What will be the heat of formation of methane, if the heat of combustion of carbon is ' -x ' kJ, heat of formation of water is ' -y ' kJ and heat of combustion of methane is ' z ' kJ?

Question

What will be the heat of formation of methane, if the heat of combustion of carbon is ' -x ' kJ, heat of formation of water is ' -y ' kJ and heat of combustion of methane is ' z ' kJ? (A) (-x-y+z) kJ (B) (-z-x+2 y) kJ (C) (-x-2 y-z) kJ (D) (-x-2 y+z) kJ

Tardigrade Admin · Accepted Answer

(I) C + O 2 longrightarrow CO 2, Δ H=-x kJ (II) H 2+(1/2) O 2 longrightarrow H 2 O , Δ H=-y kJ (III) CH 4+2 O 2 longrightarrow CO 2+2 H 2 O Δ H=-z kJ Multiply Eq. (II) by 2, adding to (I) and then, subtract Eq. (III) from the sum C +2 H 2 longrightarrow CH 4, Δ H=(-x-2 y+z) kJ

Q. What will be the heat of formation of methane, if the heat of combustion of carbon is ' $- x$ ' kJ, heat of formation of water is ' $- y$ ' $k J$ and heat of combustion of methane is ' $z$ ' kJ?

$(- x - y + z) k J$

$(- z - x + 2 y) k J$

$(- x - 2 y - z) k J$

$(- x - 2 y + z) k J$

Q. What will be the heat of formation of methane, if the heat of combustion of carbon is ' −x ' kJ, heat of formation of water is ' −y ' kJ and heat of combustion of methane is ' z ' kJ?

(−x−y+z)kJ

(−z−x+2y)kJ

(−x−2y−z)kJ

(−x−2y+z)kJ

(I) C+O2​⟶CO2​,ΔH=−xkJ (II) H2​+21​O2​⟶H2​O,ΔH=−ykJ (III) CH4​+2O2​⟶CO2​+2H2​O ΔH=−zkJ Multiply Eq. (II) by 2, adding to (I) and then, subtract Eq. (III) from the sum C+2H2​⟶CH4​,ΔH=(−x−2y+z)kJ

Q. What will be the heat of formation of methane, if the heat of combustion of carbon is ' $- x$ ' kJ, heat of formation of water is ' $- y$ ' $k J$ and heat of combustion of methane is ' $z$ ' kJ?

$(- x - y + z) k J$

$(- z - x + 2 y) k J$

$(- x - 2 y - z) k J$

$(- x - 2 y + z) k J$