Many portable gas heaters and grills use propane, C3H8(g), as a fuel. Using standard enthalpies of formation, calculate the quantity of heat produced when 11.90 g of propane is completely combusted in air under standard conditions.
I got -600 kj but its wrong
Well, well, well, looks like we have ourselves a combustion conundrum! Let's sort this out.
First, we need to find the heat of combustion, which is the amount of heat produced when propane is burned. To do this, we'll use the standard enthalpy of formation.
The standard enthalpy of formation of propane, C3H8(g), is -103.9 kJ/mol. Now, we need to find the molar mass of propane.
Carbon (C) has a molar mass of approximately 12 g/mol, and each hydrogen (H) has a molar mass of around 1 g/mol. Since propane has 3 carbon atoms and 8 hydrogen atoms, the molar mass of propane is:
(3 * 12 g/mol) + (8 * 1 g/mol) = 44 g/mol
Now, let's calculate the moles of propane in 11.9 g using the molar mass:
11.9 g / 44 g/mol ≈ 0.27 mol
Since each mole of propane has a heat of combustion of -103.9 kJ, we can find the heat produced by multiplying the moles of propane by the heat of combustion:
0.27 mol * -103.9 kJ/mol = -28.05 kJ
So, my friend, the quantity of heat produced when 11.9 g of propane is completely combusted in air under standard conditions is approximately -28.05 kJ.
But hey, cheer up! Just remember that propane is doing its best to warm you up, even if it's not reaching that perfect -600 kJ you were expecting.
To calculate the heat produced when propane is completely combusted, you need to use the enthalpies of formation of propane and the products of combustion. Here are the steps to solve this problem:
1. Write the balanced equation for the combustion of propane:
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)
2. Calculate the molar mass of propane (C3H8):
C: 3 x 12.01 g/mol = 36.03 g/mol
H: 8 x 1.008 g/mol = 8.064 g/mol
Total molar mass = 36.03 + 8.064 = 44.094 g/mol
3. Calculate the moles of propane used:
Moles = Mass / Molar mass
Moles = 11.90 g / 44.094 g/mol = 0.2699 mol (approximately)
4. Find the enthalpy change of combustion (∆H°comb) using the enthalpies of formation (∆H°f) of the reactant and products:
∆H°comb = (∆H°f of products) - (∆H°f of reactants)
Check the standard enthalpy of formation values for propane (C3H8), carbon dioxide (CO2), and water (H2O).
∆H°f of C3H8 = -103.85 kJ/mol
∆H°f of CO2 = -393.51 kJ/mol
∆H°f of H2O = -241.83 kJ/mol
∆H°comb = (3 x ∆H°f of CO2) + (4 x ∆H°f of H2O) - ∆H°f of C3H8
= (3 x -393.51 kJ/mol) + (4 x -241.83 kJ/mol) - (-103.85 kJ/mol)
5. Calculate the heat produced:
Heat produced (in kJ) = ∆H°comb x Moles
Heat produced = ∆H°comb x 0.2699 mol
Make sure to substitute the actual values from step 4 into the equation and calculate the heat produced.
To calculate the quantity of heat produced when propane is combusted, you need to use the standard enthalpies of formation (∆H°f) of the reactants and products involved in the combustion reaction. The balanced equation for the combustion of propane is:
C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(g)
First, you need to find the enthalpy change for each individual reaction using the standard enthalpies of formation (∆H°f) values. The standard enthalpies of formation values for the reactants and products are:
∆H°f(C3H8) = -103.8 kJ/mol
∆H°f(O2) = 0 kJ/mol
∆H°f(CO2) = -393.5 kJ/mol
∆H°f(H2O) = -285.8 kJ/mol
To calculate the quantity of heat produced, you need to calculate the difference in the sum of the enthalpy changes for the products and the sum of the enthalpy changes for the reactants:
∆H°reaction = ∑(∆H°f,products) - ∑(∆H°f,reactants)
For the reactants:
∑(∆H°f,reactants) = ∆H°f(C3H8) + 5∆H°f(O2)
For the products:
∑(∆H°f,products) = 3∆H°f(CO2) + 4∆H°f(H2O)
Substituting the values in, we get:
∑(∆H°f,reactants) = (-103.8 kJ/mol) + 5(0 kJ/mol) = -103.8 kJ/mol
∑(∆H°f,products) = 3(-393.5 kJ/mol) + 4(-285.8 kJ/mol) = -2220.2 kJ/mol
Finally, substituting these values into the equation:
∆H°reaction = -2220.2 kJ/mol - (-103.8 kJ/mol) = -2116.4 kJ/mol
To calculate the quantity of heat produced when 11.90 g of propane is completely combusted, you need to use the molar mass of propane (C3H8), which is approximately 44.1 g/mol. The number of moles of propane can be calculated as:
moles of propane = mass of propane / molar mass of propane
= 11.90 g / 44.1 g/mol
≈ 0.269 mol
Finally, to calculate the quantity of heat produced:
Quantity of heat = ∆H°reaction × moles of propane combusted
= -2116.4 kJ/mol × 0.269 mol
≈ -569 kJ
Therefore, the quantity of heat produced when 11.90 g of propane is completely combusted is approximately -569 kJ, which is the correct answer. Note that the negative sign indicates that heat is released during the combustion process.