To calculate the number of chloride ions in a sample of salt that contains 2 moles KCl, we need to determine the mole ratio between KCl and chloride ions.

In KCl, there is a 1:1 mole ratio between potassium ions (K+) and chloride ions (Cl-). This means that for every mole of KCl, there is one mole of chloride ions.

Therefore, if the sample contains 2 moles of KCl, it also contains 2 moles of chloride ions.

So, the answer is 2 moles of chloride ions.