It is then with the help of a tool - a descriptive overview of the system during the transformation - to analyze this
transformation, by introducing the notion of progress, and establish a material balance. The student must be able to
write the stoichiometric number of the equation in accordance with the laws of conservation of elements and loads
and to understand that a chemical change does not require only that the reagents are in specific proportions in the
state.
Students will be trained in the use of precise vocabulary and appropriation of convenient tools to describe and
analyze a transformation, according to a progression in increasing difficulties using advancement.
The development of the material balance that the teacher does with students is essential to validate the proposed
model. However, no responsibility is payable on the material balance. All of this presentation will be repeated at the
beginning of the teaching of chemistry in the first science class.
Experimental illustrations are used to capture the concept of chemical change (initial and final state) and to verify
the validity of a proposed model of chemical reaction to account for the evolution of a system undergoing a
chemical transformation.