How many millimeters of cl2 gas must you have to obtain 0.20 g at STP?
STP = Standard Temperature (273 K) Pressure (1 atm) we also have the mass of cl2, 0.2g. We use this to find the number of moles. Use the ideal gas law. PV = nRT P= pressure in atm V= volume in Liters n = number of moles of gas R = 0.082058 T = Temperature in Kelvin P = 1 atm V = ? (we are looking for this) n = moles = mass/molar mass = 0.2g/(2*35.453) = 0.0028 moles R = 0.082058 T = 273 K (1)V = (0.0028)(0.082058)(273) V = 0.063 L = 60 mL (1 sig fig) good luck!