“Artificial snow” experiment

How to make snow from a baby diaper

In this ex­per­i­ment, we’ll show you how to make ar­ti­fi­cial snow at home!

Safe­ty pre­cau­tions

You can touch ar­ti­fi­cial snow, but don’t eat it. Don’t for­get to wash your hands af­ter touch­ing the ar­ti­fi­cial snow. Dry snow must be re­moved im­me­di­ate­ly.

Reagents and equip­ment:

  • a di­a­per (sodi­um poly­acry­late);
  • wa­ter;
  • glass con­tain­er.

Step-by-step in­struc­tions

Cut the di­a­per and take the ab­sorbent sub­stance out of it. This sub­stance is sodi­um poly­acry­late. Then pour wa­ter on to the pow­der. The vol­ume in­creas­es con­sid­er­ably. You can sprin­kle the snow you’ve made on Christ­mas dec­o­ra­tions.

Pro­cess­es de­scrip­tion

Sodi­um poly­acry­late is a sodi­um salt of poly­acrylic acid. Its mol­e­cules are very long, con­sist­ing of iden­ti­cal re­peat­ing frag­ments con­tain­ing charged groups. Sodi­um poly­acry­late is a very hy­gro­scop­ic sub­stance, i.e. it likes to ab­sorb wa­ter. One of the main prop­er­ties of the com­pound is the abil­i­ty to ab­sorb liq­uid of 200-300 times its own mass. So it in­stant­ly ab­sorbs wa­ter and swells up im­mense­ly, form­ing flakes that re­sem­ble snow. Why does this hap­pen? The wa­ter mol­e­cules en­ter be­tween the chains into the gran­ules of sodi­um poly­acry­late.

Each sodi­um cation Na⁺ puts on a “coat” of wa­ter mol­e­cules. These “coats” also form around neg­a­tive­ly charged cen­ters–the car­boxy­late groups CO₂⁻.

Thus, the to­tal vol­ume of gran­ules in­creas­es by the vol­ume of wa­ter that en­ters them. Each chain of poly­acry­late that is “soaked” in this man­ner un­rav­els. How­ev­er, the wa­ter in this ex­per­i­ment is not suf­fi­cient for all of them, and goes in­side each gran­ule. So “dry” chains re­main on the out­side. From in­ner ex­pan­sion, air comes be­tween them, and the to­tal vol­ume in­creas­es. If there is too much wa­ter, the gran­ules be­come sog­gy, stick to­geth­er and turn into gel–a semi-trans­par­ent vis­cous mass which has a very sim­i­lar con­sis­ten­cy to jel­ly or as­pic.