The complete combustion of propane, C3H8(g), is represented by the equation:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ
How much heat is evolved in the complete combustion of 20.0 L C3H8(g) at STP?
20L propane = 20L x (1 mol/22.4L) = about 0.892 mols propane. You get 2220 kJ for 1 mol; therefore, you will get
2220 x (0.892 mol/1 mol) = ? kJ released.
329
Well, let me see if I can calculate that for you, but first, let me check if I have my funny calculator with me. Ah, here it is! Okay, now let's get down to business.
To solve this problem, we first need to convert the volume at STP to moles. And if I remember correctly, at STP, 1 mole of any gas occupies 22.4 liters of space. So, by dividing 20.0 liters by 22.4 liters/mol, we find that we have approximately 0.893 moles of C3H8.
Now, we can determine the heat evolved in the combustion using the stoichiometry of the balanced equation. From the equation, we see that for every 1 mole of C3H8 combusted, -2220 kJ of heat is evolved. So, for 0.893 moles, we can use a little bit of math to find out the heat evolved.
0.893 moles * (-2220 kJ/1 mole) = -1982.04 kJ
So, approximately -1982.04 kJ of heat is evolved in the complete combustion of 20.0 L of C3H8 at STP. And don't worry, the negative sign simply means that heat is being released during combustion. It's like the C3H8 is saying, "Heat, I choose you!" I hope this helps!
To find out how much heat is evolved in the complete combustion of 20.0 L of C3H8(g) at STP, we can use the stoichiometry of the reaction and the given information.
STP stands for Standard Temperature and Pressure, which is 0 degrees Celsius and 1 atmosphere of pressure. At STP, 1 mole of any gas occupies 22.4 liters. Therefore, we need to convert the given volume of 20.0 L of C3H8(g) to moles.
Step 1: Convert the volume to moles
20.0 L C3H8(g) * (1 mole C3H8(g) / 22.4 L C3H8(g)) = 0.893 moles C3H8(g)
Step 2: Calculate the heat evolved using the stoichiometry of the reaction
From the balanced equation, we know that 1 mole of C3H8(g) produces -2220 kJ of heat.
0.893 moles C3H8(g) * (-2220 kJ / 1 mole C3H8(g)) = -1984.0 kJ
Note: The negative sign indicates that the reaction is exothermic, meaning heat is evolved.
Therefore, the complete combustion of 20.0 L of C3H8(g) at STP evolves 1984.0 kJ of heat.