Question

which chemical equation shows that the total mass during a chemical reaction stays the same? a mg + cl₂ → mgcl₂ b naoh + mgcl₂ → nacl + mgoh c 2na + 2h₂o → naoh + h₂ d h₂o + o₂ → h₂o

Explanation:

Step1: Recall law of conservation of mass

The law of conservation of mass states that in a chemical reaction, the total mass of the reactants equals the total mass of the products. This is reflected in a balanced chemical equation.

Step2: Check option A

In the equation $Mg + Cl_2
ightarrow MgCl_2$, there is 1 magnesium atom and 2 chlorine atoms on both the reactant and product sides. It is a balanced chemical equation.

Step3: Check option B

The correct formula for magnesium hydroxide is $Mg(OH)_2$, and the equation $NaOH + MgCl_2
ightarrow NaCl+MgOH$ is not balanced and has an incorrect formula.

Step4: Check option C

The equation $2Na + 2H_2O
ightarrow NaOH + H_2$ is not balanced. On the reactant side, there are 2 sodium, 4 hydrogen and 2 oxygen atoms. On the product side, there is 1 sodium, 4 hydrogen and 1 oxygen atom in the given un - balanced form.

Step5: Check option D

The equation $H_2O+O_2
ightarrow H_2O$ is not balanced and makes no chemical sense as written since you cannot just have oxygen disappear.

Answer:

A. $Mg + Cl_2
ightarrow MgCl_2$