Question

the chemical reaction of propane is shown below: c₃h₈ + 5 o₂ → 3 co₂ + 4 h₂o + heat and light propane oxygen gas carbon dioxide water what is the best evidence in this reaction that a chemical reaction occurred?

Explanation:

To determine the best evidence of a chemical reaction, we analyze the reaction of propane (\(C_3H_8\)) with oxygen (\(O_2\)) to form carbon dioxide (\(CO_2\)), water (\(H_2O\)), and release heat/light. Chemical reactions involve the formation of new substances (products) with different chemical compositions than reactants. Here, new molecules (\(CO_2\), \(H_2O\)) are formed, and energy (heat/light) is released, indicating a chemical change. The presence of new products (different from reactants \(C_3H_8\) and \(O_2\)) and energy release are key signs. For example, the molecular structures of \(CO_2\) (3 molecules) and \(H_2O\) (4 molecules) are distinct from propane and oxygen, showing new substances are created. Also, the emission of heat and light is a common indicator of exothermic chemical reactions (like combustion, which this is, as propane burns in oxygen).

Answer:

The best evidence is the formation of new substances (carbon dioxide, water) and the release of heat and light. The reactants (propane, oxygen gas) have different chemical identities than the products (carbon dioxide, water), and energy (heat/light) is released, confirming a chemical reaction occurred.