A. You have a badly tarnished silver teapot. The tarnish is a result of the silver metal reacting with the oxygen in the air according to 4Ag(s)+O2(g)→2Ag2O(s),ΔH=−62.2kJ/mo l
You carefully clean the teapot and then, out of curiosity, you weigh it. The teapot has a mass of 953 g . After some more measuring and calculating, you also determine that 10.5 % of the silver is on the surface and exposed to the air. If the teapot were once again to become completely tarnished, how much mass Δm is converted to energy?
B. Cobalt-60 is a radioactive isotope that is commonly used for cancer radiation therapy. The cobalt-60 atom decays to the stable nickel-60 atom, releasing a beta particle (electron) and energy in the form of gamma rays:
60Co→60Ni+β+γ
If you captured the energy from the decay of a 0.520 g pellet of isotopically pure cobalt-60, how long could you run a 30.0 Wlight bulb?
The relevant masses are as follows:
Substance Mass (g/mol)
60Co 59.933819
60Ni 59.930788
β 0.000549