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!