After recording a prelimianry melting point range of 140-147 for an unknown solid, you identify it as o-nitrobenzoic acid. running a mixed melting point determination wiht o-nitrobenzoic acid affords a melting point range of 126-135. why did your melting point change so dramatically? what does this tell you about your intial assuption concerning the identify of your unknown solid

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

i think its 100.

hope this !