Question

How many molecules of sulfur trioxide would react with 68.9 L of water at STP to produce sulfuric acid? SO3 + H2O H2(SO4)

Answer 1

1.9×10²⁴ molecules

Step-by-step 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