# Question #8c016

Apr 4, 2014

Combustion involves a hydrocarbon, in this case methane burning in oxygen to produce carbon dioxide and water.

$C {H}_{4} + 2 {O}_{2} \to C {O}_{2} + 2 {H}_{2} O$

To balance te equation you need 2 water molecules to provide balance for the 4 hydrogen in methane and then 2 oxygen (diatomic ${O}_{2}$) to balance the 4 oxygen.

Once you have a have a balanced equation you can proceed with the Ideal gas law to determine moles of methane and then stoichiometry to convert to moles of water.

To begin with we find the knowns and unknowns for the Ideal Gas Law, PV = nRT.

P = 1.00 atm
V = 10.5 L
n = ??
R = 0.0821 $\frac{a t m L}{m o l K}$
T = 200 C + 273 = 273 K

PV = nRT can be rearranged $n = \frac{P V}{R T}$

$n = \frac{\left(1.00 a t m\right) \left(10.5 L\right)}{\left(.0821 \frac{a t m L}{m o l K}\right) \left(473 K\right)}$

n = 0.27 moles $C {H}_{4}$

Now you can use the balanced chemical equation and stoichiometry to solve for the moles of ${H}_{2} O$

moles $\to$ moles

$0.27 m o l C {H}_{4} x \frac{2 m o l {H}_{2} O}{1 m o l C {H}_{4}} = 0.54 m o l {H}_{2} O$