The Chemistry of Goblies

If you made your Goblies kit, you know the steps it takes to make Goblies. However, do you know why it happens? Let's find out why the membrane forms around the Goblies ice. 

Two ingredients are used to make the membrane: sodium alginate and calcium chloride

To form Goblies you place Goblies ice (containing calcium chloride) in a bowl of sodium alginate and water. 

Sodium Alginate is a polymer

"poly" = many & "mer" = parts

You can see three sodium alginate molecules linked together in a chain in the picture below. 

Try creating a chain with your friends like the picture below. The middle friend faces the other way. 


Each of you represent a CO2- molecule and together you are a polymer. Now pretend that each of you have an apple to represent the sodium atom, which is the Na+. 

Remember that you and your friends represent the sodium alginate solution that you put the Goblies ice in. When the Goblies ice containing (Ca2+) is placed in the sodium alginate solution the carbonate (CO2-) decides that it rather have the calcium (Ca2+) instead of the sodium (Na+).  However, the calcium is like a pineapple and is too heavy for one arm to carry. In other words, you and your friends rather have pineapples instead of the apples.

In the chemistry world "too heavy" is actually charge (positive or negative). You the carbonate (CO2-) have a negative 1 charge (1-), so you can only attach to something that has a positive 1 charge (1+), like the sodium (Na+). However, the calcium has a positive 2 charge (2+). 

To fix this problem you and your friends decide to invite another group of friends. Therefore, two people can hold each of the pineapples as seen below. 

This reaction forms the Goblies membrane. Two chains of polymers come together. This is called cross-linking in chemistry. 

You will notice that the backward facing friends still have apples. Those friends will want to get pineapples too as long as there are more friends and pineapples available. That is why it is important to leave the Goblies ice in the sodium alginate solution for a long time so that the membrane becomes thicker and thicker. 

That's how the Goblies membranes are formed!