Answer
29.8 grams of Cl2
Work Step by Step
We have the volume is 8.7L and the pressure is 895 torr. We convert the pressure to atm:
895 torr * (1atm/760torr) = 1.178 atm
We also have the temperature of 24C (add 273 for Kelvin) or 297 K
We use PV = nRT to find the number of moles
n = PV/RT = (1.178 atm * 8.70L) / (0.0821 * 297K) = 0.420 moles
To find the mass we multiply by the molar mass, which is 2 * 35.45 gmol = 70.9 g/mol
0.420 moles * (70.9g/1mol) = 29.8 grams