Question

How many molecules of O2 occupy a volume of 1.0 l at 65°C and 778 mm of Hg?

a) 0.037 molecules
b) 2.2 x 1022 molecules
c) 1.2 x 1023 molecules
d) 1.7 x 1025 molecules

Answer 1

The answer is letter C

Answer 2

Using the Ideal Gas Law, the number of molecules of O2 that occupy a volume of 1.0 L at 65°C and 778 mm Hg is approximately 2.2 x 10^22 molecules.

Step-by-step explanation:

To determine how many molecules of O2 occupy a volume of 1.0 L at 65°C and 778 mm Hg, we can use the Ideal Gas Law, which is PV = nRT. First, we need to convert the given volume to liters, temperature to Kelvin, and pressure to atmospheres.

Volume: Already in liters (1.0 L)
Temperature: 65°C + 273.15 = 338.15 K
Pressure: 778 mm Hg / 760 mm Hg per atm = 1.0237 atm

The Ideal Gas Constant (R) is 0.0821 L·atm/K·mol. Now we can rearrange the Ideal Gas Law to solve for n (number of moles):

n = PV / RT = (1.0237 atm) (1.0 L) / (0.0821 L·atm/K·mol)(338.15 K)

Now, calculate the number of moles and then use Avogadro's number (6.02 x 1023 molecules/mol) to find the number of molecules:

n = 0.0364 moles of O2
Number of molecules = 0.0364 moles * 6.02 x 1023 molecules/mol

Final answer: Approximately 2.2 x 1022 molecules of O2.

So, the correct answer is b) 2.2 x 1022 molecules.