The generally best approach when liquid from a large reagent bottle is needed in an experiment is to pour a portion of the reagent into a separate container (such as a beaker or flask), then use that aliquot in the procedure , rather than repeatedly drawing directly from the stock bottle.

Why this is preferred

  • Minimizes contamination : Repeatedly inserting pipets or funnels into the main bottle can introduce impurities or moisture, degrading the reagent over time.
  • Improves safety and control : Large bottles are awkward to handle over a reaction setup; pouring into an intermediate vessel reduces the risk of spills and makes measuring easier.
  • Preserves the stock : Keeping the original bottle closed as much as possible maintains purity, concentration, and labeling integrity for future use.

Practical steps to follow

  1. Remove the cap, keeping the label facing you so you can confirm the reagent and concentration.
  1. Carefully pour an appropriate excess amount into a clean beaker or flask (enough for the whole experiment, but not wasteful).
  1. Use a graduated cylinder, pipet, or buret from the beaker to measure the exact volumes needed for each step.
  1. Recap the original bottle promptly and return it to storage.

Common alternatives (and their drawbacks)

Approach| Why it’s less ideal
---|---
Dispense directly from the bottle each time| Harder to control flow, higher spill risk, and repeated exposure to air or contaminants. 110
Insert a pipet into the bottle many times| Increases cross‑contamination and can introduce water or microbes from the pipet. 15
Pour directly into small‑necked vessels (e.g., test tubes)| More likely to overshoot or spill; intermediate beaker gives better control. 2

In short, “pour‑into‑beaker‑then‑measure” is the standard, safe, and contamination‑conscious method taught in most introductory chemistry labs.

Information gathered from public forums or data available on the internet and portrayed here.