Why wouldn't we want to return used chemical into the original container? (Hint: Chemistry experiments often require very pure chemicals.)

Explanation:

Hello,

In this case, for the given chemical reaction:

We can notice that two sodium atoms and two hydrogen atoms are at the products but at the reactants there three and and respectively, thus, the solution given by the student is wrong since Na₂OH does not exist due to the fact that the charge of OH is -1 so there is going to be one sodium atom always in the sodium hydroxide. Besides, it is not possible to write H₃O since it correspond to hydroxonium ions (H₃O⁺) but not to water.

In such a way, by applying the law of conservation of mass which states that matter is neither created nor destroyed, we balance the chemical reaction as follows:

Whereas the addition of those twos allow us to have two sodium atoms and four hydrogen atoms at both reactants and products.

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