I'd like to take a quick survey if I could. For all who routinely create diluted solutions using volumetric flasks, I'm sure you've observed volumes changing sometimes due to chemical interactions (with the meniscus going well above or below). In instances like these, do you prefer to do weight-to-weight dilutions instead of weight-to-volume and volume-to-volume? For example, I created a 20% solution (w/v) of sodium bicarbonate in water. After mixing, the meniscus dwindled well below the line. Should the solution be diluted to the line again in situations like this? Should a weight-to-weight solution be used instead?