PV = nRT
where P is the pressure, V is the volume, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature.
At STP, the pressure is 1 atmosphere (atm) and the temperature is 0 degrees Celsius (273.15 Kelvin). The ideal gas constant R is 0.08206 liters atm / mole Kelvin.
We can rearrange the ideal gas law to solve for the density (mass per unit volume):
density = mass / volume = (n * molar mass) / V
Assuming we have 1 mole of chlorine gas (Cl2), the molar mass of Cl2 is 70.90 grams per mole.
At STP, the volume occupied by 1 mole of any gas is 22.4 liters (the molar volume).
Substituting these values into the equation:
density = (1 mole * 70.90 grams per mole) / 22.4 liters = 3.17 grams per liter
Therefore, the density of chlorine gas at STP is 3.17 grams per liter.
