How many molecules of n2 are in a 300.0 ml container at 780 mmhg and 135â°c?

To solve for the number of molecules, we need to first find the number of moles. Assuming ideal gas, we use the formula:

n = PV / RT

where P is pressure = 780 mmHg, V is volume = 300 mL = 0.3 L, T is temperature = 135°C = 408.15 K, R is gas constant = 62.36367 L mmHg / mol K

n = (780 mmHg) (0.3 L) / (62.36367 L mmHg / mol K) (408.15 K)

n = 9.19 x 10^-3 mol

Using Avogadros number, we calculate the number of molecules.

molecules = 9.19 x 10^-3 mol * 6.022 x 10^23 molecules / mol

molecules = 5.54 x 10^21 molecules

pure substance: iron,copper

impure substance: water,charcoal