What is the atomic mass of hydrogen?

Question

anonymous · Answer

I know the answer... just want to give you a medal

xishem · Answer

$$1.00794amu$$ :P

xishem · Answer

I appreciate it. :D

anonymous · Answer

Thanks for the medal! :)

xishem · Answer

You deserved it. You showed effort :D

anonymous · Answer

:)

anonymous · Answer

always go 1.01 no reason to get anything over that

xishem · Answer

I don't see a reason to go under it. If I'm using atomic weights in calculations I usually go 4-5 SFs, depending on how many SFs my original data has.

anonymous · Answer

see but i feel that you are taking it out of tolerance of what we can do by hand. so unless you are in a commerical lab there is no reason to have your numbers that exact.

xishem · Answer

You should end up rounding in your final result anyway, so I guess it's negligible. I just like to have a comfortable number of SFs in my conversion factors. (:. To each his own.

anonymous · Answer

If you calculate the molecular weight of C20H42 using 1.01 for the atomic mass of hydrogen you'll get an answer that is only precise to 3 sig dig.  There is nothing wrong with that per se, but it is fairly routine to have lab measurements that are good to 4 sig dig or more, and it would be silly to have the limitation on the precision of your calculations be your willingness to look up the most precisely known value for the atomic weight of hydrogen.