How many calcium ions are in 0.3 mol of cacl2?

One mole of CaCl2 contains 1 mole of calcium.
Therefore, 0.3 moles of CaCl2 will contain 0.3 moles of calcium.

1 mole of calcium contains Avogadro's number of ions, therefore, 0.3 moles will contain:
number of ions = 0.3 * 6.02 * 10^23 = 1.806 * 10^23 ions

1.8 x 10^23 calcium ions Each mole of CaCl2 will produce 1 mole of calcium ions. So just multiply the number of moles of CaCl2 by avogadro's number. Therefore 0.3 * 6.0221409 x 10^23 = 1.806642 x 10^23 So there will be 1.8 x 10^23 calcium ions in 0.3 moles of CaCl2.