dH is 1676 kJ/mol Al2O3 and the equation has 2 mols Al2O3 in it.
2*1676 kJ x (8.17g Al/4*atomic mass Al) = ?
4Al(s) + 3O2(g) --> 2Al2O3(s)
2*1676 kJ x (8.17g Al/4*atomic mass Al) = ?
First, we need to convert the mass of Al into moles. The molar mass of Al is 26.98 g/mol. So, 8.17 grams of Al is equal to (8.17 g) / (26.98 g/mol) = 0.303 moles of Al.
Next, we look at the balanced equation. It tells us that 4 moles of Al produces 2 moles of Al2O3. So, if we have 0.303 moles of Al, we can expect the formation of (0.303 moles / 4 moles) * 2 moles = 0.1515 moles of Al2O3.
Now, we can use the delta enthalpy change to calculate the heat released. The delta enthalpy change for the formation of Al2O3 is 1676 kJ/mol.
So, the heat released in the combustion of 8.17 grams of Al to form Al2O3 is (0.1515 moles) * (1676 kJ/mol) = 253.974 kJ.
And there you have it, the amount of heat released is approximately 253.974 kJ. Keep in mind that this is just an approximation, so don't go setting things on fire without proper safety measures!
Step 1: Determine the moles of Al
To find the moles of Al, we need to use its molar mass. The molar mass of Al is 26.98 g/mol.
Number of moles of Al = mass of Al / molar mass of Al
Number of moles of Al = 8.17 g / 26.98 g/mol
Number of moles of Al ≈ 0.303 moles
Step 2: Determine the moles of Al2O3
From the balanced equation: 4Al(s) + 3O2(g) --> 2Al2O3(s)
Since the ratio is 4:2, the moles of Al2O3 will be half the moles of Al.
Number of moles of Al2O3 = 0.5 * Number of moles of Al
Number of moles of Al2O3 = 0.5 * 0.303 moles
Number of moles of Al2O3 ≈ 0.152 moles
Step 3: Calculate the heat released
The heat released can be calculated using the heat of formation for Al2O3.
Heat released = Number of moles of Al2O3 * Delta H°f for Al2O3
Heat released = 0.152 moles * 1676 KJ/mol
Therefore, the amount of heat released in the complete combustion of 8.17 grams of Al to form Al2O3 is approximately:
Heat released ≈ 254.752 KJ
Here's how you can proceed:
1. Calculate the moles of Al:
- The molar mass of Al is 26.98 g/mol.
- Divide the mass of Al (8.17 grams) by the molar mass of Al to get the moles of Al.
2. Determine the moles of Al2O3 formed:
- According to the balanced equation, 4 moles of Al react to form 2 moles of Al2O3.
- Using the moles of Al calculated in step 1, multiply it by the mole ratio from the balanced equation to find the moles of Al2O3 formed.
3. Calculate the amount of heat released:
- The molar enthalpy of formation of Al2O3 is given as 1676 kJ/mol.
- Multiply the moles of Al2O3 formed (calculated in step 2) by the molar enthalpy of formation of Al2O3 to find the amount of heat released.
Let's calculate it:
1. Moles of Al:
- molar mass of Al = 26.98 g/mol
- moles of Al = mass of Al / molar mass of Al
2. Moles of Al2O3 formed:
- moles of Al2O3 = (moles of Al / 4) x (2 moles of Al2O3 / 4 moles of Al)
3. Amount of heat released:
- amount of heat released = moles of Al2O3 formed x molar enthalpy of formation of Al2O3
Substitute the values into the equations above and perform the calculations to find the answer.