Values of heats of formation for SiO2 and MgO are -48.4 and -34.7 kJ respectively. The heat of the reaction 2Mg + SiO2 → 2MgO + Si is

Question

Values of heats of formation for SiO2 and MgO are -48.4 and -34.7 kJ respectively. The heat of the reaction 2Mg + SiO2 → 2MgO + Si is (A) 21.16 kJ (B) - 21.00 kJ (C) - 13.62 kJ (D) 13.6 kJ

Tardigrade Admin · Accepted Answer

Δ H=[2×(-48.4)+0]-[(-34.7+0)] =-69.4+48.4 kJ =-21.00kJ

Q. Values of heats of formation for $S i O_{2}$ and $M g O$ are $- 48.4$ and $- 34.7 k J$ respectively. The heat of the reaction
$2 M g + S i O_{2} \to 2 M g O + S i$ is

$21.16 k J$

$- 21.00 k J$

$- 13.62 k J$

$13.6 k J$

$Δ H = [2 \times (- 48.4) + 0] - [(- 34.7 + 0)]$
$= - 69.4 + 48.4 k J$
$= - 21.00 k J$

Q. Values of heats of formation for SiO2​ and MgO are −48.4 and −34.7kJ respectively. The heat of the reaction 2Mg+SiO2​→2MgO+Si is

21.16kJ

−21.00kJ

−13.62kJ

13.6kJ