Question

select the correct answer.
which is a balanced chemical equation?
a. $c_7h_{16} + 5o_2 \
ightarrow 6co_2 + 4h_2o$
b. $c_7h_{16} + 11o_2 \
ightarrow 7co_2 + 8h_2o$
c. $c_7h_{16} + 14o_2 \
ightarrow 7co_2 + 5h_2o$
d. $c_7h_{16} + 22o_2 \
ightarrow 14co_2 + 16h_2o$

Explanation:

Step1: Check Carbon Atoms

For a balanced equation, number of C atoms on left (in \( C_7H_{16} \)) should equal right (in \( CO_2 \)).

• A: Left C=7, Right C=6 → Unbalanced.
• B: Left C=7, Right C=7 → Balanced so far.
• C: Left C=7, Right C=7 → Balanced so far.
• D: Left C=7, Right C=14 → Unbalanced.

Step2: Check Hydrogen Atoms

Number of H atoms (in \( C_7H_{16} \)) should equal H in \( H_2O \) (times 2, since \( H_2O \) has 2 H).

• B: Left H=16, Right H= \( 8 \times 2 = 16 \) → Balanced.
• C: Left H=16, Right H= \( 5 \times 2 = 10 \) → Unbalanced.

Step3: Check Oxygen Atoms (Final Check)

Oxygen in \( O_2 \) (left) plus O in \( C_7H_{16} \) (0) should equal O in \( CO_2 \) (times 2) plus O in \( H_2O \) (times 1).

• B: Left O= \( 11 \times 2 = 22 \), Right O= \( (7 \times 2) + 8 = 22 \) → Balanced.

Answer:

B. \( C_7H_{16} + 11O_2
ightarrow 7CO_2 + 8H_2O \)