What’s an example when substances react chemically ?

A chemical reaction happens when one or more chemicals are changed into one or more other chemicals. Examples: iron and oxygen combining to make rust. vinegar and baking soda combining to make sodium acetate, carbon dioxide and water.

Explanation:

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.

b.

the accuracy of the data.