Water RPA

Question 1

Method to identify if water is pure

Answer 1

1) with pipette add small sample of water to universal indicator- if universal indicator turns green it means the water has a PH of 7 so is neutral but not necessarily pure
2) use top pan balance to measure mass of evaporating basin
3) use measuring cylinder to add 20cm cubed of water sample to Vapor aging basin and place on tripod and gauze over Bunsen burner
4) heat until all water has evaporated
5) once the evaporating basin has cooled re measure its mass with the top pan balance
6) subtract original mass of evaporating basin away from new mass to get mass of dissolved substances
7) if mass of dissolved substances is 0 (mass of evaporating basin hasn’t changed) then the water is pure

Question 2

How to test PH of water sample

Answer 2

Universal indicator (use pipette to add a few drops of water sample into the paper)
Or PH probe (more accurate as gives exact value)

Question 3

PH of pure water and colour on universal indicator

Answer 3

7
Green

Question 4

Method (as in name for scientific process) used to purify seawater

Answer 4

Distillation