In the chemical reaction 2Na(s)+Cl_(2)(g)arrow 2NaCl(s) the metal sodium (Na) and chlorine (Cl_(2)) gas react to produce solid sodium chloride (NaCl), or table salt. In this reaction Na and Cl_(2) are the reactants, and NaCl is the product It has been repeatedly observed that the sum of the masses of Na and Cl_(2) reacting equals the mass of NaCl produced. In fact.this phenomenon has been observed for every chemical reaction to date since the scientist Lavoisier first observed it in 1789. In chemical reactions, the total mass of the reactants always equals the total mass of the products. This phenomenon is referred to generally as the conservation of mass. What is this phenomenon considered? a law anidea a theory a hypothesis

## Step 1<br />The problem describes a chemical reaction where the sum of the masses of the reactants (sodium and chlorine) equals the mass of the product (sodium chloride). This observation has been consistently confirmed in all chemical reactions, a fact first noted by the scientist Lavoisier in 1789.<br /><br />## Step 2<br />This consistent observation across all chemical reactions is referred to as the conservation of mass. This principle is not just an idea, theory, or hypothesis, but a fundamental concept in chemistry that has been repeatedly confirmed through experimentation and observation.<br /><br />## Step 3<br />In the context of scientific terminology, a law is a statement based on repeated experimental observations that describes some aspect of the world. A law is a well-established principle that has been confirmed through many experiments and is accepted as true.