Question

question 4 (2 points)
when the following combustion equation is balanced, what is the coefficient in front of h₂o?
c₂h₆ (g) + o₂ (g) → co₂ (g) + h₂o (g)
1
6
4
7
2

Explanation:

Step1: Balance carbon atoms

There are 2 carbon atoms in $C_{2}H_{6}$. So, we put a 2 in front of $CO_{2}$: $C_{2}H_{6}(g)+O_{2}(g)\to2CO_{2}(g) + H_{2}O(g)$

Step2: Balance hydrogen atoms

There are 6 hydrogen atoms in $C_{2}H_{6}$. So, we put a 3 in front of $H_{2}O$: $C_{2}H_{6}(g)+O_{2}(g)\to2CO_{2}(g)+3H_{2}O(g)$

Step3: Balance oxygen atoms

On the right - hand side, there are $2\times2 + 3\times1=7$ oxygen atoms. So, we put $\frac{7}{2}$ in front of $O_{2}$: $C_{2}H_{6}(g)+\frac{7}{2}O_{2}(g)\to2CO_{2}(g)+3H_{2}O(g)$
To get rid of the fraction, we multiply the entire equation by 2: $2C_{2}H_{6}(g)+7O_{2}(g)\to4CO_{2}(g)+6H_{2}O(g)$

Answer:

6