This method is usually used to separate dissolved solids (solute) from a solution, or in other words, to separate the heat-liable solutes from their solutions. Crystallization not only prevents the solute from decomposing but also, most soluble impurities would be left behind.
Crystallization is commonly used to obtain pure sugar in industries and to obtain very pure silicon which is used in computer chips. To begin, you will need a saturated solution, meaning a solution that contains the maximum amount of solute dissolved in a solvent at a particular temperature.
Real-life scenario...
Let's say you and your business partner are going to start a new crystal factory. Your partner insists that rapid cooling would be better for the company since production would be faster. However, you think that larger and more nicely shaped crystals are better for selling. Hence, you need to prove to your partner that the crystals would indeed be larger and more nicely shaped. So you decided to conduct an experiment with hydrated copper (II) sulphate.
Hypothesis: Slow-cooling would form better, larger and nicer-looking crystals
Process...
Step 1: Heat about 20cm^3 of water in a beaker. Stop heating and remove from the tripod stand once bubbles are observed in the ater or when the water boils
Step 2: Add one spatula of copper (II) sulphate to the hot water
Step 3: Stir the mixture until all the copper (II) sulphate can be dissolved
Step 4: Repeat step 3 until no more copper (II) sulphate can be dissolved
Step 5: Filter the solution if there are any solid impurities
Step 6: Heat the copper (II) sulphate solution in an evaporating dish
Step 7: Stop heating when about half the solvent has evaporated from the solution. DO NOT heat to dryness. If a crust is formed on the surface of the solution, stop heating and add a some distilled water to the solution, stir to redissolve the crystals to form the crust
For those doing slow cooling...
Step 8: Pour the solution into a clean small boiling tube and allow it to cool and measure the time taken for crystals to appear
Step 9: Collect the crystals and dry on filter paper
Step 10: Observe the crystals formed and compare with rapidly cooled crystals
For those doing rapid cooling...
Step 8: Pour the solution into a clean small boiling tube and cool it in ice-water and measure the time taken for crystals to appear
Step 9: Collect the crystals and dry on filter paper
Step 10: Observe the crystals formed and compare with slowly cooled crystals
Observations...
Crystallization is commonly used to obtain pure sugar in industries and to obtain very pure silicon which is used in computer chips. To begin, you will need a saturated solution, meaning a solution that contains the maximum amount of solute dissolved in a solvent at a particular temperature.
Real-life scenario...
Let's say you and your business partner are going to start a new crystal factory. Your partner insists that rapid cooling would be better for the company since production would be faster. However, you think that larger and more nicely shaped crystals are better for selling. Hence, you need to prove to your partner that the crystals would indeed be larger and more nicely shaped. So you decided to conduct an experiment with hydrated copper (II) sulphate.
Hypothesis: Slow-cooling would form better, larger and nicer-looking crystals
Process...
Step 1: Heat about 20cm^3 of water in a beaker. Stop heating and remove from the tripod stand once bubbles are observed in the ater or when the water boils
Step 2: Add one spatula of copper (II) sulphate to the hot water
Step 3: Stir the mixture until all the copper (II) sulphate can be dissolved
Step 4: Repeat step 3 until no more copper (II) sulphate can be dissolved
Step 5: Filter the solution if there are any solid impurities
Step 6: Heat the copper (II) sulphate solution in an evaporating dish
Step 7: Stop heating when about half the solvent has evaporated from the solution. DO NOT heat to dryness. If a crust is formed on the surface of the solution, stop heating and add a some distilled water to the solution, stir to redissolve the crystals to form the crust
For those doing slow cooling...
Step 8: Pour the solution into a clean small boiling tube and allow it to cool and measure the time taken for crystals to appear
Step 9: Collect the crystals and dry on filter paper
Step 10: Observe the crystals formed and compare with rapidly cooled crystals
For those doing rapid cooling...
Step 8: Pour the solution into a clean small boiling tube and cool it in ice-water and measure the time taken for crystals to appear
Step 9: Collect the crystals and dry on filter paper
Step 10: Observe the crystals formed and compare with slowly cooled crystals
Observations...
Conclusion...
Crystals formed by rapid cooling are of smaller size and are more irregular in shape. To obtain more crystals we can actually a) Add more water to dissolve more copper sulphate or b) apply slow cooling instead or rapid cooling.
And that is how the story of your very successful crystal company started...
