What is the balanced thermochemical equation for the combustion of propane and how much heat is released if 25 grams of propane are burned?
To determine the balanced thermochemical equation for the combustion of propane, we need to first know the chemical formula for propane. Propane has the molecular formula C3H8.
The balanced equation for the combustion of propane is:
C3H8 + 5O2 -> 3CO2 + 4H2O
This equation indicates that one molecule of propane (C3H8) reacts with 5 molecules of oxygen (O2) to produce 3 molecules of carbon dioxide (CO2) and 4 molecules of water (H2O).
To calculate the amount of heat released when 25 grams of propane are burned, we need to know the molar mass of propane and the enthalpy change of combustion (ΔHc).
The molar mass of propane (C3H8) can be calculated by adding the molar mass of carbon (C) and hydrogen (H):
Molar mass of C3H8 = (3 * molar mass of C) + (8 * molar mass of H)
Molar mass of C = 12.01 g/mol
Molar mass of H = 1.008 g/mol
Substituting the values:
Molar mass of C3H8 = (3 * 12.01 g/mol) + (8 * 1.008 g/mol) = 44.11 g/mol
Now, to calculate the amount of heat released during the combustion of 1 mole of propane, we refer to the enthalpy change of combustion (ΔHc). The standard enthalpy change of combustion for propane is -2219 kJ/mol.
The equation can be set up as follows:
ΔH = (Mass of propane / Molar mass of propane) * ΔHc
Mass of propane = 25 grams
Molar mass of propane = 44.11 g/mol
ΔHc = -2219 kJ/mol
Substituting the values:
ΔH = (25 g / 44.11 g/mol) * -2219 kJ/mol
Calculating the value:
ΔH = -1267 kJ
Therefore, if 25 grams of propane are burned, approximately -1267 kilojoules of heat are released.
Note: The negative sign indicates that heat is being released during the combustion reaction.
The balanced thermochemical equation for the combustion of propane (C3H8) can be written as follows:
C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(g)
According to the equation, 1 mole of propane (C3H8) reacts with 5 moles of oxygen gas (O2) to produce 3 moles of carbon dioxide (CO2) and 4 moles of water (H2O).
To calculate the amount of heat released when 25 grams of propane are burned, we need to use the molar mass of propane and the corresponding molar enthalpy of combustion. The molar mass of propane (C3H8) is 44.1 g/mol.
Given that the molar enthalpy of combustion of propane is approximately -2220 kJ/mol, we can set up the following calculation:
1 mol C3H8 -> -2220 kJ
44.1 g C3H8 -> X kJ
To find X, we can use the following conversion factor:
X = (44.1 g C3H8 * -2220 kJ) / (1 mol C3H8)
Plugging in the values, we get:
X = -97,902 kJ/mol
Since 25 grams of propane is approximately equal to 0.567 moles (25 g / 44.1 g/mol), we can calculate the heat released for this amount:
Heat released = 0.567 mol * -97,902 kJ/mol
Therefore, when 25 grams of propane are burned, approximately -55,500 kJ of heat is released. Note that the negative sign indicates the exothermic nature of the reaction, meaning heat is released.