“Iodine flower” experiment

How can you col­or a flow­er with air?

Safe­ty pre­cau­tions

Wear pro­tec­tive gloves, a mask and glass­es, and work in a well-ven­ti­lat­ed room.

Warn­ing! Only un­der adults su­per­vi­sion.

Reagents and equip­ment:

• 10% starch so­lu­tion (50 ml);
• 10% io­dine so­lu­tion in potas­si­um io­dide (5 ml);
• pa­per nap­kin;
• wood­en stick;
• scotch tape;
• glass dome;
• glass.

Step-by-step in­struc­tions

Make a flow­er from a pa­per nap­kin, at­tach it to the stick with scotch tape and coat the petals with the starch so­lu­tion. Pour the io­dine so­lu­tion in the potas­si­um io­dide into the glass, put the starched flow­er in the glass and cov­er with a glass dome. Af­ter a few sec­onds the flow­er will turn blue.

Pro­cess­es de­scrip­tion

Io­dine has high volatil­i­ty, and at room tem­per­a­ture it evap­o­rates from the potas­si­um io­dide so­lu­tion. The io­dine va­pors re­act with the starch on the flow­er petals and form a blue starch-io­dine com­plex.