Separating sand and salt by dissolving, filtering and evaporating · Concept Studio

The idea

A mixture can be separated using a property in which its parts differ: salt dissolves in water and sand does not.

Safety card

Low riskAn adult supervises

Hazards

hot evaporating basin and spitting salt solution near dryness
Bunsen burner

Controls

eye protection
stop heating before the basin is dry
tongs for the hot basin

Note

No hazardous chemicals; the risk is heat. Basic risk assessment per CSIS Section 1.7.

What you need

mixture of 5.0 g sand and 5.0 g table salt, weighed as a whole (10.0 g)
100 mL beaker, glass rod, 50 mL of water
filter funnel, filter paper, conical flask
evaporating basin, tripod, gauze, Bunsen burner, heat-resistant mat
balance reading to 0.1 g

How to do it

Weigh the mixture, tip it into the beaker, add 50 mL of water and stir for 2 minutes.
Filter into the conical flask. Rinse the sand on the paper with 10 mL of water so the last salt goes through.
Pour the filtrate into a weighed evaporating basin and heat gently until the salt starts to crackle; stop before it is fully dry and let the rest evaporate overnight.
Dry the sand on its paper overnight. Weigh the recovered sand and the recovered salt.
Compare the two recovered masses with the 5.0 g of each you started with and account for any loss.

What you should see

Sand stays on the filter paper; the filtrate is clear; white salt crystals remain in the basin. Neither recovered mass can exceed the 5.0 g put in; the total recovered falls below 10.0 g because some salt solution stays in the wet sand and paper and some spatters near dryness, and a sand mass above 5.0 g means the sand is still damp or carries salt crust. The learner knows it worked when the filtrate is clear, the dried sand shows no white crust, and every gram of shortfall can be assigned to a named step.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Salt disappears when it dissolves, so it cannot be recovered.
Filtering removes anything you cannot see.
Boiling the solution to dryness gives the best result.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science 7–10 Syllabus (2023)SC4-SOL-01 SC4-WS-04
Australian Curriculum v9AC9S7U06AC9S7I02

Sources

The pages the author read to write this activity.