Answer:
695.8kJ/mol = Enthalpy of combustion
Final temperature = 407.4°C
Explanation:
Taken the reaction:
2CH₃NO₂ + 3/2 O₂ → 2CO₂ + 3H₂O + N₂
The enthalpy of the reaction is the heat released when 1 mole of nitromethane are in combustion.
We need to find the moles presents in 121L of nitromethane using its density and molar mass (61.04g/mol). As these moles releases 1.6x10⁶kJ, we need to find heat released per mole of nitromethane
Mass nitromethane:
121L = 121000cm³ * (1.16g/cm³) = 140360g
Moles:
140360g * (1mol / 61.04g) = 2299.5 moles of nitromethane
Heat released per mole of nitromethane:
1.6x10⁶kJ / 2299.5 mol = 695.8kJ/mol = Enthalpy of combustion
The symbol - is because the heat is released, a + symbol is when the heat is absorbed.
Using:
Q = m×C×ΔT
Where Q is heat (1.6x10⁶kJ = 1.6x10⁹J)
m is mass of water:
1kL = 1000L = 1x10⁶mL = 1x10⁶g
C is specific heat of water: 4.184J/g°C
And ΔT is change in temperature.
Solving for ΔT:
1.6x10⁹J = 1x10⁶g * 4.184J/g°C * ΔT
ΔT = 382.4°C
As initial temperature was 25°C, final temperature is:
382.4°C + 25°C =
407.4°C
