객관식
Which of the following is the correctly balanced chemical equation for the combustion of propane (C_3H_8)?
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3. Chemical Reactions
Balancing Chemical Equations
객관식
Which of the following is the correctly balanced chemical equation for the reaction between hydrogen gas and oxygen gas to form water?
A
H_2 + O_2 → H_2O
B
2H_2 + 2O_2 → 2H_2O
C
H_2 + 2O_2 → 2H_2O
D
2H_2 + O_2 → 2H_2O
검증된 단계별 안내1
Write the unbalanced chemical equation for the reaction between hydrogen gas and oxygen gas to form water: \(\mathrm{H_2 + O_2 \rightarrow H_2O}\).
Count the number of atoms of each element on both sides of the equation. On the left, there are 2 hydrogen atoms and 2 oxygen atoms; on the right, there are 2 hydrogen atoms and 1 oxygen atom.
Balance the oxygen atoms first by adjusting the coefficient in front of water. Since oxygen appears as \(\mathrm{O_2}\) on the left and as a single oxygen atom in \(\mathrm{H_2O}\) on the right, place a coefficient of 2 in front of \(\mathrm{H_2O}\) to have 2 oxygen atoms on the right: \(\mathrm{H_2 + O_2 \rightarrow 2H_2O}\).
Now balance the hydrogen atoms. With 2 molecules of water, there are 4 hydrogen atoms on the right, so place a coefficient of 2 in front of \(\mathrm{H_2}\) on the left to have 4 hydrogen atoms: \(\mathrm{2H_2 + O_2 \rightarrow 2H_2O}\).
Verify that the equation is balanced by counting atoms again: 4 hydrogen atoms and 2 oxygen atoms on both sides, confirming the balanced equation is \(\mathrm{2H_2 + O_2 \rightarrow 2H_2O}\).
