Chemical Thermodynamics Question 224
Question: Values of heats of formation for $ SiO_2 $ and $ MgO $ are $ -48.4 $ and $ -34.7,kJ $ respectively. The heat of the reaction $ 2Mg+SiO_2\to 2MgO+Si $ is [KCET 1990]
Options:
A) $ 21.16,kJ $
B) $ -21.10,kJ $
C) $ -13.62,kJ $
D) $ 13.6,kJ $
Show Answer
Answer:
Correct Answer: B
Solution:
$ \Delta {H_{(reaction)}}=2\Delta H_{f}^{0},(MgO)=-\Delta H_{f}^{0},(SiO_2) $
$ =2,(-,34.7)-(-,48.4)=-21,kJ. $
