Chemical A and Chemical B react in an exothermic reaction. What can be known about what will happen when Chemical A and Chemical
B are mixed together?
2 answers:
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Answer :
The enthalpy of reaction is, -187.6 kJ/mol
The total heat will be, -2251 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
(a) The formation of will be,
The intermediate balanced chemical reaction will be,
(1)
(2)
(3)
We are multiplying equation 1 by 2 and then adding all the equations, we get :
(b) The expression for enthalpy of reaction will be,
Therefore, the enthalpy of reaction is, -187.6 kJ/mol
(c) Now we have to calculate the total heat.
or,
where,
= enthalpy change = -187.6 kJ/mol
q = heat = ?
n = number of moles of coal =
Now put all the given values in the above formula, we get:
Thus, the total heat will be, -2251 kJ