How does the law of conservation of mass apply to this reaction: C2H4 + O2 → 2H2O + 2CO2?

Responses

Only the oxygen needs to be balanced. There are equal numbers of hydrogen and carbon.
Only the oxygen needs to be balanced. There are equal numbers of hydrogen and carbon.

Each element needs to be balanced.
Each element needs to be balanced.

The equation needs to be balanced. There are fewer oxygen atoms in the equation than hydrogen or carbon.
The equation needs to be balanced. There are fewer oxygen atoms in the equation than hydrogen or carbon.

The law of conservation of mass has already been applied. There is an equal number of each element on both sides of the equation.

3 answers

The correct response is:

The equation needs to be balanced. There are fewer oxygen atoms in the equation than hydrogen or carbon.

In the given reaction:

C2H4 + O2 → 2H2O + 2CO2

You need to account for the atoms of each element on both sides of the equation to comply with the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.

Let's break it down:

  • On the left side:

    • Carbon (C): 2 (from C2H4)
    • Hydrogen (H): 4 (from C2H4)
    • Oxygen (O): 2 (from O2)
  • On the right side:

    • Carbon (C): 2 (from 2CO2, since each CO2 has 1 carbon)
    • Hydrogen (H): 4 (from 2H2O, since each H2O has 2 hydrogens)
    • Oxygen (O): 6 (2 from 2H2O and 4 from 2CO2)

As we can see, there is an imbalance in the number of oxygen atoms between the reactants and products. As such, the equation is not balanced according to the law of conservation of mass and needs adjustments to equalize the numbers of each type of atom on both sides.

choose one of the answer choices above

The best choice among the provided responses is:

The equation needs to be balanced. There are fewer oxygen atoms in the equation than hydrogen or carbon.