Question

What is the final Na+ in a solution prepared by mixing 70 ml of 1.00 M Na2SO4 with 30 ml of 3.00 M NaCl?

2.00 M

2.50M

4.00M

5.00M

Answer 1

no of mole of Na2SO4 = M*V

                                         = 70*1 = 70 mmole

1 mole Na2SO4 = 2 mole Na+

1 mole NaCl = 1 mole Na+

no of mole of NaCl = 30*3 = 90 mmole

Concentration of Na+ = (90+2*70)/(70+30)

       answer: 2.3 M