3.5 * 10 ^20 atomos Na -> gr

Peso Na = 22.989

22.989 ->  6,02 x 10^23
x -> 3.5*10^20

x = 22.989 * 3.5 * 10^20/6.02 *10^23 =  0.0133 gramos

2.

2g potasio

1mol = 39.09g
x mol = 2g

x = 2/39.09 = 0.0511 moles

1 mol - 6,02 x 10^23
0.05 mol - x

x = 6.02*10^23 * 0.05 = 3.01 * 10^22

3

3.6 gr H2O

2 x H= 2 x 1= 2 gr
O= 16 gr

16 + 2 = 18 gr

2 gr H - 18 gr H2O
x H - 3.6 gr H2O

x = 2 * 3.6 / 18 = 0.4 g


atomos H
1 gr - 6.02*10^23
0.4 gr - x

x = 6.02*10^23 * 0.4 = 2.41 * 10^23

moles H

1 gr - 1 mol
0.4 gr - x

x = 0.4 mol

moles O

16 gr - 18 gr H2O
x gr - 3.6 gr H2O

x = 16 * 3.6 / 18 = 3.2 gr

16gr - 1 mol
3.2 gr - x

x = 3.2 / 16 = 0.2 mol

atomos O
1 mol = 6.02*10^23
0.2 mol = x

x = 6.02*10^23 * 0.2 = 1.204 * 10^23


moles H2O

18 gr - 1 mol
3.6 gr - x

x = 3.6 / 18 = 0.2 mol

atomos H2O
1 mol H2O = 3 atomos

1 mol = 6.02*10^23
0.2 mol = x

x = 6.02*10^23 * 0.2 = 1.204 * 10^23 * 3 = 3.61 * 10^23

==============

0.25 mol Ca

1 mol = 6.02*10^23
0.25 mol = x

x = 0.25 * 6.02*10^23 = 1.505 * 10 ^23

5.2 g de Cl

1 mol = 35.453gr
x = 5.2gr

x = 5.2 / 35.456 = 0.1466

1 mol = 6.02*10^23
0.146 mol = x

x = 6.02*10^23 * 0.146 = 8.7892 * 10^22

1.33 mol Fe

1 mol = 6.02*10^23
1.33 mol = x

x = 1.33 * 6.02*10^23 = 8.006 * 10^23