How does the law of conservation play a role in chemical reaction?
In a chemical reaction, the law of conservation of mass must be followed: no matter may be destroyed OR created (the mass cannot change). In writing chemical equations, the mass of the left side must equal the mass on the right side. This also must be true of the number of each element. To follow the law of conservation of mass, coefficients must be used. Coefficients do NOT change the formula, just the relative amount of each substance (number of moles present). Example: Hydrogen gas (H2) and oxygen gas (O2) react to form water (H2O). H2+O2 -> H2O (this equation is not balanced as there are 2 oxygen on the left and 1 on the right) --multiply H2O by 2 H2+O2 -> 2H2O (not balanced as there are 2 hydrogen on the left and 4 on the right) --multiply H2 by 2 2H2+02 -> 2H2O (balanced equation)