Question

What Volume (in mL) of KBr solution must be taken so it will contain 2.83x10^-5 moles of KBr? KBr solution is made by dissolving 0.42 grams of KBr in enough water to yield 17 mL of solution.

Answer 1

Mass of KBr = 0.42 gm

Molar mass of KBr = 119.002 g/mol

Moles of KBr = 0.42 g / 119.002 g/ mol = 0.003529 Moles

Volume of water to be added = 0.003529 x 1000 / 2.83 x 10^-5 = 124712 ml or 124.7 Liter

Hence if we want to make 2.83 x 10^-5 M solution using 0.42 gm of KBr then we have use 124.7 Liter of water to make up.