Question

How many sodium ions are present in 825 ml of 0.825 M Na2SO4?

Answer 1

1L of 1M solution contains 1 mole

.825L of .825M contains .68 moles of Na2SO4

Each mole contains 2 Na ions

2*.68 * 6.02*10^23 = 8.2 * 10^23 Na ions