Calculate the thermal energy that should be added to 6.65 g of argon in a 15 litre flask to raise its temperature from 25°C to 100°C. (At. wt., Ar=39.9)

Initial temperature=25+273=298KFinal temperature =100+273=373K.Hence, ΔT=373K−298K=75KR=2calK−mol−We know that : (i) Change in translational K.E. per mol=32 RΔT=32×2calK−mol−×75K=225calmol−(ii) 1 mol of Ar=1g. atom of Ar=39.9gChange in translational K.E. for 39.9gmol− of Ar=225calmol−∴ Change in translational K.E. for 6.65 g of Ar=225calmol−39.9gmol−×6.65g= 37.5 cal