Can we change how water acts?
In Room 12 we tried to see if we could change when water freezes. To do this we froze water with different things added.
First we tried to freeze fresh water, water with salt and water with sugar.
We added 1 cup of salt to 800ml of water. We also added 1 cup of sugar to another 800ml of water. The last one was just fresh water.
We poured this water into muffin tins to freeze. We then put these in the freezer overnight. The next day when we checked them the salt water one hadn’t frozen (there were a few ice crystals though) – WE HAD CHANGED HOW WATER ACTS!!!
This is one of the crystals that formed in the salt water. The rest of the water didn’t freeze.
We then tried to freeze some of our salt water from Colac Bay. This water froze.
Next we wanted to melt our ice cubes to see which ones melted first.
We sat three ice cubes of each kind in containers and left them to melt. Every half an hour we looked at our ice cubes and took photos so that we could remember what had happened. At the beginning it looked like they were all melting at the same speed. After about an hour though it was clear that the fresh water one was melting the slowest and the sugar water one was melting the fastest.
From this experiment we have found that yes we have changed how water acts. If you add salt or sugar to water it will take longer for them to freeze and also it they will melt quicker.
This means that if you add salt or sugar you can lower the freezing point to below zero. This explains why in some countries they put salt on their roads to stop them freezing.
The pictures below show our ice cubes after one and a half hours of melting.
Fresh Water
Salt Water (from Colac Bay 2 tablespoons of salt to 1 litre of water)
Sugar Water (1 cup of sugar to 800ml water)
