Video Transcript
The particles in the diagram show the reaction between carbon and oxygen to form carbon dioxide. Heat is required for this reaction to take place. What does the heat do? (A) It turns the carbon into soot during burning. (B) It breaks the double covalent bond in the oxygen molecule. (C) It allows the carbon dioxide molecule to turn into a gas. (D) It forms the bonds between the carbon and oxygen atoms. (E) It sticks the carbon atom to the oxygen atoms.
The particle diagram shows the reaction of carbon with oxygen to form carbon dioxide. We are told that this reaction requires heat. This can be indicated in a chemical equation by placing a triangle over the reaction arrow.
Chemical reactions typically occur in two steps. First, chemical bonds in the reactants are broken. Breaking chemical bonds requires energy. After the chemical bonds in the reactants are broken, new chemical bonds can be formed to create the products. This step releases energy. Heat is a form of energy that is added to the reaction. So it can be used to break the chemical bonds in the reactants.
The only chemical bond in the reactants is the double covalent bond in the oxygen molecule. So this reaction requires heat because the heat breaks the double covalent bond in the oxygen molecule, answer choice (B).
