Chemical Thermodynamics Question 283
Question: In order to decompose 9 g water 142.5 kJ heat is required.
Hence the enthalpy of formation of water is [KCET 2001]
Options:
A) - 142.5 kJ
B) + 142.5 kJ
C) - 285 kJ
D) + 285 kJ
Show Answer
Answer:
Correct Answer: C
Solution:
For the decomposition of 9gm of water heat required $ =142.5,kJ $ we know $ H_2O=2+16=18 $ Therefore heat required for decomposition of 18gm water $ =\frac{18}{9}\times 142.5=285,KJ $ Than, enthalpy of formation of water is reverse of heat required = - 285 kJ.
