The standard enthalpy of formation for sulfur dioxide gas is -296.8 J. Calculate the amount of energy given off in kJ when 30.0 g of SO2 is fromed from its elements
S + O2 ==> SO2
296.8 J x (30/32) = ?? then convert to kJ.
278.25kj
To calculate the amount of energy given off when 30.0 g of SO2 is formed from its elements, we need to use the stoichiometry of the reaction and the molar mass of SO2.
From the balanced equation for the formation of SO2:
2S + O2 -> 2SO2
We can see that two moles of sulfur and one mole of oxygen are required to form two moles of sulfur dioxide.
Step 1: Calculate the moles of SO2.
To find the moles of SO2, we divide the mass of SO2 by its molar mass.
Molar mass of SO2 = 32.06 g/mol + 2 * 16.00 g/mol = 64.06 g/mol
moles of SO2 = mass of SO2 / molar mass of SO2
moles of SO2 = 30.0 g / 64.06 g/mol
moles of SO2 = 0.468 mol
Step 2: Calculate the energy given off.
The energy given off during the formation of 1 mole of SO2 gas is -296.8 J.
energy given off = standard enthalpy of formation * moles of SO2
energy given off = -296.8 J/mol * 0.468 mol
energy given off = -138.6 J
Finally, we convert the energy from joules to kilojoules:
energy given off in kJ = energy given off / 1000
energy given off in kJ = -138.6 J / 1000
energy given off in kJ = -0.1386 kJ
Therefore, the amount of energy given off when 30.0 g of SO2 is formed from its elements is approximately -0.1386 kJ. The negative sign indicates that the reaction is exothermic, meaning it releases energy.
To calculate the amount of energy given off when 30.0 g of SO2 is formed, we need to utilize the enthalpy of formation of SO2 and convert the given amount of substance to moles.
First, let's determine the number of moles of SO2. We can use the molar mass of SO2 to convert grams to moles.
The molar mass of SO2 is:
Sulfur (S) = 32.07 g/mol
Oxygen (O) = 16.00 g/mol (there are two oxygen atoms in SO2)
Molar mass of SO2 = (32.07 g/mol) + 2(16.00 g/mol) = 64.07 g/mol
Now we can calculate the number of moles of SO2:
n = m/M
n = 30.0 g / 64.07 g/mol
n ≈ 0.468 moles
Next, we can use the given enthalpy of formation to calculate the energy given off in joules.
ΔH = -296.8 J/mol
To calculate the energy given off when 0.468 moles of SO2 is formed:
ΔH = (0.468 mol) * (-296.8 J/mol)
ΔH ≈ -138.77 J
Finally, we can convert the answer to kilojoules by dividing by 1000 (since 1 kJ = 1000 J).
Energy given off = (-138.77 J) / 1000
Energy given off ≈ -0.1388 kJ
Therefore, the amount of energy given off when 30.0 g of SO2 is formed from its elements is approximately -0.1388 kJ. Note that the negative sign indicates the energy is released or given off during the formation process.