Question

Question #39c68

Answer 1

`0.50" dm"^3` or `0.50 " L"`.

Explanation:

This is based on the balanced reaction:

`HC-=CH(g) +2H_2(g)`
`rarr H_3C-CH_3(g)`.

Thus one mole of ethyne (`"C"_2"H"_2`) requires two moles of hydrogen. Given equiv temperature and pressure for a reaction between (essentially ideal) gases, the same volume ratio applies. Thus `0.25*dm^3` acetylene clearly requires `0.50*dm^3` dihydrogen gas for stoichiometric equivalence.

Note that `1" dm"^3=(10^-1" m")^3 =10^-3" m"^3=1" L"`.