Sugar shake

How to make a rainbow in a glass at home

You don’t need any chem­i­cals for this ex­per­i­ment – you can do it right now!

Safe­ty pre­cau­tions

Per­form this ex­per­i­ment only un­der adult su­per­vi­sion.

Reagents and equip­ment

  • sug­ar (re­fined sug­ar works best);
  • 500 mL boil­ing wa­ter;
  • 6 glass­es;
  • pipettes;
  • food col­or­ing (4-5 dif­fer­ent col­ors).

Step-by-step in­struc­tions

Dis­trib­ute 500 mL boil­ing wa­ter even­ly among 5 glass­es. Don’t add any sug­ar to one of the glass­es. Add to the rest of the glass­es in turn: 2.5, 5, 7.5, and 10 sug­ar cubes. Add dif­fer­ent col­ors of food col­or­ing to each glass. Stir each so­lu­tion thor­ough­ly and let cool. Use sep­a­rate pipettes to trans­fer each so­lu­tion into an­oth­er, sin­gle glass. Pour the so­lu­tions gen­tly down the wall of the glass. Start with the so­lu­tion with the most sug­ar (10 pieces) and con­tin­ue in de­creas­ing or­der. Voila, you’ve made a sug­ar rain­bow! If the so­lu­tions mix too eas­i­ly, try re­frig­er­at­ing them or in­creas­ing the dif­fer­ence in their sug­ar con­cen­tra­tions.

Process de­scrip­tion

Den­si­ty is the ra­tio of a body’s weight to the vol­ume it oc­cu­pies. If dif­fer­ent mass­es of sug­ar are dis­solved in two equal vol­umes of wa­ter, then the so­lu­tion with more dis­solved sug­ar will be denser. More­over, if you ar­range the so­lu­tions in or­der of de­creas­ing den­si­ty from the bot­tom up, they won't mix right away since no cur­rents will form that could lead to the mix­ing of the so­lu­tions. It’s worth clar­i­fy­ing that dif­fu­sion be­tween the lay­ers does oc­cur, so the sug­ar and dye mol­e­cules from the more con­cen­trat­ed (denser) so­lu­tions grad­u­al­ly dif­fuse into the less con­cen­trat­ed so­lu­tions, slow­ly equal­iz­ing their con­cen­tra­tion through­out the vol­ume of the ves­sel.