How much heat is contained in 4 liter of liquid methanol (CH3OH) when it is completely combusted (excess oxygen) to form carbon dioxide and water. the density of metanol is 0.7918 g/ml. (CH3OH = -638)
To calculate the amount of heat contained in 4 liters of liquid methanol when it is completely combusted, we need to follow a series of steps. First, we'll calculate the mass of methanol using its density. Then, we'll find the moles of methanol using its molar mass. Finally, we'll use the enthalpy of combustion to determine the amount of heat produced.
Step 1: Calculate the mass of methanol
The density of methanol is given as 0.7918 g/ml. We have 4 liters of methanol, which is equivalent to 4000 ml. Therefore, the mass of methanol can be calculated as follows:
Mass = Density * Volume
Mass = 0.7918 g/ml * 4000 ml
Mass = 3167.2 grams
Step 2: Find the moles of methanol
To find the moles of methanol, we need to know its molar mass. The molar mass of methanol (CH3OH) can be calculated by adding up the atomic masses of its constituent elements:
Molar mass = (C: 12.01 g/mol) + (H: 1.008 g/mol * 4) + (O: 16.00 g/mol)
Molar mass = 32.04 g/mol
Now we can find the number of moles of methanol using its mass:
Moles = Mass / Molar mass
Moles = 3167.2 g / 32.04 g/mol
Moles ≈ 98.90 mol
Step 3: Determine the heat produced
The enthalpy of combustion (ΔH) of methanol is given as -638 kJ/mol. Since we have 98.90 moles of methanol, we can calculate the heat produced using the following equation:
Heat = Moles * ΔH
Heat = 98.90 mol * (-638 kJ/mol)
Heat ≈ -63,145.20 kJ
Therefore, when 4 liters of liquid methanol is completely combusted, it releases approximately -63,145.20 kJ of heat. The negative sign indicates that the reaction is exothermic, meaning heat is being released.