How much heat is contained in 4 liter of liquid methanol (CH2OH) when it is completely combusted (excess oxygen) to form carbon dioxide and water. the density of metanol is 0.7918 g/ml.

To calculate the amount of heat contained in 4 liters of liquid methanol (CH3OH) when it is completely combusted, we need to follow these steps:

Step 1: Calculate the mass of methanol.
Given that the density of methanol is 0.7918 g/ml, we can calculate the mass by multiplying the density by the volume:
Mass = Density x Volume
Mass = 0.7918 g/ml x 4000 ml
Mass = 3167.2 g

Step 2: Calculate the moles of methanol.
To calculate the moles of methanol, we need to divide the mass by the molar mass of methanol. The molar mass of methanol is calculated by summing the atomic masses of its constituents: carbon (12.01 g/mol), hydrogen (1.008 g/mol), and oxygen (16.00 g/mol).
Molar Mass of Methanol = (12.01 g/mol x 1) + (1.008 g/mol x 4) + (16.00 g/mol x 1)
Molar Mass of Methanol = 32.04 g/mol
Moles = Mass / Molar Mass
Moles = 3167.2 g / 32.04 g/mol
Moles = 98.94 mol

Step 3: Determine the balanced chemical equation.
The balanced chemical equation for the combustion of methanol is:
2CH3OH + 3O2 -> 2CO2 + 4H2O

Step 4: Calculate the heat of combustion.
The molar ratio between methanol and carbon dioxide is 2:2. Using the balanced equation, we can determine that for every 2 moles of methanol combusted, 2 moles of carbon dioxide are formed.
Therefore, the heat of combustion for methanol is given as -726 kJ/mol.

Using this information, we can calculate the total heat of combustion for 98.94 moles of methanol.
Heat of Combustion = Moles of Methanol x Heat of Combustion per Mole
Heat of Combustion = 98.94 mol x -726 kJ/mol
Heat of Combustion = -71,971.44 kJ

Therefore, the heat contained in 4 liters of liquid methanol when completely combusted is approximately -71,971.44 kJ. Note that the negative sign indicates that heat is released during combustion.