Answer:
1495.81 calories = 1500 calories to 2 s.f
Explanation:
1.9 Watts of decay heat is released for every kilogram of Pu-239 that decays.
1.25 moles of Pu-239 will release which amount of heat in 3 hours (calories)
First of, we calculate how much mass of Pu-239 is contained in 1.25 moles of Pu-239.
Molar mass of Pu-239 = 244 g/mol = 0.244 kg/mol
1.25 moles of Pu-239 = 1.25 × 0.244 = 0.305 kg
1 kg of Pu-239 is equivalent 1.9 Watts
0.305 kg of Pu-239 will give (0.305×1.9/1) Watts; 0.5795 Watts.
Note: Watts is J/s
Power = Energy/time
Energy = power × time
Power = 0.5795 Watts
Time = 3 hours = 3×3600 s = 10800 s
Energy = 0.5795 × 10800 = 6258.6 J
1 J = 0.239 calorie
6258.6 J = 6258.6 × 0.239 = 1495.81 calories
