Calculate the volume and number of molecules in 8.8 g CO2.

Given:
m (CO2) = 8.8 g

To find:
V (CO2) -?
N (CO2) -?

Solution:
1) Find the molar mass of CO2 (it will be numerically equal to the molecular mass):
Mr (CO2) = Ar (C) + Ar (O) * 2 = 12 + 16 * 2 = 44 g / mol;
2) Find the amount of substance CO2:
n (CO2) = m (CO2) / Mr (CO2) = 8.8 / 44 = 0.2 mol;
3) Find the volume of CO2 gas:
V (CO2) = n (CO2) * Vm = 0.2 * 22.4 = 4.48 L;
4) Find the number of CO2 molecules:
N (CO2) = n (CO2) * NA = 0.2 * 6.02 * 10 ^ 23 = 1.2 * 10 ^ 23.

Answer: The volume of CO2 is 4.48 liters; the number of molecules is 1.2 * 10 ^ 23.