1) To calculate the number of atoms in 13.8g of sodium we need to use the formula:
Number of atoms = (mass in grams/molar mass) x Avogadro's number
The molar mass of sodium is 22.99 g/mol. Therefore, the number of atoms in 13.8g of sodium is:
(13.8/22.99) x 6.02 x 10^23 = 3.6 x 10^23 atoms
2) To calculate the number of atoms in 0.02 moles of aluminium we use Avogadro's number (6.02 x 10^23) since one mole of any substance contains 6.02 x 10^23 particles (atoms, molecules or ions).
Therefore, the number of atoms in 0.02 mol of aluminium is:
0.02 x 6.02 x 10^23 = 1.20 x 10^22 atoms
3) We need to find the number of atoms in 14.2g of sodium sulphate (Na2SO4). First, we need to calculate the molar mass of sodium sulphate:
Na: 2 x 22.99 = 45.98 g/mol
S: 32.07 g/mol
O: 4 x 16.00 = 64.00 g/mol
Total molar mass = 45.98 + 32.07 + 64.00 = 142.05 g/mol
Now, we can use the same formula as before:
Number of atoms = (mass in grams/molar mass) x Avogadro's number
(14.2/142.05) x 6.02 x 10^23 = 6.02 x 10^22 atoms of sodium sulphate
Since each molecule of sodium sulphate contains 2 sodium atoms, we need to multiply the above result by 2 to get the total number of sodium atoms:
6.02 x 10^22 x 2 = 1.20 x 10^23 sodium atoms.
calculate the number of atoms in the following
1)13.8g of sodium
2)0.02 moles of aluminium
3)14.2g of sodium sulphate
1 answer