Multiple Choice
Which of the following is the balanced chemical equation used to calculate the standard enthalpy of formation (ΔH_f^∘) of CaCO_3(s)?
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3. Chemical Reactions
Balancing Chemical Equations
Multiple Choice
Which of the following chemical equations is unbalanced?
A
H_2 + H_2 + O_2 ightarrow H_2O + H_2O
B
C + O_2 ightarrow CO_2
C
Sr + O_2 ightarrow 2SrO
D
6H_2 + 3O_2 ightarrow 6H_2O
Verified step by step guidance1
Step 1: Understand that a balanced chemical equation has the same number of atoms of each element on both sides of the reaction arrow.
Step 2: For each equation, count the number of atoms of each element on the reactant side and compare it to the number on the product side.
Step 3: For the equation \(H_2 + H_2 + O_2 \rightarrow H_2O + H_2O\), count the atoms: Reactants have 4 hydrogen atoms (2 + 2) and 2 oxygen atoms; Products have 4 hydrogen atoms (2 per \(H_2O\) times 2) but only 2 oxygen atoms total (1 per \(H_2O\) times 2). Check if these counts match.
Step 4: Repeat the atom count for the other equations: \(C + O_2 \rightarrow CO_2\), \(Sr + O_2 \rightarrow 2SrO\), and \(6H_2 + 3O_2 \rightarrow 6H_2O\), verifying that the number of atoms for each element is equal on both sides.
Step 5: Identify which equation does not have equal numbers of atoms on both sides, indicating it is unbalanced.
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