A)A reaction in aqueous solution is run in a calorimeter and it is found that th

Question

A)A reaction in aqueous solution is run in a calorimeter and it is found that the the solution gains 57 kJ of heat and the calorimeter gains 9 kJ of heat. What is the heat gained or lost by the reaction (qrxn) in kJ? (If it is negative, include the negative sign. If it is positive, include nothing)

B)In a reaction of a potential new fuel, it is found that when 2.84 moles of the fuel combusts, 1,625 kJ of energy is released. What is the delta Hrxn for the combustion of the fuel in units of kJ/mol?

Explanation / Answer

Answer – A) solution gain = 57 kJ , calorimeter gain = 9 kJ

We know the when reaction in aqueous solution is run in a calorimeter the total released is equal heat gain by solution and calorimeter

So, total heat gain = heat gain by solution + heat gain by calorimeter

                              = 57 kJ + 9 kJ

                              = 66 kJ

We know heat gain = heat loss

So, total heat loss = - 66 kJ

B) Released energy = -1625 kJ

Moles = 2.84

The negative sign for the showing the energy is released.

We are asking for energy in kJ/mol and it is as follow –

the combustion of the fuel in units of kJ/mol = -1625 kJ / 2.84 moles

                                                                         = - 572.18 kJ/mol

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