All of these reactions that show a change are known as "double-displacement" reactions. Write a summary about how aqueous (liquid) ionic compounds react, using
the term double-displacement reaction, and discussing how many reactions showed
a change and how many did not. Be sure to explain how you know a chemical
reaction has occurred.

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.

yes the answer is total mass in unchanged   : )