4.000 g of Compound X with molecular formula C4H6 are burned in a constant-pressure calorimeter containing 40.00 kg of water at 25 °C. The temperature of the water is observed to rise by 1.065 °C. (You may assume all the heat released by the reaction is absorbed by the water, and none by the calorimeter itself.) Calculate the standard heat of formation of Compound X at 25 °C. Be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.

Question

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Respuesta :

Mergus Mergus · Answer 1 · 2019-10-07T05:27:44+02:00

Answer:

2407 kJ/mol

Explanation:

Given:

Mass of water = 40.00 kg

[tex]\Delta T[/tex] = 1.065 °C

Net Heat transfer during heating:

[tex]Q=m_{water}\times C_{water}\times \Delta T[/tex]

Specific heat of water = 4.187 kJ/kg°C

[tex]Q=40.00\times 4.187\times 1.065\ kJ[/tex]

Q = 178.3662 kJ

Heat gained by water is heat lost by the compound. Thus, heat lost = 178.3662 kJ

Also,

Mass = 4.000 g

Molar mass of [tex]C_4H_6=4\times 12+6\times 1\ g/mol=54\ g/mol[/tex]

The formula for the calculation of moles is shown below:

[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]

Thus,

[tex]Moles= \frac{4.000\ g}{54\ g/mol}[/tex]

[tex]Moles= 0.0741\ mol[/tex]

Standard heat of formation = 178.3662 kJ / 0.0741 mol=2407 kJ/mol (In correct significant digits)