Calculation of Number of Oxygen Atoms in Na2SO4.10H2O

Step 1: Calculate the molar mass of Na2SO4.10H2O.

The molar mass of Na2SO4 is 142.04 g/mol, and the molar mass of 10H2O is 180.16 g/mol. Therefore, the molar mass of Na2SO4.10H2O can be calculated as follows:

Molar mass of Na2SO4.10H2O = (2 x 22.99 g/mol) + (1 x 32.06 g/mol) + (4 x 16.00 g/mol) + (10 x 18.02 g/mol)
= 322.20 g/mol

Step 2: Calculate the number of moles of Na2SO4.10H2O.

The number of moles of Na2SO4.10H2O can be calculated using the formula:

Number of moles = given mass/molar mass

Given mass = 1.61 g
Molar mass = 322.20 g/mol

Number of moles of Na2SO4.10H2O = 1.61 g/322.20 g/mol
= 0.005 mol

Step 3: Calculate the number of oxygen atoms in Na2SO4.10H2O.

The formula for Na2SO4.10H2O contains four oxygen atoms. Therefore, the number of oxygen atoms in 0.005 mol of Na2SO4.10H2O can be calculated as follows:

Number of oxygen atoms = number of moles x Avogadro's number x number of oxygen atoms in the formula

Number of moles = 0.005 mol
Avogadro's number = 6.022 x 10^23
Number of oxygen atoms in the formula = 4

Number of oxygen atoms = 0.005 mol x 6.022 x 10^23 x 4
= 1.21 x 10^22

Therefore, there are 1.21 x 10^22 oxygen atoms present in 1.61 g of Na2SO4.10H2O.

No of moles of Na2SO4.10H2O in 1.61 g=1.61/322=0.005 moles
1 mole contains 14 na oxygen atoms=14×6.022×10^23
so 0.005 moles contain 14×6.022×10^23×0.005=0.42154×10^23 oxygen atoms