Question

1. choose the best answer.

a student observes the combustion reaction of methane (ch₄) upon lighting a bunsen burner. which best describes the products of the reaction?
carbon and water
oxygen and carbon
carbon dioxide and water
oxygen and water

1. choose the best answer.

according to le chateliers principle, what will happen to the system when products are added to a system?
the reaction will shift toward the products.
nothing will happen to the reaction.
the reaction will stop.
the reaction will shift toward the reactants.

Explanation:

Question 4

The combustion of methane (\(CH_4\)) in the presence of oxygen (from the air, as in a Bunsen burner) follows the reaction: \(CH_4 + 2O_2
ightarrow CO_2 + 2H_2O\). So the products are carbon dioxide (\(CO_2\)) and water (\(H_2O\)). The other options are incorrect: carbon and water would be from incomplete combustion (not typical here), oxygen is a reactant, not a product, and oxygen and water is incorrect as oxygen is a reactant.

Le Chatelier's principle states that if a stress is applied to a system at equilibrium, the system will shift to counteract the stress. Adding products increases the concentration of products. To counteract this, the reaction will shift in the direction that consumes products, which is the reverse reaction (toward reactants). So the reaction shifts toward reactants. The other options are incorrect: shifting toward products would increase product concentration further, nothing happening or the reaction stopping are not in line with the principle.

Answer:

carbon dioxide and water

Question 5