Question

Given the reaction:

2 H2(g) + O2(g) → 2 H2O(l)


What is the total number of liters of O2(g) at STP needed to produce 6.0 × 1023 molecules of H2O(l)?

A) 33.6 L
B) 44.8 L
C) 11.2 L
D) 22.4 L

Answer 1

V = 22.34 L

Step-by-step explanation:

Given data:

Volume of O₂ needed = ?

Temperature and pressure = standard

Number of molecules of water produced = 6.0× 10²³

Solution:

Chemical equation:

2H₂ + O₂ → 2H₂O

Number of moles of water:

1 mole contain 6.022× 10²³ molecules

6.0× 10²³ molecules × 1 mole / 6.022× 10²³ molecules

0.99 mole

Now we will compare the moles of oxygen and water.

H₂O : O₂

2 : 1

0.996 : 0.996

Volume of oxygen needed:

PV = nRT

V = nRT/P

V = 0.996 mol × 0.0821 atm.L/mol.K × 273.15 K / 1 atm

V = 22.34 L