Question

`"1 L"` of `"CO"_2` is passed through red hot coke. The volume becomes `"1.4 L"` at the same temperature and pressure. What is the composition of the products?

Answer 1

Here's what I got.

Explanation:

Start by writing the balanced chemical equation that describes this reaction

`"CO"_ (2(g)) + "C"_ ((s)) -> 2"CO"_ ((g))`

Now, notice that every mole of carbon dioxide that takes part in the reaction produces `2` moles of carbon monoxide.

This implies that if the sample of carbon dioxide would react completely, you would end up with `"2 L"` of carbon monoxide--keep in mind that when working with gases kept under the same conditions for pressure and temperature, their mole ratio is equivalent to a volume ratio.

In your case, the resulting gaseous mixture has a volume of `"1.4 L"`, so you know for a fact that the carbon dioxide was not completely consumed.

If you take `x` `"L"` to be the volume of carbon dioxide consumed by the reaction, you can say that `2x` `"L"` will be the volume of carbon dioxide produced by the reaction.

This means that after the reaction is complete, you will be left with

`overbrace((1 - x)color(white)(.)color(red)(cancel(color(black)("L"))))^(color(blue)("volume of unreacted CO"_2)) + overbrace((2x)color(white)(.)color(red)(cancel(color(black)("L"))))^(color(blue)("volume of CO produced")) = 1.4color(red)(cancel(color(black)("L")))`

This will get you

`1 + x =1.4 implies x= 0.4`

Therefore, you can say that the resulting mixture will contain

`(1 - 0.4)color(white)(.)"L" = "0.6 L " -> " CO"_2`

`(2 * 0.4)color(white)(.)"L" = "0.8 L " -> " CO"`