Uploaded March 2016 | Updated September 2026, 3 weeks ago
I made a hot and slightly super saturated solution of magnesium sulfate and allowed it to cool. I then placed a grain of magnesium sulfate into the solution to observe the crystallisation rate over a period of 12 hours.
1) Weigh out 18 g of magnesium sulfate heptahydrate into a clean empty beaker.
2) Add 15 mL of deionised water.
3) Heat over a Bunsen flame or hot plate until all of the salt has dissolved. It is necessary to place a lid over the beaker to prevent premature and accelerated evaporation, which forms a crystal crust on the surface of the solution.
4) Flash cool the beaker in an ice-bath.
5) Place a crystal grain of magnesium sulfate heptahydrate to investigate crystallisation rate.
As you can see from the video, there was significant growth of the crystal grain. The growth seemed to be stable, and the morphology of the crystal was preserved. Primary nucleation set in eventually at multiple sites. The set-up could be improved by having a lid to slow down evaporation. It suffices for a simple optimisation run.
I made a hot and slightly super saturated solution of magnesium sulfate and allowed it to cool. I then placed a grain of magnesium sulfate into the solution to observe the crystallisation rate over a period of 12 hours.
1) Weigh out 18 g of magnesium sulfate heptahydrate into a clean empty beaker.
2) Add 15 mL of deionised water.
3) Heat over a Bunsen flame or hot plate until all of the salt has dissolved. It is necessary to place a lid over the beaker to prevent premature and accelerated evaporation, which forms a crystal crust on the surface of the solution.
4) Flash cool the beaker in an ice-bath.
5) Place a crystal grain of magnesium sulfate heptahydrate to investigate crystallisation rate.
As you can see from the video, there was significant growth of the crystal grain. The growth seemed to be stable, and the morphology of the crystal was preserved. Primary nucleation set in eventually at multiple sites. The set-up could be improved by having a lid to slow down evaporation. It suffices for a simple optimisation run.
