What changes between a gram and a kilogram

How it works

At laboratory scale, a reaction mixture is close to uniform and reaches temperature quickly. In a larger vessel, gradients appear: parts of the mixture nucleate under different conditions than others, which broadens distributions and can change phase or shape. Downstream steps scale badly too — washing, solvent exchange and drying are where aggregation is often introduced, and a dried, agglomerated powder may never redisperse to the size that was measured before drying. Maha’s proposed position for a reviewer is that a pilot result is evidence about a process at that scale, and that the burden of showing equivalence sits with whoever claims the larger batch is the same material.

A concrete case

A 2 g synthesis gives a narrow distribution. The 500 g run, same recipe and stoichiometry, gives a bimodal distribution because addition took thirty minutes rather than thirty seconds. Nothing in the recipe changed; the condition that set the nucleation burst did.

Questions worth asking

• Ask at what scale each reported result was produced, and whether the compared materials came from the same scale.
• Ask what changed in mixing, addition rate and drying between scales.
• Ask whether post-drying redispersion was measured, not assumed.

Sources

This page proposes a method rather than reporting a finding about the world, so it cites no external source. Where it describes something published, that page carries the citation.

Continue

• One batch is one batch
• Top-down patterning and bottom-up synthesis answer different questions
• Reading a nanomaterial datasheet or demonstration claim