If 50.0 dm3 of methane, CH4, react with 10.0 dm3 of air, calculate the grams of water produced.
CH4 (g) + 2 O2 (g) --> CO2 (g) + 2 H2O (l)

Respuesta :

Answer : The mass of [tex]H_2O[/tex] produced will be, 8.1 grams.

Explanation : Given,

Volume of [tex]CH_4[/tex] = [tex]50dm^3=50L[/tex]    [tex](1dm^3=1L)[/tex]

Volume of [tex]O_2[/tex] = [tex]10dm^3=10L[/tex]

Molar mass of [tex]H_2O[/tex] = 18 g/mole

First we have to calculate the moles of [tex]CH_4[/tex] and [tex]O_2[/tex].

As, 22.4 L volume of [tex]CH_4[/tex] present in 1 mole of [tex]CH_4[/tex]

So, 50 L volume of [tex]CH_4[/tex] present in [tex]\frac{50}{22.4}=2.23[/tex] mole of [tex]CH_4[/tex]

and,

As, 22.4 L volume of [tex]O_2[/tex] present in 1 mole of [tex]O_2[/tex]

So, 10 L volume of [tex]O_2[/tex] present in [tex]\frac{10}{22.4}=0.45[/tex] mole of [tex]O_2[/tex]

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

[tex]CH_4+2O_2\rightarrow CO_2+2H_2O[/tex]

From the balanced reaction we conclude that

As, 2 moles of [tex]O_2[/tex] react with 1 mole of [tex]CH_4[/tex]

So, 0.45 moles of [tex]O_2[/tex] react with [tex]\frac{0.45}{2}=0.225[/tex] moles of [tex]CH_4[/tex]

From this we conclude that, [tex]CH_4[/tex] is an excess reagent because the given moles are greater than the required moles and [tex]O_2[/tex] is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of [tex]H_2O[/tex].

As, 2 moles of [tex]O_2[/tex] react to give 2 moles of [tex]H_2O[/tex]

As, 0.45 moles of [tex]O_2[/tex] react to give 0.45 moles of [tex]H_2O[/tex]

Now we have to calculate the mass of [tex]H_2O[/tex].

[tex]\text{Mass of }H_2O=\text{Moles of }H_2O\times \text{Molar mass of }H_2O[/tex]

[tex]\text{Mass of }H_2O=(0.45mole)\times (18g/mole)=8.1g[/tex]

Therefore, the mass of [tex]H_2O[/tex] produced will be, 8.1 grams.