Answer:
1.9×10²⁴ molecules
Explanation:
Equation of reaction:
SO₃ + H₂O → H₂SO₄
Since the gas is at STP, then we can use ideal gas equation,
PV = nRT
P = pressure of the gas
V = volume of the gas
n = number of moles of the gas
R = ideal gas constant
T = temperature of the ideal gas
P = 1.0atm
V = 68.9L
n = ?
R = 0.082J/mol.K
T = 273.15K
n = PV / RT
n = (1.0 × 68.9) / (0.082 × 273.15)
n = 68.9 / 22.3983
n = 3.076 moles = 3.1 moles
From the equation of reaction,
1 moles of SO₃ will react with 1 mole of H₂O,
Therefore
3.1 moles of SO₃ will react with 3.1 moles of H₂O
Number of moles of SO₃ = 3.1 moles
1 moles = 6.023×10²³ molecules(Avogadro's constant)
3.1 moles = x molecules
X = 3.1 × 6.023×10²³
X = 1.867×10²⁴ molecules
The number of molecules of SO₃ is approximately 1.9×10²⁴ molecules
