Given the following equation,
C3H8 (g) + 5O2 (g) -> 3CO2 (g) + 4H2O (g); H comb = -2219 kJ/mole
A) how much heat will be released when 10 g of propane is burned?
B) how much heat will be released when 10 g of water (H2O) is formed?
Please show all work.
A. You get 2219 kJ for a mol (44 g) propane; therefore,
2219 x (10/44) = ? kJ.
B. You get 2219 kJ for 4 mol H2O (4*18 = 72g). Therefore,
2219 kJ x (10/72) = ? kJ.
volume of oxygen in liters at .91 ml of oxygen
To find the amount of heat released when a given mass of a substance is burned or formed, we need to use stoichiometry and the given enthalpy change of the reaction. Here's how we can calculate the heat released for both cases:
A) To find the heat released when 10 g of propane (C3H8) is burned, we need to determine the number of moles of propane first.
1. Calculate the molar mass of propane (C3H8):
Molar mass of C = 12.01 g/mol
Molar mass of H = 1.01 g/mol
Molar mass of propane (C3H8) = (3 * 12.01 g/mol) + (8 * 1.01 g/mol) = 44.11 g/mol
2. Calculate the number of moles of propane:
moles of propane = (mass of propane) / (molar mass of propane)
moles of propane = 10 g / 44.11 g/mol = 0.227 mol
3. Apply stoichiometry to determine the heat released:
From the balanced equation, we see that the ratio between propane (C3H8) and heat released (H comb) is 1:1, meaning 1 mole of propane releases -2219 kJ of heat.
Therefore, the heat released when 10 g of propane is burned is:
Heat released = (number of moles of propane) * (H comb)
Heat released = 0.227 mol * (-2219 kJ/mol) = -504 kJ (rounded to three significant figures)
B) To find the heat released when 10 g of water (H2O) is formed, we need to determine the number of moles of water first.
1. Calculate the molar mass of water (H2O):
Molar mass of H = 1.01 g/mol
Molar mass of O = 16.00 g/mol
Molar mass of water (H2O) = (2 * 1.01 g/mol) + (1 * 16.00 g/mol) = 18.02 g/mol
2. Calculate the number of moles of water:
moles of water = (mass of water) / (molar mass of water)
moles of water = 10 g / 18.02 g/mol = 0.555 mol
3. Apply stoichiometry to determine the heat released:
From the balanced equation, we see that the ratio between water (H2O) and heat released (H comb) is 4:3, meaning 3 moles of water releases -2219 kJ of heat.
Therefore, the heat released when 10 g of water is formed is:
Heat released = (number of moles of water) * (H comb) * (3/4)
Heat released = 0.555 mol * (-2219 kJ/mol) * (3/4) = -930 kJ (rounded to three significant figures)
So, the heat released when 10 g of propane is burned is -504 kJ, and the heat released when 10 g of water is formed is -930 kJ.
To answer these questions, we need to use the balanced chemical equation and the given enthalpy change of combustion (or heat of combustion), which is -2219 kJ/mol.
A) To determine the heat released when 10 g of propane (C3H8) is burned, we need to use the molar mass of propane and convert it to moles. Then we can use the stoichiometry of the balanced equation to determine the amount of heat released.
1. Calculate the molar mass of propane (C3H8):
C: 3 mol(12.01 g/mol) = 36.03 g/mol
H: 8 mol(1.01 g/mol) = 8.08 g/mol
Total molar mass of C3H8 = 36.03 g/mol + 8.08 g/mol = 44.11 g/mol
2. Convert grams of propane to moles of propane:
Moles = mass (g) / molar mass (g/mol)
Moles = 10 g / 44.11 g/mol ≈ 0.227 mol
3. Calculate the heat released using the stoichiometry of the balanced equation:
According to the balanced equation, 1 mol of propane (C3H8) produces -2219 kJ of heat.
Therefore, 0.227 mol of propane will produce:
Heat released (kJ) = 0.227 mol × (-2219 kJ/mol) = approximately -504 kJ
Thus, 10 g of propane will release approximately 504 kJ of heat.
B) To determine the heat released when 10 g of water (H2O) is formed, we need to use the same approach as before.
1. Calculate the molar mass of water (H2O):
H: 2 mol(1.01 g/mol) = 2.02 g/mol
O: 1 mol(16.00 g/mol) = 16.00 g/mol
Total molar mass of H2O = 2.02 g/mol + 16.00 g/mol = 18.02 g/mol
2. Convert grams of water to moles of water:
Moles = mass (g) / molar mass (g/mol)
Moles = 10 g / 18.02 g/mol ≈ 0.554 mol
3. Calculate the heat released using the stoichiometry of the balanced equation:
According to the balanced equation, 4 moles of water (H2O) are produced per 1 mole of propane burned.
Therefore, 0.227 mol of propane would produce:
Moles of water produced = 0.227 mol × 4 = 0.908 mol
To find the heat released when 0.908 mol of water is formed:
Heat released (kJ) = 0.908 mol × (-2219 kJ/mol) = approximately -2017 kJ
Thus, 10 g of water (H2O) being produced will release approximately 2017 kJ of heat.
Note: The negative sign in the enthalpy change implies that the reaction is exothermic (heat is released).