NDLI: Why is mass conserved in chemical reactions?

Content Provider	Science Questions with Surprising Answers
Description	A chemical reaction absorbs energy, and therefore gains mass, it's not like electrons are created. The extra mass is not caused by the appearance of new particles. Rather, the extra mass is held in the system as a whole. Depending on the position and state of particles in a system relative to each other, the system gains or loses mass in addition to the individual masses of the particles. This concept is very similar to the classical concept of potential energy, but we now know that the energy is actually stored as mass.
File Format	HTM / HTML
Language	English
Publisher Date	2013-10-21
Requires	HTML5 supported browser
Access Restriction	Open
Subject Keyword	Chemical Reaction Conservation of Energy Conservation of Mass Energy Mass Reaction Chemistry Chemistry Questions and Answers Chemistry Questions Chemistry Questions Answers Questions on Chemistry Topics with Answers Questions on Chemistry General Question on Chemistry Science Questions with Answers
Content Type	Text
Educational Role	Student Teacher
Educational Use	Reading Classroom Solution Self Learning
Education Level	Class XI Class IX Class XII Class X
Resource Type	Model Answer Question
Subject	Chemistry

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Why is mass conserved in chemical reactions?