One mole of
and 14.0 mol of oxygen are placed into a lab scale batch reactor. The reactor then is placed into a water bath at
; the
water bath contains 20.0 kg of water. The contents of the reactor are burned. The
combusts completely to give
and
. At the end of the combustion, the water bath and the reactor and its contents are at
. Under these conditions, the water produced during the combustion can be assumed to be completely in its liquid form. The top surface of the batch reactor is insulated such that all heat lost from the reactor goes to the water bath. What is the standard state heat of combustion of the
?
The following reaction took place:
water bath contains 20.0 kg of water. The contents of the reactor are burned. The
The following reaction took place:
Passo 1
Resumindo o enunciado: temos um mol de
queima completamente num reator, liberando calor que vai para um banho de
kg de água, que se aquece de
até
. Queremos a entalpia padrãode combustão de
em
.
Passo 2
Aplicamos o balanço de energia para calorimetria: todo o calor liberado pela reação,
, é absorvido pela água do banho. Assim,
onde
com
kg,
,
e
,K.
Passo 3
Calculando o calor absorvido pela água:
Passo 4
Como a reação libera calor, temos
por mol de
.