a 2.00 g sample of C6H402 is burned in a calorimeter whose heat capacity is 8kj/C. The delta T is +7.13 degrees C. What is the enthalpy change per mole?
(8 x 7.13)/(2/108) = ________ Kj/mol exothermic
66.0
To calculate the enthalpy change per mole (ΔH) of a reaction, you need to use the formula:
ΔH = q / n
where:
ΔH is the enthalpy change per mole,
q is the heat absorbed or released by the reaction in Joules (J),
n is the number of moles of the substance involved in the reaction.
In this case, we need to find the heat (q) first using the formula:
q = mcΔT
where:
m is the mass of the substance in grams (g),
c is the heat capacity of the calorimeter in Joules per degree Celsius (J/°C),
ΔT is the change in temperature in degrees Celsius (°C).
Let's calculate it step by step:
1. Convert the mass from grams to moles using the molar mass (MM) of C6H402.
MM(C6H402) = (6 * MM(C)) + (4 * MM(H)) + (2 * MM(O))
= (6 * 12.01 g/mol) + (4 * 1.01 g/mol) + (2 * 16.00 g/mol)
= 144.14 g/mol
Moles (n) = mass / MM
= 2.00 g / 144.14 g/mol
2. Calculate the heat (q) absorbed or released by the reaction.
q = mcΔT
= (8 kJ/C * 1000 J/1 kJ) * (7.13 °C)
= 57,040 J
3. Finally, calculate the enthalpy change per mole (ΔH).
ΔH = q / n
= 57,040 J / (2.00 g / 144.14 g/mol)
= 408,800 J/mol
So, the enthalpy change per mole of C6H402 is 408,800 J/mol.