The value of ΔH° for the reaction below is -1107 kJ:
2Ba (s) + O2(g) → 2BaO (s)
How many kJ of heat are released when 5.75 g of Ba (s) reacts completely with oxygen to form BaO (s)?
1107 kJ/2 mol Ba = (1107/2) kJ/mol
(1107/2) kJ/mol x 5.75g/atomic mass Ba = ?
To determine the amount of heat released when 5.75 g of Ba (s) reacts completely with oxygen to form BaO (s), you can use the equation:
q = nΔH°
where:
q is the amount of heat released or absorbed (in kJ)
n is the number of moles of the substance undergoing the reaction
ΔH° is the standard enthalpy change (in kJ/mol) for the given reaction
First, we need to calculate the number of moles of Ba (s) involved in the reaction. To do this, we divide the given mass of Ba (s) by its molar mass (atomic weight of Ba):
molar mass of Ba (s) = 137.33 g/mol
n = mass / molar mass
n = 5.75 g / 137.33 g/mol
Calculating n, we find:
n = 0.0419 mol
Now, we can use the given value of ΔH° and the calculated value of n to find the amount of heat released:
q = nΔH°
q = 0.0419 mol * (-1107 kJ/mol)
Evaluating this:
q ≈ -46.3 kJ
Therefore, approximately 46.3 kJ of heat are released when 5.75 g of Ba (s) reacts completely with oxygen to form BaO (s).
To determine how many kJ of heat are released when 5.75 g of Ba (s) reacts completely with oxygen to form BaO (s), we can use the concept of stoichiometry and molar masses.
First, let's calculate the number of moles of Ba (s) in 5.75 g. To do this, we need to know the molar mass of Ba, which is 137.33 g/mol.
Number of moles of Ba (s) = Mass of Ba (s) / Molar mass of Ba
= 5.75 g / 137.33 g/mol
Next, we need to determine the stoichiometric ratio between Ba (s) and BaO (s) from the balanced equation. The balanced equation shows that 2 moles of Ba (s) react to form 2 moles of BaO (s).
To calculate the number of moles of BaO (s) formed, we can use the stoichiometric ratio:
Number of moles of BaO (s) = Number of moles of Ba (s) * (2 moles of BaO / 2 moles of Ba)
Finally, we can calculate the heat released using the equation:
Heat released = ΔH° * Number of moles of BaO (s)
Substituting the given value of ΔH° as -1107 kJ and the calculated number of moles of BaO (s), we can find the answer:
Heat released = -1107 kJ * (Number of moles of BaO (s))
By plugging in the numbers from our previous calculations, we can determine the amount of heat released.