Na2SO4 dissociates to give 2
Na+ and one SO4- ions
So 1.5 * 1020 anions means 1.5 * 1020
SO4- ions which means it requires 1.5 *
1020 molecules of Na2SO4
Number of moles of Na2SO4 = 1.5
*1020 / avagadro number
                                                 Â
= 1.5 * 1020/ 6.022 * 1023
                Â
                                 =
0.24908 * 10-3 moles of Na2SO4
One mole of Na2SO4 means 322.30 gm of
Na2SO4
So 0.24908 * 10-3 moles of
Na2SO4 = 322.30 * 0.24908 *
10-3
                                               Â
                 =80.2785
* 10-3
                                                              Â
= 0.0803 gm of Na2SO4
Hence 0.0803 gm off Na2SO4 decahydrate is
required to prepare solution containing 1.5 * 1020
anions
