Question

When solid sodium metal is placed in water, energy is released and sparks fly as sodium hydroxide is formed. Which of these best describes this situation? The release of energy is a sign of a ___________ change. A) chemical B) endothermic Eliminate C) phase D) physical

Answer 1

Answer is: A) chemical change.

Balanced chemical reaction: 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g).

This is chemical change (chemical reaction), because two new substances are formed (sodium hydroxide and hydrogen), the atoms are rearranged and the reaction is followed by an energy change (exothermic reaction because energy is released).

Answer 2

Sodium becoming sodium hydroxide is a chemical process as molecular bonds are changing.

A new substance being formed is a sign of chemical change.