The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy from the formation of
mole of the compound from its constituent elements, with all substances in their standard states at
kPa and
K.
The above shows the enthalpy change in formentation of glucose(C
H
O
) to produce ethanol(C
H
OH). Which of the following statements is correct?
a) The standard heat of formation of C
H
O
(
) (
H) is
kJ/mol.
b) The standard heat of formation of C
H
OH(
) (
H) can be calculated from the above data.
c) The standard enthalpy of reaction(
H) when
mol of C
H
O
(
) is fermented to produce C
H
OH(
) and CO
(
) is
kJ.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
The standard starts from 6 C ( s ) + 6 H 2 ( g ) + 3 O 2 ( g ) .
a) Heat released and therefore Δ H < 0 .
b) From the standard, Δ H = − 1 3 4 2 k J / m o l is obtained from data instead of calculation.
c) 1 mole required Δ H = − 8 2 k J instead of 8 2 k J .
Answer: a )