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What did Van Helmont want to find out about plants?
Where their mass comes from
What did Van Helmont grow in his experiment?
A willow tree
How long did his experiment run?
5 years
True or False: Van Helmont thought soil was the main source of a plant’s mass.
False
What did Van Helmont add to the plant besides soil?
Water
How much soil did Van Helmont find was lost after 5 years?
Almost none (only a few grams)
What changed more: the mass of the soil or the mass of the plant?
The mass of the plant
What conclusion did Van Helmont make?
Plants gain mass from water
Why was Van Helmont's conclusion only partly correct?
He didn’t know about carbon dioxide
Which gas do plants actually use to gain most of their mass?
Carbon dioxide (CO₂)
What key process (unknown at the time) explains how plants gain mass?
Photosynthesis
What modern scientific method did Van Helmont demonstrate?
Careful measurement and controlled variables
What was one flaw in Van Helmont’s experiment?
He didn’t account for gases / limited controls
What part of the plant did Van Helmont measure at the end?
The tree’s mass
What element in CO₂ becomes the main building block of plants?
Carbon
