A sample of carbon dioxide is contained in a 250.0 mL flask at 0.917 atm and 19.3 ∘ C. How many molecules of gas are in the sample?

The correct answer is 5.76 x 10²¹ molecules

Explanation:

From the problem, we have the following data:

V= 250.0 mL = 0.25 L

P= 0.917 atm

T= 19.3∘C + 273 = 292.3 K

We can use the ideal gas law to find n (number of moles of gas):

PV= nRT

⇒ n = PV/RT = (0.917 atm x 0.25 L)/(0.082 L.atm/K.mol x 292.3 K) = 9.6 x 10⁻³ mol

We know that 1 mol of any compound is equal to 6.022 x 10²³ molecules of the compound⇒ ratio : 6.022 x 10²³ molecules/1 mol

Thus, we multiply n by the ratio to obtain the number of molecules of gas:

9.6 x 10⁻³ mol x 6.022 x 10²³ molecules/1 mol = 5.76 x 10²¹ molecules