Question

In chemistry class, Melissa observes an exothermic reaction when she combines magnesium and oxygen under a fume hood. The equation for the reaction is shown:

2Mg(s) + O₂(g) → 2MgO(s) + energy

Which statement best describes the reactants and products?
A) Twice as many oxygen atoms are in the reactants as in the products.
B) Equal numbers of magnesium atoms are in the reactants as in the products.
C) Fewer overall atoms are in the products than in the reactants.
D) More atoms are in the products than in the reactants.

Answer 1

Twice as many oxygen atoms are in the reactants as in the products.

Step-by-step explanation:

The equation for the reaction between magnesium and oxygen is:

2Mg(s) + O₂(g) → 2MgO(s) + energy

In this reaction, two magnesium atoms combine with one oxygen molecule (which has two oxygen atoms) to produce two units of magnesium oxide (MgO).

Therefore, the statement that best describes the reactants and products is:

A) Twice as many oxygen atoms are in the reactants as in the products.