To solve this problem, we need to use the ideal gas law:
PV=nRT
P is pressure in atmospheres, V is volume in liters, n is moles, R is the universal gas constant, and T is the temperature in Kelvins.
First, we will need to convert each of the units.
894color(white)(l)-:1000=0.894 color(white)(l)L
(772color(white)(l)mmHg)/1times(1color(white)(l)atm)/(760color(white)(l)mmHg)=1.02 atm
28+273=301color(white)(l)K
Now, plug the above values into the equation and solve for moles.
(1.02)(0.894)=(n)(0.08206)(301)
n=((1.02)(0.894))/((0.08206)(301))=0.0369color(white)(l)molcolor(white)(l)ClF_3
Finally convert moles of ClF_3 to grams:
(0.0369color(white)(l)molcolor(white)(l)ClF_3)/1times(92.448color(white)(l)gcolor(white)(l)ClF_3)/(1color(white)(l)molcolor(white)(l)ClF_3)=3.41color(white)(l)gcolor(white)(l)ClF_3