chemistry homwork

Question

1) what is the molar mass of Al2(SO4)3 show all the steps, calculations and units?

2) show all the steps, calculations, and units. how many atoms are represented by the followings

a) 3,5 mol of nitrogen N

b) 4,56 mol of iron, Fe

3) How many molecules are represented by the followings( show all the calculating steps)

a) 22,5 mol of Br2

b) 15,55 mol of ammonia, NH3

Answer 1

1) From the periodic table:

Al = 26.98 x 2 = 53.96 g/mol

S = 32.07 x 3 = 96.21 g/mol

O = 15.9994 x 12 = 191.99 g/mol

Add them all up to get a total of 342.16 g/mol

2a) 3.5 mol N x 6.02x10²³ atoms/mole = 2.1x10²⁴ atoms of N

2b) 4.56 mol Fe x 6.02x10²³ atoms/mol = 2.75x10²⁴ atoms of Fe

3a) 22.5 mol Br₂ x 6.02x10²³ molecules/mol = 1.35x10²⁵ molecules of Br₂

3b) 15.55 mol NH₃ x 6.022x10²³ molecules/mol = 9.364x10²⁴ molecules of NH₃