Copper sulfate Making a big crystal Potassium aluminium sulfate(alum) Use a slip knot to tie your seed crystal to a 20 cm length of thread. This is not Potassium hexacyanoferrate(III) easy! Suspend the crystal in your beaker of saturated solution, as shown. Now follow the instructions below to make the best crystals you can. Cover the beaker. Making a saturated solution Leave the beaker for a few days, ideally in a place where the temperature will not change, for example in a cupboard. First make a saturated solution. This is a solution in which no more solid can Write down your observations as often as possible. dissolve. Solubility data ºC ºC. Use the table to find the solubility of your substance at 50 or 60 This is the maximum mass that can dissolve in 100 g of water. Weigh out this mass. Solubility (g of substance / 100 g of water) Use a measuring cylinder to measure out 100 cm3 of pure water. Substance ºC ºC ºC Pour the water into a beaker. Place it on a tripod and gauze over a Bunsen 20 50 60 ºC ºC. copper sulfate (hydrated) burner. Heat the water to 50 or 60 Turn off the Bunsen burner. 32 − 62 Add your weighed out substance to the beaker of hot water. Stir. potassium aluminium Allow your solution to cool to room temperature. 14 37 − sulfate With a spatula, add a few tiny crystals of your substance to the solution. potassium 46 − 70 Cover the top of the beaker with a piece of card. Leave for two or three days. hexacyanoferrate(III) Pour off the solution into another beaker, leaving behind any solid. Cover with a piece of card. This is your saturated solution. Key Stage 3 - Quality Crystal Making a seed crystal Record sheet Pour a little of your solution into a watch glass. Leave the rest of your solution in the beaker, covered with a piece of card. Crystal progress Leave the solution in the watch glass for a few days. Small crystals will form. Once all the water has evaporated from the watch glass, use a magnifying Write down your observations as your crystal forms. If you can, take photos, too. glass to look at the crystals that have formed. Choose the biggest crystal with the best shape. Remove it with tweezers. This is your seed crystal. Date Observations
Copper sulfate Potassium aluminium sulfate(alum) Potassium hexacyanoferrate(III) Now follow the instructions below to make the best crystals you can. Making a saturated solution First make a saturated solution. This is a solution in which no more solid can dissolve. Use the table to find the solubility of your substance at 50 ºC or 60 ºC. This is the maximum mass that can dissolve in 100 g of water. Weigh out this mass. Use a measuring cylinder to measure out 100 cm3 of pure water. Pour the water into a beaker. Place it on a tripod and gauze over a Bunsen burner. Heat the water to 50 ºC or 60 ºC. Turn off the Bunsen burner. Add your weighed out substance to the beaker of hot water. Stir. Allow your solution to cool to room temperature. With a spatula, add a few tiny crystals of your substance to the solution. Cover the top of the beaker with a piece of card. Leave for two or three days. Pour off the solution into another beaker, leaving behind any solid. Cover with a piece of card. This is your saturated solution. Making a seed crystal Pour a little of your solution into a watch glass. Leave the rest of your solution in the beaker, covered with a piece of card. Leave the solution in the watch glass for a few days. Small crystals will form. Once all the water has evaporated from the watch glass, use a magnifying glass to look at the crystals that have formed. Choose the biggest crystal with the best shape. Remove it with tweezers. This is your seed crystal. Making a big crystal Use a slip knot to tie your seed crystal to a 20 cm length of thread. This is not easy! Suspend the crystal in your beaker of saturated solution, as shown. Cover the beaker. Leave the beaker for a few days, ideally in a place where the temperature will not change, for example in a cupboard. Write down your observations as often as possible. Solubility data Substance Solubility (g of substance / 100 g of water) 20 ºC 50 ºC 60 ºC copper sulfate (hydrated) 32 − 62 potassium aluminium sulfate 14 37 − potassium hexacyanoferrate(III) 46 − 70 Key Stage 3 - Quality Crystal Record sheet Crystal progress Write down your observations as your crystal forms. If you can, take photos, too. Date Observations