If the products of a reaction are $CO _2$ and $2 H _2 O$, what is known about the reactants?
A. The reactants include $CO _2$ and $H _2 O$.
B. The reactants include substances with only $C , O$, and H atoms.
C. The reactants do not include any $C , O$, or H atoms.
D. The reactants are also $CO _2$ and $H _2 O$.
Answer (1)
The products of a reaction are C O 2 and H 2 O .
The reactants must contain at least C, H, and O atoms.
Option A is not necessarily true.
Option B is possible: the reactants contain only C, H, and O atoms.
Option C is impossible.
Option D is not necessarily true.
The correct answer is B: B .
Explanation
Analyze the Products The products of the reaction are carbon dioxide ( C O 2 ) and water ( H 2 O ). This means that the reactants must contain at least carbon (C), hydrogen (H), and oxygen (O) atoms to form these products. We need to determine which statement about the reactants is correct.
Evaluate Each Option Let's analyze each option:
A. The reactants include C O 2 and H 2 O . This is not necessarily true. The products are what are formed, not necessarily what the reactants are.
B. The reactants include substances with only C, O, and H atoms. This is possible. If the reactants only contain carbon, hydrogen, and oxygen, then the products C O 2 and H 2 O can be formed. For example, a carbohydrate like glucose ( C 6 H 12 O 6 ) could react with oxygen to produce carbon dioxide and water.
C. The reactants do not include any C, O, or H atoms. This is impossible because the products C O 2 and H 2 O contain C, O, and H atoms, so these atoms must come from the reactants.
D. The reactants are also C O 2 and H 2 O . This is not necessarily true. The products are what are formed, not necessarily what the reactants are.
Determine the Correct Statement Based on the analysis, the correct answer is that the reactants include substances with only C, O, and H atoms.
Examples
Consider a combustion reaction, like burning methane ( C H 4 ) in oxygen ( O 2 ). The products are carbon dioxide ( C O 2 ) and water ( H 2 O ). This illustrates that reactants containing only carbon, hydrogen, and oxygen can indeed produce these products. Understanding this helps in predicting reaction outcomes and designing chemical processes.
