Question

lf, \[\ce{C_{(s)} + O2_{(g)} -> CO2_{(g)}}\], ∆H = x .........(i)

\[\ce{CO_{(g)} + 1/2O2_{(g)} -> CO2_{(g)}}\], ∆H = y .......(ii)

Then, the heat of formation of CO is:

Options

• x + y

• x − y

• y − x

• `(("x" - "y"))/2`

Answer 1

x − y

Explanation:

For the formation of CO,

Adding eq. (i) and (ii)

\[\ce{C_{(s)} + O2_{(g)} -> CO2_{(g)}}\]; ∆H = x

\[\ce{CO2_{(g)} -> CO_{(g)} + 1/2O2_{(g)}}\]; ∆H = −y
_____________________________________________________
\[\ce{C_{(s)} + 1/2O2_{(g)} -> CO_{(g)}}\] ∆H = x + (−y) = x − y