“Exothermic processes” experiment

How to boil a liquid boil by mixing substances

In this ex­per­i­ment, you’ll find out about pro­cess­es that take place with the re­lease of heat. These pro­cess­es sur­round us ev­ery­where, from cook­ing food to heat­ing the home. You’ll learn what these pro­cess­es are from our video!

Safe­ty pre­cau­tions

  • Wear pro­tec­tive gloves, a mask and glass­es.
  • Ob­serve safe­ty rules when work­ing with con­cen­trat­ed acids.
  • When pre­par­ing so­lu­tions of acids, acid must be added to wa­ter, not wa­ter to acid.

Warn­ing! Don’t try to re­peat this ex­per­i­ment with­out a pro­fes­sion­al su­per­vi­sion!

Reagents and equip­ment:

  • beaker;
  • test tube;
  • ace­tone (5 ml);
  • wa­ter (70 ml);
  • con­cen­trat­ed sul­fu­ric acid (50 ml);
  • lighter.

Step-by-step in­struc­tions

Low­er a test tube filled with ace­tone into the beaker. Then pour in wa­ter, then acid. Ob­serve the ace­tone boil. Ig­nite the va­pors that form.

Pro­cess­es de­scrip­tion

Many re­ac­tions and pro­cess­es take place with the re­lease of heat, and are called exother­mic. Thanks to the com­bus­tion (or ox­i­da­tion) re­ac­tion, we can heat our homes and cook food by burn­ing fuel. But there are pro­cess­es in which there is no com­bus­tion. One of them is the dis­so­lu­tion of acids in wa­ter.

In the dis­so­lu­tion of sul­fu­ric acid in wa­ter, enough heat is re­leased to make the ace­tone (which has a boil­ing point of 56 °C (133 °F) in the test tube boil, and there will be enough va­pors to ig­nite. The com­bus­tion of ace­tone is an exother­mic re­ac­tion.

One should dis­tin­guish be­tween an exother­mic process and an exother­mic re­ac­tion. In an exother­mic process (dis­so­lu­tion of acid), the chem­i­cal com­po­si­tion does not change, but in a re­ac­tion (com­bus­tion of ace­tone), ace­tone burns with the for­ma­tion of car­bon diox­ide and wa­ter:

СН₃-С(О)-СН₃ + 4О₂ = 3СО₂ + 3Н₂О