Question

We have 2.89 L of an aqueous NaBr solution. We add an excess of AgNO3. We form 8.73 g of AgBr(s). What was the initial concentration of Br- (in mol/L) in this aqueous NaBr solution?

Answer 1

aqueous solutious of Na By reacts with AgNO3 to form precipitate of AgBrand NANOZ Ag Noz + Nash -> AGBY + NaNO3 · Excess limiting reagent ASNO, is Excess reagent I left after reacticy) and NaBr is limiting reagent (Totally consuured in the reaction). Imole of NaBr - Imole of AgBe tormed, Mass Ot AGB & tormed = 8.73 9 no at moles of Ag Br tormed = . molar wars z 8.73 9 188 Slot = 188 8.13 8x mot q = 0.046 role. Imole of Ag Br formed → Imole of NaBr required formed - ? ? 0.046 mole at Aggr no ot moles of Nabe required = 0.046* = 0.046mole.

no ot moles of NaBr = 0.046 more volume of NaBr solution = 2.89L Molarity of Aqueous Naße solution - no of moles volume of solectics in = 0.046 mole 2.89 2 = 0.0159 M ~ 0.016 M. NABI (29) Nat (aq) + B8 (aq) IM IM 0.016 M. 6.016 M Initial concentration of Br= = 0.016 M 0.016 motey