Answer:
2 H₂O → 2 H₂ + O₂
Step-by-step explanation:
The correct question is with options, as it's shown in the following:
"The decomposition of water into hydrogen gas H2 and oxygen gas O2 can be modeled by the balanced chemical equation
A) H2 + O2 → H2O
B) H2O → H2 + O2
C) 2H2 + O2 → 2H2O
D) 2H2O → 2H2 + O2"
In a decomposition reaction, a single substance decomposes, producing two or more different substances. That is, in this type of reactions from a compound two or more substances are formed according to the formula:
AB → A + B
This type of reaction can occur spontaneously or caused by certain external factors.
So, in this case, you have:
H₂O → H₂ + O₂
The law of conservation of matter states that since no atom can be created or destroyed in a chemical reaction, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products. Then, you must balance the chemical equation to comply with this law.
The sub-index indicates the amount of each element present in each reagent and product.
The coefficients located in front of each molecule indicate the amount of each molecule for the reaction.
By multiplying the coefficient mentioned by the subscript, you get the amount of each element present in the reaction.
Finally, you should keep in mind that on each side of the reaction there must be the same amount of each element for the reaction to be balanced.
So the balanced equation is:
2 H₂O → 2 H₂ + O₂
where you can see that on each side of the equation there are:
Left side: 2*2=4 hydrogen and 2 oxygen.
Right side: 2*2=4 hydrogen and 2 oxygen.
In this way the law of conservation of matter is fulfilled.