Chemistry - decay question, please help?

Question

Calcium-39 undergoes positron decay. Each positron carries 5.49 MeV of energy. How much energy will be emitted when 0.0025 mol of calcium-39 decays?

Answer 1

This is just bookkeeping, made to look difficult.

You have 5.49 MeV per event. You want the total energy. So you need to multiply energy per event by a number of events.

The number of events per mole is NA, Avogadro's Number. So the number of events per 0.0025 mol is 0.0025 x NA.

You will get an answer in MeV. If you want it in other units,

1 MeV converted to J = energy acquired by an electron accelerated through 10^6V

= charge on electron (C) x 10^6 (V )

Because coulombs x volts = Joules (definition of volt)

Answer 2

It depends a lot on what you like. I'm in AP chemistry right now and let me tell you it's difficult. There so much crammed in your head at once it's hard to remember it all unless you have super memory. But Chem also has a ton of fun labs, that's why I love Chem cause the labs help explain the complicated math equations your writin down so it makes it more worth it. I really really dislike physics cause to me it's another math class. It would be like taking two AP calc classes cause they actually intertwine (more so if its AP physics bc Ur taking) they do a lot less labs in physics too. If you love math though AP Physics is definitely your choice, but if your More hands On then I'd say AP Chem (: hope I helped