The heat of combustion of carbon is -393.5kj/mol. Calculate the heat change, when 45.0g of carbon undergoes complete combustion given that c =12
...........GC + O2 ==> CO2
dH = -393.5 kJ for 12 g carbon. You have 45 g C so
dH = -393.5 kJ x 45/12 = ?
To calculate the heat change when 45.0g of carbon undergoes complete combustion, we need to follow these steps:
Step 1: Convert the mass of carbon to moles.
Given:
- Mass of carbon = 45.0g
- Atomic mass of carbon (C) = 12 g/mol
To find the number of moles, use the formula:
moles = mass / molar mass.
moles of carbon = 45.0g / 12 g/mol = 3.75 mol.
Step 2: Use the heat of combustion to calculate the heat change.
Given:
- Heat of combustion of carbon = -393.5 kJ/mol
To calculate the heat change, use the formula:
heat change = moles of carbon * heat of combustion.
heat change = 3.75 mol * -393.5 kJ/mol = -1475.62 kJ.
Therefore, the heat change when 45.0g of carbon undergoes complete combustion is -1475.62 kJ.
To calculate the heat change when a certain mass of carbon undergoes combustion, we can use the following equation:
Heat change = (mass of carbon) x (heat of combustion per mole)
First, we need to convert the given mass of carbon to moles. We can use the molar mass of carbon to do this calculation.
Step 1: Calculate the moles of carbon
Molar mass of carbon (C) = 12.01 g/mol
moles of carbon = (mass of carbon) / (molar mass of carbon)
= 45.0 g / 12.01 g/mol
= 3.746 mol (approximately)
Step 2: Calculate the heat change
Heat change = (moles of carbon) x (heat of combustion per mole)
Given: Heat of combustion of carbon (C) = -393.5 kJ/mol
Heat change = 3.746 mol x -393.5 kJ/mol
= -1473.61 kJ
Therefore, the heat change when 45.0 g of carbon undergoes complete combustion is approximately -1473.61 kJ. The negative sign indicates an exothermic reaction, meaning heat is released during combustion.