Friday, January 8, 2010

Melting coloured ice

Use some food colouring to make some ice in the 3 primary colours.
We had our three primary colours a little bit back and then the 3 glasses in between where we mixed two primary colours. This helped to show the colours of the rainbow. On the far right we put all three primary colours in to see if we could get brown.
Enjoy watching them melt and mix.
Our final colours. The orange and purple looked better with more light behind them.
We created our own colour wheel. Sorry about the shine of the flash though.

Salt Crystals

We are going to compare the growth of crystals made from Table Salt, Epsom Salt and Rock Salt.
We added a little food colouring to make it interesting. Start with 2 cups of boiling water and slowly add the salt. We only added 1/2 a cup to start with and then we added slowly so that we did not over saturate the solution. You want all the salt to disolve.
This is the amount of salt we were able to add.
Table Salt - 1/2 cup + 3 teaspoons. (RED)
Epson Salt - 1/2 cup + 8 tablespoons + 2 teaspoons. (GREEN)
Rock Salt - 1/2 cup + an extra 2 tablespoons of boiling water to get that to disolve. (BLUE)
In less than a week we already had lovely - perfectly square - crystals growing from the Table Salt.
In less than 2 weeks we saw how crystals were forming up the string and on the pencil.
At this stage we could also see the tiniest little crystals starting to form on the string of the Epsom Salt. But the bottle was bumped and they all broke. They were the finest little hair like crystals growing off the string - but just way too fine. You can see one tiny "hair" like crystal off to the left in the lighter area just above half way up the string.
In less than 3 weeks we had so many stunning Table Salt Crystals. We also had the crystals forming on the string above the water - but a totallydifferent texture and structure.
The Rock Salt contines to grow on the string and pencil with nothing on the string in the water.
Crystals had started to form on the bottom of the bottle - so we changed all the bottles today. We pour the water into a clean bottle, catching all the crystals so that there is clear water to continue. If you leave these cryastals in they will just grow bigger and you won't get any development on the string.
In less than 4 weeks we noticed the Table Salt solution had also saturated the pencil and crystals were starting to form.

The Table Salt crystlas contine to grow and we finally have lovely Rock Salt crystals on the string too. Amazing that the Table Salt produces a misty crystal where the Rock salt's crystals are clear. Beautiful square edges though and really amazing to see.
At 7 weeks the growth on the pencils is massive as well as up the sides of the bottles. I have not changed the bottles for the last 3 weeks so allowed that to grow.
Amazingly the Table Salt crystals on the pencil are very hard while the Rock Salt crystals on the pencil are very soft and just crumble when you try to break a piece off.
The Epsom Salt solution did start to form beautiful thin crystals off the string on the surface of the liquid, but with the slightest touch of the glass they break.
Amazing that the Epsom Salt solution did not even get up to the pencil. I am glad we had added the food colouring. It helped us to see the capillary action of the liquid (or lack of it in the case of the Epsom salt - perhaps because there was so much salt in the solution - far more than the others).

It's really been wonderful to watch. Unfortuantely the liquid level (especially in the Table Salt bottle) is getting lower, so the chunky crystals forming above the liquid are taking over the pretty squrae ones.