base Where's aid? a) Nabro - everything base; HBO-seren en acid 6 Nuott-string base; HBrO - weak and s NaOH + HBrO H₂O + Nasro - c) HEI- String aid; Nte-wean base wouЧ ,ах да is Hel+ NH3 2 cl + Nut you (d) Ntyll - weak anid; NHz-weak base e) NaOH - String base; NHg-weak base

^ This is how I worked it out, I understand why E is not a buffer (two bases), but I cannot understand why B is a buffer? Please explain conceptually

Answer 1

NaOH + HBrO ------------> NaBrO + H2O

millimoes of NaOH--- 25 * 0.1 = 2.5

millimoles of HBrO---40 * 0.2 = 8.0

so millimoles of HBrO are in excess ( present after reacting also) and also NaBrO 2.5 millimoles are formed so weak acid and its salt are present .. that will act as buffer.