Just how strong is “chemical compression”?

How to make plastic bottle contract

Crush­ing a plas­tic bot­tle us­ing the pow­er of chem­istry!

Safe­ty pre­cau­tions

  • Cau­tion! Ob­serve safe­ty rules when work­ing with these sub­stances.
  • Wear pro­tec­tive gloves, eye­wear, and a mask.


  • plas­tic bot­tle;
  • wood­en stick;
  • 4 tbsp bak­ing soda;
  • 100 mL 6% vine­gar so­lu­tion;
  • drain clean­er con­tain­ing sodi­um hy­drox­ide.

Step-by-step in­struc­tions

Pour 4 tbsp bak­ing soda into a plas­tic bot­tle and add 100 mL 6% vine­gar so­lu­tion. This ini­ti­ates a tu­mul­tuous re­ac­tion; wait for it to die down. Check that the bot­tle is filled with car­bon diox­ide by in­sert­ing a lit splint; the splint should go out. Pour some sodi­um hy­drox­ide-based drain clean­er into the bot­tle. Close the bot­tle and shake. The mix­ture in­side heats up no­tice­ably, and the bot­tle col­laps­es!

Pro­cess­ de­scrip­tion

The bak­ing soda and 6% vine­gar so­lu­tion re­act to form sodi­um ac­etate, wa­ter, and car­bon diox­ide.

NaH­CO₃ + CH₃­COOH → CH₃­COONa + H₂O + CO₂↑

Wait un­til the re­ac­tion is over and check that the bot­tle is full of car­bon diox­ide us­ing a lit splint. The splint should be ex­tin­guished at the bot­tle’s neck. Сar­bon diox­ide doesn't sup­port com­bus­tion, so if the splint is ex­tin­guished, this in­di­cates that a sig­nif­i­cant por­tion of the air in the bot­tle has been re­placed by car­bon diox­ide.

2NaOH + CO₂ → Na₂­CO₃ + H₂O

Drain clean­er usu­al­ly con­tains sodi­um hy­drox­ide which, when in­tro­duced to the bot­tle, in­ter­acts with car­bon diox­ide and re­leas­es a sig­nif­i­cant amount of heat, form­ing sodi­um bi­car­bon­ate. It may even melt a lit­tle! The amount of gas in the bot­tle de­creas­es, and the bot­tle is crushed un­der ex­ter­nal pres­sure.

Learn about the awe­some prop­er­ties of oth­er sub­stances with the sets from the MEL Chem­istry sub­scrip­tion!