Question

Determine the limiting reactant of the unbalanced chemical reaction if 2.00 mole of ethane is reacted with unlimited oxygen? `C^2H^6(g)+ O^2(g) --> CO^2(g) + H^2O(l)`

Please help me. I don't know how to find the mole of O2.

Answer 1

In all stoichiometric equations `"GARBAGE IN EQUALS GARBAGE OUT"`.

Explanation:

Do you appreciate what I mean in the given context....?

We know that hydrocarbons and alcohols combust completely, to give carbon dioxide and water. The normal rigmarole in these combustion reactions is to:

`"(i) Balance the carbons as carbon dioxide:"`
`C_2H_6(g)+O_2(g) rarr 2CO_2(g) +H_2O`

`"(ii) Balance the hydrogens as water:"`
`C_2H_6(g)+O_2(g) rarr 2CO_2(g) +3H_2O`

`"(iii) Then balance the oxygens:"`
`C_2H_6(g)+7/2O_2(g) rarr 2CO_2(g) +3H_2O`

`"Equation (iii)"` is balanced with respect to mass and charge. Of course if you use a half-integral coefficient you might die, so you could also double `"(iii)"` to give what?

And clearly the limiting reactant in the given scenario is ethane. The hydrocarbon is the limiting reactant in most combustion reactions. Sometimes, incomplete combustion occurs under conditions of LIMITED DIOXYGEN, to give SOME `CO` or even `"C"` as soot....this usually occurs in longer hydrocarbons, especially in a diesel engine, or even in the internal combustion engine...