Ocean water contains dissolved salts. When water evaporates, most of that salt stays behind. A smaller amount of water holding the same salt becomes saltier. Rain adds fresh water and makes the mixture less salty. Track water and salt separately instead of treating saltiness as a colour alone.
Water and oceans · Discover & try
Why does evaporation leave the ocean’s salt behind?
Reading level 1 of 5 · EarlyChange
Word help
Salinity
The concentration of dissolved salts in water.
Dilution
A reduction in concentration when more solvent is added.
Dissolved
Mixed into a liquid at the molecular or ionic scale.
Watch · Try · Explain
See how it works
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Ideal well-mixed basin using grams per litre; no crystallization, overflow or full ocean chemistry.
What to look for
- Keep salt mass fixed while water changes.
- Compare evaporation with fresh-water addition.
- Read grams per litre separately from total grams.
Explain what you noticed
A new covered bowl contains 20 grams of dissolved salt in 2 litres of water. It gains 2 litres of fresh water without losing salt. What happens?
Keep this idea: Evaporation removes water while leaving most dissolved salt; rain adds fresh water and dilutes it.
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Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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