Question

Carbon dioxide and water are produced when pentane (C
5
​
H
12
​
) reacts with oxygen. What is the balanced equation for this reaction?
A. C
5
​
H
12
​
(g)+O
2
​
(g)→CO
2
​
(g)+H
2
​
O(g)
B. C
5
​
H
12
​
(g)+O
2
​
(g)→5CO
2
​
(g)+H
2
​
O(g)
C. C
5
​
H
12
​
(g)+8O
2
​
(g)→5CO
2
​
(g)+6H
2
​
O(g)
D. 5CO
2
​
(g)+6H
2
​
O(g)→C
5
​
H
12
​
(g)+8O
2
​
(g)

Answer 1

To balance the combustion reaction of pentane (\(C_5H_{12}\)) with oxygen (\(O_2\)), we need to ensure that the number of atoms of each element on the reactants side equals the number of atoms on the products side.

The general form of the combustion reaction is:

\[
C_xH_y + O_2 \rightarrow CO_2 + H_2O
\]

For pentane (\(C_5H_{12}\)):

1. **Count the number of carbon atoms**: There are 5 carbons in \(C_5H_{12}\), so we will produce 5 \(CO_2\).
2. **Count the number of hydrogen atoms**: There are 12 hydrogens in \(C_5H_{12}\), which will produce 6 \(H_2O\) (since each \(H_2O\) contains 2 H).
3. **Calculate the number of oxygen atoms needed**:
- From 5 \(CO_2\), we get \(5 \times 2 = 10\) O.
- From 6 \(H_2O\), we get \(6 \times 1 = 6\) O.
- Total O required = 10 + 6 = 16 O.

Since oxygen is diatomic (\(O_2\)), we need 16/2 = 8 O\(_2\) molecules.

So, the balanced equation for the complete combustion of pentane is:

\[
C_5H_{12} + 8O_2 \rightarrow 5CO_2 + 6H_2O
\]

Therefore, the correct answer is:

**C. \(C_5H_{12}(g) + 8O_2(g) \rightarrow 5CO_2(g) + 6H_2O(g)\)**.