If the heat of combustion for a specific compound is -1180.0 kJ/mol and its molar mass is 40.91 g/mol, how many grams of this compound must you burn to release 114.50 kJ of heat?
To solve this problem, we can use the concept of molar mass and the heat of combustion. The heat of combustion represents the amount of heat released when one mole of a compound undergoes combustion.
Given:
Heat of combustion = -1180.0 kJ/mol
Molar mass = 40.91 g/mol
Required heat release = 114.50 kJ
To find the number of grams of the compound that must be burned, we can solve this problem in three steps:
Step 1: Calculate the number of moles of the compound:
We can use the formula: Moles = Given mass (in grams) / Molar mass (in g/mol)
Given heat release = -1180.0 kJ/mol
Required heat release = 114.50 kJ
To find the number of moles burned, we can rearrange the equation as follows:
Moles = Required heat release / Heat of combustion
Substituting the values:
Moles = 114.50 kJ / -1180.0 kJ/mol
Step 2: Convert moles to grams:
We need to convert the number of moles to grams using the molar mass of the compound.
Mass (in grams) = Moles × Molar mass
Substituting the values:
Mass (in grams) = Moles × 40.91 g/mol
Step 3: Calculate the mass of the compound:
Now, we can calculate the mass of the compound that must be burned to release the required heat.
Mass of the compound (in grams) = Mass (in grams) obtained from Step 2
Let's perform the calculations:
Moles = 114.50 kJ / -1180.0 kJ/mol = -0.097 mol (The negative sign indicates the exothermic nature of the reaction)
Mass (in grams) = (-0.097 mol) × (40.91 g/mol) ≈ -3.97 g
Since a negative mass is not meaningful in this context, we can assume that a positive mass of 3.97 g of the compound must be burned to release 114.50 kJ of heat.