[Ranowa]

Information given:
Ra-226 decays by alpha decay into Ra-222
Energy of an alpha particle is 4.79 MeV
Suppose 1.00 grams of 226-Ra, freed of all its radioactive progeny, were placed in a calorimeter that contained 10.0 grams of water, initially at 25 degrees C. Assume all alpha particle energy is thermalized, and neglect both the heat capacity of the calorimeter and heat loss to the surroundings. Calculate the temperature the water would reach after one hour.

Attempt at solution: It seems relatively simple; I'm using Q=mcdeltaT, but I'm unsure if I'm calculating Q right. First I took Avogadro's number and divided it by 226, to try and get the number of alpha particles that would be emitted if we let the sample decay entirely. Then, I took that number and divided by two, and set up a proportion with alpha particles/2 / half life = x/1 hour, x being the number of alpha particles emitted. Eventually I went on to get 26.7 degrees C- which seems really high to me. Can someone point me to the problem (if there even is one) in my process of calculating Q? (And I converted everything to the right units, of course, so it's not that) Thanks in advance!