A laboratory manager must prepare exactly 100.0 g of solid NaCl that is 99.50 % pure…
MATHEMATICS · Multi-part · CBSE · Mathematics · Pair of Linear Equations in Two Variables · Pair of Linear Equations in Two Variables
Problem
A laboratory manager must prepare exactly 100.0 g of solid NaCl that is 99.50 % pure by mass. Two stock samples are available.
• Sample A: 97.0 % NaCl by mass
• Sample B: 99.9 % NaCl by mass
Assume the balance used to weigh the solids is precise to ±0.01 g.
(a) Describe qualitatively how the required masses of Sample A and Sample B are related to the target purity of the final mixture.
(b) Write, but do not solve, a pair of algebraic equations that could be used to calculate the exact masses of the two samples needed.
(c) Outline a step-by-step experimental procedure (no calculations required) that the manager could follow to obtain the target sample, including any checks needed to confirm the purity after mixing.
(d) Explain how a systematic 0.5 % overestimation of the purity of Sample A would affect the purity of the final mixture and whether the target specification would still be met.